Significant improvement in activity, durability, and light-to-fuel efficiency of Ni nanoparticles by La2O3 cluster modification for photothermocatalytic CO2 reduction

• Published in: Applied catalysis. B, Environmental Environmental, 2020-05, Vol.264, p.118544, Article 118544
• Main Authors: Zhang, Gequan, Wu, Shaowen, Li, Yuanzhi, Zhang, Qian
• Format: Article
• Language: English
• Subjects: Carbon; Carbon dioxide; Carbon monoxide; Catalytic activity; Clusters; CO2 reduction; Deposition; Disproportionation; Durability; Energy efficiency; Fuel consumption; Fuel economy; I.R. radiation; Irradiation; Labeling; Lanthanum oxides; Light-to-fuel efficiency; Methane; Nanocomposites; Nanoparticles; Photoactivation; Photocatalytic; Photothermocatalytic; Reduction; Silica; Silicon dioxide; Ultraviolet radiation
• ISSN: 0926-3373; 1873-3883
• DOI: 10.1016/j.apcatb.2019.118544

[Display omitted] •La2O3-Ni/SiO2 shows excellent catalytic activity and durability for photothermocatalytic CRM.•Both high fuel production rate and light-to-fuel efficiency are achieved.•La2O3 cluster modification promotes catalytic activity and durability of Ni nanoparticles.•A novel photoactivation is found to improve catalytic activity and restrain carbon deposition.•The origin of the role of La2O3 cluster modification and photoactivation are revealed. A novel nanocomposite of La2O3 cluster modified Ni nanoparticles loaded on mesoporous silica (Ni-La2O3/SiO2) was synthesized. Under focused UV–vis-IR irradiation, Ni-La2O3/SiO2 exhibits high production rates of CO (rCO) and H2 (rH2) (42.90 and 38.11 mmol min−1 g−1) for photothermocatalytic CO2 reduction by CH4 (CRM). A high light-to-fuel efficiency (η) of 20.3 % is achieved. Ni-La2O3/SiO2 also exhibits excellent photothermocatalytic durability. Its photothermocatalytic activity almost remains unchanged after reacted for 90 h. It is found for the first time that the photothermocatalytic activity, durability, and η value of Ni nanoparticles are substantially promoted by the La2O3 cluster modification. The results of TG-MS, TEM, XRD, isotope labelling experiment using 12CH4 and 12C18O2 as reactants, and Raman show that oxygen of La2O3 clusters in Ni-La2O3/SiO2 takes part in oxidization of carbon species formed by CH4 dissociation. This causes a substantial reduction in carbon deposition rate, thus promoting the catalytic activity and durability. It is found that the focused irradiation substantially decreases the apparent activation energy of CRM on Ni-La2O3/SiO2, thus promoting the catalytic activity. The new photoactivation also restrain CO disproportionation as major side-reaction of carbon deposition, thus decreasing the rate of carbon deposition.