Activity For Oxidation Research Articles

Tailoring Pd/M@CoAlO core-shell catalyst morphology for efficient methane oxidation

The control of low-concentration methane (CH4) emissions is a critical component of the ‘dual carbon’ strategy, and catalytic combustion technology focused on catalyst design is recognized as a promising avenue for achieving it. However, the zeolite-based catalysts are highly prone to deactivation under hydrothermal environments, thus limiting their practical applicability. Herein, we have utilized layered double hydroxides (LDHs) as precursors and integrated them with Pd/M through a co-precipitation method to fabricate Pd/M@CoAlO composite catalysts with a core–shell structure, focused on the impact of CoAlO morphology on the activity and stability for CH4 oxidation. It revealed that the incorporation of CoAlO significantly enhanced the catalytic combustion efficiency and the hydrothermal stability of Pd/M. Furthermore, an increase in the calcination temperature led to a progressive degradation of the sheet-like or petal-shaped structure of CoAlO within the Pd/M@CoAlO composite catalysts. This structural collapse eventually resulted in the formation of CoAlO dense particles that enveloped the Pd/M, adversely affecting the adsorption of oxygen and the exposure of active sites. This work underscores the importance of morphological control, providing significant guidance for the strategic design and development of catalysts tailored for CH4 catalytic combustion.

Bifunctional ArsI Dioxygenase from Acidovorax sp. ST3 with Both Methylarsenite [MAs(III)] Demethylation and MAs(III) Oxidation Activities.

Methylated arsenicals, including highly toxic species, such as methylarsenite [MAs(III)], are pervasive in the environment. Certain microorganisms possess the ability to detoxify MAs(III) by ArsI-catalyzed demethylation. Here, we characterize a bifunctional enzyme encoded by the arsI gene from Acidovorax sp. ST3, which can detoxify MAs(III) through both the demethylation and oxidation pathways. Deletion of the 22 C-terminal amino acids of ArsI increased its demethylation activity while reducing the oxidation activity. Further deletion of 44 C-terminal residues enhanced the MAs(III) demethylation activity. ArsI has four vicinal cysteine pairs, with the first pair being necessary for MAs(III) demethylation, while at least one of the other three pairs contributes to MAs(III) oxidation. Molecular modeling and site-directed mutagenesis indicated that one of the C-terminal vicinal cysteine pairs is involved in modulating the switch between oxidase and demethylase activity. These findings underscore the critical role of the C-terminal region in modulating the enzymatic activities of ArsI, particularly in MAs(III) demethylation. This research reveals the structure-function relationship of the ArsI enzyme and advances our understanding of the MAs(III) metabolism in bacteria.

Studies on a novel oxo-vanadium(V) complex of a tridentate ONO Schiff base ligand: Synthesis, characterization, X-ray crystal structure, Hirshfeld surface analysis, biological and catalytic activity

This study reports the successful synthesis and characterization of a novel oxovanadium(V) complex, [VO(L)(MeOH)(MeO)], prepared from 2-hydroxy-3-methoxybenzaldehyde and 2-methyl-3-aminoquinazoline. To elucidate the structure of the complex, we employed comprehensive characterization techniques such as CHN analysis, molar conductivity measurements, FT-IR, 1H NMR, UV-Vis spectroscopy, and single-crystal X-ray diffraction. The X-ray analysis confirmed an octahedral geometry around the V(V) center, coordinated with donor atoms from the deprotonated Schiff base ligand, an oxido group, a methanol molecule, and a methoxy group. Hirshfeld surface analysis was employed to evaluate intermolecular interactions.Furthermore, the complex exhibited impressively efficient catalytic activity in glucose oxidation under mild conditions (aqueous solution, room temperature, O2 oxidant), achieving a conversion rate of 98 %. Additionally, the antibacterial activity of the ligand and complex against various bacterial strains, including Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa, and Bacillus cereus, was evaluated. The results demonstrated promising antibacterial potential of the [VO(L)(MeOH)(MeO)] complex, particularly against E. coli, P. aeruginosa, and B. cereus. These findings suggest potential applications of this new oxovanadium(V) complex in both catalysis and antibacterial treatments.

Oxyanion-Sensitive Catalytic Activity of Ni(II)/Oxyanion Systems for Heterogeneous Organic Degradation: Differential Oxidizing Capacity of Ni(III) and Ni(IV) as High-Valent Intermediates.

This study demonstrated that NiO and Ni(OH)2 as Ni(II) catalysts exhibited significant activity for organic oxidation in the presence of various oxyanions, such as hypochlorous acid (HOCl), peroxymonosulfate (PMS), and peroxydisulfate (PDS), which markedly contrasted with Co-based counterparts exclusively activating PMS to yield sulfate radicals. The oxidizing capacity of the Ni catalyst/oxyanion varied depending on the oxyanion type. Ni catalyst/PMS (or HOCl) degraded a broad spectrum of organics, whereas PDS enabled selective phenol oxidation. This stemmed from the differential reactivity of two high-valent Ni intermediates, Ni(III) and Ni(IV). A high similarity with Ni(III)OOH in a substrate-specific reactivity indicated the role of Ni(III) as the primary oxidant of Ni-activated PDS. With the minor progress of redox reactions with radical probes and multiple spectroscopic evidence on moderate Ni(III) accumulation, the significant elimination of non-phenolic contaminants by NiOOH/PMS (or HOCl) suggested the involvement of Ni(IV) in the substrate-insensitive treatment capability of Ni catalyst/PMS (or HOCl). Since the electron-transfer oxidation of organics by high-valent Ni species involved Ni(II) regeneration, the loss of the treatment efficiency of Ni/oxyanion was marginal over multiple catalytic cycles.

