硫取代氮增强g-C3N4光催化产氢性能OA北大核心CSTPCD

The use of solar energy as an inexhaustible resource to conduct photocatalytic water splitting in hydrogen(H2)production can alleviate the worldwide energy crisis and achieve carbon neutrality.However,research in photocatalytic H2 evolution reaction(HER)is extremely challenging in terms of exploring the current development of an active and durable graphitic carbon nitride(g-C3N4)-based photocatalyst.Several parameters of pristine g-C3N4 require structural,physical,and chemical improvements,such as optimization of the surface area,electron transfer,and photo-generated carrier recombination,to render the g-C3N4 suitable for photocatalysis.In this study,the development of an efficient and robust S-doped g-C3N4(S-g-CN)catalyst was pursued that involves doping nitrogen(N)active sites of g-C3N4 with sulfur(S)dopants via one-step calcination of the sulphate and melamine precursors.A combination of structural and spectroscopic fingerprints was established to distinctly determine the realization of S-doping onto the g-C3N4 structure.We obtained the optimum Gibbs free energy of adsorbed hydrogen(ΔGH*)for S-g-CN at the S active sites,which is nearly zero(～0.26 eV),suggesting that the filled S dopants play an essential role in optimizing the adsorption and desorption processes of H-active intermediates.The results of atomic force and transmission electron microscopies(AFM and TEM)demonstrated that the produced S-g-CN catalyst has an ultrathin nanosheet structure with a lamellar thickness of approximately 2.5 nm.A subsequent N2 sorption isotherms test revealed a substantial increase in the specific surface area after the integration of S dopants into the g-C3N4 nanoskeleton.Moreover,the incorporation of S atoms into the g-C3N4 significantly increased the carrier concentrations,improving the transfer,separation,as well as the oxidation and reduction abilities of the photo-generated electron-hole pairs.Leveraging the favorable material characteristics of the S-doped two-dimensional nanostructures,the resulting S-g-CN achieved a high H2 evolution rate of 4923 μmol·g-1·h-1,which is 28 times higher than that of the pristine g-C3N4.Additionally,the developed S-g-CN possessed a high apparent quantum efficiency(3.64%)at visible-light irradiation.When compared to the recently reported S-doped g-C3N4-based photocatalysts,our optimal S-g-CN catalyst(S-CN1.0)showed one of the best HER catalytic activities.Our rational design is based on an effective strategy that not only explored a promising HER photocatalyst but also aimed to pave the way for the development of other high-performance g-C3N4 based catalysts.