Deciphering the Electronic Coupling Dynamics of Laser‐induced Ru/Cu Electrocatalyst for Dual‐Side Hydrogen Production and Formic Acid Co‐synthesis via DFT Analysis

Herein, a straightforward approach using pulsed laser technology to synthesize selective hexagonal-close-packed (hcp) Ru nanoparticles attached to Cu nanospheres (Ru/Cu) as bifunctional electrocatalyst for catalyzing the hydrogen evolution reaction (HER) and formaldehyde oxidation reaction (FOR) are reported. Initially, Ru-doped CuO flakes are synthesized using a coprecipitation method followed by transformation into Ru/Cu composites through a strategy involving pulsed laser irradiation in liquid. Specifically, the optimized Ru/Cu-4 composite not only demonstrates a low overpotential of 182 mV at 10 mA·cm^-2 for the HER but also an ultralow working potential of 0.078 V (versus reversible hydrogen electrode) for the FOR at the same current density. Remarkably, the FOR∥HER-coupled electrolyzer employing the Ru/Cu-4∥Ru/Cu-4 system achieves H₂ production at both electrodes with a cell voltage of 0.42 V at 10 mA·cm^-2 while co-synthesizing formic acid. Furthermore, density functional theory analyses elucidate that the superior activity of the Ru/Cu composite originates from optimized adsorption energies of reactive species on the catalyst surfaces during the HER and FOR, facilitated by the synergistic coupling between Ru and Cu. This study presents an alternative strategy for synthesizing highly effective electrocatalytic materials for use in energy-efficient H₂ production with the cosynthesis of value-added chemicals suitable for practical applications.