Co-reporter:Yanli Chen, Guangtao Yu, Wei Chen, Yipu Liu, Guo-Dong Li, Pinwen Zhu, Qiang Tao, Qiuju Li, Jingwei Liu, Xiaopeng Shen, Hui Li, Xuri Huang, Dejun Wang, Tewodros Asefa, and Xiaoxin Zou
Journal of the American Chemical Society September 13, 2017 Volume 139(Issue 36) pp:12370-12370
Publication Date(Web):July 7, 2017
DOI:10.1021/jacs.7b06337
Developing nonprecious hydrogen evolution electrocatalysts that can work well at large current densities (e.g., at 1000 mA/cm2: a value that is relevant for practical, large-scale applications) is of great importance for realizing a viable water-splitting technology. Herein we present a combined theoretical and experimental study that leads to the identification of α-phase molybdenum diboride (α-MoB2) comprising borophene subunits as a noble metal-free, superefficient electrocatalyst for the hydrogen evolution reaction (HER). Our theoretical finding indicates, unlike the surfaces of Pt- and MoS2-based catalysts, those of α-MoB2 can maintain high catalytic activity for HER even at very high hydrogen coverage and attain a high density of efficient catalytic active sites. Experiments confirm α-MoB2 can deliver large current densities in the order of 1000 mA/cm2, and also has excellent catalytic stability during HER. The theoretical and experimental results show α-MoB2’s catalytic activity, especially at large current densities, is due to its high conductivity, large density of efficient catalytic active sites and good mass transport property.
Co-reporter:Yuhui Hou, Yipu Liu, Ruiqin Gao, Qiuju Li, Huizhang Guo, Anandarup Goswami, Radek Zboril, Manoj B. Gawande, and Xiaoxin Zou
ACS Catalysis October 6, 2017 Volume 7(Issue 10) pp:7038-7038
Publication Date(Web):September 5, 2017
DOI:10.1021/acscatal.7b02341
We present a facile synthetic method that yields Ag@CoxP core–shell-type heterogeneous nanostructures with excellent oxygen evolution reaction (OER) activity. This nanocatalyst can deliver a current density of 10 mA/cm2 at a small overpotential of 310 mV and exhibits high catalytic stability. Additionally, the catalytic activity of Ag@CoxP is 8 times higher than that of the Co2P nanoparticles, owing primarily to the strong electronic interaction between the Ag core and the CoxP shell.Keywords: core−shell nanomaterials; electrocatalysis; metal phosphide; oxygen evolution reaction;
Co-reporter:Xue Wang, Juan Su, Hui Chen, Guo-Dong Li, Zhifang Shi, Haifeng Zou, and Xiaoxin Zou
ACS Applied Materials & Interfaces May 17, 2017 Volume 9(Issue 19) pp:16335-16335
Publication Date(Web):April 24, 2017
DOI:10.1021/acsami.7b04395
Nitric oxide (NOx, including NO and NO2) is one of the most dangerous environmental toxins and pollutants, which mainly originates from vehicle exhaust and industrial emission. The development of sensitive NOx gas sensors is quite urgent for human health and the environment. Up to now, it still remains a great challenge to develop a NOx gas sensor, which can satisfy multiple application demands for sensing performance (such as high response, low detection temperature, and limit). In this work, ultrathin In2O3 nanosheets with uniform mesopores were successfully synthesized through a facile two-step synthetic method. This is a success due to not only the formation of two-dimensional (2D) nanosheets with an ultrathin thickness of 3.7 nm based on a nonlayered compound but also the template-free construction of uniform mesopores in ultrathin nanosheets. The sensors based on the as-obtained mesoporous In2O3 ultrathin nanosheets exhibit an ultrahigh response (Rg/Ra = 213) and a short response time (ca. 4 s) toward 10 ppm NOx, and a quite low detection limit (10 ppb NOx) under a relatively low operating temperature (120 °C), which well satisfies multiple application demands. The excellent sensing performance should be mainly attributed to the unique structural advantages of mesopores and 2D ultrathin nanosheets.Keywords: gas sensing; In2O3; mesopores; nitric oxide; ultrathin nanosheets;
Co-reporter:Xu Zou;Yipu Liu;Guo-Dong Li;Yuanyuan Wu;Da-Peng Liu;Wang Li;Hai-Wen Li;Dejun Wang;Yu Zhang
Advanced Materials 2017 Volume 29(Issue 22) pp:
Publication Date(Web):2017/06/01
DOI:10.1002/adma.201700404
Developing nonprecious oxygen evolution electrocatalysts that can work well at large current densities is of primary importance in a viable water-splitting technology. Herein, a facile ultrafast (5 s) synthetic approach is reported that produces a novel, efficient, non-noble metal oxygen-evolution nano-electrocatalyst that is composed of amorphous Ni–Fe bimetallic hydroxide film-coated, nickel foam (NF)-supported, Ni3S2 nanosheet arrays. The composite nanomaterial (denoted as Ni-Fe-OH@Ni3S2/NF) shows highly efficient electrocatalytic activity toward oxygen evolution reaction (OER) at large current densities, even in the order of 1000 mA cm−2. Ni-Fe-OH@Ni3S2/NF also gives an excellent catalytic stability toward OER both in 1 m KOH solution and in 30 wt% KOH solution. Further experimental results indicate that the effective integration of high catalytic reactivity, high structural stability, and high electronic conductivity into a single material system makes Ni-Fe-OH@Ni3S2/NF a remarkable catalytic ability for OER at large current densities.
