ZnBi38O60/Bi2O3 photocathode for hydrogen production from water splitting

Hydrogen production from water splitting into photoelectrochemical cells is a promising alternative for reducing the use of fossil fuels. Here, we synthesize by spray pyrolysis a porous ZnBi38O60/γ-Bi2O3 film with a surface area of 744 m2 g−1 for use as a photocathode in water-splitting cells. The film of ZnBi38O60 with 3 wt% Bi2O3 has 2.3 eV bandgap energy and a conduction band energy of −2.14 V vs. RHE at pH 6.99, which is thermodynamically suitable for reducing H+ to H2. Under illumination, the film produces a current density of −1.55 mA cm−2 at 0 V vs. RHE with an onset potential of 0.84 V vs. RHE. HC-STH efficiency is 0.09% at 0.17 V vs. RHE and IPCE at 0 V vs. RHE is 3.8% at 480 nm. Under continuous operation, the ZnBi38O60/γ-Bi2O3 film shows a stable photocurrent of −0.4 mA cm−2 at 0 V vs. RHE for 1800 s with 100% Faradaic efficiency.