摘要
随着社会发展,传统化石能源消耗加剧,人类迫切需要开发新型的清洁能源.半导体光催化分解水产氢是一种非常具有潜力解决能源危机的清洁技术.目前,金属硫化物半导体有着合适的能带结构和高效的光催化产氢能力而得到了广泛的研究.通常,为了提高光催化剂产氢性能,添加贵金属助催化剂是一个行之有效的方法.但是贵金属昂贵的价格限制了其大规模的应用,因此有必要研究储量丰富,价格低廉的高效助催化剂.Ni_(2)P,CoP,Co_(2)P,MoP,Cu_(3)P等过渡金属磷化物具有价格低廉,优异的稳定性和催化性能而被用作电催化产氢的催化剂.通常,用于电催化产氢的催化剂往往可以作为光催化产氢的助催化剂.众所周知,催化性能与材料的形貌密切相关,因此,具有棒状、中空、片状等形貌的金属硫化物被制备并用于光催化产氢.然而,四足状结构的金属硫化物研究较少.在已有的Ni_(2)P(NP)相关研究中,仅合成了纳米颗粒状的NP.本文成功合成了四足状Cd_(0.9)Zn_(0.1)S(CZS)和珊瑚状形貌的NP,进一步得到一系列Ni_(2)P-Cd_(0.9)Zn_(0.1)S(NPCZS)光催化剂,采用XRD,SEM,TEM,XPS和ICP-AES测试了样品的结构、形貌、表面成分和元素含量,并测试了样品的光催化产氢性能.采用水热法合成的CZS样品具有特殊的四足状形貌,足部由纳米棒组成.XRD结果表明,四足状CZS中立方相(WZ)和六方相(ZB)共存.经TEM进一步分析,发现CZS中心部位呈ZB相结构,而足部却是WZ相.经光催化性能测试,这种新型四足状CZS表现出优异的光催化产氢性能.进一步通过超声或研磨破坏四足状结构后,发现CZS的产氢性能显著下降,说明四足状形貌是材料性能提高的关键.通过分析WZ和ZB两物相的价带顶和导带底的电位发现,ZB/WZ间形成的同质结可以加速光生载流子的分离和传输.NP也采用水热法制备,其具有珊瑚状形貌.该形貌具有高的比表面积,可以提供更多的活性位点,进一步提高了材料的光催化性能.光催化性能测试表明,NP负载量为12 wt%的NPCZS-12样品表现出很好的产氢性能(l.88 mmol h^(-1)),是纯CZS的1.43倍.同时,NPCZS-12具有良好的光稳定性和循环使用性能.结合光催化实验、光谱实验、表面光电压和电化学测试的结果发现,四足状形貌、同质结和NP助催化剂的协同效应是NPCZS具有良好光催化性能的主要原因.
In this study,Ni_(2)P-Cd_(0.9)Zn_(0.1)S(NPCZS)composites were synthesized by coupling tetrapod bundle Cd_(0.9)Zn_(0.1)S(CZS)and coralline-like Ni_(2)P(NP)via a simple calcination method.CZS shows outstanding activity in photocatalytic hydrogen evolution(1.31 mmol h^(‒1)),owing to its unique morphology and heterophase homojunctions(ZB/WZ),which accelerate the separation and transfer of photogenerated charges.After coupling with NP,the photoactivity of NPCZS was enhanced,and the maximum hydrogen evolution rate of 1.88 mmol h^(‒1)was reached at a NP content of 12 wt%,which was 1.43 times higher than that of pure CZS.The experimental results of the photocatalytic activity,viz.photoluminescence spectra,surface photovoltage spectra,and electrochemical test showed that the enhanced photoactivity of NPCZS should be attributed to the synergistic effects of the novel tetrapod-bundle morphology,heterophase homojunctions,and decoration of the NP co-catalyst.Moreover,the as-prepared NPCZS composites exhibited excellent photostability and recyclability.Herein,we propose a possible mechanism for the enhanced photocatalytic activity.
作者
邵珠旺
孟晓
赖红
张大凤
蒲锡鹏
苏昌华
李红
任小珍
耿延玲
Zhuwang Shao;Xiao Meng;Hong Lai;Dafeng Zhang;Xipeng Pu;Changhua Su;Hong Li;Xiaozhen Ren;Yanling Geng(School of Materials Science and Engineering,Shandong Provincial Key Laboratory of Chemical Energy Storage and Novel Cell Technology,Liaocheng University,Liaocheng 252000,Shandong,China;State Key Laboratory Base of Eco-chemical Engineering,College of Chemistry and Molecular Engineering,Qingdao University of Science and Technology,Qingdao 266042,Shandong,China)
基金
山东省自然科学基金(ZR2018MEM019).
