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 (VO_x) 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 VO_x 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 VO_x for CO₂ adsorption. This work demonstrates the potential of liquid-Bi-based catalysts for selective and efficient CO₂-to-syngas conversion.