Co-reporter:Hui Chen, Guo-Dong Li, Meihong Fan, Qian Gao, Jiabo Hu, Saren Ao, Cundi Wei, Xiaoxin Zou
Sensors and Actuators B: Chemical 2017 Volume 240(Volume 240) pp:
Publication Date(Web):1 March 2017
DOI:10.1016/j.snb.2016.09.037
•Reporting a simple and effective electrospinning method to systematically prepare mesoporous MGa2O4 (MNi, Cu, Co) nanofibers.•Characteristic sensing properties of the sensing materials are revealed toward benzene.•NiGa2O4 exhibits efficient sensitivity, fast response speed and good stability for the detection of ppm-level benzene.•Discussed the gas sensing mechanism of MGa2O4 (MNi, Cu, Co).Transition metal spinel semiconductors, with a general formula of AB2O4, have been shown as a promising group for gas sensor applications. This paper reports a simple and effective electrospinning method to systematically prepare mesoporous MGa2O4 (MNi, Cu, Co) nanofibers. It is found that gas sensing reaction process of the materials is decisively influenced by transition metal M(II)-ions. The gas response tends to decrease in the order of NiGa2O4 > CuGa2O4 > CoGa2O4. In addition, NiGa2O4 and CoGa2O4 show p-type behaviors, and CuGa2O4 shows an n-type behavior. Further analysis reveals that charge carrier hopping (e− hopping or h+ hopping) processes between different valent metal cations, which is mainly dominated by octahedral sites of spinel, are responsible for the conductivity type, the surface redox reaction and thereby the gas sensing properties.
Co-reporter:Yuanyuan Wu, Yipu Liu, Guo-Dong Li, Xu Zou, Xinran Lian, Dejun Wang, Lei Sun, Tewodros Asefa, Xiaoxin Zou
Nano Energy 2017 Volume 35(Volume 35) pp:
Publication Date(Web):1 May 2017
DOI:10.1016/j.nanoen.2017.03.024
•A self-standing, noble metal-free, stable bifunctional electrocatalyst synthesized.•The catalyst was Ni foam-supported small NixCo3−xS4-decorated Ni3S2 nanosheets.•The catalyst was synthesized by a partial cation exchange reaction.•The material efficiently electrocatalyzed the overall water splitting reaction.•An electrolyzer withthe electrocatalyst at both anode and cathode was demonstrated.The overall water splitting into hydrogen and oxygen is one of the most promising ways to store intermittent solar and wind energy in the form of chemical fuels. However, this process is quite thermodynamically uphill, and thus needs to be mediated simultaneously by efficient hydrogen evolving and oxygen evolving catalysts to get any feasible output from it. Herein, we report the synthesis of such a catalyst comprising ultrasmall NixCo3−xS4-decorated Ni3S2 nanosheet arrays supported on nickel foam (NF) via a partial cation exchange reaction between NF-supported Ni3S2 nanosheet arrays and cobalt(II) ions. We show that the as-prepared material, denoted as NixCo3−xS4/Ni3S2/NF, can serve as a self-standing, noble metal-free, highly active and stable, bifunctional electrocatalyst for the two half reactions involved in the overall water splitting: the hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER). Furthermore, we demonstrate that a high-performance electrolyzer for the overall water splitting reaction can be assembled by using NixCo3−xS4/Ni3S2/NF as the electrocatalyst at both the cathode and the anode sides of the electrolyzer. This electrolyzer delivers water-splitting current densities of 10 and 100 mA/cm2 at applied potentials of 1.53 and 1.80 V, respectively, with remarkable stability for >200 h in both cases. The electrolyzer's performance is much better than the performances of electrolyzers assembled from many types of other bifunctional electrocatalysts as catalyst couple. Moreover, the overall performance of the electrolyzer is comparable with the performances of electrolyzers containing two different, benchmark, monofunctional HER and OER electrocatalyst couple (i.e., Pt/C-IrO2).Download high-res image (212KB)Download full-size image
Co-reporter:Nan Li, Xin Liu, Guo-Dong Li, Yuanyuan Wu, ... Xiaoxin Zou
International Journal of Hydrogen Energy 2017 Volume 42, Issue 15(Volume 42, Issue 15) pp:
Publication Date(Web):13 April 2017
DOI:10.1016/j.ijhydene.2017.01.191
•Nanohybrid with CoS nanosheets vertically grown on carbon cloth was prepared.•This novel nanohybrid is a highly active catalyst for H2 evolution.•This nanohybrid exhibits high catalytic stability in basic and acidic media.The development of efficient and inexpensive water splitting electrocatalysts is essential for the large-scale production of hydrogen. Herein, we show that a novel nanohybrid with CoS nanosheets vertically grown on carbon cloth (CoS/CC) can be used as an efficient self-supported hydrogen-evolving cathode for water splitting over a wide pH range. This material affords a current density of 10 mA/cm2 at a small overpotential of 192 mV and 212 mV in basic and acidic media, respectively, along with a long-term stability for over 50 h. The unique 3D structure constructed by the vertically arranged nanosheets and the intimate contact between the CoS nanosheets and the underlying conductive carbon are believed to be responsible for the excellent catalytic performance.
