Amine functionalized surface frustrated Lewis pairs boost CO2 photocatalysis

The archetype surface frustrated Lewis pair (SFLP) that facilitates CO2 photocatalytic hydrogenation to methanol and carbon monoxide, is an InOH & ctdot;In site positioned in the surface of a nanoscale indium oxide hydroxide, denoted In2O3-x(OH)y. Proximal Lewis acid In(iii) and Lewis base InOH of this genre serve as surface active sites that enable the photochemical heterolytic H2 dissociation and reduction of CO2 to the mentioned products. The conversion rate enabled by light has been found to far exceed that enabled by heat. Efforts to enhance the CO2 photocatalytic performance of the SFLP have involved modifications of the Lewis acidity and basicity through isomorphic substitution of In(iii) with Bi(iii) and changes in the population of oxygen vacancies through control of oxide non-stoichiometry. Replacement of the Lewis base hydroxide InOH by the stronger Lewis base amine InNH2 heretofore remains unexplored. The strategy described herein to explore this opportunity begins with the synthesis of In2O3-x(EDA)y. This new material is proven to contain an InNH2 & ctdot;In SFLP and its CO2 photocatalytic performance is demonstrated to outperform that of its In2O3-x(OH)y progenitor. Tailored Lewis acidity and basicity surfaces bring CO2 photocatalysis another step closer to the vision of solar CO2 refineries.