Fe–Co–P multi-heterostructure arrays for efficient electrocatalytic water splitting

Abstract

Rational design and construction of high-efficiency bifunctional catalysts for the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) is crucial for large-scale hydrogen production by water splitting. Herein, by a self-sacrificial template method, Fe–Co–P multi-heterostructure arrays consisting of CoP, Co₂P and FeP are built for water splitting. Such multi-heterostructures adjust the local electronic structure and then improve adsorption of reaction intermediates on active sites, which is further proved through density functional theory (DFT) calculations. Thus, without noble metals, the as-prepared Fe–Co–P multi-heterostructure catalyst exhibits very high catalytic performance, which only needs 227 and 87 mV to reach a current density of 20 and 10 mA cm⁻² for the OER and HER, respectively, better than most of the related catalysts reported so far. Moreover, when used in alkaline electrolyzers, it delivers a current density of 10 mA cm⁻² at a cell voltage of 1.55 V, superior to commercial Pt-group electrodes (1.59 V). Our work offers a novel approach to rationally design catalysts toward water splitting.