Classical group theory was applied to prove the Pt3Ni crystallographic transformation from Platonic cubic to Archimedean cuboctahedral structures and the formation of Pt3Ni polypods. The role of W(CO)6 as a shape-controlling agent is discussed with respect to the crystallographic features of the clusters and superstructures generated as control samples.

Carbon–polymer composites have great application potential in the field of organic batteries, capacitors, capacitive water desalination reactors and as the conductive platforms for electrochemical sensors. Although numerous studies have been carried out with respect to the synthesis, the optimization of composition, the carbon type and the morphology control, there is still a lack of understanding about which kind of intermolecular connection between carbon and polymer phases is preferential, and how the system should be designed to achieve the application demand of long-term electrochemical stability. Herein, we propose two model systems that employ the most well-known commercial carbons (SWCNTs and carbon black Vulcan XC72-R) to generate polypyrrole–C composites and validate the type of chemical bonding that is preferential to maintain electrochemical stability. In this work we used a simple oxidative polymerization of pyrrole and generated various formulations (with variable polymer content). Based on the surface XPS combined with bulk TGA-MS analysis we were able to evaluate the concentration and type of oxygen-containing functionalities, revealing a high oxygen content for the carbon black. It was further correlated with XPS analysis of the respective composites showed evidence of the electronic interaction called π–π* stacking between SWCNTs and PPy, and the binding energy shifts associated with the formation of hydrogen bridge bonds in the case of Vulcan XC-72R-PPy. Furthermore, the electrochemical stability of these model samples was investigated by AC impedance spectroscopy. The charge transfer resistance (Rct) was analyzed upon the oxidative potential, revealing SWCNT–PPy as an ultra-stable composite, even for the high polymer content (1:4 weight ratio of C–PPy). In contrast, the carbon black–PPy underwent rapid degradation in the whole composition range. The durability is associated with the type and strength of the polymer–carbon bonding as revealed by EIS impedance correlated with spectroscopic studies. The electronic interactions between SWCNTs and PPy result in superior stability while the carbon black–PPy, where the hydrogen bridge bonds are generated, is not stable under the same experimental conditions.

•Nano-sized Pd catalyst was electro-synthesized on MWCNTs from aqueous media.•We recognized Pt-carbon electronic interaction by X-ray photoelectron spectroscopy.•Pd-MWCNTs showed superior catalytic activity toward Suzuki–Miyaura and Sonogashira reactions.•The Pd-MWCNTs can be recovered and re-used.Platinum group metals (PGM) catalyze many important chemical processes including hydrogenation; electro-catalysis applied to fuel cell and battery technologies and one of the most prominent the Csp2–Csp2 cross-coupling reactions such as Sonogashira, Suzuki–Miyaura, and Csp2–Nsp3 cross-coupling as for the Buchwald–Hartwig type reactions.The main concern of the catalytic reaction is the recovery and recyclability of used catalytic entities. Recent efforts in the catalyst fabrication focus on combining a nano-sized metal with various high surface area supports like resins or carbon-based materials that allow recovering the catalyst after each reaction in a simple and convenient way. This work aims to investigate the catalytic activity of the carbon-supported (MWCNTs) electrodeposited metallic nanoparticles (Pd) and their applications in several cross-coupling reactions. We propose a simple and affordable synthesis of the high surface area Pd–C composite that can be re-used until deactivated. The intramolecular interactions between carbon and metallic fractions studied by X-ray photoelectron spectroscopy are discussed with respect to the catalytic efficiencies.

