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光催化制氢是一种十分绿色、环保可持续的产氢方式.为了构建高效的光催化体系,对光催化剂进行表面修饰可以提高反应分子的吸附/活化的能力和电荷转移的效率.在本文中,我们通过Y.射线辐射还原法一步合成了聚乙烯吡咯烷酮包裹的硫化镉(P-CdS)同质结纳米粒子,之后通过室温下的碱化后处理,将P-CdS表面的PVP水解成为具有羧酸根和铵根的MPVP,而CdS的WZ-ZB同质结的晶体结构并未受到影响.一方面,由于MPVP在碱性溶液中的溶解度的提高,一部分MPVP溶解于溶液中,最终从MP-CdS表面去除,从而暴露出更多WZ-ZB同质结的活性位点.另一方面,水解后的MPVP保留在CdS表面,其羧酸根离子与CdS的配位作用,会影响到催化剂的价带结构,进而促进光催化析氢过程.在二者的协同作用下,当碱化NaOH浓度为1 mol·L-1时,MP-CdS-3碱化样品的光催化析氢速率达到477μmol·g-1·h-1,是未碱化样品的2倍.这种碱化后处理的策略简单且廉价,可以引申到合成一些PVP包裹的各类光催化剂的表面修饰当中,有利于促进硫化镉材料的光催化应用.“,”Photocatalytic hydrogen evolution is a scalable pathway to generate hydrogen fuels while mitigating environmental crisis.Strategies based on modification of the host photocatalyst surface are key to improve the adsorption/activation ability of the reaction molecules and the efficiency of charge transport,so that high-efficiency photocatalytic systems can be realized.Cadmium sulfide(CdS),a visible light-responsive semiconductor material,is widely used in photocatalysis because of its simple synthesis,low cost,abundant raw materials,and appropriate bandgap structure.Many researchers have focused on improving the photocatalytic efficiency of CdS because the rapid charge recombination in this material limits its applications.Among the various strategies proposed in this regard,surface modification is an effective and simple method used to improve the photocatalytic performance of materials.In this work,polyvinyl pyrrolidone(PVP)-capped CdS(denoted as P-CdS)nanopopcorns with hexagonal wurtzite(WZ)-cubic zinc blende(ZB)homojunctions were fabricated via one-step gamma-ray radiation-induced reduction under ambient conditions.Subsequent alkaline treatment under ambient conditions led to a dramatic improvement in the activity of the alkalized PVP-capped CdS(MP-CdS)photocatalyst.The structure and properties of the photocatalyst were determined by X-ray diffraction(XRD)analysis,field-emission scanning electron microscopy(FE-SEM),transmission electron microscopy(TEM),X-ray photoelectron spectroscopy(XPS),Fourier transform infrared(FTIR)analysis,Brunauer-Emmett-Teller(BET)specific surface area measurements,and photoelectric tests.The photocatalytic performance was evaluated based on the photocatalytic H2 evolution under visible-light irradiation.The mechanism underlying the enhancement of the photocatalytic activity is also discussed.The results showed that after the alkaline treatment,the crystal structure of CdS with WZ-ZB homojunctions was preserved,but PVP on the surface of CdS hydrolyzed to form PVP hydrolysis product(MPVP)with carboxyl and amino groups.Owing to the increased alkaline solubility,a portion of MPVP dissolved into the solution and was removed from the surface of MP-CdS,exposing a greater number of active sites of the WZ-ZB phase junctions with a larger specific surface area.On the other hand,the carboxyl groups in MPVP coordinated with CdS could affect the bandgap and valence band position of CdS to facilitate the photocatalysis.Because of the synergistic effects of the exposure of WZ-ZB phase junctions and band structure engineering,the alkalized samples at a 1 mol·L-1 concentration of NaOH showed a H2 evolution rate of 477 μmol g-1·h-1 under visible-light illumination,which was twice that obtained for the pristine P-CdS photocatalysts.This simple and low-cost post-synthesis strategy can be extended to the preparation of diverse functional photocatalysts.The present work is expected to contribute to the practical application of sulfide photocatalysts.