Uncovering near-free platinum single-atom dynamics during electrochemical hydrogen evolution reaction.

ABSTRACT: Single-atom catalysts offering intriguing activity and selectivity are subject of intense investigation. Understanding the nature of single-atom active site and its dynamics under working state are crucial to improving their catalytic performances. Here, we identify at atomic level a general evolution of single atom into a near-free state under electrocatalytic hydrogen evolution condition, via operando synchrotron X-ray absorption spectroscopy. We uncover that the single Pt atom tends to dynamically release from the nitrogen-carbon substrate, with the geometric structure less coordinated to support and electronic property closer to zero valence, during the reaction. Theoretical simulations support that the Pt sites with weakened Pt-support interaction and more 5d density are the real active centers. The single-atom Pt catalyst exhibits very high hydrogen evolution activity with only 19?mV overpotential in 0.5?M H2SO4 and 46?mV in 1.0?M NaOH at 10?mA?cm-2, and long-term durability in wide-pH electrolytes.

SUBMITTER: Fang S 

PROVIDER: S-EPMC7042219 | biostudies-literature | 2020 Feb

REPOSITORIES: biostudies-literature