Electron‐Deficient Boron‐Doped g‐C₃N₄ as an Efficient and Robust Photocatalyst for Visible‐Light Driven Hydrogen Evolution from Water Splitting

Abstract Elemental doping is considered to be a promising approach for altering the electronic structure, optical absorbance, and charge separation characteristics of graphitic carbon nitride (g‐C₃N₄, termed as CN), thus boosting its photocatalytic performance for practical applications. Herein, a series of boron (B) doped g‐C₃N₄ (named as BCN) photocatalysts are developed via one‐step pyrolysis of a mixture of urea and 3‐methoxycarbonyl‐5‐nitriophenylboronic acid (MCNPBA). The results show that B‐atoms have been successfully incorporated into the g‐C₃N₄ network. The as‐synthesized BCN‐x (x shows the weight content of MCNPBA) photocatalysts are evaluated in photocatalytic hydrogen (H₂) evolution from water splitting under visible‐light (λ ≥ 420 nm). The optimized BCN‐10 sample shows a maximum H₂ evolution rate of 1789.93 µmol h^─1 g^─1, which is 6.2 times higher than that of g‐C₃N₄ (289.73 µmol h^─1 g^─1). This is attributed to the fact that the electron‐deficient B‐atoms are lewis acids that trap electrons, which in turn expands visible‐light absorption, narrows the bandgap, and prevents the recombination of photogenerated charge carriers. Moreover, B‐doping can readily modify the valence and conduction band positions of g‐C₃N₄, therefore augmenting the photocatalytic H₂ evolution activity. This paper presents a unique rational framework for developing other functionalized electron‐deficient elemental‐doping g‐C₃N₄‐based photocatalysts for practical applications in solar‐to‐fuel conversion.