Co-reporter:Hui Chen, Jiabo Hu, Guo-Dong Li, Qian Gao, Cundi Wei, and Xiaoxin Zou
ACS Applied Materials & Interfaces 2017 Volume 9(Issue 5) pp:
Publication Date(Web):January 13, 2017
DOI:10.1021/acsami.6b13520
The design of appropriate composite materials with unique surface structures is an important strategy to achieve ideal chemical gas sensing. In this paper, efficient and selective detection of formaldehyde vapor has been realized by a gas sensor based on porous GaxIn2-xO3 nanofibers assembled by small building blocks. By tuning the Ga/In atomic ratios in the materials, crystallite phase, nanostructure, and band gap of as-obtained GaxIn2-xO3 nanofibers can be rationally altered. This further offers a good opportunity to optimize the gas sensing performances. In particular, the sensor based on porous Ga0.6In1.4O3 nanofibers assembled by small nanoparticles (∼4.6 nm) exhibits best sensing performances. Toward 100 ppm formaldehyde, its highest response (Ra/Rg = 52.4, at 150 °C) is ∼4 times higher than that of the pure In2O3 (Ra/Rg = 13.0, at 200 °C). Meanwhile, it has superior ability to selectively detect formaldehyde against other interfering volatile organic compound gases. The significantly improved sensing performance makes the Ga0.6In1.4O3 sensor very promising for selective detection of formaldehyde.Keywords: formaldehyde; Ga2O3; gas sensor; In2O3; porous nanofibers;
Co-reporter:Yuanyuan Wu;Guo-Dong Li;Yipu Liu;Lan Yang;Xinran Lian;Tewodros Asefa
Advanced Functional Materials 2016 Volume 26( Issue 27) pp:4839-4847
Publication Date(Web):
DOI:10.1002/adfm.201601315
Making highly efficient catalysts for an overall water splitting reaction is vitally important to bring solar/electrical-to-hydrogen energy conversion processes into reality. Herein, the synthesis of ultrathin nanosheet-based, hollow MoOx/Ni3S2 composite microsphere catalysts on nickel foam, using ammonium molybdate as a precursor and the triblock copolymer pluronic P123 as a structure-directing agent is reported. It is also shown that the resulting materials can serve as bifunctional, non-noble metal electrocatalysts with high activity and stability for the hydrogen evolution reaction (HER) as well as the oxygen evolution reaction (OER). Thanks to their unique structural features, the materials give an impressive water-splitting current density of 10 mA cm−2 at ≈1.45 V with remarkable durability for >100 h when used as catalysts both at the cathode and the anode sides of an alkaline electrolyzer. This performance for an overall water splitting reaction is better than even those obtained with an electrolyzer consisting of noble metal-based Pt/C and IrOx/C catalytic couple—the benchmark catalysts for HER and OER, respectively.
Co-reporter:Liang-Liang Feng, Meihong Fan, Yuanyuan Wu, Yipu Liu, Guo-Dong Li, Hui Chen, Wei Chen, Dejun Wang and Xiaoxin Zou
Journal of Materials Chemistry A 2016 vol. 4(Issue 18) pp:6860-6867
Publication Date(Web):18 Dec 2015
DOI:10.1039/C5TA08611F
The development of efficient non-noble metal hydrogen-evolving electrocatalysts is of paramount importance for sustainable hydrogen production from water. Herein, we report the direct growth of metallic Co9S8 nanosheets on carbon cloth (CC) through a facile one-pot solvothermal method. We also show that the introduction of a tiny amount of Zn2+ ions (Zn:Co mol ratio of 0.5–1:100) in the synthesis system can reduce the thickness, improve the crystallinity, and optimize the surface structure of Co9S8 nanosheets, without Zn-doping. Furthermore, we show that the resulting Co9S8/CC materials can serve as efficient, binder-free, non-noble metal electrocatalysts for the hydrogen evolution reaction (HER) under neutral conditions (pH 7). In particular, the Co9S8/CC material (synthesized in the presence of Zn2+ ions) affords a current density of 10 mA cm−2 at a low overpotential of 175 mV, has great catalytic stability as long as 100 h, and gives about 100% faradaic yield towards the HER in neutral media. The material's excellent catalytic performance toward the HER is attributed primarily to the synergistic effects of Co9S8's intrinsic catalytic ability, the ultrathin nanosheet array architecture and the self-supporting feature.
Co-reporter:Xiaoxi Huang, Li-Jing Zhou, Damien Voiry, Manish Chhowalla, Xiaoxin Zou, and Tewodros Asefa
ACS Applied Materials & Interfaces 2016 Volume 8(Issue 29) pp:18891-18903
Publication Date(Web):June 30, 2016
DOI:10.1021/acsami.6b05739
In our quest to make various chemical processes sustainable, the development of facile synthetic routes and inexpensive catalysts can play a central role. Herein we report the synthesis of monodisperse, polyaniline (PANI)-derived mesoporous carbon nanoparticles (PAMCs) that can serve as efficient metal-free electrocatalysts for the hydrogen peroxide reduction reaction (HPRR) as well as the oxygen reduction reaction (ORR) in fuel cells. The materials are synthesized by polymerization of aniline with the aid of (NH4)2S2O8 as oxidant and colloidal silica nanoparticles as templates, then carbonization of the resulting PANI/silica composite material at different high temperatures, and finally removal of the silica templates from the carbonized products. The PAMC materials that are synthesized under optimized synthetic conditions possess monodisperse mesoporous carbon nanoparticles with an average size of 128 ± 12 nm and an average pore size of ca. 12 nm. Compared with Co3O4, a commonly used electrocatalyst for HPRR, these materials show much better catalytic activity for this reaction. In addition, unlike Co3O4, the PAMCs remain relatively stable during the reaction, under both basic and acidic conditions. The nanoparticles also show good electrocatalytic activity toward ORR. Based on the experimental results, PAMCs’ excellent electrocatalytic activity is attributed partly to their heteroatom dopants and/or intrinsic defect sites created by vacancies in their structures and partly to their high porosity and surface area. The reported synthetic method is equally applicable to other polymeric precursors (e.g., polypyrrole (PPY)), which also produces monodisperse, mesoporous carbon nanoparticles in the same way. The resulting materials are potentially useful not only for electrocatalysis of HPRR and ORR in fuel cells but also for other applications where high surface area, small sized, nanostructured carbon materials are generally useful for (e.g., adsorption, supercapacitors, etc.).
