Distance Synergy of MoS -Confined Rhodium Atoms for Highly Efficient Hydrogen Evolution.

Perturbing the electronic structure of the MoS basal plane by confining heteroatoms offers the opportunity to trigger in-plane activity for the hydrogen evolution reaction (HER). The key challenge consists of inducing the optimum HER activity by controlling the type and distribution of confined atoms. A distance synergy of MoS -confined single-atom rhodium is presented, leading to an ultra-high HER activity at the in-plane S sites adjacent to the rhodium. By optimizing the distance between the confined Rh atoms, an ultra-low overpotential of 67 mV is achieved at a current density of 10 mA cm in acidic solution. Experiments and first-principles calculations demonstrate a unique distance synergy between the confined rhodium atoms in tuning the reactivity of neighboring in-plane S atoms, which presents a volcanic trend with the inter-rhodium distance. This study provides a new strategy to tailor the activity of MoS surface via modulating the distance between confined single atoms.