Insight into methanol photooxidation over mono- (Au, Cu) and bimetallic (AuCu) catalysts supported on niobium pentoxide — An operando-IR study

Abstract

The aim of this study was to gain deeper insight into the factors determining the activity and selectivity of mono- (Au, Cu) and bimetallic (AuCu) catalysts supported on Nb2O5 in methanol photooxidation. For this purpose, the prepared catalysts were characterized with the use of XRD, nitrogen sorption, ICP-OES, UV–vis, XPS, TEM and FTIR spectroscopy. Photocatalytic activity of materials was evaluated with the use of operando-IR system under UV and visible light irradiation. It was demonstrated that under visible light irradiation, the decoration of the niobia with bimetallic nanoparticles of gold and copper led to a synergic enhancement of the photocatalyst performance relative that of monometallic and non-doped niobia photocatalysts, tested under the same reaction conditions. It was also demonstrated that selectivity over the bimetallic gold-copper/Nb2O5 catalyst was strongly affected by the nature of light source: visible light promoted a total oxidation versus a partial oxidation of methanol under UV light.