Publisher：Chem Catalysis  

CO2 methanation is a promising large-scale carbon neutralization process for industrial exhaust gases. However, the moderate activities of catalysts to date have always limited large-scale practical applications of CO2 methanation. Solid solutions with abundant active sites and adjustable electronic states are good candidates for achieving higher activities. Here, we developed a carbon neutralization platform system and synthesized CuxRu1-x solid solutions for CO2 methanation by coreduction methodology. Among them, Cu0.05Ru0.95 showed the best CO2 methanation activity, outperforming the best monometallic catalyst Ru. The origin of excellent activity was attributed to the rapid CO2 asymmetric dissociation on Cu-Ru dual-atom sites. Furthermore, anomalous electron transfer from Ru to Cu was found, resulting in high electron density in Cu-atom sites, which mainly induced the rapid CO2 dissociation for CuxRu1-x solid solutions. In addition, the Cu0.7Ru0.3 solid solution had high intrinsic activity for CO2 hydrogenation and 100% CO selectivity.

DOI： 10.1016/j.checat.2023.100705

Web of Science

Scopus

Language：Japanese   Publishing type：Research paper (scientific journal)  

DOI： https://doi.org/10.1016/j.checat.2023.100705

Publisher：Applied Surface Science  

The hydrogen absorption and diffusion processes in cube-shaped palladium (Pd) nanoparticles (NPs) were studied by the combination of ambient-pressure X-ray photoelectron spectroscopy (AP-XPS) and density functional theory (DFT) calculations. A size dependence of the subsurface hydrogen absorption was observed. More hydrogen atoms were absorbed in the subsurface of the smaller-sized Pd NPs owing to the enhancement of the diffusivity of H atoms from the surface into the subsurface rather than the adsorption or absorption rates at the initial stages. This results from the weakened Pd-H bond caused by surface disordering of Pd NPs with the reduction of the size of the particles. Furthermore, we discuss the H absorption sites in the bulk by comparing the relative Pd 3d core-level binding energy shifts of the Pd atoms obtained from the AP-XPS results and the theoretical calculations. The octahedral (O) sites are shown to be more favorable than the tetrahedral (T) sites for hydrogen occupation by comparing the experimental results and theoretical calculations. Finally, we proposed an interaction model between hydrogen and the Pd NPs during H2 absorption and diffusion to provide new insights into the hydrogen absorption process.

DOI： 10.1016/j.apsusc.2022.152797

Scopus

Language：Japanese   Publishing type：Research paper (scientific journal)  

DOI： 10.1039/d2nr01982e

Publisher：Zeitschrift fur Anorganische und Allgemeine Chemie  

H2 is regarded to play a crucial role in the transition from a fossil fuel-based energy economy towards an environmentally friendly one. However, storage of H2 is still challenging, but palladium (Pd) based materials show exciting properties. Therefore, nanoparticulate Pd has been intensely studied for hydrogen storage in the past years. Here, we stabilize Pd nanoparticles by intercalation between inorganic nanosheets of hectorite (NaHec). Compared to nanoparticles stabilized by the polymer polyvinylpyrrolidone (PVP), the H2 storage capacity was found to be 86 % higher for identical Pd nanoparticles being intercalated between nanosheets. We attribute this remarkably enhanced H2 storage capacity to the partial oxidation of Pd, as evidenced by X-ray photoelectron spectroscopy (XPS). The higher amount of holes in the 4d band leads to a higher amount of H2 that can be absorbed when Pd is stabilized between the nanosheets of hectorite compared to the PVP stabilized nanoparticles.

DOI： 10.1002/zaac.202100370

Scopus

Language：English   Publishing type：Research paper (scientific journal)  

DOI： https://doi.org/10.1039/C6CP04088H