Copper bismuthate (CuBi2O4, CBO) has attracted attention as a promising photocathode material for photoelectrochemical (PEC) water-splitting because of its small bandgap (1.6–1.8 eV), high internal photovoltage, and moderate stability in aqueous media. Herein, we report a novel solution synthesis method to fabricate bulky crystalline CBO photocathodes via an evaporation decomposition controlled process. The CBO photocathode synthesized under optimal conditions exhibited a uniform, dense film with intimate substrate contact and large-grains, allowing an enhanced charge transport and photocurrent stability in comparison to porous CBO counterparts. Consequently, the dense CBO achieved a photocurrent density of − 1.16 mA/cm2 at 0.4 V versus the reversible hydrogen electrode (RHE) without a scavenger addition under simulated sunlight irradiation (AM 1.5 G, 100 mW/cm2). Significantly, the coupling of the CBO with a cupric oxide (CuO) underlayer and a Pt electrocatalyst increased the photocurrent density further to − 2.8 and − 3.5 mA/cm2 at 0.4 V versus RHE, respectively, which is the highest value to date among all reported CBO based photocathodes.
This research was supported by the Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Science, ICT and Future Planning, South Korea (grant number NRF- 2019R1A2C2002024).This research was supported by the Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Science, ICT and Future Planning , South Korea (grant number NRF- 2019R1A2C2002024 ).
