Anchoring Ultralow Platinum by Harnessing Atomic Defects Derived from Self‐reconstruction for Alkaline Hydrogen Evolution Reaction

Abstract The sluggish kinetics of alkaline hydrogen evolution reaction (HER) hinders practical exploitation of water splitting. Catalysts, known as platinum single atoms (Pt‐SAs) anchored in Ni₄Mo/Ni alloys on nickel foam (Pt SAs‐Ni₄Mo/Ni@NF) with ultralow Pt mass loading (m_Pt = 0.3 wt.%) derived from self‐reconstruction, with boosted atomic utilization in alkaline HER are demonstrated. In situ characterizations confirm the leaching of Mo species during the self‐reconstruction of NiMoO₄, which facilitates the anchoring of Pt‐SAs through the generation of atomic defects. Further, density functional theory (DFT) calculations indicate that the atomic defects can effectively capture Pt²⁺ in salt solution, aiding in the distribution of Pt‐SAs. Besides, theoretical results emphasize that Pt SAs‐Ni₄Mo/Ni with unique Pt‐Ni interaction can accelerate the desorption of hydroxides in alkaline electrolytes during HER, as well as lower energy barriers for reaction steps. Pt SAs‐Ni₄Mo/Ni@NF shows remarkable catalytic activity toward alkaline HER with a low overpotential of 17 mV (j = 10 mA cm⁻²), together with high atomic utilization of Pt (8.92 A mg_Pt⁻¹ at 30 mV) and excellent durability. This work not only provides a scalable preparation for efficient and robust low‐Pt catalysts but also establishes in‐depth understanding of the synergistic interaction between Pt SAs and Ni‐Mo alloys in alkaline HER, which is likely to accelerate the development of water‐splitting technique.