Photoelectrocatalytic H2 evolution enhancement over CuO-decorated TiO2 nanocatalysts and promoting E. coli degradation

Abstract

The objective of this research is to improve cathode electrode fabrication for high-efficiency hydrogen (H2) evolution and to promote Escherichia coli (E. coli) degradation at the anode electrode. The heterojunction of the TiO2/CuO photocathode was synthesized via sputtering of the TiO2 nanocatalyst on the CuO electrode for enhancing the H2 evolution efficiency. The effect of calcination temperatures for Cu2O conversion to high-catalytic CuO and priority deposition of the TiO2 layer were optimized to improve the photoelectrocatalytic (PEC) activity and charge transfer process. The optical properties, morphology, crystalline structure, and chemical composition were characterized to clarify the PEC activity improvement. The developed TiO2/CuO photocathode combined with the BiVO4/WO3 photoanode was designed in the PEC cell for H2 production and simultaneous E. coli degradation. Cu2O was changed to a narrower bandgap energy of CuO at the calcination temperature over 400 °C and presented high crystallinity and proper morphology when the temperature was increased to 550 °C. The CuO-decorated TiO2 nanocatalyst can improve the morphology and charge transfer process at the heterojunction of the TiO2/CuO electrode. The small particle size of TiO2 at the outer side can improve the surface roughness and serve as electron separation to reduce the recombination effect of CuO, resulting in high-efficiency H2 evolution. The developed PEC cell can produce H2 up to 5800 μL for 150 min and E. coli degradation up to 100% for 22 min under the PEC process. We can confirm that the developed TiO2/CuO cathode electrode is highly effective in H2 production and is sufficient in promoting the E. coli degradation process at the BiVO4/WO3 anode electrode. The findings of this research are beneficial in high-efficiency heterojunction semiconductor electrodes development and PEC cell designs for energy and environmental applications.