Hydrogen dissociation and CO2 activation in cascade CO2 fixation on PdIn/TiO2 catalyst

Abstract

Reduction of CO₂ emissions and conversion of CO₂ to valuable chemicals is an urgent mission, as it is vital to the global environment and sustainable development. The activation of CO₂ is always considered to be the key step for its transformation. Herein, we verified that the activation and dissociation behavior of H₂ was the controlling step for CO₂ reduction. PdIn alloy was an active center and played a pivotal role in CO₂ hydrogenation to the methyl reagent of HCOO∗. H₂ split to active H^δ− species on PdIn alloy sites. Strong nucleophilic H^δ− reacted with the CO₂ adsorbed on oxygen defects to form ∗HCOO in situ. A high yield of up to 99% was achieved for the cascade fixation of CO₂ to valuable amines. The new insights into the activation of CO₂ and H₂ and their contributions to CO₂ conversion that we present will attract the attention of researchers in catalysis, synthesis, surface, and interface chemistry.