Search

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‐N4 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 (E1/2) is up to 0.908 V, and negligible changes in E1/2 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. [ABSTRACT FROM AUTHOR]

Defect and interface engineering are recognized as effective strategies to regulate electronic structure and improve activity of metal sulfide. However, the practical application of sulfide is restricted by their low conductivity and rapid decline in activity derived from large volume fluctuation during electrocatalysis process. More importantly, the determination of exact active site of sulfide is complicated due to the inevitable electrochemical reconstruction. Herein, ZnS nanoparticles with Zn defect are anchored onto the surface of NiCo2S4 nanosheet to construct NiCo2S4/ZnS hybrids, which exhibit outstanding oxygen evolution performance with an ultralow overpotential of 140 mV. The anchoring of defective ZnS nanoparticles inhibit the volume expansion of NiCo2S4 nanosheet during the cycling process. Density‐functional theory reveals that the build‐in interfacial potential and Zn defect can facilitate the thermodynamic formation of *O to *OOH, thus improve their intrinsic activity. [ABSTRACT FROM AUTHOR]

Vacancy defects of catalysts have been extensively studied and proven to be beneficial to various electrocatalytic reactions. Herein, an ultra‐stable three‐dimensional PtCu nanowire network (NNW) with ultrafine size, self‐supporting rigid structure, and Cu vacancy defects has been developed. The vacancy defect‐rich PtCu NNW exhibits an outstanding performance for the oxygen reduction reaction (ORR), with a mass activity 14.1 times higher than for the commercial Pt/C catalyst (20 %.wt, JM), which is currently the best performance. The mass activity of the PtCu NNW for methanol oxidation reaction (MOR) is 17.8 times higher than for the commercial Pt/C catalyst. Density‐functional theory (DFT) calculations indicate that the introduction of Cu vacancies enhances the adsorption capacity of Pt atoms to the HO* intermediate and simultaneously weakens the adsorption for the O* intermediate. This work presents a facile strategy to assemble efficient electrocatalysts with abundant vacancy defects, at the same time, provides an insight into the ORR mechanism in acidic solution. [ABSTRACT FROM AUTHOR]