摘要
Constructing S-scheme heterojunctions preserves the intrinsic redox capabilities of both semiconductors while promoting the separation of photogenerated electrons and holes,making it a promising approach for enhancing the properties of semiconductors.In this study,an S-scheme Cd_(0.8)Zn_(0.2)S-CeO_(2)(CZS-CeO_(2))heterojunction was successfully fabricated via the in-situ growth of CZS nanowires on CeO_(2)nanocubes.The S-scheme charge-transfer mechanism of the CZS-CeO_(2)composites during photocatalytic reactions was confirmed through in-situ X-ray photoelectron spectroscopy and density functional theory calculations.These results demonstrate that the interfacial electric field(IEF)significantly facilitates charge separation and transport within the heterojunction.Consequently,the CZS-CeO_(2)composites exhibited excellent photocatalytic hydrogen production performance under simulated sunlight irradiation,surpassing that of blank CZS.Particularly,the optimal photocatalytic hydrogen generation rate for CZS-15%CeO_(2)reached 58 mmol·g^(-1)·h^(-1),approximately 8.8 times higher than that of blank CZS.After five consecutive cycles of testing,CZS-15%CeO_(2)retained a relatively high level of activity.This enhanced stability can be attributed to the fabrication of S-scheme heterojunctions,which effectively suppressed hole-induced photocorrosion of CZS.This investigation provides a beneficial reference for the rational design of S-scheme heterojunction photocatalysts for efficient and stable photocatalytic hydrogen production.
Cd_(0.8)Zn_(0.2)S(CZS)因具有良好的光催化还原能力和较宽的光吸收范围,在光催化产氢领域备受关注.然而,单组分的CZS仍存在光生载流子复合速率快、易发生光腐蚀等固有缺陷,导致其光催化活性较低、稳定性较差.在众多光催化剂改性策略中,异质结构建是应对上述问题的有效方法.其中,S型异质结因其能保留各组分强氧化还原能力,同时通过独特的能带结构促进光生载流子的定向分离与迁移,成为近年来的研究热点.因此,将CZS与能带位置匹配的CeO_(2)结合,构建S型异质结,有望改善复合光催化剂中光生载流子快速复合等问题,从而实现高性能的光催化产氢.本文通过水热法在CeO_(2)纳米立方体上原位生长CZS纳米线,制备了一系列S型CZS-CeO_(2)异质结复合光催化剂,并用于在模拟太阳光照射下的高效光催化产氢.通过透射电镜和扫描电镜等表征手段,证实了CZS纳米线均匀负载在CeO_(2)纳米立方体上,形成紧密的异质结界面结构,为载流子的高效转移提供了基础.进一步通过紫外-可见漫反射光谱、Tauc曲线和莫特-肖特基图谱等证实了CZS和CeO_(2)之间存在匹配的能级结构,其导带(CB)与价带(VB)位置有利于形成S型异质结.随后,通过原位X射线光电子能谱与密度泛函理论计算,共同验证了CZS-CeO_(2)复合材料中的S型电荷转移机制.在CZS-CeO_(2)复合光催化体系中,S型异质结的形成保留了更强的氧化还原能力,同时有效抑制了光生空穴氧化光腐蚀CZS,并促进了光生载流子的高效分离.因此,与纯CZS和CeO_(2)相比,CZS-CeO_(2)复合材料的光催化产氢性能显著提升.值得注意的是,CZS-15%CeO_(2)复合材料的光催化产氢速率达到58 mmol·g^(-1)·h^(-1),约为纯CZS的8.8倍.此外,CZS-CeO_(2)复合材料在5次循环测试后仍保持相对较高的光催化产氢活性,表明S型异质结的构建有效地改善了CZS的光腐蚀问题.系列光电化学表征结果表明,S型CZS-CeO_(2)异质结的形成拓宽了复合材料的光吸收范围,增大了反应活性面积,并有效促进了光生载流子的分离与迁移,从而提高了光催化产氢性能.综上,本文通过将CZS纳米线原位生长在CeO_(2)纳米立方体上,成功构建了一种S型CZS-CeO_(2)异质结光催化剂,并阐明了其S型光催化产氢电荷转移机理.该S型异质结光催化剂凭借独特的能带结构,实现了高效的电荷转移,展现出良好的光催化产氢活性与稳定性,有望为设计高效的S型异质结光催化体系提供新思路.
基金
国家自然科学基金(22462010,22366018)
江西省自然科学基金(20252BAC220013,20224BAB203018,20212BAB213016,20232ACB203022)
江西省“双千计划”(jxsq2023102143,jxsq2023102142,jxsq2023201086,jxsq2023102141,jxsq2019102053).
