High-stability electrocatalytic CO2 reduction in seawater over heterostructure Cu–Bi nanosheets with H-spillover effect

Abstract

Direct electrocatalytic CO₂ reduction in seawater to produce valuable products offers significant advantages for CO₂ mitigation and minimizes the use of freshwater resources or electrolytes. Nevertheless, the complexity and high concentration of ions in seawater can lead to the corrosion of catalysts, posing challenges to their activity and stability. This study presents a kind of ultrathin heterostructure Cu–Bi nanosheet (Cu/BMO NSs) for CO₂ electroreduction by embedding copper nanoparticles (Cu NPs) in Bi₂MoO₆ nanosheets (BMO NSs), which feature abundant active sites, high chemical stability, a strong H-spillover effect and favorable electron transfer during the electrocatalytic process, leading to superior CO₂ reduction performance in seawater. Remarkably, in natural seawater, the faradaic efficiency for HCOOH (FE_HCOOH) can remain above 90% (−1.0 V) over 50 h of electrocatalysis. The achieved performance is superior to that of almost all the electrocatalysts reported for electrocatalytic CO₂ reduction in seawater. Theoretical calculations reveal that the introduction of Cu NPs could induce an H-spillover effect in Cu/BMO NSs to facilitate the water dissociation process when reacting with CO₂ to form the key intermediate *OCHO and subsequently hydrogenate to produce HCOOH. This work would promote the development of sustainable electrocatalytic technology in seawater.