Wan Hao, Chen Fashen, Ma Wei, Liu Xiaohe, Ma Renzhi
School of Chemical Engineering, Zhengzhou University, Zhengzhou 450001, PR China.
World Premier International Center for Materials Nanoarchitectonics (WPI-MANA), National Institute for Materials Science (NIMS), Namiki 1-1, Tsukuba, Ibaraki 305-0044, Japan.
Nanoscale. 2020 Nov 5;12(42):21479-21496. doi: 10.1039/d0nr05072e.
The electrocatalytic oxygen reduction reaction (ORR) is a crucial part in developing high-efficiency fuel cells and metal-air batteries, which have been cherished as clean and sustainable energy conversion devices/systems to meet the ever-increasing energy demand. ORR electrocatalysts currently employed in the cathodes of fuel cells and metal-air batteries are mainly based on high-cost and scarce noble metal elements. It is thus of great importance to develop cheap and earth-abundant ORR electrocatalysts. In this aspect, redox-active transition metal hydroxides, a class of multifunctional inorganic layered materials, have been proposed as prospective candidates on account of their abundance and high ORR activities. In this article, the preparation and structural evolution of transition metal hydroxides, in particular their exfoliation into two-dimensional (2D) nanosheets, as well as compositing/integrating with catalytic active and/or conductive components to overcome the insulating nature of hydroxides in alkaline ORR, are summarized. Recent advances have demonstrated that 2D transition metal hydroxides with carefully tuned compositions and elaborately designed nanoarchitectures can achieve both high activity and high pathway selectivity, as well as excellent stability comparable to those of commercial Pt/C electrocatalysts. To realize the dream of renewable electrochemical energy conversion, new strategies and insights into rational designing of 2D hydroxide-based nanostructures with further enhanced electrocatalytic performance are still to be vigorously pursued.
电催化氧还原反应（ORR）是开发高效燃料电池和金属空气电池的关键部分，这些电池一直被视为清洁且可持续的能量转换装置/系统，以满足不断增长的能源需求。目前用于燃料电池和金属空气电池阴极的ORR电催化剂主要基于高成本且稀缺的贵金属元素。因此，开发廉价且储量丰富的ORR电催化剂具有重要意义。在这方面，氧化还原活性过渡金属氢氧化物作为一类多功能无机层状材料，因其储量丰富和高ORR活性而被视为有前景的候选材料。在本文中，总结了过渡金属氢氧化物的制备和结构演变，特别是它们剥离成二维（2D）纳米片的过程，以及与催化活性和/或导电成分复合/整合以克服氢氧化物在碱性ORR中的绝缘性质。最近的进展表明，具有精心调整的组成和精心设计的纳米结构的二维过渡金属氢氧化物可以实现高活性和高路径选择性，以及与商业Pt/C电催化剂相当的优异稳定性。为了实现可再生电化学能量转换的梦想，仍需大力探索具有进一步增强电催化性能的二维氢氧化物基纳米结构的合理设计的新策略和见解。
