Optimizing heterointerface of NiCoP–Co/MXene with regulated charge distribution via built-in electric field for efficient overall water-splitting

Abstract

The quest for sustainable energy solutions has intensified the need for efficient water electrolysis techniques, pivotal for hydrogen production. However, developing effective bifunctional electrocatalysts capable of driving the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) remains a formidable challenge. Addressing this, we introduce a novel built-in electric field (BEF) strategy to synthesize NiCoP–Co nanoarrays directly on Ti₃C₂T_x MXene substrates (NiCoP–Co/MXene). This approach leverages a significant work function difference (ΔΦ), propelling these nanoarrays as adept bifunctional electrocatalysts for comprehensive water splitting. MXene, in this process, plays a dual role. It acts as a conductive support, enhancing the catalyst’s overall conductivity, and facilitates an effective charge transport pathway, ensuring efficient charge transfer. Our study reveals that the BEF induces an electric field at the interface, prompting charge transfer from Co to NiCoP. This transfer modulates asymmetric charge distributions, which intricately control intermediates’ adsorption and desorption dynamics. Such regulation is crucial for enhancing the reaction kinetics of both HER and OER. Furthermore, under oxidative conditions, the NiCoP–Co/MXene catalyst undergoes a structural metamorphosis into Ni(Co) oxides/hydroxides/MXene, increasing OER performance. This research demonstrates the BEF’s role in fine-tuning interfacial charge redistribution and underscores its potential in crafting more sophisticated electrocatalytic designs. The insights gained here could pave the way for the next generation of electrocatalysis, with far-reaching implications for energy conversion and storage technologies.

Graphical abstract