Dual-Vacancy Synergy in Vertically Aligned In ₂ O ₃ –MoS ₂ for High-Efficiency CO ₂ Hydrogenation to Methanol

In recent years, In 2 O 3 catalysts have demonstrated high selectivity for CO 2 -to-methanol conversion at elevated temperatures, while MoS 2 exhibits high activity at lower temperatures. Herein, we engineer a vertically aligned In 2 O 3 –MoS 2 nanocomposite through crystal phase and interface engineering. The vertical growth of MoS 2 nanosheets on In 2 O 3 enhances interfacial electron transfer and creates abundant sulfur and oxygen vacancies, which synergistically promote the formation of the key intermediate HCOO* for methanol synthesis. Spectroscopic studies and density functional theory calculations confirm that the vertically aligned interface strengthens the CO 2 adsorption and lowers the energy barrier for HCOO* formation. The hexagonal-phase In 2 O 3 –MoS 2 -h catalyst exhibits improved stability and performance, achieving a methanol selectivity of 78.2% and a space-time yield of 0.80 g MeOH g cat. –1 h –1 at 260 °C, outperforming both In 2 O 3 -based and MoS 2 -based benchmarks. In situ and quasi-in situ characterizations reveal that the hexagonal In 2 O 3 phase suppresses structural reconstruction into inactive In 2 (MoO 4 ) 3, thereby preserving active vacancies during the prolonged reaction. This work highlights the crucial role of vertically oriented heterostructures and dual-vacancy synergy in the design of efficient CO 2 hydrogenation catalysts.