Local Charge Transport at the Interface of Semiconductor and Charge Transport Mediator

Charge transport mediators are commonly used in photoelectronic devices to promote selective charge transport and mitigate carrier losses. However, related investigations are mainly carried out by the trial‐and‐error method, and a deeper understanding of its local charge transport behavior is still lacking. Herein, a comprehensive study is performed on a BiVO4/Ti3C2 photoanode to reveal its local charge transport properties by combing microprobe technologies and numerical computations. For the first time, a nano‐Schottky junction is directly shown at the BiVO4/Ti3C2 interface and the band bending is quantified with promoted hole transport and prolonged photocarrier's lifetime. These mechanistic insights leverage a path to further optimize performance through interface engineering and achieve a photocurrent of 5.38 mA cm−2 at 1.23 V versus reversible hydrogen electrode. This work provides deeper insight into the function of charge transport mediators in view of interface contact rather than material nature and demonstrates a strategy to improve photoelectrochemical performance through Fermi‐level engineering. Local photocurrent imaging analysis provides a deeper understanding of interfacial charge transport behavior at the nanoscale, which facilitates the development and optimization of charge select materials for the photoelectrochemical system to efficient solar fuel production.