Ceria modified crystalline mesoporous Cr2O3 based nanocomposites supported metal oxide for benzene complete oxidation

Strong metal-support interactions between atomically dispersed Ru and CrO x for improved durability of chlorobenzene oxidation

In this work, two single-atom catalysts (SACs) with atomically dispersed RuO₂ supported on CrO _x were successfully synthesized with a simple reduction strategy for the efficient catalytic oxidation of chlorobenzene (CB). With characterizations like Cs-corrected STEM, XPS, H₂-TPR, and O₂-TPD, the structure-activity relationship is addressed. The noble metal precursor Ru³⁺ was anchored with different oxygen species and exposed facets based on the physicochemical properties of catalyst supports. Based on the analysis results, the Ru³⁺ precursor could be mainly anchored into the surface lattice oxygen of Cr₂O₃-M over high-index facets (223) and adsorbed oxygen of Cr₂O₃-P over low-index facets (104), where the precursor Ru³⁺ was all oxidized to RuO₂ when being anchored with the oxygen species of Cr₂O₃-M and Cr₂O₃-P, respectively according to XPS analysis. There is a stronger metal-support interaction (SMSI) between Ru ions and the surface lattice oxygen of Cr₂O₃-M, according to H₂-TPR and O₂-TPD characterizations. Further, the catalytic performance for CB combustion at a high space velocity of 120 000 mL (g^-1 h^-1) was tested, and 1RuCr₂O₃-M performed better than 1RuCr₂O₃-P in both durability and activity. This could be attributed to the SMSI between single-atom Ru and the lattice oxygen of the 1RuCr₂O₃-M catalyst and the abundant active sites from the exposed high-index facets. The study provided a novel synthesis strategy for Ru-based SACs with SMSI effect, and the good durability of the catalyst (1RuCr₂O₃-M) extended the great potential for practical application.

Resistance-based H2S gas sensors using metal oxide nanostructures: A review of recent advances

Gas sensors play an undeniable role in most fields of technology in the modern world; they are broadly used for public safety, pollution monitoring, quality control, breath analysis, smart homes and automobiles, and so on. Due to their low cost, high sensitivity, compact size, online detection, ease of use, portability, and low power consumption, metal oxide (MO) gas sensors have exceptional potential for detection of more than 150 gases. This paper reviews the current state-of-the-art H₂S conductometric MO gas sensors. In the first part, the H₂S sensing mechanism for MOs is presented in detail. In the next part, the H₂S sensing characteristics of the different MOs are presented, focusing on strategies such as metal doping, heterojunction composites, and different morphologies that are applied to enhance their sensing characteristics. In general, CuO, ZnO, and SnO₂ show the highest sensitivity to H₂S; therefore, most of this review is dedicated to these oxides. In the last part, some unusual and emerging MOs for H₂S sensing are presented.