新加坡国立大学Xue Junmin团队报道了可逆NiO6几何转化在析氧过程中的关键作用。相关研究成果于2022年10月26日发表于国际一流学术期刊《自然》。
通过改变费米能级周围的电子状态，在氧释放反应中实现有效的电子转移过程，对于开发高性能和鲁棒的电催化剂至关重要。通常，电子转移仅通过金属氧化还原化学（吸附质释放机制（AEM），费米能级周围有金属带）或氧氧化还原化学（晶格氧氧化机制（LOM），费米能级附近有氧带），而在相同的电子转移路径中不会同时出现金属和氧的氧化还原化学。
该文中，研究人员报道了一种电子转移机制，该机制涉及以光为触发物的氢氧化镍基材料中可切换的金属和氧氧化还原化学。与传统的AEM和LOM不同，所提出的光触发耦合析氧机制，要求单元电池在八面体（NiO6）和正方形平面（NiO4）之间进行可逆的几何转换，以在整个析氧过程中实现具有交替金属和氧特征的电子态（费米能级附近）。利用这一电子转移途径可以绕过潜在的限制步骤，即AEM中的氧-氧键合和LOM中的脱质子化。通过这一途径运行的电催化剂与之前报道的电催化剂相比显示出优异的活性。因此，预计所提出的光触发耦合氧释放机制将为氧释放研究领域增加一层理解。
附：英文原文
Title: Pivotal role of reversible NiO6 geometric conversion in oxygen evolution
Author: Wang, Xiaopeng, Xi, Shibo, Huang, Pengru, Du, Yonghua, Zhong, Haoyin, Wang, Qing, Borgna, Armando, Zhang, Yong-Wei, Wang, Zhenbo, Wang, Hao, Yu, Zhi Gen, Lee, Wee Siang Vincent, Xue, Junmin
Issue&Volume: 2022-10-26
Abstract: Realizing an efficient electron transfer process in the oxygen evolution reaction by modifying the electronic states around the Fermi level is crucial in developing high-performing and robust electrocatalysts1,2,3. Typically, electron transfer proceeds solely through either a metal redox chemistry (an adsorbate evolution mechanism (AEM), with metal bands around the Fermi level) or an oxygen redox chemistry (a lattice oxygen oxidation mechanism (LOM), with oxygen bands around the Fermi level), without the concurrent occurrence of both metal and oxygen redox chemistries in the same electron transfer pathway1,2,3,4,5,6,7,8,9,10,11,12,13,14,15. Here we report an electron transfer mechanism that involves a switchable metal and oxygen redox chemistry in nickel-oxyhydroxide-based materials with light as the trigger. In contrast to the traditional AEM and LOM, the proposed light-triggered coupled oxygen evolution mechanism requires the unit cell to undergo reversible geometric conversion between octahedron (NiO6) and square planar (NiO4) to achieve electronic states (around the Fermi level) with alternative metal and oxygen characters throughout the oxygen evolution process. Utilizing this electron transfer pathway can bypass the potential limiting steps, that is, oxygen–oxygen bonding in AEM and deprotonation in LOM1,2,3,4,5,8. As a result, the electrocatalysts that operate through this route show superior activity compared with previously reported electrocatalysts. Thus, it is expected that the proposed light-triggered coupled oxygen evolution mechanism adds a layer of understanding to the oxygen evolution research scene.
DOI: 10.1038/s41586-022-05296-7
Source: https://www.nature.com/articles/s41586-022-05296-7