Surface engineering of cobalt silicate nanobelts boosting electrocatalytic water-splitting properties

The development of highly efficient and low-cost electrocatalysts for water splitting represents a crucial yet challenging research objective, particularly due to the requirement for precise control over composition and structure through surface engineering strategies. Cobalt silicate (denoted as CS) has been considered as a promising oxygen evolution reaction (OER) catalyst, however, its overpotential ( η ) is comparatively high and it is important practical significance to reduce η . Herein, we propose a surface engineering approach to optimize the electronic structure of CS by encapsulating it with a Co-zeolitic imidazolate framework (Co-ZIF), forming a CS/Co-ZIF composite (denoted as CS-Z). The experimental data demonstrates that the geometric effect and the introduced active sites are benefit for more active sites exposing, as well as that the DFT results prove that Co-ZIF encapsulation guarantees quick kinetics and enhances the conductivity, resulting in boosting OER properties. At 10 mA cm −2 , CC-Z2 reaches the η of 295 mV, and this value is lower than the values of most metal silicates. CS-Z2||CS-Z2 system even exhibits the overall water splitting (OWS) properties with a low voltage of 1.42 V at 10 mA cm −2 . The underlying mechanisms for the enhanced electrocatalytic performance are systematically discussed. The current research work offers a potential strategy for the exploration of high-efficient electrocatalysts based on silicates through surface engineering strategy, which will shed light on developing future renewable energy conversion technologies. • A surface engineering is developed to modulate electronic structure of CoSi with developed electrical conductivity. • The Co-ZIF is introduced on the surface of CoSi to form CS-Z as the electrocatalyst. • The geometric effect and synergistic effect are benefit for more active sites exposing and activity of Co sites improving. • CS-Z2 archives the lowest η of 295 mV at 10 mA cm −2 , which is superior to the state-of-the-art OER electrocatalysts.