Boosting CO ₂ Hydrogenation to Formate over Organometallic Catalyst via Pt Nanoparticle-Mediated H ₂ Activation

CO2 hydrogenation to formic acid/formate enables carbon-neutral energy systems by converting CO2 into a liquid hydrogen carrier, simultaneously achieving CO2 utilization and renewable H2 storage. Organometallic complexes stand out as efficient catalysts; however, enhancement of their H2 activation capability is accompanied by an increase in the binding energy of the M–H bond. This strengthened M–H interaction, in turn, poses a significant barrier to the subsequent CO2 insertion step, ultimately leading to a decline in catalytic activity. In this work, we propose a strategy to overcome this inherent trade-off by leveraging the synergistic effect between Pt nanoparticles (NPs) and an Ir complex, where the Pt NPs play a pivotal role in promoting H2 activation. Consequently, the formate yield on [Cp*Ir(6,6′-(OH)2-bpy)(H2O)]2+ was enhanced by a factor of 4.2 via the addition of Pt NPs. Mechanism investigations show that active hydrogen transfer from Pt to Ir contributes to a less-bound transition state, leading to the fast formation of Ir–H. This is further verified by Ir–H formation no longer being the rate-determining step in the presence of Pt NPs. The insights obtained herein hold promise to assist the development of an efficient hydrogenation system dominated by organometallic complexes beyond sophisticated ligand design and synthesis.