A Robust Carbon Overlayer as Hydrogen Spillover Highway and CO-Binding Barrier Enhances Reverse Water-Gas Shift

Selective CO₂ hydrogenation into CO via the reverse water-gas shift (RWGS) reaction is a pivotal route for large-scale carbon abatement, yet it remains hindered by the scarcity of efficient and scalable catalysts. Here, we report the construction of a high-performance Ni/TiO₂ catalyst by encapsulating in an in situ-created, robust carbon layer for boosting CO₂ conversion and CO selectivity. Mechanistic studies reveal that this catalyst follows an oxygen-vacancy-mediated redox pathway that spatiotemporally decouples CO₂ and H₂ activation, thereby offering a straightforward route to mitigate the activity-selectivity trade-off inherent in RWGS catalysis. The carbon overlayer, featuring a substantially lower hydrogen diffusion barrier than the bare TiO₂ surface, serves as a hydrogen spillover highway that generates abundant and distal oxygen vacancies on TiO₂, thereby driving efficient CO₂ dissociation. While ensuring effective H₂ activation through the formed surface Ni-C species, the carbon overlayer suppresses CO adsorption on Ni by blocking charge transfer, thus inhibiting the undesirable side reactions of methanation and CO disproportionation. This dual functionality enables the carbon-coated Ni/TiO₂ catalyst to sustain equilibrium CO₂ conversion with a near-100% CO selectivity for over 500 h under industrially relevant conditions, outperforming the majority of previously developed catalysts. Decorating an economical and effective carbon layer for geometric and electronic tuning provides a promising avenue for the design of novel hydrogenation catalysts.