Sulfur-regulated metal–support interaction boosting the hydrogen evolution performance of Ru clusters in seawater at industrial current densities†

Regulating the metal–support interaction (MSI) is an effective strategy to enhance the catalytic activity of electrocatalysts. Herein, taking Ru clusters as an example, we report a hybrid electrocatalyst with ultrafine Ru nanoclusters anchored on sulfur and nitrogen co-doped carbon (Ru/SNC) hollow spheres for efficient hydrogen evolution reaction (HER) in an alkaline electrolyte and real seawater. The optimal Ru/SNC hollow spheres on a glassy carbon electrode exhibit superior HER activity, with small overpotentials of only 12 and 30 mV to reach 10 mA cm⁻² in alkaline media and alkaline real seawater, respectively. When loaded on carbon paper, the Ru/SNC hollow spheres only need small overpotentials of 171 (in alkaline solution) and 205 mV (in alkaline real seawater) to deliver an industrial current density of 1000 mA cm⁻². Furthermore, the assembled Ru/SNC||RuO₂ electrolysis cell displays a high current density of 1000 mA cm⁻² at a cell voltage of 2.3 V and impressive stability up to 100 h at a current density of 1000 mA cm⁻² in alkaline real seawater at an elevated temperature of 80 °C. Density functional theory (DFT) calculations suggest that S-doping can induce a strong MSI between Ru clusters and the carbon support to boost the HER activity and stability. S-doping triggers the downshift of the d-band center, weakening the adsorption of H* on Ru clusters and thereby enhancing the hydrogen spillover.