Highly selective photocatalytic CO2 reduction to ethylene in pure water by Nb2O5 nanoparticles with enriched surface –OH groups under simulated solar illumination

Photocatalytic CO2 reduction to valuable chemical compounds could be a promising approach for carbon-neutral practice. In this work, a simple and robust thermal decomposition process was developed with ammonium carbonate ((NH4)2CO3) as both precipitation agent and sacrificial template to produce fine Nb2O5 nanoparticles with the rich existence of surface hydroxyl (–OH) groups. It was found by density functional theory (DFT) calculations and experiments that the rich existence of the surface –OH groups enhanced the adsorption of both reactants (CO2 and H2O molecules) for the photocatalytic CO2 reduction on these fine Nb2O5 nanoparticles, and the highly selective conversion of CO2 to the high-value chemical compound of ethylene (C2H4, ~68 μmol·g−1·h−1 with ~100% product selectivity) was achieved under simulated solar illumination without usage of any sacrificial agents or noble metal cocatalysts. This synthesis process may also be readily applied as a surface engineering method to enrich the existence of the surface –OH groups on various metal oxide-based photocatalysts for a broad range of technical applications.