Atomistic origin of high-concentration Ce3+ in {100}-faceted Cr-substituted CeO2 nanocrystals

Atomic-level characterization of the oxygen storage material YBaCo4O7+δ synthesized at low temperature

“…45 In addition, the presence of surface defects possibly modifies the coordinate configuration of cations in the lattice and hence alters the oxidation state. 46 The surface analysis by EELS reasonably explains the discrepancy from the X-ray absorption analysis by Chen et al 28 where the reported higher cobalt valence state of their low-temperature synthesized YBCO would come from the limit of the spatial resolution in the X-ray beam. We suggest that the surface information or the averaging information was detected and contributed to the measured results priorly.…”

Increasing oxygen vacancies in CeO2 nanocrystals by Ni doping and reduced graphene oxide decoration towards electrocatalytic hydrogen evolution

“…2H. 42–44,57 The ratio was 1.088 for the CeO 2 /rGO-0.05 NCP sample, indicating that the fraction of Ce 3+ cations was 44.5%, which is larger than 38.5% in CeO 2 /rGO-0.02 and 36.0% in CeO 2 /rGO-0.25. The above results demonstrate that the adjustment of the rGO ratio induced a reduction in the valence state of Ce cations.…”

“…Previous reports by our group have described the fine-tuning of CeO 2 nanocrystals (NCs) using controllable size, exposed facets, and active dopants, which lead to high V O concentration, oxygen mobility, and active sites. 42–44 In addition, the introduction of transition metals, such as Co and Ni, can further enhance the electrocatalytic HER performance of CeO 2 nanostructures. 30,37 Therefore, it is promising to construct V O -rich CeO 2 electrocatalysts with active doping and appropriate structural modulation.…”

Polarized Active Pairs at Grain Boundary Boost CO2 Chemical Fixation

“…To further investigate the differences in the electronic structure of Ce at grain boundary and center, electron energy loss spectroscopy (EELS) spectra with high sensitivity to the valence states were collected in the above locations, respectively. As shown in Figure b and Figure S11, both Ce M 5 and Ce M 4 peaks at grain boundary are shifted toward lower energies compared to that of the central position, indicating the lower valence state of Ce at grain boundary . In combination with the ESR and XPS results, it can be concluded that there is a large amount of coordination-unsaturated Ce 3+ atoms at the grain boundary, which can act as electron-rich active sites to donate electrons.…”

“…As shown in Figure 2b and Figure S11, both Ce M 5 and Ce M 4 peaks at grain boundary are shifted toward lower energies compared to that of the central position, indicating the lower valence state of Ce at grain boundary. 30 In combination with the ESR and XPS results, it can be concluded that there is a large amount of coordinationunsaturated Ce 3+ atoms at the grain boundary, which can act as electron-rich active sites to donate electrons. To go further, density functional theory (DFT) calculations were carried out to investigate the electronic structure at grain boundary.…”