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 H₂SO₄ 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 H₂SO₄ 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.