TiO2/β-C3N4 for sunlight-driven overall water splitting

beta-C3N4 is one of the most difficult phases to synthesize among the C3N4 structures (alpha, beta, cubic, pseudo cubic, and graphitic), and it has attracted marked attention because of its unique super hardness, optical properties, low density, good chemical resistance, and thermal stability. In this paper, a uniform beta-C3N4 layer is successfully prepared and coated on a TiO2 nanotube substrate via a calcination treatment using ethylenediamine as the carbon nitride precursor. The as-obtained TiO2/C3N4 exhibites a promising sunlight-driven overall water splitting ability, with 1026.7 mu mol(H2) g(cat).(-1) h(-1) and a 446.4 mu mol(O2) g(cat).(-1) h(-1) generation rates simultaneously realized. Importantly, the turnover frequency for O-2 in the photocatalytic splitting process reaches up to 4472.8 h(-1) for the overall water splitting process, which is similar to 77.6 times that of the single beta-C3N4 system (57.6 h(-1)) for O-2 generation. In-situ Raman investigation demonstrates that N vacancy defects in beta-C3N4 served as the active site for O-2 generation from H2O, which is a hard nut to crack for C3N4 all the time. (C) 2022 Published by Elsevier B.V.

Automated summary

In this paper, a uniform beta-C3N4 layer is successfully prepared and coated on a TiO2 nanotube substrate via calcination treatment using ethylenediamine as the carbon nitride precursor. The TiO2/C3N4 composite material exhibits promising sunlight-driven overall water splitting ability, with N vacancy defects in beta-C3N4 serving as the active site for oxygen generation from water.