Co-reporter:Meihong Fan, Ruiqin Gao, Yong-Cun Zou, Dejun Wang, Ni Bai, Guo-Dong Li, Xiaoxin Zou
Electrochimica Acta 2016 Volume 215() pp:366-373
Publication Date(Web):10 October 2016
DOI:10.1016/j.electacta.2016.08.129
Developing efficient nonprecious electrocatalysts to accelerate the hydrogen evolution reaction (HER) is of importance for the hydrogen energy technology. Herein, we report the in situ growth of single-crystalline γ-Cu2S nanoplates on copper foam (CF) in a hydrothermal system, with the assistance of a small amount of cobalt(II) acetate. The presence of cobalt(II) acetate in the synthesis system has been proven to have multiple roles: (i) inhibiting the formation of copper(I) oxide (Cu2O); (ii) directing the fromation of the crystal phase of γ-Cu2S; and (iii) controlling the morphology of the as-formed γ-Cu2S. Furthermore, we show that the resulting γ-Cu2S/CF material can serve as an efficient integrated 3D electrode toward HER at neutral pH. The γ-Cu2S/CF delivers a current density of 10 mA/cm2 at a small overpotential of 190 mV, gives 100% Faradaic yield during HER, and maintains its electrocatalytic activity for >10 hours. To the best of our knowledge, this is the first time that a copper(I) sulfide-based material is demonstrated to electrocatalyze the HER efficiently. Identifying copper(I) sulfide as the active phase for HER and constructing advantageous 3D γ-Cu2S nanostructure via an ion-induced method might open a door for the further investigation of Cu-based hydrogen-evolution electrocatalysts.
Co-reporter:Shuang Gao, Yipu Liu, Guo-Dong Li, Yuchun Guo, Yongcun Zou, Xiaoxin Zou
Electrochimica Acta 2016 Volume 199() pp:99-107
Publication Date(Web):1 May 2016
DOI:10.1016/j.electacta.2016.03.104
Elaborate design and synthesis of efficient and stable non-Pt electrocatalysts for some renewable energy-related conversion/storage processes is one of the major goals of sustainable chemistry. Herein, we report a facile, general, one-step synthetic method that leads to a family of non-noble metal hydrogen-evolving electrocatalysts that composed of metal phosphide nanoparticles embedded within nitrogen-doped carbon matrix. The synthesis of the materials is achieved via a facile one-step thermal treatment in inert atmosphere of homogeneously mixed urea, diammonium hydrogen phosphate and metal salts (e.g., ammonium molybdate for the synthesis of MoP). The use of inexpensive urea is crucial in the synthesis as it helps the deoxygenation-reduction of some metal salts and phosphor source (i.e., diammonium hydrogen phosphate) and undergoes in situ carbonization, leading to the formation of a composite material containing metal phosphide nanoparticles and nitrogen-doped carbon (NC) in one pot. Furthermore, we show that the resulting composite nanomaterials can serve as highly active, stable, noble metal-free electrocatalysts towards the hydrogen evolution reaction (HER). In particular, the MoP@NC material exhibits the best electrocatalytic activity in our study. This material affords a current density of 10 mA/cm2 at a low overpotential of 135 mV, exhibits excellent catalytic stability as long as 20 h, and gives nearly 100% Faradaic yield towards HER.
Co-reporter:Song Wan, Yipu Liu, Guo-Dong Li, Xiaotian Li, Dejun Wang and Xiaoxin Zou
Catalysis Science & Technology 2016 vol. 6(Issue 12) pp:4545-4553
Publication Date(Web):08 Feb 2016
DOI:10.1039/C5CY02292D
Increasing the number of active sites of a non-noble metal catalyst is an effective route to make its overall catalytic performance close to that of noble metals. Herein, we report a novel confinement strategy for preparing well-dispersed octahedral CoS2 nanocrystals through in situ sulfidization of the carbon fibre-wrapped Co nanoparticles, in order to fully expose the active sites of every nanocatalytic unit. The successful synthesis of the material includes three main steps: (i) electrospinning synthesis of Co ion-containing polyacrylonitrile fibres (Co2+-PANF), (ii) thermal conversion of the Co2+-PANF at 900 °C under N2 atmosphere into a Co-embedded carbon fibre network (Co-CFN), and (iii) direct sulfidization of Co-CFN using sublimed sulphur, leading to the confinement growth of CoS2 nano-octahedra on CFN. Furthermore, this material, denoted as CoS2-CFN, can serve as a highly active, stable, non-noble metal electrocatalyst for hydrogen evolution reaction in acidic medium. This material generates a current density of 10 mA cm−2 at a small overpotential of 136 mV with about 100% Faradaic yield and maintains its catalytic activity for at least 20 hours. The excellent catalytic properties of CoS2-CFN are attributed primarily to the synergistic effects of the intrinsic catalytic ability of CoS2, the well-dispersed CoS2 nanocrystals as the catalytically active phase, as well as the high conductivity and porous structure of the carbon fibre network as a support material.
Co-reporter:Feifan Guo, Meihong Fan, Panpan Jin, Hui Chen, Yuanyuan Wu, Guo-Dong Li and Xiaoxin Zou
CrystEngComm 2016 vol. 18(Issue 22) pp:4068-4073
Publication Date(Web):06 Nov 2015
DOI:10.1039/C5CE01398D
Hollow micro-/nanostructures have a wide range of applications in catalysis, rechargeable batteries, drug delivery, and gas sensors, as well as energy storage and conversion. Herein, we report a facile, template-free, precursor-mediated method to synthesize V2O5 nanomaterials with three different architectures: double-shelled hollow nanospheres, single-shelled hollow nanospheres and nanoparticles. These V2O5 nanostructures are obtained via a simple thermal treatment in air of a “pre-synthesized” vanadyl glycerolate precursor, and their morphologies can be easily tuned by varying the thermal treatment temperatures. Electrochemical studies show that the double-shelled V2O5 hollow nanospheres as a cathode material for lithium-ion batteries deliver an initial capacity of 256.7 mA h g−1 with a Coulombic efficiency of nearly 100%, and their capacity is superior to the two other V2O5 nanostructures (i.e., single-shelled hollow nanospheres and nanoparticles), mainly due to their unique double-shelled hollow structure.
