Understanding of Oxygen Redox in the Oxygen Evolution Reaction

Abstract

The electron‐transfer process during the oxygen evolution reaction (OER) often either proceeds solely via a metal redox chemistry (adsorbate evolution mechanism (AEM), with metal bands around the Fermi level) or an oxygen redox chemistry (lattice oxygen oxidation mechanism (LOM), with oxygen bands around the Fermi level). Unlike the AEM, the LOM involves oxygen redox chemistry instead of metal redox, which leads to the formation of a direct oxygen–oxygen (OO) bond. As a result, such a process is able to bypass the rate‐determining step, that is, OO bonding, in AEM, which highlights the critical advantage of LOM as compared to the conventional AEM. Thus, it has been well reported that LOM‐based catalysts are able to demonstrate higher OER activities as compared to AEM‐based catalysts. Here, a comprehensive understanding of the oxygen redox in LOM and all documented and possible characterization techniques that can be used to identify the oxygen redox are reviewed. This review will interpret the origins of oxygen redox in the reported LOM‐based electrocatalysts and the underlying science of LOM‐induced surface reconstruction in transition metal oxides. Finally, perspectives on the future development of LOM electrocatalysts are also provided.

Doping engineering: modulating the intrinsic activity of bifunctional carbon-based oxygen electrocatalysts for high-performance zinc–air batteries

“…Theoretical calculations show that the too weak binding strength of the oxygen-containing adsorbed state will cause the oxidation of HO* to become the rate-controlling step. 34 At the same time, the too strong binding strength of the oxygen-containing adsorbed state will cause the formation of HOO* to become the rate-controlling step. 35 Fig.…”

Tuning OER Electrocatalysts toward LOM Pathway through the Lens of Multi-Descriptor Feature Selection by Artificial Intelligence-Based Approach

“…The OER reaction takes place through the two possible reaction pathways (Figures and ), namely adsorbate evolution mechanism (AEM) and lattice oxygen mediated mechanism (LOM). ,− The AEM involves adsorption and decomposition of water molecules on the surface metal ion to produce proton (H + ) and HO*. The HO* further dissociates to release the second proton and transform into O* in the second cyclic step.…”

“…The evolution of O 2 molecules proceeds through a coupling process between adsorbed O* and surface lattice O leaving behind the surface oxygen vacancy. The cycle completes with the restoration of surface lattice by successive H 2 O adsorption and dissociation over the vacancy . In alkaline medium, a consensus is that AEM and LOM are thermodynamically combined .…”

“…The cycle completes with the restoration of surface lattice by successive H 2 O adsorption and dissociation over the vacancy. 43 In alkaline medium, a consensus is that AEM and LOM are thermodynamically combined. 50 As shown in Figure 2a, the conventional AEM assumes that the O 2 evolution takes place only around the metal active center.…”

Recent Advances and Future Prospects on Industrial Catalysts for Green Hydrogen Production in Alkaline Media

“…。因此，可以对低成本的AEM电解槽进行制 造，并有助于发展稳定的产氢能力，增加耐久性， 并提高固定式、便携式和运输式发电系统的能源 效率 16,17 20 。实验结果表明， 大多数电催化剂在碱性介质(pH = 13)中的HER活 性比在酸性介质(pH = 1)中低2-3个数量级 21,22 公式(7-10)是假设AEM涉及四个连续的质子-电子转移步骤，发生在单金属活性位点(M)上 53,57 : 58 。因此， 催化剂表面释放、交换、氧化晶格氧配体是提供 OER循环的必要条件 59 。一旦晶格氧引入循环， OH/H 2 O物种将结合在氧空位位点，作为新的"晶 格氧"进入下一个循环。因此，晶格氧激活是LOM 途径能够成功触发的先决条件 60,61 体对垒所带来的高过电势屏障，而且通过优化氧 空位的数量， 能够有效促进晶格氧机制的进行。 同 样地，Wang等 84…”