Owing to the peculiar synergistic interaction between CuO and CeO 2 at the interface, CuO/CeO 2 is one of the most efficient catalysts to purify a H 2 source, which is used in a proton exchange membrane fuel cell by preferential oxidation (PROX) of CO. The defective structure in CeO 2 is considered to be a crucial factor affecting the synergistic interaction. However, the defect−interaction relationship has not been well established due to the complex variation in different types of defects. Therefore, in this study, a novel ultrasound-assisted precipitation method was used to separately modulate diverse types of defects. The structural variation was explored by characterization techniques and theoretical calculations. It was found that the synergistic interaction was mainly related to two-electron defects on the CeO 2 surface. The two-electron defects could absorb O 2 to form the η 2 peroxide, and Cu ions could incorporate with the η 2 peroxide. Then, the two additional electrons in the two-electron defects would induce the electronic redispersion in CuO/CeO 2 , synchronously producing Cu + and Ce 3+ . The resulting Cu + and Ce 3+ were related to unsaturated CuO and redox capacity, which intimately affected the CO adsorption and oxygen activation. Thus, the catalytic performance was significantly promoted by increasing the amount of twoelectron defects in CeO 2 . Our study not only demonstrates a feasible way to finely control the synergistic interaction between CuO and CeO 2 but also deeply reveals the direct influence of two-electron defects on the CeO 2 surface on PROX.

Different from the addition of promotor to bismuth molybdate to enhance its oxygen mobility in oxidative dehydrogenation (ODH) reaction, Bi2MoO6 nanosheet catalysts with different thickness were controllably synthesized via hydrothermal...

CuO/CeO2 with strong metal–support interaction was considered to be a highly efficient catalyst in the PROX (preferential CO oxidation) reaction. Multiple Cu species from this interaction were believed to play a key role in catalytic activity. However, due to the complex chemical properties of copper, there was still controversy about the nature of active sites in the PROX reaction. In this work, the types and proportion of Cu species (Cu–[O] x –Ce, amorphous CuO x , and aggregated CuO x ) could be well-controlled since CuO was loaded on surface-modified CeO2. Their properties were studied in detail through a series of characterizations. The Cu–[O] x –Ce structure was found to be the most favorable for preferential CO oxidation. While the amorphous CuO x cluster could facilitate CO oxidation, it would greatly reduce the selectivity. The aggregated CuO x caused by excessive CuO only had activity at high temperature, resulting in an upper limit of the CuO loading amount. The proportion of these Cu species varied with the CuO loading amount, and the catalytic performance was the synergetic result of all Cu species.