Cu掺杂SnO_2阴极材料的制备及低过电位下对CO_2的电催化还原

Preparation of Cu Doped SnO_2 Cathode Material for Electroreduction of Carbon Dioxide at Low Overpotential

以无机盐SnCl_4·5H_2O为前驱体,CuCl_2为掺杂剂通过一步水热法制备了Cu掺杂SnO_2阴极材料.采用扫描电子显微镜(SEM)、X射线衍射(XRD)和X射线光电子能谱(XPS)对该物质的形貌、晶型结构和元素组成及价态进行表征.在常温常压下于0.5 mol/L NaHCO3溶液中,通过循环伏安曲线、塔菲尔(Tafel)曲线和阻抗谱等考察了该阴极材料及其还原CO_2的性能.结果表明,该物质为金红石相SnO_2,且掺杂后晶粒减小,Cu^(2+)取代了SnO_2晶格中的Sn^(4+);当Cu掺杂量为1.5%时材料的催化活性最好.催化剂负载量为0.8mg/cm^2时,电流密度可达到3.5mA/cm^2,产甲酸的塔菲尔曲线斜率为55.1 mV/dec,最大法拉第效率约为23%,是纯SnO_2的12倍.

Cu doped SnO 2 was prepared through one-step hydrothermal method with SnCl 4·5H 2O as precursor material and CuCl 2 as dopant.The surface morphology,crystal structure and element composition as well as valence state were characterized by scanning electron microscopy(SEM),X-ray diffraction(XRD)and X-ray photoelectron spectroscopy(XPS).The properties of the material and the reduction of CO 2 were investigated by cyclic voltammetry,Tafel plot and electrochemical impedance spectroscopy under normal temperature and pressure in 0.5 mol/L NaHCO 3 solution.The results show that SnO 2 has rutile structure and Cu 2+ions replace some Sn 4+ions of SnO 2.Besides,the particles size decreases slightly after doping Cu+.Through electrochemical performance evaluation,the best catalytic performance was achieved as the Cu doping content was 1.5%.The current density reached 3.5 mA/cm 2,the Tafel slope was 55.1 mV/dec and the maximum Faradic efficiency reached 23%when the catalyst loading amount was 0.8 mg.The Faradic efficiency is 12 times that of pure SnO 2.Therefore,the Cu doped SnO 2 can be used as cathode material for electrocatalytic reduction of CO 2.