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

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.