•Polypyrrole-grafted-carbon reveals the effect of the reversal doping of the polymer.•Composite electrode shows the synergy of double layer and pseudo-capacitance.•The covalently bounded polypyrrole-carbon has better stability than the polymer alone.The multiwall carbon nanotubes-polypyrrole (MWCNTs-PPy) composite is a well-known hybrid material suitable for energy storage applications such as capacitors. Since the electrochemical activity, and long-term stability of carbon-PPy systems are critical for their application, we examined the effect of grafting PPy via a 3-ABA linker with MWCNTs with respect to the preference of the donor–acceptor pairs, and furthermore, the durability. X-ray photoelectron spectroscopy studies of C 1s and O 1s signals reveal the electronic interaction between carbon and polymer (π−π* stacking), as well as a binding energy shift for C 1s and O 1s carbonyl signals due to the chemical bonding via the electron donating linker and grafted polymer. Cyclic voltammetry and galvanostatic charge–discharge studies of the capacitor electrode reveal the effect of the reversal doping of the polymer with chloride, as well as the synergy of double layer capacitance (MWCNTs) and pseudo-capacitance of the poly(pyrrole). Impedance spectroscopy studies confirm the improved electrochemical stability for the composite (stable until 1.2 V) in comparison to the bare polymer (degradation at 0.58 V).

Nitrogen-doped carbon is a promising metal-free catalyst for oxygen reduction reaction in fuel cells and metal-air batteries. However, its practical application necessitates a significant cost reduction, which can be achieved in part by using new synthetic methods and improvement of catalytic activity by increasing the density of redox active centers. This can be modulated by using polymer as the carbon and nitrogen sources. Although, superior catalytic activity of such N-doped C has been investigated in details, the electrochemical long-term stability of polymer-derived doped-carbon is still unclear. Herein, in this study we generated N-doped carbon from the most recommended polymer that is comparable to the state-of-the-art materials with porosity as high as 2,086 m2 g−1 and a nitrogen doping level of 3–4 at.%, of which 56 % is pyrrolic N, 36.1 % pyridinic and ~8 % graphitic. The electrochemical characterization shows that N-doped carbon is catalytic toward oxygen reduction in an alkaline electrolyte via a favorable four-electron process, however, not stable under long-term potential scanning. The irreversible electrochemical oxidation of this material is associated with the presence of a significant content or pyrrolic and pyridinic N close to the edge of the carbon network originating from the polypyrrole precursor. These structures are less stable under operating electrochemical potential. The role of polypyrrole as the precursor of N-doped carbons has to be carefully revised since it supplies sufficient number of catalytic sites, but also generates unstable functionalities on the carbon surface.

Carbon–polymer composites have great application potential in the field of organic batteries, capacitors, capacitive water desalination reactors and as the conductive platforms for electrochemical sensors. Although numerous studies have been carried out with respect to the synthesis, the optimization of composition, the carbon type and the morphology control, there is still a lack of understanding about which kind of intermolecular connection between carbon and polymer phases is preferential, and how the system should be designed to achieve the application demand of long-term electrochemical stability. Herein, we propose two model systems that employ the most well-known commercial carbons (SWCNTs and carbon black Vulcan XC72-R) to generate polypyrrole–C composites and validate the type of chemical bonding that is preferential to maintain electrochemical stability. In this work we used a simple oxidative polymerization of pyrrole and generated various formulations (with variable polymer content). Based on the surface XPS combined with bulk TGA-MS analysis we were able to evaluate the concentration and type of oxygen-containing functionalities, revealing a high oxygen content for the carbon black. It was further correlated with XPS analysis of the respective composites showed evidence of the electronic interaction called π–π* stacking between SWCNTs and PPy, and the binding energy shifts associated with the formation of hydrogen bridge bonds in the case of Vulcan XC-72R-PPy. Furthermore, the electrochemical stability of these model samples was investigated by AC impedance spectroscopy. The charge transfer resistance (Rct) was analyzed upon the oxidative potential, revealing SWCNT–PPy as an ultra-stable composite, even for the high polymer content (1:4 weight ratio of C–PPy). In contrast, the carbon black–PPy underwent rapid degradation in the whole composition range. The durability is associated with the type and strength of the polymer–carbon bonding as revealed by EIS impedance correlated with spectroscopic studies. The electronic interactions between SWCNTs and PPy result in superior stability while the carbon black–PPy, where the hydrogen bridge bonds are generated, is not stable under the same experimental conditions.

Classical group theory was applied to prove the Pt3Ni crystallographic transformation from Platonic cubic to Archimedean cuboctahedral structures and the formation of Pt3Ni polypods. The role of W(CO)6 as a shape-controlling agent is discussed with respect to the crystallographic features of the clusters and superstructures generated as control samples.