武汉大学罗威团队报道了分子间能隙诱导在钴硫化物上的CoOOH表层形成高价钴物种以实现高效水氧化。相关研究成果于2022年1月17日发表在《德国应用化学》。

过渡金属基电催化剂将通过表面重构以形成活性羟基杂化物，这被认为是析氧反应（OER）的“真正催化剂”。人们在理解表面重建方面投入了大量的精力，但在确定由基底效应产生的增强性能的来源方面却很少。

该文中，研究人员报道了在各种硫化钴（CoSα）表面上电化学合成非晶态CoOOH层，发现CoOOH的价带最大值（VBM）和CoSα的导带最小值（CBM）之间减小的分子间能隙（Δinter）可以加速形成更活泼的高价Co⁴⁺物种。电化学和原位光谱方法（包括循环伏安法（CV）、操作电子顺磁共振（EPR）和拉曼光谱）综合研究表明，与CoOOH和其他CoOOH/CoSα中的Co物种相比，CoOOH/CO9S8中的Co物种更容易氧化为COO2/CO9S8。该工作为过渡金属基OER电催化剂提供了新的设计原则。

附：英文原文

Title: Intermolecular Energy Gap-Induced Formation of High-Valent Cobalt Species in CoOOH Surface Layer on Cobalt Sulfides for Efficient Water Oxidation

Author: Na Yao, Gongwei Wang, Hongnan Jia, Jinlong Yin, Hengjiang Cong, Shengli Chen, Wei Luo

Issue&Volume: 2022-01-17

Abstract: Transition metal-based electrocatalysts will undergo surface reconstruction to form active oxyhydroxide-based hybrids, which have been regarded as the “true-catalysts” for oxygen evolution reaction (OER). Much effort has been devoted to understanding the surface reconstruction, but little on identifying the origin of enhanced performance derived from substrate effect. Herein, we report the electrochemical synthesis of amorphous CoOOH layers on the surface of various cobalt sulfides (CoS  α  ), and identify that the reduced intermolecular energy gap (Δ  inter  ) between valence band maximum (VBM) of CoOOH and conduction band minimum (CBM) of CoS  α  can accelerate the formation of OER active high-valent Co  4+  species. The combination of electrochemical and  in situ  spectroscopic approaches, including cycle voltammetry (CV),  operando  electron paramagnetic resonance (EPR) and Raman, reveals that Co species in the CoOOH/Co  9  S  8  is more readily oxidized to CoO  2  /Co  9  S  8  than in CoOOH and other CoOOH/CoS  α  . This work provides a new design principle for transition metal-based OER electrocatalysts.

DOI: 10.1002/anie.202117178

Source: https://onlinelibrary.wiley.com/doi/10.1002/anie.202117178