Controlled oxygen doping in highly dispersed Ni-loaded g-C3N4 nanotubes for efficient photocatalytic H2O2 production

[Display omitted] •An oxygen doping Ni-loaded g-C3N4 nanotubes were synthesized successfully.•A high H2O2 production rate of 2464 μmol g−1 h−1 has been achieved.•The Ni/OtCN enables a fast separation of photogenerated charge carriers.•The Ni/OtCN presents a high selectivity for H2O2 generation. Hydrogen peroxide (H2O2) is both a key component in several industrial processes and a promising liquid fuel. The production of H2O2 by solar photocatalysis is a suitable strategy to convert and store solar energy into chemical energy. Here we report an oxygen-doped tubular g-C3N4 with uniformly dispersed nickel nanoparticles for efficient photocatalytic H2O2 generation. The hollow structure of the tubular g-C3N4 provides a large surface with a high density of reactive sites and efficient visible light absorption during the photocatalytic reaction. The oxygen doping and Ni loading enable a fast separation of photogenerated charge carriers and a high selectivity toward the two-electron process during the oxygen reduction reaction (ORR). The optimized composition, Ni4%/O0.2tCN, displays an H2O2 production rate of 2464 μmol g−1·h−1, which is eightfold higher than that of bulk g-C3N4 under visible light irradiation (λ > 420 nm), and achieves an apparent quantum yield (AQY) of 28.2% at 380 nm and 14.9% at 420 nm.