In Situ Transformation of Metal–Organic Frameworks into Hollow Nickel–Cobalt Double Hydroxide Arrays for Efficient Water Oxidation
Gao Li, Lei Lü, Lang Pei, Zhanfeng Ma, Yongjun Yuan, Mao‐Lin Hu, Qian Miao, Jiasong Zhong
Abstract
Developing earth-abundant electrocatalysts for efficient oxygen evolution reaction (OER) is of paramount significance for electrochemical water splitting. Herein, an efficient in situ etching–deposition growth strategy is employed to transform pristine two-dimensional (2D) Co-metal–organic frameworks into hollow Ni/Co double hydroxide arrays (denoted as Ni/Co-DH), which not only yields a larger surface area and exposes more active sites but also decreases the activation energy to the OER. With structural and compositional benefits, the Ni/Co-DH exhibits high performance with an overpotential of 229 mV at 10 mA cm–2 and exceptional long-term stability of over 90 h in 1 M KOH medium for OER, comparable to most non-noble oxygen evolution catalysts reported so far. In addition, a two-electrode Ni/Co-DH∥Pt/C electrolyzer also requires a considerably low voltage of 1.58 V at 10 mA cm–2 for overall water splitting. This study affords a rational strategy to develop water–alkali electrolyzers with great complexity for large-scale water-splitting systems.