Volcanic Relationship Between Hydrogen Binding Energy and Acidic Hydrogen Evolution in Single‐Atom Alloy Catalysts

Abstract Generally fabricating single‐atom alloys (SAAs) remains a major challenge. Herein, a SAAs library of PdM 1 (M = Os, Ir, Pt, Au, Pb, and Bi) is constructed and uncovered a volcano‐type relationship between hydrogen evolution reaction (HER) activity and hydrogen binding energy (HBE). Remarkably, PdPt 1 SAAs, located at the top of the volcano plot, only require 10 mV at 10 mA cm −2 and exhibit 32.9 times higher intrinsic activity than commercial Pt/C in acidic condition. Moreover, PdPt 1 SAAs assembled in the proton exchange membrane water electrolyzer can maintain superior durability over 1000 h under the industrial current density of 1500 mA cm −2 . In situ spectroscopy measurements show PdPt 1 SAAs with moderate HBE display the fastest hydrogen adsorption and desorption kinetics in the SAAs library. Further theoretical calculations reveal PdPt 1 SAAs exhibit a moderate d ‐band center value, which leads to an optimal Pt─H bond strength and thus significantly lowers the Tafel step barrier during acidic HER. Finally, this approach is extended to prepare the other five additional binary, ternary, and high‐entropy Pd‐based SAAs.