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

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 (H-2) evolution from water splitting under visible-light (lambda >= 420 nm). The optimized BCN-10 sample shows a maximum H-2 evolution rate of 1789.93 mu mol h(& horbar;1) g(& horbar;1), which is 6.2 times higher than that of g-C3N4 (289.73 mu mol h(& horbar;1) g(& horbar;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 H-2 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.