Ordered PtMn Intermetallic with Electron‐Rich Pt Sites and Mn‐Facilitated H₂O Activation for Durable Alkaline Industrial Hydrogen Production

Platinum (Pt)‐based catalysts are recognized as highly efficient electrocatalysts for the hydrogen evolution reaction (HER), primarily due to their moderate adsorption energy for *H intermediates. However, the weak adsorption of H 2 O and high dissociation energy barrier in alkaline media hinder the overall catalytic efficiency of Pt‐based catalysts. Herein, ordered PtMn and Pt 3 Mn intermetallic compounds on carbon black (i.e., PtMn/C and Pt 3 Mn/C), demonstrating exceptional HER performance in both alkaline and acidic electrolytes, are designed and synthesized. Notably, the prepared PtMn/C with electron‐rich Pt sites exhibits superior HER performance, achieving a low overpotential of 17 mV at 10 mA cm −2 in alkaline media, outperforming Pt 3 Mn/C (21 mV), commercial Pt/C (27 mV), and most previously reported HER electrocatalysts. Density functional theory calculations demonstrate that incorporated Mn enhances H 2 O adsorption and reduces the energy barrier of H 2 O dissociation. Meanwhile, the electron transfer from Mn to Pt downshifts the d‐band center of Pt, thereby optimizing the *H adsorption energy and facilitating H 2 desorption, which synergistically boosts alkaline HER performance. Additionally, PtMn/C is integrated into an anion exchange membrane water electrolyzer, demonstrating exceptional performance with a current density of 1 A cm −2 at only 1.77 V and exhibiting negligible degradation over 500 h of continuous operation.