Ordered PtMn Intermetallic with Electron‐Rich Pt Sites and Mn‐Facilitated H ₂ O Activation for Durable Alkaline Industrial Hydrogen Production

Abstract 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.