Engineering Interfaces to Steer Hole Dynamics of BiVO 4 Photoanodes for Solar Water Oxidation

Solar‐driven photo‐electrochemical (PEC) water splitting paves a promising route toward the future of scalable hydrogen production. However, water oxidation dominated by hole carriers excited in the photoanode is a critical bottleneck that hampers PEC overall efficiency due to sluggish hole transfers and surface reaction kinetics for most semiconductors. Herein, dual interface layers including a buried p–n junction and an active catalytic surface to synergistically accelerate hole extraction and injection toward water oxidation over n‐type BiVO 4 photoanodes by successive deposition of discrete p‐type Co 3 O 4 and amorphous Co‐Fe‐layered double hydroxide (CoFe‐LDH) are introduced. Compared with the bare BiVO 4 photoanode, the resultant BiVO 4 /Co 3 O 4 /CoFe‐LDH photoanode yields a near fourfold enhanced photocurrent density of 3.9 mA cm −2 at 1.23 V RHE with a cathodic shift of ≈410 mV at onset potential under AM 1.5G illumination. Stoichiometric oxygen and hydrogen generation with a Faraday efficiency of unity over 10 h enable an outstanding applied bias solar‐to‐hydrogen efficiency of 1.23%, among the best records for reported single‐photon photoanodes. Furthermore, the decoupled dynamics analysis determines that the designed dual interfaces contribute to both hole extraction efficiency of up to 90% and a surface injection efficiency of up to 71%. This work describes an effective strategy of interface engineering to steer hole dynamics in solar fuel conversion devices.