Promotion effect of Nb5+ for Cu/CeO2 water–gas shift reaction catalyst by generating mobile electronic carriers

•Cu/CeO2 with high catalytic activity was fabricated by doping of Nb2O5.•Substitution of Nb5+ with Ce4+ results in creation of mobile electronic carriers.•The weak and medium basic sites are favor for the performance of Cu/CeO2 catalyst.

A series of CuO/CeO2 catalysts doping with Nb2O5 were fabricated by co-precipitation method. It is found that the introduction of Nb5+ will result in the substitution of Ce4+ with Nb5+, thus creating mobile electronic carriers in the as-prepared catalysts. The characterization results correlating with the catalytic activity evaluation disclose that the catalyst added with 1 wt. % Nb2O5 shows the most mobile electronic carries, certain amount of weak, medium basic sites and enhanced reducibility and chemical adsorption of CO, thus the best catalytic activity for water–gas shift reaction. However, excessive Nb2O5 addition prevents the incorporation of Cu2+ into CeO2 lattice and partially covers the surface of CuO and CeO2, resulting in weaken their reducibility and interaction between them, thus leading to inferior catalytic performance.

Graphical abstractCyclic voltammograms (A) and TPR profiles (B) of the CuO/CeO2–Nb2O5 catalysts: (a) Cu/CN-0, (b) Cu/CN-1, (c) Cu/CN-5, (d) Cu/CN-10. The reduction properties of CuO/CeO2 catalyst are greatly changed by introducing Nb2O5, particularly for the one doped with 1 wt. % Nb2O5. It was concluded that the mobile electronic carriers in CuO/CeO2 catalyst can be well modulated by the substitution of Nb5+ with Ce4+, thus resulting in the variation of their surface properties, the amount of mobile electronic carries, finally promoting their catalytic activities for water–gas shift reaction.Figure optionsDownload full-size imageDownload as PowerPoint slide