Intermediate State of Dense Ru Assembly Captured by High-Temperature Shock for Durable Ampere-Level Hydrogen Production

Green hydrogen, generated through water electrolysis using renewable electricity, serves as an environmentally sustainable energy carrier. However, affordable transition metal catalysts require a significant overpotential to sustain the H 2 production at a high current density (>500 mA cm –2 ) over an extended duration. In this study, we employ the high-temperature shock (HTS) method to fabricate densely assembled ruthenium (Ru) nanoparticles and single atoms on porous carbon (DA-Ru NP+SA /C), achieving a high metal loading of up to 85.5 wt %. Microscopic and spectroscopic results confirm the coexistence of nanoparticles and single atoms embedded in the porous carbon matrix. Short reaction time during HTS guarantees the controllable migration of Ru atoms over the carbon matrix, effectively suppressing the vicious aggregation into larger particles at high temperatures. High temperature reinforces the interaction between metal and substrate, benefiting the structural robustness and electron transfer at the interface. Both experimental and theoretical analyses of the reaction mechanism propose that Ru nanoparticles serve as catalytic sites, while single atoms modulate the electronic structure of Ru nanoparticles to regulate their water dissociation capability and optimize hydrogen adsorption energy. Consequently, the DA-Ru NP+SA /C catalyst delivers an ultralow overpotential of 13 mV at 10 mA cm –2 and remarkable durability. It sustains continuous operation for 550 h at a current density of 1 A cm –2 in an alkaline solution, surpassing the stability of almost all previously reported Ru-based catalysts.