Polydopamine Nanocages Orchestrate Multi-Site Networks on the Ni 4 Mo Electrocatalyst for Efficient and Ultrastable Hydrogen Evolution

Breaking the activity-stability trade-off remains a formidable challenge in the pursuit of nonprecious metal electrocatalysts for water splitting. Here, we report a programmable electrochemical assembly of wet-adhesive polydopamine (PDA) nanocages on Ni4Mo alloys to enhance the hydrogen evolution reaction (HER). We demonstrate that the catechol groups strongly coordinate with Ni/Mo active sites, reinforcing interfacial adhesion and suppressing metal dissolution under harsh electrochemical conditions. Benefiting from a porous rigid-flexible nanocage architecture, the Ni4Mo@PDA electrode operates stably for 3000 h at 500 mA cm-2 with a low HER overpotential of 125 mV in alkaline electrolyte and for over 500 h in anion exchange membrane water electrolyzers. First-principles calculations unravel the formation of a multisite catalytic network that reconfigures the interfacial energetics of HER intermediates through PDA-mediated Ni and Mo coordination. By leveraging biomimetic PDA nanocages, this study underscores the importance of interfacial buffering toward efficient and durable electrocatalysis on nonprecious alloys.