Highly selective photocatalytic CO_(2) reduction to ethylene in pure water by Nb_(2)O_(5) nanoparticles with enriched surface –OH groups under simulated solar illumination

Photocatalytic CO_(2) 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 Nb_(2)O_(5) 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(CO_(2) and H_(2)O molecules)for the photocatalytic CO_(2) reduction on these fine Nb_(2)O_(5) nanoparticles,and the highly selective conversion of CO_(2) to the high-value chemical compound of ethylene(C_(2)H_(4),~68μmol·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.

Creation of Sn_(x)Nb_(1−x)O_(2) solid solution through heavy Nb-doping in SnO_(2) to boost its photocatalytic CO_(2) reduction to C_(2+) products under simulated solar illumination

Photocatalytic CO_(2)reduction driven by green solar energy could be a promising approach for the carbon neutral practice.In this work,a novel defect engineering approach was developed to form the Sn_(x)Nb_(1-x)O_(2)solid solution by the heavy substitutional Nb-doping of SnO_(2)through a robust hydrothermal process.The detailed analysis demonstrated that the heavy substitution of Sn^(4+)by a higher valence Nb^(5+)created a more suitable band structure,a better photogenerated charge carrier separation and transfer,and stronger CO_(2)adsorption due to the presence of abundant acid centers and excess electrons on its surface.Thus,the Sn_(x)Nb_(1-x)O_(2)solid solution sample demonstrated a much better photocatalytic CO_(2)reduction performance compared to the pristine SnO_(2)sample without the need for sacrificial agent.Its photocatalytic CO_(2)reduction efficiency reached~292.47μmol/(g·h),which was 19 times that of the pristine SnO_(2)sample.Furthermore,its main photocatalytic CO_(2)reduction product was a more preferred multi-carbon(C_(2+))compound of C_(2)H_(5)OH,while that of the pristine SnO_(2)sample was a one-carbon(C1)compound of CH_(3)OH.This work demonstrated that,the heavy doping of high valence cations in metal oxides to form solid solution may enhance the photocatalytic CO_(2)reduction and modulate its reduction process,to produce more C_(2+)products.This material design strategy could be readily applied to various material systems for the exploration of high-performance photocatalysts for the solar-driven CO_(2)reduction.