Up-cycling of waste paper for increased photo-catalytic hydrogen generation of graphitic carbon nitride under visible light exposure

Background Up-cycling of waste papers to value-added carbon products has significant environmental and economic benefits in real life. This work aims to recycle the waste papers to construct amorphous carbon modified graphitic carbon nitride composite photocatalysts for efficient photocatalytic hydrogen generation from water under visible light. Methods Amorphous carbon (labeled as a-C) was yielded from the office waste papers by simple sulphuric-acid treatment and then combined with graphitic carbon nitride (g-CN) to form the g-CN/a-C composite photocatalysts by the thermolysis of a-C and melamine mixture. Significant Findings The addition of a-C enlarges the surface area of g-CN from 11.52 m2 g−1 of pristine g-CN to 28.12 m2 g−1 of g-CN/a-C-100. In addition, the a-C incorporation can significantly separate the electrons from the photoexcited g-CN owing to the excellent conductivity of a-C. As a result, an increased photocatalytic H2 generation was realized under visible light exposure. The g-CN/a-C-100 sample with optimized a-C contents offers the highest photocatalytic H2 generation rate of up to 17.1 μmol h−1, which is ∼12 times higher than that of pristine g-CN under the same condition. The present study manifests the great potential of the recycling of office waste papers for increased photocatalytic H2 generation.