Liao Huanyun, Guo Xingzhong, Hou Yang, Liang Hao, Zhou Zheng, Yang Hui
State Key Laboratory of Silicon Materials, School of Materials Science and Engineering, Zhejiang University, Hangzhou, 310027, P. R. China.
Key Laboratory of Biomass Chemical Engineering of Ministry of Education, College of Chemical and Biological Engineering, Zhejiang University, Hangzhou, 310027, P. R. China.
Small. 2020 Mar;16(10):e1905223. doi: 10.1002/smll.201905223. Epub 2020 Feb 12.
Designing elaborate nanostructures and engineering defects have been promising approaches to fabricate cost-efficient electrocatalysts toward overall water splitting. In this work, a controllable Prussian-blue-analogue-sacrificed strategy followed by an annealing process to harvest defect-rich Ni-Fe-doped K MnO cubic nanoflowers (Ni-Fe-K MnO CNFs-300) as highly active bifunctional catalysts for oxygen and hydrogen evolution reactions (OER and HER) is reported. Benefiting from many merits, including unique morphology, abundant defects, and doping effect, Ni-Fe-K MnO CNFs-300 shows the best electrocatalytic performances among currently reported Mn oxide-based electrocatalysts. This catalyst affords low overpotentials of 270 (320) mV at 10 (100) mA cm for OER with a small Tafel slope of 42.3 mV dec , while requiring overpotentials of 116 and 243 mV to attain 10 and 100 mA cm for HER respectively. Moreover, Ni-Fe-K MnO CNFs-300 applied to overall water splitting exhibits a low cell voltage of 1.62 V at 10 mA cm and excellent durability, even superior to the Pt/C||IrO cell at large current density. Density functional theory calculations further confirm that doping Ni and Fe into the crystal lattice of δ-MnO can not only reinforce the conductivity but also reduces the adsorption free-energy barriers on the active sites during OER and HER.
设计精细的纳米结构和引入工程缺陷一直是制备用于全水解的经济高效电催化剂的有效方法。在这项工作中，报道了一种可控的普鲁士蓝类似物牺牲策略，随后进行退火处理，以制备富含缺陷的镍铁掺杂锰酸钾立方纳米花（Ni-Fe-KMnO CNFs-300）作为用于析氧反应和析氢反应（OER和HER）的高活性双功能催化剂。得益于独特的形貌、丰富的缺陷和掺杂效应等诸多优点，Ni-Fe-KMnO CNFs-300在目前报道的基于锰氧化物的电催化剂中表现出最佳的电催化性能。该催化剂在10（100）mA cm²的析氧反应中提供270（320）mV的低过电位，塔菲尔斜率为42.3 mV dec⁻¹，而析氢反应分别需要116和243 mV的过电位才能达到10和100 mA cm²。此外，应用于全水解的Ni-Fe-KMnO CNFs-300在10 mA cm²时表现出1.62 V的低电池电压和优异的耐久性，甚至在大电流密度下优于Pt/C||IrO₂电池。密度泛函理论计算进一步证实，将镍和铁掺杂到δ-MnO₂的晶格中不仅可以增强导电性，还可以降低析氧反应和析氢反应过程中活性位点上的吸附自由能垒。
