Ultrathin Metal Silicate Hydroxide Nanosheets with Moderate Metal–Oxygen Covalency Enables Efficient Oxygen Evolution

Abstract Exploring efficient, cost‐effective, and durable electrocatalysts for electrochemical oxygen evolution reaction (OER) is pivotal for the large‐scale application of water electrolysis. Recent advance has demonstrated that the activity of electrocatalysts exhibits a strong dependence on the surface electronic structure. Herein, a series of ultrathin metal silicate hydroxide nanosheets (UMSHNs) M3Si2O5(OH)4 (M = Fe, Co, and Ni) synthesized without surfactant are introduced as highly active OER electrocatalysts. Cobalt silicate hydroxide nanosheets show an optimal OER activity with overpotentials of 287 and 358 mV at 1 and 10 mA cm−2, respectively. Combining experimental and theoretical studies, it is found that the OER activity of UMSHNs is dominated by the metal–oxygen covalency (MOC). High OER activity can be achieved by having a moderate MOC as reflected by a σ*‐orbital (eg) filling near unity and moderate [3d]/[2p] ratio. Moreover, the UMSHNs exhibit favorable chemical stability under oxidation potential. This contribution provides a scientific guidance for further development of active metal silicate hydroxide catalysts.