Dynamic dual-atom synergistic catalysis boosted by liquid metal for direct seawater electroreduction

Abstract

Ga-based liquid metal is an ideal matrix to dissolve and disperse other metal atoms for catalysis. Seawater electrolysis is a promising alternative technology for hydrogen production in the crisis of freshwater resources. Herein, we prepared a dynamic Co, Pt dual-atom synergistic catalyst by dispersing Co and Pt atoms in a Ga-based liquid metal (denoted as Ga–CoPt). Liquid Ga boosts the dispersion, mobility and synergy of Co and Pt atoms and leads to a dramatic increase in the catalytic performance for direct seawater electroreduction. Specifically, compared with solid Ga–CoPt, liquid Ga–CoPt shows much higher activity and stability in the hydrogen evolution reaction at 100 mA cm⁻² for 169 h in natural seawater with a lower overpotential (249 mV at 10 mA cm⁻²) and Tafel slope (145 mV dec⁻¹). Furthermore, atomically dispersed Co, Pt atoms in liquid Ga provide more active sites at the interface of Ga–CoPt under low contents of Co (5 wt%) and Pt (1 wt%). The fluidity of liquid Ga and the mobility of Co, Pt atoms enhance the replenishment and regeneration of active sites in liquid Ga–CoPt, which simultaneously promote the catalytic activity and stability. Moreover, the synergy of the Co and Pt atoms in liquid Ga is confirmed, with the Co atom as the active site for water splitting and some generated H species being adsorbed by the Pt atom to form H*. At the same time, the other generated H species are combined with adjacent H₂O, generating H₃O⁺. Subsequently, the adsorbed H* reacts with H₃O⁺ to generate H₂via the Heyrovsky step.