Co-reporter:Hui Chen;Xiaoxi Huang;Li-Jing Zhou; Guo-Dong Li;Meihong Fan; Xiaoxin Zou
ChemCatChem 2016 Volume 8( Issue 5) pp:992-1000
Publication Date(Web):
DOI:10.1002/cctc.201501326
Abstract
The development of earth-abundant water oxidation electrocatalysts with high activity and durability is very important for many renewable energy conversion/storage processes. Herein, we report a facile synthetic method for the preparation of amorphous nickel–iron oxide/carbon composite nanofibers with high electrocatalytic activity and stability for the oxygen evolution reaction (OER). This method involves two main steps: (i) the electrospinning synthesis of Ni- and Fe-embedded polyvinylpyrrolidone (PVP) polymer nanofibers as the precursor and (ii) the thermal conversion of this precursor in air at 250 °C into nickel–iron oxide/carbon composite nanofibers. Moreover, we show that the as-obtained composite material exhibits a comparable catalytic activity and a superior catalytic stability to IrOx/C and RuOx, which are state-of-the-art noble-metal-based water oxidation electrocatalysts. In particular, the obtained amorphous nickel–iron oxide/carbon composite nanofibers with an optimal Ni/Fe molar ratio of 1:2 afford a small overpotential of 310 mV at a current density of 10 mA cm−2, show high catalytic stability for >15 h, and give >90 % Faradaic yield toward the OER. The efficient catalytic activity of the material can be attributed to its overall conducive structural features for the OER, mainly including the amorphous phase structure of nickel–iron oxide, tunable Ni/Fe atomic ratio, and strongly coupled interaction between nickel–iron oxide and nanocarbon.
Co-reporter:Xue Wang, Yuying Meng, Guo-Dong Li, Yongcun Zou, Yang Cao, Xiaoxin Zou
Sensors and Actuators B: Chemical 2016 Volume 224() pp:559-567
Publication Date(Web):1 March 2016
DOI:10.1016/j.snb.2015.10.100
Hollow micro-/nanostructures, especially those with well-defined nanoscale subunits, have been widely used in a variety of areas including catalysis, sensing, energy storage, drug delivery, etc. Herein, we report a novel, UV-assisted, template-free synthesis of hollow indium oxide microstructures that are composed of ultrathin nanosheets (∼2.5 nm). The two key steps for the synthesis of the materials being successful are: (i) the UV-induced conversion of a photoactive solid indium alkoxide precursor into hollow indium hydroxide microspheres composed of ultrathin nanosheets, and (ii) the thermal treatment of the resulting hollow hydroxide microspheres into the hollow In2O3 material with a morphological preservation. Moreover, we show that the as-obtained hollow nanomaterials exhibit excellent sensing performance (e.g., high response value, good stability, as well as fast response speed) for the detection of ppm-level gaseous formaldehyde. The efficient sensing performance of the material is attributed to their overall conducive structural features, including their hollow architecture and ultrathin nanoscale building blocks. These structural features can offer a large amount of active sites on the surface, facilitate the diffusion and adsorption of the target gas, and thus enhance the material's sensing performance.
Co-reporter:Liang-Liang Feng; Guangtao Yu; Yuanyuan Wu; Guo-Dong Li; Hui Li; Yuanhui Sun; Tewodros Asefa; Wei Chen
Journal of the American Chemical Society 2015 Volume 137(Issue 44) pp:14023-14026
Publication Date(Web):September 9, 2015
DOI:10.1021/jacs.5b08186
Elaborate design of highly active and stable catalysts from Earth-abundant elements has great potential to produce materials that can replace the noble-metal-based catalysts commonly used in a range of useful (electro)chemical processes. Here we report, for the first time, a synthetic method that leads to in situ growth of {2̅10} high-index faceted Ni3S2 nanosheet arrays on nickel foam (NF). We show that the resulting material, denoted Ni3S2/NF, can serve as a highly active, binder-free, bifunctional electrocatalyst for both the hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER). Ni3S2/NF is found to give ∼100% Faradaic yield toward both HER and OER and to show remarkable catalytic stability (for >200 h). Experimental results and theoretical calculations indicate that Ni3S2/NF’s excellent catalytic activity is mainly due to the synergistic catalytic effects produced in it by its nanosheet arrays and exposed {2̅10} high-index facets.
Co-reporter:Shuang Gao, Guo-Dong Li, Yipu Liu, Hui Chen, Liang-Liang Feng, Yun Wang, Min Yang, Dejun Wang, Shan Wang and Xiaoxin Zou
Nanoscale 2015 vol. 7(Issue 6) pp:2306-2316
Publication Date(Web):15 Oct 2014
DOI:10.1039/C4NR04924A
One of the main barriers blocking sustainable hydrogen production is the use of expensive platinum-based catalysts to produce hydrogen from water. Herein we report the cost-effective synthesis of catalytically active, nitrogen-doped, cobalt-encased carbon nanotubes using inexpensive starting materials—urea and cobalt chloride hexahydrate (CoCl2·6H2O). Moreover, we show that the as-obtained nanocarbon material exhibits a remarkable electrocatalytic activity toward the hydrogen evolution reaction (HER); and thus it can be deemed as a potential alternative to noble metal HER catalysts. In particular, the urea-derived carbon nanotubes synthesized at 900 °C (denoted as U-CNT-900) show a superior catalytic activity for HER with low overpotential and high current density in our study. Notably also, U-CNT-900 has the ability to operate stably at all pH values (pH 0–14), and even in buffered seawater (pH 7). The possible synergistic effects between carbon-coated cobalt nanoparticles and the nitrogen dopants can be proposed to account for the HER catalytic activity of U-CNT-900. Given the high natural abundance, ease of synthesis, and high catalytic activity and durability in seawater, this U-CNT-900 material is promising for hydrogen production from water in industrial applications.
