Oxygen electrochemistry plays a key role in industrial hydrogen fuel production from water electrolysis, but the slow kinetics of anodic oxygen evolution reaction (OER) under large current density restricts the commercialization of such energy devices. Here, we design a new type of valence-variable metal-modified CuCo2S4 thiospinels, termed as v-M-CuCo2S4 (v-M=Mn, V, Cr), to achieve large-current-density OER performances. The introduction of valence-variable metals (v-M) can promote the generation of a special oxyhydroxide-like active phase with contractive interatomic Co‒Co distance, which breaks the limit of the inherent linear scaling relationship and causes the OER on v-M-CuCo2S4 to follow a more efficient oxide path mechanism. Therefore, the v-M-CuCo2S4, taking Mn-CuCo2S4 as a representative, delivers low overpotentials of 255 and 378 mV to achieve large current densities of 500 and 1500 mA cm-2 in alkaline electrolytes. The optimal catalyst shows a large mass activity of 3000 A gmetal-1 and a high turnover frequency of 16500 h-1 at a low overpotential of 378 mV (1500 mA cm-2), tens of times larger than commercial RuO2. The design principle provides some hints for optimizing the abundant spinel materials as large current density OER catalysts.
