Synergistic upcycling of Pt/Pd and graphite from city mines for highly efficient seawater hydrogen evolution catalysis†

Abstract

Seawater electrolysis presents a promising approach for the sustainable production of green hydrogen. However, developing low-cost and highly stable electrocatalysts remains a critical challenge. Herein, we developed a waste materialization strategy to directly construct a novel Pt/Pd@SOG electrocatalyst from a recycled automobile catalyst and graphite anode. The as-fabricated catalyst exhibited superior performance in alkaline seawater electrolysis, delivering a low overpotential of 195 mV and 333 mV at current densities of 10 mA cm⁻² and 100 mA cm⁻² for the hydrogen evolution reaction (HER), respectively, outperforming commercial Pt/C (228 mV and 372 mV). A state-of-the-art turnover frequency (TOF) of 43.745 s⁻¹ was achieved. Additionally, the catalyst demonstrated exceptional stability at a current density of 100 mA cm⁻² for over 192 hours. A comprehensive characterization and mechanistic study reveals that the graphene-based material provides a fast electron transport pathway and guarantees excellent electron conductivity to the catalytic active center, while the d–d orbital coupling between Pt and Pd within the as-synthesized Pt/Pd@SOG significantly lowers the energy barrier for electron transfer during catalytic reaction and stabilizes the adsorption of intermediates at the Pt sites, thus promoting the HER. This research demonstrates a rapid valorization pathway for synergistically materializing multiple city mine wastes for advanced seawater electrocatalysts, which synergistically addresses the critical element cycling challenge and paves the way for sustainable energy catalysis.