Oxidation Of HCOO Research Articles

Phase reconstruction of Co3O4 with enriched oxygen vacancies induced by cold plasma for boosting methanol-to-formate electro-oxidation

Developing high-performance Pt-free electrocatalysts for the electro-oxidation of methanol (MeOH) into high-value-added formate in alkaline media offers a sustainable avenue for synchronous biomass valorization and MeOH oxidation-assisted hydrogen production. Herein, electrodeposited Co(OH)2 on Ni foam (NF) was treated by an O2 cold plasma to obtain oxygen vacancies enriched Co3O4-x/NF-P. The resultant Co3O4-x/NF-P only requires a potential of 1.318 V vs. RHE to upgrade MeOH into formate at 10 mA·cm−2. Characterization and calculation results reveal that oxygen vacancy induced irreversible phase transformation of Co3O4-x/NF-P, facilitating the deprotonation of MeOH, and suppressing further oxidation of HCOO* for selective and efficient formate electrosynthesis. Impressively, a Co3O4-x/NF-P||Co3O4-x/NF-P pair was built to couple the MeOH electro-oxidation with H2 evolution, where it only supplies a cell voltage of 1.540 V at 10 mA·cm−2 and the anodic Faraday efficiency exceeds 95 %. This work clarifies in-depth insight the underlying mechanism of MeOH selective oxidation into formate.

Sodium-promoted Ag/CeO2 nanospheres for catalytic oxidation of formaldehyde

Ag/CeO2 nanosphere catalysts were successfully tuned by sodium doping to promote low-temperature catalytic oxidation of formaldehyde (HCHO). It was observed that sodium-promoted Ag/CeO2 nanosphere catalysts exhibited relatively high intrinsic catalytic activity. Different characterization techniques were performed on the catalysts to elucidate the physicochemical properties that contributed to the improvement of the catalytic performance. Due to electron charge transfer from Ag to CeO2 nanospheres, Ag species should comprise of Ag2O as main components along with parts of metallic Ag over CeO2 nanospheres, while remaining as metallic Ag over conventional CeO2 bulk particles. The well-dispersed Ag species on CeO2 nanospheres could activate surface oxygen from CeO2, and facilitate the surface reduction of CeO2 nanospheres. The doped sodium might exist in the forms of NaHCO3 and Na2CO3 compounds, which could cause that surface hydroxyl (OH−) concentrations significantly increased on the surface of CeO2 nanospheres. The presence of sodium compounds could prevent hydrogen spillover from Ag to CeO2 supports, attesting to the inhibiting role of sodium species in the reduction process. However, with the introduction of sodium into Ag/CeO2 nanospheres, surface hydroxyl groups would become important reaction species and directly react with adsorbed surface formate species (HCOO−) to form H2O and CO2. This reaction route was inconsistent with that over Ag/CeO2 nanospheres, on which bidentate HCOO− were the key intermediates during catalytic oxidation of HCHO, and the further oxidation of HCOO− by activated surface lattice oxygen was the rate-determining step. These results provide guidance for designing highly efficient and economic silver-based catalysts for HCHO catalytic oxidation.

Mechanism of highly selective low temperature PROX reaction of CO in H 2: Oxidation of CO via HCOO with OH

Oxidation of CO is markedly enhanced by H 2 and/or H 2O on FeO x loaded Pt/TiO 2 (FeO x /Pt/TiO 2) catalyst. Similarly, oxidation of CO on the Pt/CNT and Pt/CNF was enhanced by H 2 and/or H 2O. As a result, highly selective preferential oxidation (PROX) of CO is established at low temperature on these catalysts. The oxidation of CO on these catalysts has a hydrogen isotope effect by H 2O/D 2O and H 2/D 2, which suggests the intermediate at the rate determining step involves hydrogen atom. Dynamics of in situ DRIFT spectroscopy on FeO x /Pt/TiO 2 suggests that the rate determining step of the PROX reaction of CO is the oxidation of HCOO with OH. TEM image proves that Pt particles are on the outer wall of the CNT but Ni–MgO and FeO x are localized at the end of CNT and CNF. If Ni–MgO and Fe in CNT and CNF were removed (CNT-p and CNF-p), the Pt lost the activity for low temperature PROX reaction of CO. Characteristic feature of the PROX reaction suggests a dual functional catalysis involving ionic process of CO + OH − → HCOO −, which is responsible for the low temperature PROX reaction of CO.

Shenandoah Cloud and Photochemistry Experiment (SCAPE): Overview

The Shenandoah Cloud and Photochemistry Experiment (SCAPE) investigated the chemistry of the atmosphere at a high‐elevation forested site in central Virginia with particular focus on the factors controlling concentrations of ozone, carbonyl compounds, and carboxylic acids. Carbonyl compounds and carboxylic acids are ubiquitous chemical constituents of the global troposphere, but many aspects of their biogeochemical cycling are poorly understood. Carbonyls are generated from the oxidation of hydrocarbons; formaldehyde (HCHO) produced via this pathway is an important precursor for OH. Thus the carbonyls are intermediates in and tracers of tropospheric photochemistry [e.g., Carlier et al., 1988]. Carboxylic acids are major natural sources of atmospheric acidity thereby partially controlling pH‐dependent chemical transformations in clouds [e.g., Keene and Galloway, 1988]. The aqueous‐phase oxidation of HCHO in clouds has been hypothesized as a significant source of formic acid (HCOOH) and the aqueous‐phase oxidation of HCOO− a potentially important in‐cloud sink for OH [Chameides and Davis, 1983; Jacob, 1986]. Under many conditions, clouds should be a net sink for tropospheric HCOOH [Jacob and Wofsy, 1988]. Specific research objectives were (1) to assess the relative importance of NOx and hydrocarbons in limiting regional ozone production, (2) to investigate sources and sinks for carbonyl compounds and caiboxylic acids, and (3) to examine the droplet‐size dependence of solute concentrations and the thermodynamics of phase partitioning for carbonyl compounds and carboxylic acids in clouds.

Isotopieeffekte bei der Formiatoxydation durch Formicodehydrogenase aus Phaseoulus

AbstractThe oxidation of HCOO‐ and DCOO‐ by plant formicodehydrogenase in presence of DPN has been measured manometrically and spectrophotometrically. There is an isotopic effect, the factor of reaction rates varying with temperature from 2 to 3.