Atomically dispersed platinum supported onto nanoneedle-shaped protonated polyaniline for efficient hydrogen production in acidic water electrolysis

Developing high-performance single-atom platinum (Pt) catalysts for acidic hydrogen evolution reaction (HER) is of significance. However, their HER kinetics are limited due to the low concentration of hydrogen ions (H+) near the Pt sites in acidic electrolytes, where hydronium ions are undesirably formed with H+ surrounded by water molecules. Here, we seek to improve the HER kinetics by anchoring single-atom Pt catalyst on nanoneedle-shaped protonated polyaniline supports, which can not only capture H+ from the hydronium ions but also facilitate the electroreduction of H+ by promoting the electron accumulation. As a result, the turnover frequency of single-atom Pt supported on the nanoneedle-shaped protonated polyaniline is appreciably enhanced, compared with that of the single-atom Pt supported on the flat-shaped protonated polyaniline. By combining the X-ray photoelectron spectroscopy, finite-element simulation and electrochemical studies, we find that the enhanced HER activity of single-atom Pt on nanoneedle-shaped protonated polyaniline support may arise from a hydrogen spillover pathway induced by the increased local concentration of H+ near the Pt sites.