Electrostatic Self-Assembly Synthesis of Pd/In 2 O 3 Nanocatalysts with Improved Performance Toward CO 2 Hydrogenation to Methanol.

CO 2 hydrogenation to methanol has emerged as a promising strategy for achieving carbon neutrality and mitigating global warming, in which the supported Pd/In 2 O 3 catalysts are attracting great attention due to their high selectivity. Nonetheless, conventional impregnation methods induce strong metal-support interaction (SMSI) between Pd and In 2 O 3 , which leads to the excessive reduction of In 2 O 3 and the formation of undesirable PdIn alloy in hydrogen-rich atmospheres. Herein, we innovatively synthesized Pd/In 2 O 3 nanocatalysts by the electrostatic self-assembly process between surface-modified composite precursors with opposite charges. And the organic ligands concurrently serve as Pd nanoparticle protective agents. The resultant Pd/In 2 O 3 nanocatalyst demonstrates the homogeneous distribution of Pd nanoparticles with controllable sizes on In 2 O 3 supports and the limited formation of PdIn alloy. As a result, it exhibits superior selectivity and stability compared to the counterparts synthesized by the conventional impregnation procedure. Typically, it attains a maximum methanol space-time yield of 0.54 g MeOH  h -1 g cat -1 (300 °C, 3.5 MPa, 21,000 mL g cat -1  h -1 ). Notably, the correlation characterization results reveal the significant effect of small-size, highly dispersed Pd nanoparticles in mitigating MSI. These results provide an alternative strategy for synthesizing highly efficient Pd/In 2 O 3 catalysts and offer a new insight into the strong metal-support interaction.