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

Selective CO 2 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/TiO 2 catalyst by encapsulating in an in situ-created, robust carbon layer for boosting CO 2 conversion and CO selectivity. Mechanistic studies reveal that this catalyst follows an oxygen-vacancy-mediated redox pathway that spatiotemporally decouples CO 2 and H 2 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 TiO 2 surface, serves as a hydrogen spillover highway that generates abundant and distal oxygen vacancies on TiO 2, thereby driving efficient CO 2 dissociation. While ensuring effective H 2 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/TiO 2 catalyst to sustain equilibrium CO 2 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.