Internal Electric Field Enhances B Refilling and Carbon Vacancy Double Modulation to Promote Photocatalytic Hydrogen Evolution

Defect engineering is an effective mean to improve the photocatalytic evolution of H₂, but the increase of activity caused by a single modification method is often limited. Although the carbon vacancy plays a very important role in promoting the hydrogen evolution activity, it is easy to inactivate due to the instability of the vacancy. Precise B refilling induced by surface carbon defects can not only stabilize the carbon vacancy but also adjust the energy band structure of g-C₃N₄ (CN), so that B refilling carbon vacancies CN (B_Rf-V_C-CN) shows the highest electron reduction ability. The electrochemical results show that B_Rf-V_C-CN represent the strongest ability of carrier separation and transfer, and the large internal electric field also indicates that the enhanced interlayer electron transfer. At the same time, surface heteroatom refilling can also improve the H₂O adsorption. As a result, the hydrogen evolution of the sample after B refilling is greatly increased to 18,100 μL g⁻¹ h⁻¹, which is 27.2 times higher than that of CN. This work will provide reliable and clear insights for the controlled defect engineering of photocatalysts, and provide general modification strategies for conventional typical heteroatoms used in H₂ production. Graphical Abstract: A defect-induced heteroatom refilling strategy is used here to synthesize B introduced in carbon nitride by precisely controlling the “introduction” sites on C1 sites. The interaction between vacancy and refilled heteroatoms makes B-refilled samples show high internal electric field strength and greatly improve the photocatalytic activity. (Figure presented.)