BiFeO₃-Based All Perovskite Oxides Direct Z-Scheme Heterostructure for Efficient Oxygen Evolution

BiFeO₃ (BFO) has gained significant attention recently in photocatalytic water splitting due to its visible light active profile and facile synthesis design. However, a single component photocatalyst usually suffers from significant photoexcited charge-carrier recombination. To overcome this problem, BFO nanocuboids are coupled with two-dimensional Ca₂Nb₃O₁₀ (CNO) nanosheets via a facile electrostatic self-assembly method. The surface charge of BFO nanocuboids is modulated via deposition of Co-nanoparticles to obtained positively charged BFO-Co nanocuboids. Resultantly, the combination of positively charged BFO-Co nanocuboids and negative charged CNO nanosheets demonstrated a direct Z-scheme heterojunction. The optimized BFO-Co/CNO heterostructure achieved outstanding photocatalytic O₂ evolution (48.19 mmol g^-1), which is 6.72 times higher than pristine BFO (7.17 mmol h^-1 g^-1). Different characterization confirmed that BFO-Co/CNO heterostructures exhibited improved charge-carrier separation and utilization compared to individual components. This improved response can be associated with a better contact interface between the oppositely charged surfaces with the added advantage of the perovskite nature of both components. As a result, BFO-Co/CNO heterostructures achieved the highest O₂ evolution response for BFO-based heterostructures to date. This study offers a novel strategy for modulating the BFO nanocuboids surface charge via Co-nanoparticles deposition, which concomitantly worked as a cocatalyst, a potential strategy that can be applied for the design of various heterostructures.