Engineered interfaces in indium-hafnium oxide catalysts unlock superior methanol productivity

Indium–zirconium oxides (InZrOx) rank among the most selective and stable catalysts for CO2 hydrogenation to methanol. Yet, despite extensive research, the exceptional promotional effect of monoclinic zirconia (m-ZrO2) remains under debate and unsurpassed. Here, we show that monoclinic hafnium oxide (m-HfO2), a wide bandgap material underexplored in heterogeneous catalysis, can exceed this benchmark. Nanostructured indium-hafnium oxides (InHfOx) prepared via flame spray pyrolysis achieve up to 70% higher indium-specific methanol productivity than InZrOx, with the strongest promotional effect observed for atomically dispersed indium species. Complementary experimental and theoretical analyses reveal that enhanced stability of the monoclinic support surface, flexible chemical potential of indium single atoms, and a favourable hydride–proton reservoir in InHfOx act cooperatively to promote CO2 activation and intermediate hydrogenation. Precise control over the support surface hydroxylation is, however, essential. These findings establish a new benchmark for green methanol synthesis and provide generalizable principles for oxide–oxide interface engineering in catalyst design.