Outer delocalized electron aggregation of bromide bridged core–shell CuBr@C for hydrogen evolution reaction

Modulation of the surface electron distribution is a challenging problem that determines the adsorption ability of catalytic process. Here, we address this challenge by bridging the inner and outer layers of the core–shell structure through the bridge Br atom. Carbon shell wrapped copper bromide nanorods (CuBr@C) are constructed for the first time by chemical vapour deposition with hexabromobenzene (HBB). HBB pyrolysis provides both bridge Br atom and C shells. The C shell protects the stability of the internal halide structure, while the bridge Br atom triggers the rearrangement of the surface electrons and exhibits excellent electrocatalytic activity. Impressively, the hydrogen evolution reaction (HER) activity of CuBr@C is significantly better than that of commercial N-doped carbon nanotubes, surpassing commercial Pt/C at over 200 mA·cm⁻². Density functional theory (DFT) calculations reveal that bridge Br atoms inspire aggregation of delocalized electrons on C-shell surfaces, leading to optimization of hydrogen adsorption energy.