Shang Xiao, Liu Zi-Zhang, Zhang Jia-Qi, Dong Bin, Zhou Yu-Lu, Qin Jun-Feng, Wang Lei, Chai Yong-Ming, Liu Chen-Guang
State Key Laboratory of Heavy Oil Processing, Institute of New Energy , China University of Petroleum (East China) , Qingdao 266580 , PR China.
Shandong Key Laboratory of Biochemical Analysis, College of Chemistry and Molecular Engineering , Qingdao University of Science and Technology , Qingdao 266042 , PR China.
ACS Appl Mater Interfaces. 2018 Dec 12;10(49):42217-42224. doi: 10.1021/acsami.8b13267. Epub 2018 Nov 27.
The traditional synthesis for bimetallic-based electrocatalysts is challengeable for fine composition and elemental distribution because of the uncontrollable growth speed of nanostructures utilizing metal salt precursors. Herein, a unique electrochemical corrosion engineering strategy is developed via electrochemically transforming metal solid substrates (iron foil and nickel foam) into a highly active Ni-Fe oxide film for oxygen evolution, rather than directly utilizing metal ion precursors. This synthesis involves electrochemical corrosion of a Fe foil in an aqueous electrolyte along with electrochemical passivation of Ni foam (NF). The released trace Fe ions gradually incorporate into passivated NF surfaces to construct Ni-Fe oxide film and crucially improve composition distribution in the catalyst film. As a result, the resulted film with an ultralow mass loading (0.22 mg cm) delivers large current densities of 500 mA cm at overpotential of only 270 mV in 6.0 M KOH at 60 °C, outperforming many reported NiFe catalysts requiring much higher mass loadings. More interestingly, the as-prepared catalyst almost reaches the standard (500 mA cm within the overpotential of 300 mV) in commercial water electrolysis with long-term stability for at least 10 h. This work may provide a unique synthesis strategy for nonprecious transition-metal catalysts for desirable water splitting and can be expanded to many other electrocatalysis systems.
由于利用金属盐前驱体时纳米结构的生长速度不可控，传统的双金属基电催化剂合成在精细组成和元素分布方面具有挑战性。在此，开发了一种独特的电化学腐蚀工程策略，通过将金属固体基底（铁箔和泡沫镍）电化学转化为用于析氧的高活性Ni-Fe氧化物薄膜，而不是直接使用金属离子前驱体。这种合成方法包括在水性电解质中对铁箔进行电化学腐蚀以及对泡沫镍（NF）进行电化学钝化。释放出的微量铁离子逐渐融入钝化的NF表面，以构建Ni-Fe氧化物薄膜，并关键地改善了催化剂薄膜中的组成分布。结果，所得薄膜具有超低的质量负载（0.22 mg/cm²），在60°C的6.0 M KOH中，在仅270 mV的过电位下就能提供500 mA/cm²的大电流密度，优于许多报道的需要更高质量负载的NiFe催化剂。更有趣的是，所制备的催化剂在商业水电解中几乎达到了标准（在300 mV的过电位内达到500 mA/cm²），并具有至少10小时的长期稳定性。这项工作可能为用于理想水分解的非贵金属过渡金属催化剂提供一种独特的合成策略，并可扩展到许多其他电催化系统。
