BiFeO₃ photocathodes for efficient H₂O₂ production via charge carrier dynamics engineering

Metal oxide semiconductors are promising candidate photoelectrodes for photoelectrochemical H₂O₂ production if the issues of poor efficiency and selectivity can be resolved. An unfavorable charge transport barrier causes poor carrier collection and kinetics, limiting their efficiency and selectivity. Herein, BiFeO₃ was used as the model photocathode, and its interfacial charge transport barrier between fluorine-doped tin oxide substrates was modulated by introducing a LaNiO₃ layer as the charge collection layer. Our findings show the significantly enhanced photoelectrochemical activity of the composite photocathode with an improved photocurrent by three times (-0.9 mA cm^-2 at 0.6 V vs. RHE) and the H₂O₂ formation up to 278 μmol L^-1 with doubled faradaic efficiency. It is shown that these enhancements are due to the promoted charge carrier collection and kinetics. This work demonstrates the significant role of the charge collection layer in improving the collection and usage of photocarriers to accelerate the application of solar-to-fuel conversion.