Improved Conductivity and in Situ Formed Heterojunction via Zinc Doping in CuBiO for Photoelectrochemical Water Splitting.

As a photocathode with a band gap of about 1.8 eV, copper bismuthate (CuBiO) is a promising material for photoelectrochemical (PEC) water splitting. However, weak charge transfer capability and severe carrier recombination suppress the PEC performance of CuBiO. In this paper, the conductivity and carriers transport of CuBiO are improved via introducing Zn into the synthesis precursor of CuBiO, driving a beneficial 110 mV positive shift of onset potential in photocurrent. Detailed investigations demonstrate that the introduction of an appropriate amount of zinc leads to in situ segregation of ZnO which serves as an electron transport channel on the surface of CuBiO, forming heterojunctions. The synergistic effect of heterojunctions and doping simultaneously promotes the charge transfer and the carrier concentration. OCP experiment proves that ZnO/Zn-CuBiO possesses better charge separation; the Mott-Schottky curve shows that the doping of Zn significantly enhances the carrier concentration; carrier lifetime calculated from time-resolved photoluminescence confirms faster extraction of carriers.