Dynamic evolution of single-atom Rh site and MoS2 support for hydrogen evolution

The dynamic evolution and structure-performance relationships of single-atom catalysts (SACs) under operating conditions are one of the most concerned hotspots at present. Here, we employed Anderson-type polyoxometalates as a precursor to prepare the SAC Rh-MoS₂, which shows excellent hydrogen evolution reaction (HER) performance with a mass activity of 4.26 A mg⁻¹ at 100 mV. Such a result is much better than that of 20% Pt/C. Extensive experimental characterization combined with density functional theory (DFT) calculations suggest that the active site undergoes a dynamic evolution from Rh-S to Rh-S/O, while at the same time, the support is transformed from 1T MoS₂ to 1T-2H MoS₂. It is this dynamic evolution of the catalyst structure that causes a series of changes in the activity, and eventually, a balance between catalytic activity and stability is achieved. This work offers a good research demonstration of the dynamic evolution of SACs under operating conditions and provides a new perspective on the design of SACs.