Local Electric Fields Coupled with Cl<sup>−</sup> Fixation Strategy for Improving Seawater Oxygen Reduction Reaction Performance
Yu‐Rong Liu, Miao Zhang, Yanhui Yu, Yalin Liu, Jing Li, Xiaodong Shi, Zhenye Kang, Daoxiong Wu, Peng Rao, Ying Liang, Xinlong Tian
Abstract
Development of robust electrocatalyst for oxygen reduction reaction (ORR) in a seawater electrolyte is the key to realize seawater electrolyte-based zinc-air batteries (SZABs). Herein, constructing a local electric field coupled with chloride ions (Cl−) fixation strategy in dual single-atom catalysts (DSACs) was proposed, and the resultant catalyst delivered considerable ORR performance in a seawater electrolyte, with a high half-wave potential (E1/2) of 0.868 V and a good maximum power density (Pmax) of 182 mW·cm−2 in the assembled SZABs, much higher than those of the Pt/C catalyst (E1/2: 0.846 V; Pmax: 150 mW·cm−2). The in-situ characterization and theoretical calculations revealed that the Fe sites have a higher Cl− adsorption affinity than the Co sites, and preferentially adsorbs Cl− in a seawater electrolyte during the ORR process, and thus constructs a low-concentration Cl− local microenvironment through the common-ion exclusion effect, which prevents Cl− adsorption and corrosion in the Co active centers, achieving impressive catalytic stability. In addition, the directional charge movement between Fe and Co atomic pairs establishes a local electric field, optimizing the adsorption energy of Co sites for oxygen-containing intermediates, and further improving the ORR activity.