Phosphorus and sulphur co-doping of g-C3N4 nanotubes with tunable architectures for superior photocatalytic H2 evolution

Non-metal doping not only optimizes the energy band structure of g-C3N4 to improve the absorption of visible light, but also exacerbates the distortion of lowest and highest unoccupied molecular orbital plane, causing polarization, thereby improving photocatalytic activity. For the first time, S and P are co-introduced into g-C3N4 network to enhance photocatalytic performance and create various tubular morphologies. The ratio of S to P is crucial to control the tubular morphology and property. In the photocatalytic process, the separation of electrons and holes causes by the polarization of the S and P elements and the synergy of the tubular morphology results in new migration paths for photogenerated electrons and holes. Using optimized preparation conditions, g-C3N4 tubes co-doped with S and P (CNSP) reveal very high H-2 generation efficiency (163.27 umol/h), which is two orders of magnitude higher compared to that of pure g-C3N4 and apparent quantum yield is 18.93% at 420 nm. Fast degradation of Rhodamine B by using CNSP occurs within 5 min under visible light irradiation. Because of the reproducible process, the synthetic strategy provides a novel method for controlling the morphology of g-C3N4-based materials with super activity. (C) 2019 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.