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

Abstract

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.