Short chain chlorinated paraffins have recently attracted great attention because of their environmental persistence and biological toxicity as an important organic pollutant. In this work, reduced graphene oxide/CoFe2O4/Ag (RGO/CoFe2O4/Ag) nanocomposite was prepared and employed for photocatalytic degradation of short chain chlorinated paraffins. The process of photocatalytic degradation of short chain chlorinated paraffins over RGO/CoFe2O4/Ag under visible light (λ > 400 nm) was investigated by in situ Fourier transform infrared spectroscopy and the related mechanisms were proposed. An apparent degradation ratio of 91.9% over RGO/CoFe2O4/Ag could be obtained under visible light illumination of 12 h, while only about 21.7% was obtained with commercial P25 TiO2 under the same experimental conditions, which demonstrates that the RGO/CoFe2O4/Ag nanocomposite is a potential candidate for effective photocatalytic removal of short chain chlorinated paraffins.

⿢BiFeO3/TiO2 nanotube arrays prepared via an ultrasound-assisted SILAR strategy.⿢Higher amount of photo-generated charge carriers could be produced by the composite.⿢Enhanced efficiency of MB degradation over BiFeO3/TiO2 nanotube arrays.In this work, a facile strategy of ultrasound-assisted successive ionic layer adsorption and reaction was successfully employed to modify TiO2 nanotube arrays with BiFeO3 nanoparticles. An enhanced positive surface photovoltage was observed with the obtained BiFeO3/TiO2 nanotube arrays as well as a longer lifetime of charges separation state, as probed by transient photovoltage technique. The higher photocurrent density produced by BiFeO3/TiO2 nanotube arrays further indicated that BiFeO3 nanoparticles contributed to photo conversion and promoted the generation of photo-induced charge carriers over TiO2 nanotube arrays. Besides, the prepared BiFeO3/TiO2 electrode exhibited a much enhanced photoelectrocatalytic performance in removing methyl blue compared with bare TiO2 nanotube arrays.

•α-Bi2O3/TiO2 nanotube arrays were prepared via a vacuum-assisted impregnation strategy.•Enhanced photoelectrochemical performance of α-Bi2O3/TiO2 nanotube arrays.•Superoxide radicals are predominant reactive species upon illumination as detected by ESR.With the aim of improving the performance of TiO2 nanotube arrays (NTAs), α-Bi2O3 nanoparticles were successfully implanted into the nanotube arrays via a vacuum-assisted impregnation strategy for the first time. Photoelectrochemical characterizations and comparative investigations on the degradation efficiency of 2-Chlorophenol demonstrate the enhanced photo activity of α-Bi2O3/TiO2 nanotube arrays over the pure nanotube arrays. The as-prepared α-Bi2O3/TiO2-NTAs grown on Ti behaved as a recyclable and stable electrode and outperformed pure TiO2-NTAs. The α-Bi2O3 nanoparticles modified TiO2 nanotube arrays could favor the separation and transfer of photoinduced charge carriers, which promote the energy conversion and the generation of reactive radicals upon irradiation. The predominant superoxide radicals were evidenced by electron spin resonance signals.

This work aims at the exploration of nanostructured ferroelectric-material-modified semiconductor electrodes for enhanced photo-induced activity. A well-aligned BiFeO3/TiO2-nanotubes (NTs) array with visible-light activity was successfully synthesized on a titanium sheet by combining anodization and an ultrasonic-immersion method followed by annealing. The structural and optical properties of the TiO2-NTs and the composite BiFeO3/TiO2-NTs were comparatively characterized. The composite BiFeO3/TiO2-NTs grown on a Ti sheet and used as an electrode exhibited a stronger absorption in the visible region and a much higher photoconversion efficiency than the pure TiO2-NTs/Ti electrode. Electrochemical impedance investigation attested to a significant improvement of the interfacial electron-transfer kinetics with enhanced separation of electron-hole pairs. The as-prepared composite electrode showed a high efficiency for photoelectrocatalytic degradation towards rhodamine B under visible-light irradiation (λ > 400 nm). The enhanced photoelectrocatalytic activity of the composite electrode could be attributed to the synergistic effect between the lowered electron-hole recombination rate by the applied bias and the wider spectral response promoted by the BiFeO3 component.Keywords: composite electrode; nanotube arrays; photocurrent; photoelectrocatalytic activity; surface photovoltage;