Ultralow-temperature photochemical synthesis of atomically dispersed Pt catalysts for the hydrogen evolution reaction

Efficient control of nucleation is a prerequisite for the solution-phase synthesis of nanocrystals. Although the thermodynamics and kinetics of the formation of metal nanoparticles have been largely investigated, fully suppressing the nucleation in solution synthesis remains a major challenge due to the high surface free energy of isolated atoms. In this article, we largely decreased the reaction temperature for ultraviolet (UV) photochemical reduction of H₂PtCl₆ solution to -60 °C and demonstrated such a method as a fast and convenient process for the synthesis of atomically dispersed Pt. We showed that the ultralow-temperature reaction efficiently inhibited the nucleation process by controlling its thermodynamics and kinetics. Compared with commercial platinum/carbon, the synthesized atomically dispersed Pt catalyst, as a superior HER catalyst, exhibited a lower overpotential of approximately 55 mV at a current density of 100 mA cm^-2 and a lower Tafel slope of 26 mV dec^-1 and had higher stability in 0.5 M H₂SO₄.