Electronic-state engineering of two-dimensional electrocatalytic interfaces for clean-energy conversion

Two-dimensional (2D) materials have been extensively explored in electrocatalysis owing to their atomic-scale thickness, high surface exposure, tunable structures, and versatility in constructing hybrid interfaces. Beyond conventional structural optimization, recent studies have shown that 2D electrocatalysts can be engineered as electronically tunable interfaces, where finite density of states (DOS), quantum capacitance, Fermi-level modulation, localized electronic states, interlayer coupling, and moiré electronic structures provide new degrees of freedom for regulating electrochemical reactions. These electronic parameters can directly influence interfacial electron transfer, potential distribution, electric-double-layer structure, local electric fields, adsorption energetics, and proton-coupled electron-transfer processes, thereby regulating interfacial reaction pathways and ultimately determining catalytic activity and selectivity. This review summarizes the emerging concept of electronic-state engineering in 2D electrocatalytic interfaces, moving beyond conventional structure-based design toward electronically tunable hybrid interfaces for clean-energy conversion. We discuss static and dynamic strategies for regulating electronic states, including doping, defects, phase engineering, strain, heterointerfaces, electrostatic gating, ionic modulation, and interlayer charge transfer. The effects of these strategies on representative clean-energy reactions, including hydrogen evolution reaction, carbon dioxide reduction reaction, oxygen reduction reaction, oxygen evolution reaction, and photoelectrochemical transformations, are systematically discussed. Finally, key design principles and challenges are highlighted for developing stable and electronically controllable 2D electrocatalytic interfaces.