Optoelectrical Regulation of CuBi₂O₄ Photocathode via Photonic Crystal Structure for Solar–Fuel Conversion

Abstract

Metal oxide semiconductors have been regarded as ideal candidates for photoelectrochemical (PEC) CO2 reduction if the contradiction between photon harvesting and photocarrier collection can be resolved. The novel three-dimensional structure provides an available approach to balancing the above-mentioned contradiction. In this work, CuBi2O4 photonic crystal photocathodes with different feature sizes were developed to realize the regulation of optoelectrical properties. The resulted photocathode displays promoted PEC activity as the enhanced photocurrent and CO2 reduction activity. Such an excellent performance was attributed to the improved efficiency of charge carrier generation and collection through extending the optical path and shortening the carrier transport distance inside films. COMSOL simulations and PEC spectroscopy analysis confirmed the promoted photon harvesting capacity and carrier dynamics. This work demonstrates a feasible strategy for developing novel photocathodes with modulated microstructures in solar–fuel conversion.