摘要
Photocatalysis is regarded as an ideal technology for solving the urgent environmental and energy issues that we face today.Among the reported photocatalysts,molybdenum disulfide（MoS2） is very promising for applications in hydrogen production and pollutant photodegradation.However,its lack of active sites and the difficulty of recovering catalysts in powder form have hindered its wide application.Here,we report the successful preparation of a macroscopic visible-light responsive MoS2/reduced graphene oxide（MoS2/RGO） aerogel.The obtained MoS2/RGO aerogel exhibits enhanced photocatalytic activity towards hydrogen production and photoreduction of Cr（Ⅵ） in comparison with the MoS2 powder.In addition,the low density（56.1 mg/cm^3） of the MoS2/RGO aerogel enables it to be used as an efficient adsorption material for organic pollutants.Our results demonstrate that this very promising multifunctional aerogel has potential applications in environmental remediation and clean energy production.
近年来,光催化技术在解决环境污染和能源短缺方面展现出巨大潜力.二硫化钼(MoS_2)作为一种二维层状光催化材料受到广泛关注.MoS_2具有可调的带隙(1.2-1.9 eV)、低的成本和高的存储量,是一种可替代铂的理想助催化剂.然而,MoS_2本身光催化活性较低.理论和实验已经证明,MoS_2只有暴露的边缘具有催化活性,并且MoS_2的光生电子-空穴对容易复合,导致其光催化效率低.增加暴露的活性边缘以及有效分离电子-空穴对是提高MoS_2光催化活性的关键.而石墨烯气凝胶是一种理想的催化剂载体,其高比表面积和高空隙率可以有效提高催化剂利用率.同时,其高导电性可以促进光生电子-空穴对分离.因此,将MoS_2负载到石墨烯气凝胶上制备宏观可回收光催化材料具有广阔的应用前景.然而,目前尚未见到有关MoS_2/石墨烯气凝胶光催化产氢以及还原Cr(Ⅵ)的报道.本文以钼酸铵为钼源,硫脲为硫源和还原剂,同时加入氧化石墨烯及其还原剂氨水,通过一步水热法制备出二硫化钼/还原氧化石墨烯(MoS_2/RGO)水凝胶.最后通过冷冻干燥得到MoS_2/RGO气凝胶.经光催化测试发现其产氢达到38.9μmol/g,光还原Cr(Ⅵ)达到92%,明显高于MoS_2粉体.采用X射线衍射(XRD)、扫描电镜(SEM)、透射电镜(TEM)、X射线光电子能谱(XPS)、紫外-可见-近红外吸收光谱(UV-Vis-NIR)及红外光谱(FTIR)等手段研究了其光催化性能提高的原因.XRD测试显示,过量的NH_4^+离子插入到MoS_2层与层之间增加了(002)面的晶面间距;SEM观察到在形成气凝胶后,MoS_2从粉末的片状转变成花状,这是因为氧化石墨烯上的含氧官能团促进MoS_2成核同时限制其生长导致的;TEM观察到MoS_2上存在大量的脱节和扭曲,这是由于过量硫脲阻碍了MoS_2晶体的取向生长而产生缺陷;XPS发现,除了形成MoS_2之外,还形成了MoO_2,同时大量的暴露边缘导致不饱和硫产生;FTIR表明MoS_2与RGO之�
基金
supported by the National Natural Science Foundation of China (U1232119, 21403172)
the Sichuan Youth Science and Technology Foundation (2013JQ0034, 2014JQ0017)
the Innovative Research Team of Sichuan Province (2016TD0011)~~
