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

Photoelectrochemical water splitting based on nanostructured bismuth vanadate (BiVO4) can be a promising strategy to produce low‐cost and green H2 to replace fossil fuels and realize carbon neutrality. Herein, a simple chemical way to realize in situ carbon doping into BiVO4 crystalline structure is designed and obtained carbon‐doped BiVO4, namely C‐BiVO4, can improve the electronic conductivity of BiVO4. In addition, the introduction of the synthesized carbon quantum dots (CQDs) as a co‐catalyst, immobilizes CQDs onto the C‐BiVO4 nanosheet and acquires the optimized C‐BiVO4/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‐BiVO4/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‐BiVO4/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 H2. The authors demonstrate that nonmetallic carbon materials can significantly improve the photoelectrochemical water oxidation performance of bismuth vanadate (BiVO4). The resulting C‐doped BiVO4/carbon quantum dots photoanode exhibits excellent photocurrent density of 4.83 mA cm−2 at 1.23 V versus the RHE without any hole scavenger.