Phosphorous doped graphitic-C3N4 hierarchical architecture for hydrogen production from water under visible light

Enriched macro/mesoporous graphitic-C3N4 (g-C3N4) micro-rods (CNRs) are prepared by direct calcination of reflux treated ethylene diphosphonic acid-melamine complex fiber network. The optimized phosphorous doped CNRs (P-CNRs) exhibit a high hydrogen-evolution rate of 4960 mu mol h(-1) g(-1) (5.5 times that of pristine g-C3N4) with a remarkable recycling stability. The significantly enhanced performance is found to be attributed to the intentionally designed morphology and electronic properties of PCNRs. This distinctive hierarchical architecture of CNRs enhances the light scattering, and provides a high specific surface area and thus more catalytically active sites. The P doping of g-C3N4 greatly increases the visible light absorption, narrows the band gap. It also results in a boost in the density state of the conduction band as revealed by the electron paramagnetic resonance (EPR) spectra. The strong visible light emission quenching, observed from the photoluminescence of P-CNRs and photocurrent measurements, implies an enhanced charge transfer/separation process. This work presents a very simple and direct method of designing and developing high-performance visible light driven catalysts for hydrogen production. (C) 2017 Elsevier Ltd. All rights reserved.