Confining ultrafine Pt nanoparticles on In2O3 nanotubes for enhanced selective methanol production by CO2 hydrogenation

A novel Pt@In2O3 catalyst assembled from ultrafine Pt nanoparticles confined on In2O3 nanotubes is fabricated from in situ topological transformation of H2PtCl6-soaked In-MIL-68 in an air atmosphere, which exhibits high performance for methanol production by CO2 hydrogenation. The Pt@In2O3 catalyst is revealed to exhibit a strong confinement effect to stabilize the interaction between Pt and In2O3, affording improvements in methanol production, selectivity, and stability, compared with bare In2O3 nanotubes and the Pt/In2O3 catalyst made by directly loading Pt species on In2O3 nanotubes. The optimal Pt@In2O3 catalyst shows a high methanol yield of 29.0 mmol g(-1) h(-1) and a selectivity of 73% at 260 degrees C, together with a catalytic turnover number (TON) of 4128 based on the Pt species. Such a methanol production activity is about 2 times that of the commercial Cu/ZnO/Al2O3 catalyst and surpasses that of state-of-the-art In2O3-supported catalysts. Diverse techniques including aberration-corrected scanning transmission electron microscopy (AC-STEM), temperature-programmed desorption (TPD) of H-2 and CO2, and in situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) are used to demonstrate the crucial confinement effect of the In2O3 substrate on the Pt species for promoting the CO2-to-methanol conversion. This work may motivate the employment of MOFs to pre-anchor metal precursors for the on site construction of supported catalysts with intimate contact and tailorable compositions for high-efficiency CO2 conversion reactions.