A crystalline nanoparticle-decorated amorphous nanosheet CoEr@ErFeP@CoMo2S4 heterostructure electrocatalyst for highly efficient overall water splitting

Abstract

Crafting cost-effective bifunctional electrocatalysts capable of handling both the oxygen evolution reaction and the hydrogen evolution reaction is critical for advancing water-splitting technologies. Constructing amorphous–crystalline heterostructures has emerged as a promising strategy. In this work, a Co–Er-based amorphous/crystalline heterostructure (CoEr@ErFeP@CoMo₂S₄) fabricated on nickel foam (NF) via hydrothermal synthesis and subsequent phosphidation exhibits outstanding bifunctional electrocatalytic performance for both the OER and the HER. The optimized CoEr@ErFeP@CoMo₂S₄/NF catalyst requires overpotentials of only 171 mV for the OER and 135 mV for the HER to achieve a current density of 10 mA cm⁻². Furthermore, a complete water-splitting device employing CoEr@ErFeP@CoMo₂S₄/NF requires just 1.51 V to drive a current density of 10 mA cm⁻² while demonstrating excellent stability. The amorphous–crystalline heterointerface packs a double punch, offering a diverse array of active hotspots for both the oxygen evolution and hydrogen evolution reactions while also creating superhighways for charge transfer across the boundary, all of which gives the electrocatalytic reaction kinetics a serious boost. This research presents a clear-cut approach to manufacture highly effective and durable electrocatalysts on a grand scale, paving the way for efficient overall water splitting in alkaline environments.