Liquid Bismuth Catalyst Enables High-CO-Selectivity in CO2 Hydrogenation.

Here, we introduce a dynamic liquid-bismuth (Bi) catalyst that exploits a reversible Bi3+/Bi0 redox cycle to address the challenge of poor CO selectivity in the reverse water-gas shift (RWGS) reaction at moderate temperatures. Molten Bi nanodroplets were stabilized via in situ confinement during H2-induced reduction of a BiVO4 precursor, resulting in their firm anchoring on a defective vanadium oxide (VOx) support while preserving dynamic surface mobility at 400°C, striking a balance between stability and fluidity. Combined mechanistic studies and DFT calculations revealed that Ni-Bi dual sites on oxygen-deficient VOx facilitate an H2-assisted redox mechanism: Bi sites enable direct CO2 dissociation and weak CO* binding, favoring rapid CO desorption, while the Ni cocatalyst promotes H2 dissociation and induces electron enrichment of VOx for CO2 adsorption. This work demonstrates the potential of liquid-Bi-based catalysts for selective and efficient CO2-to-syngas conversion.