Designing coral-like Fe2O3-regulated Se-rich CoSe2 heterostructure as a highly active and stable oxygen evolution electrocatalyst for overall water splitting

Abstract

The electrocatalytic oxygen evolution reaction (OER) is the bottleneck to overall water splitting because of the slow kinetics of the four-electron transfer process. Therefore, it is of great significance to develop OER electrocatalysts with high activity, long durability, and scalability. Herein, we present a selenium-coated cobalt selenide (CoSe2@Se) catalyst that was first synthesized by in-situ growth on carbon cloth (CC) surface by hydrothermal method, followed by soaking treatment to prepare a three-dimensional coral-like Fe2O3-CoSe2@Se/CC composite. Electrochemical studies revealed that the optimized Fe2O3-CoSe2@Se/CC catalyst only requires 250 mV to reach 10 mA cm−2 current density, yields a small Tafel slope (50.2 mV dec−1), and has good stability (10 mA cm−2@70 h) in the electrocatalytic OER process. The overall water splitting using Fe2O3-CoSe2@Se/CC as anode only requires 1.58 and 1.69 V to achieve 10 and 100 mA cm−2, respectively, much better than most previously reported catalysts. Analysis showed that the three-dimensional coral-like morphology exposing more active sites and the synergy between different species (giving rise to, inter alia, a favorable electronic structure that lowers the electrode overpotential) are the key to the observed improved electrocatalytic performance. This work provides a novel strategy for the rational design of nanostructured OER hybrid catalysts in the future.