Influence of Ni Addition on Au/CeO2 Photocatalysts for Solar Photocatalytic H2 Production by Glycerol Photoreforming

Abstract

Solar glycerol photoreforming was investigated on Au-Ni/CeO2 photocatalysts with an overall metal content equal to 1wt% and different Au/Ni weight ratios. The deposition of gold over ceria was performed by two different methods, deposition–precipitation and photoreduction. Deposition–precipitation was the best method to deposit gold on CeO2 with the formation of small Au nanoparticles (around 4 nm). The most active sample (0.9 wt% Au-0.1 Ni wt%/CeO2) provided a H2 production rate of 350 µmol/gcat∙h, much higher than the corresponding monometallic samples. A higher amount of Ni led to detrimental effects in H2 production, likely due to the covering of the gold surface active sites by Ni. On the contrary, the presence of a small amount of Ni (0.1 wt%) allowed a remarkable improvement of the Au/CeO2 photocatalytic stability after consecutive runs of simulated solar irradiation. This finding, as well as the activation of synergistic effects, the improved charge carrier separation, and the exploitation of the localized surface plasmon resonance property of gold, led to the proposal of an alternative photocatalytic system to the most investigated TiO2-based photocatalysts for H2 production. The enhanced stability is promising to further foster the investigation of these photocatalysts applied to sustainable H2 production.