Co-reporter:Meihong Fan, Hui Chen, Yuanyuan Wu, Liang-Liang Feng, Yipu Liu, Guo-Dong Li and Xiaoxin Zou
Journal of Materials Chemistry A 2015 vol. 3(Issue 31) pp:16320-16326
Publication Date(Web):07 Jul 2015
DOI:10.1039/C5TA03500G
Design and synthesis of efficient noble metal-free hydrogen evolution catalysts is of paramount importance for the practical application of water-splitting devices. Herein, we report a novel synthetic method to grow dispersed molybdenum carbide (Mo2C) micro-islands on flexible carbon cloth (CC). This method involves the controlled synthesis of a supramolecular hybrid between cetyltrimethyl ammonium cations and molybdate anions on CC, followed by simple thermal treatment of this supramolecular hybrid in Ar to form Mo2C on CC in situ. In this synthesis, the presence of cetyltrimethyl ammonium bromide is proven to be important because it effectively immobilizes molybdate ions on CC on the one hand and functions as a carbon source for the formation of Mo2C on the other. Moreover, the as-prepared Mo2C/CC composite material can serve as efficient binder-free cathodes toward the hydrogen evolution reaction (HER). The Mo2C/CC affords a current density of 10 mA cm−2 at a low overpotential of 140 mV and works stably in acidic media with a Faraday yield of ∼100%. The isolated island architecture of Mo2C ensures rich active sites to be exposed and allows the easy interaction of reactants (e.g., protons) with the active sites. Also, the strong adhesion between Mo2C and carbon cloth facilitates electron transport/transfer in the composite material and is helpful for the achievement of excellent catalytic stability.
Co-reporter:Yipu Liu, Guo-Dong Li, Long Yuan, Lei Ge, Hong Ding, Dejun Wang and Xiaoxin Zou
Nanoscale 2015 vol. 7(Issue 7) pp:3130-3136
Publication Date(Web):12 Jan 2015
DOI:10.1039/C4NR06295G
The hydrogen evolution reaction (HER) is one of the two important half reactions in current water-alkali and chlor-alkali electrolyzers. To make this reaction energy-efficient, development of highly active and durable catalytic materials in an alkaline environment is required. Herein we report the synthesis of carbon-coated cobalt–tungsten carbide nanoparticles that have proven to be efficient noble metal-free electrocatalysts for alkaline HER. The catalyst affords a current density of 10 mA cm−2 at a low overpotential of 73 mV, which is close to that (33 mV) required by Pt/C to obtain the same current density. In addition, this catalyst operates stably at large current densities (>30 mA cm−1) for as long as 18 h, and gives nearly 100% Faradaic yield during alkaline HER. The excellent catalytic performance (activity and stability) of this nanocomposite material is attributed to the cooperative effect between nanosized bimetallic carbide and the carbon protection layer outside the metal carbide. The results presented herein offer the exciting possibility of using carbon-armoured metal carbides for an efficient alkaline HER, although pristine metal carbides are not, generally, chemically stable enough under such strong alkaline conditions.
Co-reporter:Liang-Liang Feng, Guo-Dong Li, Yipu Liu, Yuanyuan Wu, Hui Chen, Yun Wang, Yong-Cun Zou, Dejun Wang, and Xiaoxin Zou
ACS Applied Materials & Interfaces 2015 Volume 7(Issue 1) pp:980
Publication Date(Web):December 23, 2014
DOI:10.1021/am507811a
Splitting water to produce hydrogen requires the development of non-noble-metal catalysts that are able to make this reaction feasible and energy efficient. Herein, we show that cobalt pentlandite (Co9S8) nanoparticles can serve as an electrochemically active, noble-metal-free material toward hydrogen evolution reaction, and they work stably in neutral solution (pH 7) but not in acidic (pH 0) and basic (pH 14) media. We, therefore, further present a carbon-armoring strategy to increase the durability and activity of Co9S8 over a wider pH range. In particular, carbon-armored Co9S8 nanoparticles (Co9S8@C) are prepared by direct thermal treatment of a mixture of cobalt nitrate and trithiocyanuric acid at 700 °C in N2 atmosphere. Trithiocyanuric acid functions as both sulfur and carbon sources in the reaction system. The resulting Co9S8@C material operates well with high activity over a broad pH range, from pH 0 to 14, and gives nearly 100% Faradaic yield during hydrogen evolution reaction under acidic (pH 0), neutral (pH 7), and basic (pH 14) media. To the best of our knowledge, this is the first time that a transition-metal chalcogenide material is shown to have all-pH efficient and durable electrocatalytic activity. Identifying Co9S8 as the catalytically active phase and developing carbon-armoring as the improvement strategy are anticipated to give a fresh impetus to rational design of high-performance noble-metal-free water splitting catalysts.Keywords: carbon; cobalt; hydrogen evolution; sulfide; water splitting
Co-reporter:Li-Jing Zhou, Xiaoxi Huang, Hui Chen, Panpan Jin, Guo-Dong Li and Xiaoxin Zou
Dalton Transactions 2015 vol. 44(Issue 25) pp:11592-11600
Publication Date(Web):15 May 2015
DOI:10.1039/C5DT01474C
Layered double hydroxide has been used in a variety of areas, including but not limited to catalysis, energy storage, drug or gene delivery, water treatment, etc. Herein, we report a new simple hydrothermal method to prepare a high surface area flower-like Ni–Fe layered double hydroxide (LDH) assembled by nanosheets by using nickel alkoxide and FeSO4 as the only starting materials. It is free of alkaline solution and other additives for directing or supporting in the synthesis procedure. The formation mechanism of this flower-like LDH formed by ultrathin nanosheets is also discussed. Moreover, the as-obtained LDH material shows increased electrocatalytic activity and stability toward WOR in alkaline media compared with the materials prepared without a Ni alkoxide precursor or Fe precursor, namely α-Fe2O3 and Ni(OH)2, respectively. In addition, the electrocatalytic activity is demonstrated to be related to the molar ratio of Fe and Ni in the final Ni–Fe material, and the best activity is achieved when the ratio reaches 0.52:1. The phase compositions of the resulting Ni–Fex are discussed. Furthermore, the Ni–Fe LDH material reported herein might be employed as a promising noble-metal-free water oxidation catalyst to replace the IrOx material—the state-of-the-art water oxidation catalyst.
