New Design and Construction of Abundant Active Surface Interfacial Copper Entities in Cu<sub><i>x</i></sub>Ce<sub>1–<i>x</i></sub>O<sub>2</sub> Nanorod Catalysts for CO-PROX
Zhihuan Qiu, Xiaolin Guo, Jianxin Mao, Renxian Zhou
Abstract
Composite CuxCe1–xO2 nanorod catalysts with abundant Cu–Ce interface for CO preferential oxidation are synthesized via a one-pot co-precipitation method at ambient temperature, and then copper species are induced to migrate and enrich on the surface and subsurface of CuxCe1–xO2 by thermal treatment. The best low temperature catalytic activity (T50% = 77 °C) and widest operation window (95–150 °C) are achieved by thermal treatment at 700 °C. With the thermal treatment temperature increasing from 200 to 700 °C, first Cu–Ce solid solution forms (at 400 °C), then Cu species migrate to the surface and subsurface of CuxCe1–xO2 nanorods, forming a lattice relaxation layer containing abundant highly dispersed CuOx species and strongly bonded Cu–[Ox]–Ce species, whose thickness is gradually reduced but the tightness is increased, thus strengthening the Cu–Ce interaction. The amount changing and redox process of the active copper entities respectively involving low and high temperature CO-PROX reaction are in-depth clarified.