Platinum single-atom catalyst with self-adjustable valence state for large-current-density acidic water oxidation
Hui Su, Mikhail A. Soldatov, Victor Roldugin, Qinghua Liu
Abstract
The design of active acidic oxygen evolution reaction (OER) catalysts is of paramount importance to achieve efficient large-current-density industrial hydrogen fuel production via water electrolysis. Herein, we develop a Pt-based catalyst with high electrochemical activity for the OER in acidic conditions under a large current. We achieve this by modulating the electronic structure of Pt into a high-valence, electron-accessible Pt1(2.4+δ)+ (δ = 0–0.7) state during the reaction. This electron-accessible Pt1(2.4+δ)+ single-site catalyst can effectively maintain a large OER current density of 120 mA cm−2 for more than 12 h in 0.5 M H2SO4 at a low overpotential of 405 mV, and it shows a high mass activity of ∼3350 A gmetal−1 at 10 mA cm−2 current density and 232 mV overpotential. Using in situ synchrotron radiation infrared and X-ray absorption spectroscopies, we directly observe in an experiment that a key (∗O)–Pt1–C2N2 intermediate is produced by the potential-driven structural optimization of square pyramidal Pt1–C2N2 moieties; this highly favors the dissociation of H2O over Pt1(2.4+δ)+ sites and prevents over-oxidation and dissolution of the active sites.