Co-reporter:Yang Cao, Xiaoxi Huang, Yuanyuan Wu, Yong-Cun Zou, Jun Zhao, Guo-Dong Li and Xiaoxin Zou
RSC Advances 2015 vol. 5(Issue 74) pp:60541-60548
Publication Date(Web):07 Jul 2015
DOI:10.1039/C5RA09063F
Ultrathin materials have a wide range of applications in catalysis and sensing owing to their very large surface to volume ratio and great amount of exposed active sites. Herein, we report the synthesis of three dimensional (3D) In2O3 materials with a high surface area composed of ultrathin nanosheets, ca. 2 nm, using indium glycerolate as the precursor. The structural evolution process of the indium glycerolate precursor was monitored by thermogravimetric analysis, infrared spectroscopy and transmission electron microscopy. The resulting In2O3 nanosheets show excellent amine sensing performance at room temperature because ultrathin nanosheets offer a large amount of active sites on the surface and the 3D structure adds an additional advantage of avoiding aggregation and facilitating the diffusion of the target gas. In addition, the gas sensing mechanism is also proposed in this study.
Co-reporter:Song Wan, Jiabo Hu, Guo-Dong Li, Lan Yang, Yipu Liu, Ruiqin Gao, Xiaotian Li, Xiaoxin Zou
Journal of Alloys and Compounds (25 April 2017) Volume 702() pp:
Publication Date(Web):25 April 2017
DOI:10.1016/j.jallcom.2017.01.207
•CoSe2 nanoparticles on the three-dimensional nano-netlike carbon fibers (CoSe2-CFN) were prepared.•The obtained CoSe2 nanoparticles are highly dispersed on carbon fibers.•CoSe2-CFN exhibits high HER catalytic activity even at a low loading amount of catalytic species CoSe2.•Highly dispersed CoSe2 nanoparticles provide more active sites.More active sites and high conductivity are two effective ways to improve the activity of non-noble metal electrocatalysts. Herein, we present a facile electrostatic spinning technique to synthesize highly dispersed CoSe2 nanoparticles on three-dimensional nano-netlike carbon fibers through simple thermal treatment of polyacrylonitrile fibers containing Co ions (Co2+-PANF) and subsequent in-situ selenization. Moreover, we show that the resulting material (denoted as CoSe2-CFN) can serve as highly active, efficient and stable non-precious metal electrocatalyst for HER in acidic media. This material achieves a current density of 10 mA/cm2 at an overpotential of 133 mV with a loading amount of the active material CoSe2 about 0.128 mg/cm2, which is lower than that of the reported CoSe2-based materials. Meanwhile, CoSe2-CFN exhibits excellent catalytic stability for at least 20 h and gives nearly 100% Faradaic yield. The excellent hydrogen evolution reaction performance is due to the highly dispersed CoSe2 nanoparticles providing more active sites as well as the high electrical conductivity of the carbon fibers.
Co-reporter:Meihong Fan, Hui Chen, Yuanyuan Wu, Liang-Liang Feng, Yipu Liu, Guo-Dong Li and Xiaoxin Zou
Journal of Materials Chemistry A 2015 - vol. 3(Issue 31) pp:NaN16326-16326
Publication Date(Web):2015/07/07
DOI:10.1039/C5TA03500G
Design and synthesis of efficient noble metal-free hydrogen evolution catalysts is of paramount importance for the practical application of water-splitting devices. Herein, we report a novel synthetic method to grow dispersed molybdenum carbide (Mo2C) micro-islands on flexible carbon cloth (CC). This method involves the controlled synthesis of a supramolecular hybrid between cetyltrimethyl ammonium cations and molybdate anions on CC, followed by simple thermal treatment of this supramolecular hybrid in Ar to form Mo2C on CC in situ. In this synthesis, the presence of cetyltrimethyl ammonium bromide is proven to be important because it effectively immobilizes molybdate ions on CC on the one hand and functions as a carbon source for the formation of Mo2C on the other. Moreover, the as-prepared Mo2C/CC composite material can serve as efficient binder-free cathodes toward the hydrogen evolution reaction (HER). The Mo2C/CC affords a current density of 10 mA cm−2 at a low overpotential of 140 mV and works stably in acidic media with a Faraday yield of ∼100%. The isolated island architecture of Mo2C ensures rich active sites to be exposed and allows the easy interaction of reactants (e.g., protons) with the active sites. Also, the strong adhesion between Mo2C and carbon cloth facilitates electron transport/transfer in the composite material and is helpful for the achievement of excellent catalytic stability.
Co-reporter:Liang-Liang Feng, Meihong Fan, Yuanyuan Wu, Yipu Liu, Guo-Dong Li, Hui Chen, Wei Chen, Dejun Wang and Xiaoxin Zou
Journal of Materials Chemistry A 2016 - vol. 4(Issue 18) pp:NaN6867-6867
Publication Date(Web):2015/12/18
DOI:10.1039/C5TA08611F
The development of efficient non-noble metal hydrogen-evolving electrocatalysts is of paramount importance for sustainable hydrogen production from water. Herein, we report the direct growth of metallic Co9S8 nanosheets on carbon cloth (CC) through a facile one-pot solvothermal method. We also show that the introduction of a tiny amount of Zn2+ ions (Zn:Co mol ratio of 0.5–1:100) in the synthesis system can reduce the thickness, improve the crystallinity, and optimize the surface structure of Co9S8 nanosheets, without Zn-doping. Furthermore, we show that the resulting Co9S8/CC materials can serve as efficient, binder-free, non-noble metal electrocatalysts for the hydrogen evolution reaction (HER) under neutral conditions (pH 7). In particular, the Co9S8/CC material (synthesized in the presence of Zn2+ ions) affords a current density of 10 mA cm−2 at a low overpotential of 175 mV, has great catalytic stability as long as 100 h, and gives about 100% faradaic yield towards the HER in neutral media. The material's excellent catalytic performance toward the HER is attributed primarily to the synergistic effects of Co9S8's intrinsic catalytic ability, the ultrathin nanosheet array architecture and the self-supporting feature.
