摘要
Amorphous iridium oxides(IrO_(x))are highly active for oxygen evolution reaction(OER)in acid media;however,it is generally unstable compared with commercial IrO_(2).Recently,many non-noble metal-iridium mixed oxides are prepared for catalyzing OER efficiently.Herein,we report a cubic fluorite-type praseodymium iridium oxide with the surface of IrO_(x)(IrO_(x)/Pr_(3)IrO_(7))that shows the improved activity and stability in 0.1 mol L^(-1) HClO_(4) solution,characterized by an overpotential of 305 mV at the benchmark of 10 mA cm^(-2) and a small Tafel slope of 37 mV dec^(-1),indicating a fast reaction kinetics and a competitive activity compared with the benchmark IrO_(2) and most reported electrocatalysts.The initial potential increases by less than 0.07 V after continuous OER testing over 60,000 s.In contrast,IrO_(2) becomes nearly inactive for the OER within 20,000 s.Density functional theory calculations uncover that the optimal energy level path follows lattice oxygen mechanism(LOM).This work enlarges the family of the IrO_(x)-type OER electrocatalyst in acid media.
非晶态铱氧化物(IrO_(x))在酸性介质中具有高的电催化析氧反应(OER)活性,但其稳定性不如商业IrO_(2).近年来,多种非贵金属-铱混合氧化物展现出高效催化析氧反应的性能.本文报道了一种含IrO_(x)高活性表面层的立方萤石结构镨铱氧化物(Pr_(3)IrO_(7))催化剂.该催化剂在0.1 mol L^(-1)HClO_(4)溶液中,表现出高的析氧反应催化活性和良好的稳定性,优于商业IrO_(2)和目前报道的大多数催化剂.在电流密度为10 mA cm^(-2)时,该催化剂的过电位为305 mV,并具有低的Tafel斜率,约为37 mV dec^(-1),表明该催化剂具有更快的反应动力学.在持续60000 s的稳定性测试后,该催化剂的初始电位仅增加了0.07 V,而IrO_(2)只经过20000 s测试就几乎丧失活性.密度泛函理论计算表明,IrO_(x)/Pr_(3)IrO_(7)催化析氧反应遵循晶格氧机理(LOM).这项工作拓展了IrO_(x)型酸性OER电催化剂的种类.
基金
supported by Taishan Scholar Program of Shandong Province,China(ts201712045)
Shandong Provincial Key Research and Development Program(SPKR&DP,2019GGX102069)
the Natural Science Foundation of Shandong Province of China(ZR2018BB008)
the Doctoral Found of Qingdao University of Science and Technology(0100229001,010029081,010029075)。
