Better than Pt in all-pH media: A charge transfer modulating hydrogen adsorption in cobalt-rhodium alloy aerogel to boost hydrogen evolution

In this study, a series of X-Rh (X = Fe, Co, Ni) alloy aerogels (AGs) are constructed via a galvanic replacement strategy. Due to the optimized electronic structure and the unique features of metal aerogel, the resultant Co AG-Rh500 electrocatalyst exhibits much better HER activity and robust stability than the benchmark commercial Pt/C catalyst in all-pH media. Theoretical result further reveals that the top sites of Co and Rh atoms in the (0   0   1) and (1   0   0) surfaces of the hybrid CoRh alloy systems can act as the active sites especially in an acidic condition, while the bridge and hollow sites on the (0   0   1) and (1   0   0) surfaces of CoRh alloy contribute a lot to the superior HER kinetics in alkaline and neutral electrolytes. Furthermore, the apparent electron transfer between Co and Rh atoms modulates the adsorption state of H*, thereby promoting the HER performance.