铬掺杂黄钾铁矾微球的制备及OER性能研究

采用水热合成法制备出不同微观形貌的铬掺杂黄钾铁矾纳米球(KFe3-xCrx(SO4)2(OH)6)。利用XRD、SEM、FTIR和Raman对催化剂的微观结构及物理化学性质进行了表征，使用电化学工作站对样品进行电催化析氧性能(OER)测试。结果表明，Cr3+取代部分Fe3+的位置，随着摩尔比n(Fe3+/Cr3+)的提高，黄钾铁钒由不规则的纳米颗粒转变成尺寸均一的纳米球。当n(Fe3+/Cr3+)=2时，合成的KFe2Cr1(SO4)2(OH)6表面光滑、直径约为450~550 nm。当电流密度为10 mA/cm2时，过电位为362 mV，塔菲尔斜率为73 mV dec-1；恒电位测试20 h后电压无明显变化，基本趋于稳定。说明KFe2Cr1(SO4)2(OH)6微球表现出良好的OER催化活性和稳定性，为黄钾铁矾的应用提供了新的方向。

Research on Preparation and OER Properties of Chromium-doped Jarosite Microspheres

A series of chromium-doped jarosite nanospheres KFe3-xCrx(SO4)2(OH)6) with diverse microstructures were prepared by hydrothermal synthesis method. Microstructure and physicochemical properties of catalyst were investigated with the aid of XRD, SEM, FT-IR and Raman, and electrocatalytic oxygen evolution performance (OER) of samples were measured through electrochemical workstation. The results show that Cr3+ replaces part of Fe3+, and with the increase of the molar ratio of n(Fe3+/Cr3+), morphology of jarosite transforms from irregular nanoparticles to uniformly sized nanospheres. When n(Fe3+/Cr3+)=2, the synthesized KFe2Cr1(SO4)2(OH)6 is a nano-microsphere with smooth surface and diameter is about 450~550 nm. When the current density is 10 mA/cm2, the over potential is 362 mV and the Tafel slope is 73 mV dec-1, meanwhile, the voltage does not change significantly after 20 h of constant potential test and basically stabilized, which indicates that KFe2Cr1(SO4)2(OH)6 microsphere exhibits excellent OER catalytic performance and stability, and providing a new direction for application of jarosite.