Interface engineering of Rh cluster-anchored MoN@Co₄C core-shell heterostructures for efficient overall water splitting

Rational interface engineering is an effective strategy for overcoming the activity‒stability trade-off in bifunctional water-splitting. Herein, density functional theory calculations were employed to investigate Rh clusters (8.06 at%) anchored on a MoN@Co₄C core‒shell heterostructure. The results reveal an interface-induced charge polarization mechanism in which Rh cluster exhibit heterogeneous charge redistribution depending on their local coordination environments through strong coupling with the MoN shell, enhancing cluster stability, whereas surface Rh atoms retain metallic characteristics favourable for catalytic turnover. Bader charge analysis supports this dual-role electronic configuration, which may promote the adsorption of reaction intermediates at Rh active sites. Consequently, Rh-MoN@Co₄C exhibits a near-thermoneutral hydrogen adsorption free energy of ΔG_H* = −0.094 eV and an AEM-based theoretical OER overpotential of 0.396 V. Ab initio molecular dynamics simulations at 500 K indicate short-timescale dynamic stability within the simulated conditions, highlighting Rh-MoN@Co₄C as a theoretically promising bifunctional electrocatalyst model for overall water splitting.