Development of Sulfur-Doped Graphitic Carbon Nitride for Hydrogen Evolution under Visible-Light Irradiation

Tamer M Khedr; Said M El-Sheikh; Maya Endo-Kimura; Kunlei Wang; Bunsho Ohtani; Ewa Kowalska

doi:10.3390/nano13010062

Development of Sulfur-Doped Graphitic Carbon Nitride for Hydrogen Evolution under Visible-Light Irradiation

Nanomaterials (Basel). 2022 Dec 23;13(1):62. doi: 10.3390/nano13010062.

Authors

Tamer M Khedr^{1

2}, Said M El-Sheikh², Maya Endo-Kimura¹, Kunlei Wang¹, Bunsho Ohtani¹, Ewa Kowalska^{1

3}

Affiliations

¹ Institute for Catalysis, Hokkaido University, N21, W10, Sapporo 001-0021, Japan.
² Nanomaterials and Nanotechnology Department, Central Metallurgical Research and Development Institute (CMRDI), Cairo 11421, Egypt.
³ Faculty of Chemistry, Jagiellonian University, Gronostajowa 2, 30-387 Kraków, Poland.

Abstract

Developing eco-friendly strategies to produce green fuel has attracted continuous and extensive attention. In this study, a novel gas-templating method was developed to prepare 2D porous S-doped g-C₃N₄ photocatalyst through simultaneous pyrolysis of urea (main g-C₃N₄ precursor) and ammonium sulfate (sulfur source and structure promoter). Different content of ammonium sulfate was examined to find the optimal synthesis conditions and to investigate the property-governed activity. The physicochemical properties of the obtained photocatalysts were analyzed by X-ray diffraction (XRD), field emission-scanning electron microscopy (FE-SEM), scanning transmission electron microscopy (STEM), specific surface area (BET) measurement, ultraviolet-visible light diffuse reflectance spectroscopy (UV/vis DRS), X-ray photoelectron spectroscopy (XPS), photoluminescence (PL) spectroscopy and reversed double-beam photo-acoustic spectroscopy (RDB-PAS). The as-prepared S-doped g-C₃N₄ photocatalysts were applied for photocatalytic H₂ evolution under vis irradiation. The condition-dependent activity was probed to achieve the best photocatalytic performance. It was demonstrated that ammonium sulfate played a crucial role to achieve concurrently 2D morphology, controlled nanostructure, and S-doping of g-C₃N₄ in a one-pot process. The 2D nanoporous S-doped g-C₃N₄ of crumpled lamellar-like structure with large specific surface area (73.8 m² g^-1) and improved electron-hole separation showed a remarkable H₂ generation rate, which was almost one order in magnitude higher than that of pristine g-C₃N₄. It has been found that though all properties are crucial for the overall photocatalytic performance, efficient doping is probably a key factor for high photocatalytic activity. Moreover, the photocatalysts exhibit significant stability during recycling. Accordingly, a significant potential of S-doped g-C₃N₄ has been revealed for practical use under natural solar radiation.

Keywords: 2D nanostructure; H2 generation; RDB-PAS; S-doped g-C3N4; porous materials.

Abstract

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