Efficient charge–carrier separation and their utilization are the key factors in overcoming sluggish four-electron reaction kinetics involved in photocatalytic oxygen evolution. Here, a novel study demonstrates the significance of Na2S2O8 as a sacrificial agent in comparison to AgNO3. Resultantly, BiFeO3 (BFO) and titanium doped-oxygen deficient BiFeO3 (Ti-BFO-R) nanostructures achieve ≈64 and 44.5 times higher O2 evolution in the presence of Na2S2O8 compared to AgNO3 as a sacrificial agent, respectively. Furthermore, the presence of Co single atoms (Co-SAs) deposited via immersion method on BFO and Ti-BFO-R nanostructures led to achieving outstanding O2 evolution at a rate of 16.11 and 23.89 mmol g−1 h−1, respectively, which is 153 and 227.5 times higher compared to BFO (in the presence of AgNO3), the highest O2 evolution observed for BFO-based materials to date. The successful deposition of Co-SAs is confirmed by aberration-corrected high-angle annular dark-field scanning transmission electron microscopy (AC HAADF-STEM) and X-ray absorption near-edge structure (XANES). The charge transfer investigations confirm the significance of Co-SAs on BFO-based photocatalysts for improved charge–carrier separation, transport, and utilization. This novel study validates the excellent role of Na2S2O8 as a sacrificial agent and Co-SAs as a cocatalyst for BFO-based nanostructures for efficient O2 evolution.