Co-reporter:Ruiqin Gao, Guo-Dong Li, Jiabo Hu, Yuanyuan Wu, Xinran Lian, Dejun Wang and Xiaoxin Zou
Catalysis Science & Technology (2011-Present) 2016 - vol. 6(Issue 23) pp:NaN8275-8275
Publication Date(Web):2016/10/03
DOI:10.1039/C6CY01810F
Despite the superior oxygen evolution electrocatalytic activity of metal-selenide nanostructures, especially when compared with their oxide counterparts, the origin behind their excellent activity remains unclear. Herein, we conduct a thorough and meticulous study on the NiSe oxygen evolution nanoelectrocatalyst—a representative metal selenide that was recently reported to be effective for the oxygen evolution reaction (OER). Our results unambiguously show that NiSe undergoes deselenization under electrocatalytic conditions, finally in situ transforming into a NiSe/NiOx core/shell nanostructure; the latter core/shell nanomaterial gives a superior activity towards OER. The NiSe/NiOx nanomaterial affords a current density of 10 mA cm−2 at an overpotential as low as ∼243 mV, outperforming most of the previously reported nickel (hydro)oxide OER electrocatalysts. These results further imply that the electrocatalytic activity of the so-called NiSe catalysts should originate from the in situ formed amorphous NiOx shell in nature, with the NiSe core having some auxiliary effects on the catalytic activity. Additionally, the NiSe/NiOx nanomaterial is also found to show a higher electrocatalytic activity than NiSe itself for the hydrogen evolution reaction (HER) in basic media.
Co-reporter:Song Wan, Yipu Liu, Guo-Dong Li, Xiaotian Li, Dejun Wang and Xiaoxin Zou
Catalysis Science & Technology (2011-Present) 2016 - vol. 6(Issue 12) pp:NaN4553-4553
Publication Date(Web):2016/02/08
DOI:10.1039/C5CY02292D
Increasing the number of active sites of a non-noble metal catalyst is an effective route to make its overall catalytic performance close to that of noble metals. Herein, we report a novel confinement strategy for preparing well-dispersed octahedral CoS2 nanocrystals through in situ sulfidization of the carbon fibre-wrapped Co nanoparticles, in order to fully expose the active sites of every nanocatalytic unit. The successful synthesis of the material includes three main steps: (i) electrospinning synthesis of Co ion-containing polyacrylonitrile fibres (Co2+-PANF), (ii) thermal conversion of the Co2+-PANF at 900 °C under N2 atmosphere into a Co-embedded carbon fibre network (Co-CFN), and (iii) direct sulfidization of Co-CFN using sublimed sulphur, leading to the confinement growth of CoS2 nano-octahedra on CFN. Furthermore, this material, denoted as CoS2-CFN, can serve as a highly active, stable, non-noble metal electrocatalyst for hydrogen evolution reaction in acidic medium. This material generates a current density of 10 mA cm−2 at a small overpotential of 136 mV with about 100% Faradaic yield and maintains its catalytic activity for at least 20 hours. The excellent catalytic properties of CoS2-CFN are attributed primarily to the synergistic effects of the intrinsic catalytic ability of CoS2, the well-dispersed CoS2 nanocrystals as the catalytically active phase, as well as the high conductivity and porous structure of the carbon fibre network as a support material.
Co-reporter:Li-Jing Zhou, Xiaoxi Huang, Hui Chen, Panpan Jin, Guo-Dong Li and Xiaoxin Zou
Dalton Transactions 2015 - vol. 44(Issue 25) pp:NaN11600-11600
Publication Date(Web):2015/05/15
DOI:10.1039/C5DT01474C
Layered double hydroxide has been used in a variety of areas, including but not limited to catalysis, energy storage, drug or gene delivery, water treatment, etc. Herein, we report a new simple hydrothermal method to prepare a high surface area flower-like Ni–Fe layered double hydroxide (LDH) assembled by nanosheets by using nickel alkoxide and FeSO4 as the only starting materials. It is free of alkaline solution and other additives for directing or supporting in the synthesis procedure. The formation mechanism of this flower-like LDH formed by ultrathin nanosheets is also discussed. Moreover, the as-obtained LDH material shows increased electrocatalytic activity and stability toward WOR in alkaline media compared with the materials prepared without a Ni alkoxide precursor or Fe precursor, namely α-Fe2O3 and Ni(OH)2, respectively. In addition, the electrocatalytic activity is demonstrated to be related to the molar ratio of Fe and Ni in the final Ni–Fe material, and the best activity is achieved when the ratio reaches 0.52:1. The phase compositions of the resulting Ni–Fex are discussed. Furthermore, the Ni–Fe LDH material reported herein might be employed as a promising noble-metal-free water oxidation catalyst to replace the IrOx material—the state-of-the-art water oxidation catalyst.
![Zinc,[1,2,3-propanetriolato(2-)-kO1,kO2]-](http://img.cochemist.com/ccimg/16800/16754-68-0.png)
![Zinc,[1,2,3-propanetriolato(2-)-kO1,kO2]-](http://img.cochemist.com/ccimg/16800/16754-68-0_b.png)
