Heterojunction BiVO4/WO3 electrodes for enhanced photoactivity of water oxidation

Abstract

Heterojunction electrodes were fabricated by layer-by-layer deposition of WO 3 and BiVO 4 on a conducting glass, and investigated for photoelectrochemical water oxidation under simulated solar light. The electrode with the optimal composition of four layers of WO 3 covered by a single layer of BiVO 4 showed enhanced photoactivity by 74% relative to bare WO 3 and 730% relative to bare BiVO 4 .According to the flat band potential and optical band gap measurements, both semiconductors can absorb visible light and have band edge positions that allow the transfer of photoelectrons from BiVO 4 to WO 3 . The electrochemical impedance spectroscopy revealed poor charge transfer characteristics of BiVO 4 , which accounts for the low photoactivity of bare BiVO 4 . The measurements of the incident photon-to-current conversion efficiency spectra showed that the heterojunction electrode utilized effectively light up to 540 nm covering absorption by both WO 3 and BiVO 4 layers. Thus, in heterojunction electrodes, the photogenerated electrons in BiVO 4 are transferred to WO 3 layers with good charge transport characteristics and contribute to the high photoactivity. They combine merits of the two semiconductors, i.e. excellent charge transport characteristics of WO 3 and good light absorption capability of BiVO 4 for enhanced photoactivity.

TiO2 nanocluster modified-rutile TiO2 photocatalyst: a first principles investigation

“…We also find that the workfunction of the composite is reduced by around 1 eV compared to the bare surface, which will be important for enhanced reactivity. The importance of forming an interface between two materials 20 to enhance photocatalytic activity is discussed in the literature [23][24][25][26][27][28][29][30][31][32][33][34][35][36][37][38][39][40][41] and new materials combinations are being prepared, e.g. Ismail reported a synthesis of PdO-TiO 2 nanocomposite through one-step sol-gel reaction with enhanced photocatalytic activities 78 .…”

Molecular Metal Oxide Cluster-Surface Modified Titanium(IV) Dioxide Photocatalysts

“…[23] The interface between the two oxides can result in electron and hole separation upon photoexcitation which is one of the key factors in efficient photocatalysis. Heterostructures of TiO 2 with metals, [24,25] semiconductors [26,27] and heterostructures of two different metal oxides [28][29][30] have been shown to induce visible light absorption and improved photocatalytic activity when compared with the isolated materials. The formation of a heterostructure of two metal oxides could provide a promising approach for developing materials with improved photocatalytic activity.…”

Efficient Water‐Splitting Device Based on a Bismuth Vanadate Photoanode and Thin‐Film Silicon Solar Cells

“…[12] The low carrier mobility in the material has recently been counterbalanced by introducing an internal electrical field by gradient doping with tungsten (W). [9] Carrier drift then competes favorably with the recombination processes, which results in a considerably enhanced photocurrent and makes BiVO 4 the photoelectrode with the hitherto highest photocurrent density within its material class.…”