Highly selective photocatalytic CO 2 reduction to ethylene in pure water by Nb 2O 5 nanoparticles with enriched surface –OH groups under simulated solar illumination

Abstract

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 as both the precipitation agent and sacrificial template to produce fine Nb₂O₅ nanoparticles with a rich existence of surface -OH groups. It was found by Density Functional Theory (DFT) calculations and experiments that the rich existence of surface -OH groups enhanced the adsorption of both reactants (CO₂ and H₂O molecules) for the photocatalytic CO₂ reduction on these fine Nb₂O₅ nanoparticles, and a highly selective conversion of CO₂ to a high value chemical compound of ethylene (~ 68 mmol·g^-1·h^-1 with ~ 100% product selectivity) was achieved under simulated solar illumination without the 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 surface -OH groups on various metal oxide-based photocatalysts for a broad range of technical applications.