Charge Relays via Dual Carbon‐Actions on Nanostructured BiVO4 for High Performance Photoelectrochemical Water Splitting

Abstract Photoelectrochemical water splitting based on nanostructured bismuth vanadate (BiVO 4 ) can be a promising strategy to produce low‐cost and green H 2 to replace fossil fuels and realize carbon neutrality. Herein, a simple chemical way to realize in situ carbon doping into BiVO 4 crystalline structure is designed and obtained carbon‐doped BiVO 4 , namely C‐BiVO 4 , can improve the electronic conductivity of BiVO 4 . In addition, the introduction of the synthesized carbon quantum dots (CQDs) as a co‐catalyst, immobilizes CQDs onto the C‐BiVO 4 nanosheet and acquires the optimized C‐BiVO 4 /CQDs heterogeneous structure, which not only boosts light absorption, but also enhances the separation and transfer of the photo‐generated charges. Stemming from the dual carbon actions, the as‐prepared C‐BiVO 4 /CQDs photoanode exhibits an excellent photocurrent density of 4.83 mA cm −2 at 1.23 V versus the RHE without the use of any hole scavengers. To assure the practical application of the sensitive photocatalyst, a polyaniline layer is electroplated onto the C‐BiVO 4 /CQDs catalyst as a conducting, electroactive, and protective layer to sustain a remarkable long‐term photocurrent density of 2.75 mA cm −2 for 9 hours. This work suggests that the proposed low‐cost, environmentally friendly dual carbon actions can modify photocatalyst and achieve green production of H 2 .