Deactivation of Supported Pt Catalysts during Alcohol Oxidation Elucidated by Spectroscopic and Kinetic Analyses

Pt-Decorated ZnO Nanorods for Light-Assisted Ethanol Sensing and In Situ Analysis of the Sensing Mechanism under Light Irradiation

ZnO nanorods have attracted much attention owing to their outstanding properties for chemical gas sensors. Although they show greater sensing properties than conventional nanoparticulate ZnO, high operation temperature (>250-350 °C) is required for them to work even if precious metals are deposited on them to sensitize their sensing properties. Light irradiation is one solution for overcoming the high operation temperature and the gas selectivity because it assists the oxidation activity on the surface that affects the sensor response. In this work, the sensing properties of Pt/ZnO nanorods and ZnO nanorods are examined under light irradiation, and the relationship between their sensing properties and surface reaction (ethanol oxidation) is elucidated. Pt/ZnO nanorods show selective sensor responses to ethanol (conditions: 150 °C, 50 ppm ethanol; sensor response, 843; response time, 4.0 min; recovery time, 22 min). In situ spectroscopic observations reveal that the largest amount of oxidation intermediates (acetate species) and oxidation products (CO2 and acetaldehyde) is confirmed during light irradiation. The oxidation reaction of ethanol is facilitated by the deposition of Pt and light irradiation. Thus, the operation temperature of ZnO nanorods decreases, and the selectivity to ethanol is enhanced.

Bicarbonate Rebalances the *COOH/*OCO- Dual Pathways in CO2 Electrocatalytic Reduction: In Situ Surface-Enhanced Raman Spectroscopic Evidence

Understanding the reactive site/CO₂/electrolyte interfacial behaviors is very crucial for the design of an advantageous CO₂ electrocatalytic reduction (CO₂ER) system. One important but unrevealed question is how the CO₂ER process is influenced by the high concentration of HCO₃^-, which is deliberately added as electrolyte or from the inevitable reaction between dissolved CO₂ and OH^-. Here, we provide unambiguous in situ spectroscopic evidence that on Ag-based catalysts, HCO₃^- is apt to facilitate *OCO^- generation and therefore rebalances CO₂ER pathways. By employing an alternative acid electrolyte to restrict the exchange between CO₂ and HCO₃^- and eliminating the effect of solution pH, we reveal that HCO₃^- can decrease the onset potential of *OCO^- and promote further formate production. Theoretical calculations indicate HCO₃^- can stabilize the adsorption of *OCO^- instead of *COOH. The renewed understanding of the role of HCO₃^- could facilitate the judicious selection of electrolytes to regulate the CO₂ER pathway and product distribution.

A Perspective on Heterogeneous Catalysts for the Selective Oxidation of Alcohols

Selective oxidation of higher alcohols using heterogeneous catalysts is an important reaction in the synthesis of fine chemicals with added value. Though the process for primary alcohol oxidation is industrially established, there is still a lack of fundamental understanding considering the complexity of the catalysts and their dynamics under reaction conditions, especially when higher alcohols and liquid-phase reaction media are involved. Additionally, new materials should be developed offering higher activity, selectivity, and stability. This can be achieved by unraveling the structure-performance correlations of these catalysts under reaction conditions. In this regard, researchers are encouraged to develop more advanced characterization techniques to address the complex interplay between the solid surface, the dissolved reactants, and the solvent. In this mini-review, we report some of the most important approaches taken in the field and give a perspective on how to tackle the complex challenges for different approaches in alcohol oxidation while providing insight into the remaining challenges.

Palladium nanoparticles supported on exfoliated g-C3N4 as efficient catalysts for selective oxidation of benzyl alcohol by molecular oxygen

Palladium catalysts supported on exfoliated g-C₃N₄ materials demonstrate high catalytic activity in selective oxidation of benzyl alcohol using ambient oxygen as an oxidant.

Bioprivileged Molecules: Integrating Biological and Chemical Catalysis for Biomass Conversion

Further development of biomass conversions to viable chemicals and fuels will require improved atom utilization, process efficiency, and synergistic allocation of carbon feedstock into diverse products, as is the case in the well-developed petroleum industry. The integration of biological and chemical processes, which harnesses the strength of each type of process, can lead to advantaged processes over processes limited to one or the other. This synergy can be achieved through bioprivileged molecules that can be leveraged to produce a diversity of products, including both replacement molecules and novel molecules with enhanced performance properties. However, important challenges arise in the development of bioprivileged molecules. This review discusses the integration of biological and chemical processes and its use in the development of bioprivileged molecules, with a further focus on key hurdles that must be overcome for successful implementation.

Deactivation and regeneration of carbon supported Pt and Ru catalysts in aqueous phase hydrogenation of 2-pentanone

Aqueous phase conversion of biomass-derived molecules requires development of catalysts and operating strategies that create viable operation for extended performance as necessitated for industrial applications.

Effects of carbon number and bond saturation on hydrocarbon combustion over a diesel oxidation catalyst

The poisoning effect of hydrocarbons (C3–C16) on a diesel oxidation catalyst was clarified by in situ FTIR and kinetic analysis. The light-off temperature depends on the competitive adsorption of hydrocarbons and oxygen.

Shaping well-defined noble-metal-based nanostructures for fabricating high-performance electrocatalysts: advances and perspectives

This review highlights recent advances in shaping protocols and structure-activity relationships of noble-metal-based catalysts with well-defined nanostructures in electrochemical reactions.

Metal-free catalytic oxidation of benzylic alcohols for benzaldehyde

Metal-free catalytic oxidation of benzylic alcohols for benzaldehyde and process intensification by using a rotating packed bed reactor were demonstrated.

Aerobic oxidation of C4–C6 α,ω-diols to the diacids in base-free medium over zirconia-supported (bi)metallic catalysts

Aerobic oxidation of (C₄–C₆) α,ω-diols in water produces the corresponding α,ω-diacids in high 83–96% yields over a Au–Pt/ZrO₂ catalyst.