Triangular-ordered Co atoms activate substrates for ampere-level durable hydrogen production

Practical electrolyzer-level hydrogen production, exemplified by alkaline anion exchange membrane (AEM) ones, typically operates at harsh conditions, e.g., high-current densities (> 1 A cm^-2) and long-term duration, which present significant challenges for the durability of catalysts. These challenges are amplified in atomically dispersed catalysts due to their weak point-to-point interactions. Here, we present an atom-ordering strategy to fabricate Co triangular orders that enable the activation of the substrate for durable AEM electrolyzers. We demonstrate that Co atoms thermodynamically favor triangular arrangements within the VN lattice, which are successfully synthesized via a photo-induced self-assembly method. This Co-triangular order enables the activation of adjacent V atoms, driving the exponential propagation of active sites for hydrogen production under high currents. Notably, this catalyst exhibits an extended linear region in the Tafel slope and performs stably at a current density of 1 A cm^-2. The assembled AEM water electrolyzer achieves a cell voltage of 1.97 V with long-term operational durability. Our work provides a strategy for designing atom-ordered catalysts that strike a balance between activity and long-term stability under industrial operating conditions.