Non-layered dysprosium oxysulfide as an electron-withdrawing chainmail for promoting electrocatalytic oxygen evolution

Summary Rare-earth doping is an efficient strategy to elevate the oxygen evolution reaction activity of transition-metal-based electrocatalysts, yet it often leads to deleterious electrochemical corrosion. Here, we introduce non-layered dysprosium oxysulfide (Dy 2 O 2 S) to a cobalt catalyst to address this issue. Benefiting from an electron-withdrawing Dy 2 O 2 S shell, the optimum chainmail-structured catalyst displays low overpotentials of 225 ± 1 and 299 ± 5 mV at 0.1 and 1.0 A·cm −2 , respectively, for the oxygen evolution reaction under industrially relevant conditions. Moreover, Dy 2 O 2 S blocks the dissolution of dysprosium and cobalt, endowing the catalyst with almost 100% activity retention for at least 120 h at 1 A·cm −2 . A variety of in situ / ex situ characterization techniques and theoretical calculations unveil the active sites and the interfacial electron redistribution, which facilitate the oxygen intermediate adsorption and oxygen desorption. This work provides a route to utilize rare-earth elements to optimize the performance of electrocatalysts.