M-O-M bond mediated three-dimensional materials accelerates photoelectrochemical kinetics across length scales and timescales

Reasonable design and couple of efficient co-catalysts on photoanodes for the oxygen evolution reaction (OER) are crucial for photoelectrochemical (PEC) water splitting. However, the interaction principles and charge transport mechanisms at the interface remain unclear. Herein, SrCoO 3-δ perovskite single-crystal quantum dots (PSC QDs) are coupled onto the BiVO 4 surface via M-O-M bonds, forming a three-dimensional porous topological network structure. The band alignment between BiVO 4 and SrCoO 3-δ is favorable for charge carrier separation. The interfacial field in BiVO 4 /SrCoO 3-δ via M-O-M bonds facilitates the redistribution of charges by detailed experiments and density functional theory (DFT) calculations. The enhanced band bending at the interface promotes efficient charge separation and fast hole transfer. The introduction of SrCoO 3-δ PSC QDs modulates the electronic structure for BiVO 4 , inducing an increase in the electron density near the Bi/V sites. The p-type SrCoO 3-δ , with Co 3 + -O 2- -Co 4+ double exchange interactions, improves conductivity and provides active Co sites for OER, reducing the reaction energy barrier of the rate-determining step (RDS) (*O→*OOH) and thus facilitating rapid water oxidation. A significant photocurrent density of 5.05 mA cm −2 at 1.23 V vs. REH is achieved for the BiVO 4 /SrCoO 3-δ photoanode. Meanwhile, temporal and spatial evolution for charge carrier transfer kinetics and OER dynamics were systematically investigated for the BiVO 4 /SrCoO 3-δ photoanode. This work sheds new insights into the design and understanding of efficient co-catalysts for solar water splitting.