Directional Growth and Density Modulation of Single-Atom Platinum for Efficient Electrocatalytic Hydrogen Evolution.

Dispersion of single atoms (SAs) in the host is important for optimizing catalytic activity. Herein, we propose a novel strategy to tune oxygen vacancies in CeO 2-X directionally anchoring the single atom platinum (Pt SA ), which is uniformly dispersed on the rGO. The catalyst's performance for the hydrogen evolution reaction (HER) can be enhanced by controlling different densities of CeO 2-X in rGO. The Pt SA performs best optimally densified and loaded on homogeneous and moderately densified CeO 2-X /rGO (Pt SA -M-CeO 2-X /rGO). It exhibited higher activity in HER with an overpotential of 25 mV at 0.5 M H 2 SO 4 and 33 mV at 1 KOH than that of almost reported electrocatalysts. Furthermore, it exhibited stability for 90 hours at -100 mA cm -2 in 1 KOH and -150 mA cm -2 in 0.5 M H 2 SO 4 conditions, respectively. Through comprehensive experiments and theoretical calculations, the suitable dispersion density of Pt SA on the defects of CeO 2-X with more active sites gives the potential for practical applications. This research paves the way for developing single-atom catalysts with exceptional catalytic activity and stability, holding promise in advanced green energy conversion through defects engineering.