Pits confined in ultrathin cerium(IV) oxide for studying catalytic centers in carbon monoxide oxidation

Abstract

Finding ideal material models for studying the role of catalytic active sites remains a great challenge. Here we propose pits confined in an atomically thin sheet as a platform to evaluate carbon monoxide catalytic oxidation at various sites. The artificial three-atomic-layer thin cerium(IV) oxide sheet with approximately 20% pits occupancy possesses abundant pit-surrounding cerium sites having average coordination numbers of 4.6 as revealed by X-ray absorption spectroscopy. Density-functional calculations disclose that the four-and five-fold coordinated pit-surrounding cerium sites assume their respective role in carbon monoxide adsorption and oxygen activation, which lowers the activation barrier and avoids catalytic poisoning. Moreover, the presence of coordination-unsaturated cerium sites increases the carrier density and facilitates carbon monoxide diffusion along the two-dimensional conducting channels of surface pits. The atomically thin sheet with surface-confined pits exhibits lower apparent activation energy than the bulk material (61.7 versus 122.9 kJ mol À 1 ), leading to reduced conversion temperature and enhanced carbon monoxide catalytic ability.

Fabrication of Ce-doped MnO2decorated graphene sheets for fire safety applications of epoxy composites: flame retardancy, smoke suppression and mechanism

“…55 Moreover, the presence of cerium can improve the oxygen storage capacity of the catalyst through the transformation between Ce 4+ and Ce 3+ under controlled conditions, which promotes the catalytic ability of the catalyst. 56,57 Therefore, it is reasonable to believe that the catalytic effect of CeMnO2 plays an important role in the elimination of volatile organic compounds and toxic gases. The reduction of the volatile organic compounds and toxic gases in the smoke and gases will be beneficial to fire rescue when an accident occurs.…”

X-ray absorption fine structure spectroscopy in nanomaterials

“…EXAFS spectroscopy and first-principles calculations revealed considerable surface distortion of the nanosheets which gives them excellent structural stability and a much increased density of states, resulting in a 2-fold higher electrical conductivity relative to the bulk material. The same group also studied pits-confined in ultrathin CeO 2 nanosheets for studying catalytic centers in carbon monoxide oxidation [86]. EXAFS analysis revealed the average coordination numbers of 4.6 for the artificial three-atomic-layer thin CeO 2 nanosheets that have approximately 20% pits occupancy.…”

“…Our group have conducted a series of studies for various nanosheets materials [83][84][85][86][87][88], and EXAFS has played important roles in determining their structure and understanding their unique stability.…”

Boosting the Electrocatalytic Activity of Co3O4 Nanosheets for a Li-O2 Battery through Modulating Inner Oxygen Vacancy and Exterior Co3+/Co2+ Ratio

“…25 Recently, 2D nanosheets based on transition metal oxides have also attracted great attention as efficient electrocatalysts. [26][27][28][29] In addition, another study also indicates that the surface atoms with lowered coordination number can act as active sites for adsorption of O2. 29 However, the design and large-scale synthesis of noble metal free cathode catalysts with both high ORR and OER reactivity is still a big challenge for the development and application of lithium-air battery.…”