S‐Block Potassium Single‐atom Electrocatalyst with K−N<sub>4</sub> Configuration Derived from K<sup>+</sup>/Polydopamine for Efficient Oxygen Reduction
Niankun Guo, Hui Xue, Rui Ren, Jing Sun, Tianshan Song, Hongliang Dong, Zhonglong Zhao, Jiangwei Zhang, Qin Wang, Limin Wu
Abstract
Abstract Currently, single‐atom catalysts (SACs) research mainly focuses on transition metal atoms as active centers. Due to their delocalized s/p‐bands, the s‐block main group metal elements are typically regarded as catalytically inert. Herein, an s‐block potassium SAC (K−N−C) with K‐N 4 configuration is reported for the first time, which exhibits excellent oxygen reduction reaction (ORR) activity and stability under alkaline conditions. Specifically, the half‐wave potential ( E 1/2 ) is up to 0.908 V, and negligible changes in E 1/2 are observed after 10,000 cycles. In addition, the K−N−C offers an exceptional power density of 158.1 mW cm −2 and remarkable durability up to 420 h in a Zn‐air battery. Density functional theory (DFT) simulations show that K−N−C has bifunctional active K and C sites, can optimize the free energy of ORR reaction intermediates, and adjust the rate‐determining steps. The crystal orbital Hamilton population (COHP) results showed that the s orbitals of K played a major role in the adsorption of intermediates, which was different from the d orbitals in transition metals. This work significantly guides the rational design and catalytic mechanism research of s‐block SACs with high ORR activity.