Sn-MFI zeolite nanosponge having high content of Lewis acid sites on external surfaces, exhibiting high activity in Baeyer-Villiger oxidation of bulky ketone

We developed a three-step synthesis strategy to obtain Sn-incorporated MFI-type zeolite nanosponge (Sn-MFI-ns) assembled by ultrathin (∼2.5 nm) zeolite frameworks possessing uniform-sized (∼4 nm) mesopores: 1) synthesis of MFI-type borosilicate nanosponge using a zeolite structure-directing-surfactant, 2) deboronation of the borosilicate using HNO3, and 3) gas-phase incorporation of Sn into the boron-vacant sites via silanol groups using (CH3)2SnCl2 as a precursor. The Sn-MFI-ns shows high crystallinity, consequently high thermal stability, and highly porous structure. The Sn content can be systematically controlled by the amount of the precursor, with Si/Sn ratios ranging from 30 to 200. The Sn species is highly dispersed over entire range of the zeolite surfaces, acting as Lewis acid sites. Due to the highly mesoporous structure, the Sn-MFI-ns has a significant number of Lewis acid sites on the external surfaces and mesopore walls, which are easily accessible to bulky molecules, compared to solely microporous zeolite (Sn-bulk-MFI). Consequently, the Sn-MFI-ns exhibits much higher catalytic activity than the Sn-bulk-MFI with high product selectivity in Baeyer-Villiger oxidation of 2-adamantanone, a molecule larger than the micropore apertures of MFI-type zeolite. The activity of Sn-MFI-ns is comparable to Sn-MCM-41 exposing almost all Sn to mesopore walls, advantageous to the bulky molecules’ reaction.

Exploring the dynamic evolution of lattice oxygen on exsolved-Mn2O3@SmMn2O5 interfaces for NO Oxidation

Lattice oxygen in metal oxides plays an important role in the reaction of diesel oxidation catalysts, but the atomic-level understanding of structural evolution during the catalytic process remains elusive. Here, we develop a Mn2O3/SmMn2O5 catalyst using a non-stoichiometric exsolution method to explore the roles of lattice oxygen in NO oxidation. The enhanced covalency of Mn–O bond and increased electron density at Mn3+ sites, induced by the interface between exsolved Mn2O3 and mullite, lead to the formation of highly active lattice oxygen adjacent to Mn3+ sites. Near-ambient pressure X-ray photoelectron and absorption spectroscopies show that the activated lattice oxygen enables reversible changes in Mn valence states and Mn-O bond covalency during redox cycles, reducing energy barriers for NO oxidation and promoting NO2 desorption via the cooperative Mars-van Krevelen mechanism. Therefore, the Mn2O3/SmMn2O5 exhibits higher NO oxidation activity and better resistance to hydrothermal aging compared to a commercial Pt/Al2O3 catalyst.

Unraveling the Impact of Oxygen Vacancy on Electrochemical Valorization of Polyester Over Spinel Oxides.

Electrochemical upcycling of end-of-life polyethylene terephthalate (PET) using renewable electricity offers a route to generate valuable chemicals while processing plastic wastes. However, it remains a huge challenge to design an electrocatalyst with reliable structure-property relationships for PET valorization. Herein, spinel Co3O4 with rich oxygen vacancies for improved activity toward formic acid (FA) production from PET hydrolysate is reported. Experimental investigations combined with theoretical calculations reveal that incorporation of VO into Co3O4 not only promotes the generation of reactive hydroxyl species (OH*) species at adjacent tetrahedral Co2+ (Co2+ Td), but also induces an electronic structure transition from octahedral Co3+ (Co3+ Oh) to octahedral Co2+ (Co2+ Oh), which typically functions as highly-active catalytic sites for ethylene glycol (EG) chemisorption. Moreover, the enlarged Co-O covalency induced by VO facilitates the electron transfer from EG* to OH* via Co2+ Oh-O-Co2+ Td interaction and the following C─C bond cleavage via direct oxidation with a glyoxal intermediate pathway. As a result, the VO-Co3O4 catalyst exhibits a high half-cell activity for EG oxidation, with a Faradaic efficiency (91%) and productivity (1.02mmol cm-2 h-1) of FA. Lastly, it is demonstrated that hundred gram-scale formate crystals can be produced from the real-world PET bottles via two-electrode electroreforming, with a yield of 82%.

Electrodeposited Pt nanoparticles loaded on support composites of metal-organic frameworks and carbon quantum dots for the enhancement of alcohol electrooxidation

Metal-organic frameworks comprising divalent metal (M)-linked 4,4′-bipyridine (bpy), {[CuII4(bpy)3(OH)2(mal)3]·4H2O}n(Cubpy) and Ni2(bpy)3(NO3)4(H2O)4(Nibpy) were modified with carbon quantum dots (Mbpy/CQD; M = Cu, Ni) to prepare a composite support. Then, platinum (Pt) nanoparticles were electrodeposited onto the modified Mbpy/CQD support for the preparation of Pt-based catalysts (Pt/Mbpy/CQD) for the electrocatalytic improvement of alcohol oxidation. The influence of Mbpy with electrodeposited Pt nanostructures on CQD support electrodes is particularly discussed in detail through numerous physical characterizations, e.g., SEM, TEM, EDX, XPS, XRD, and elemental mapping. Dispersed Pt nanoparticles with diameters of 3-10 nm can be obtained on the modified Mbpy/CQD supports with suitable chemical and structural conditions for electrocatalytic oxidation improvement. The various prepared Pt/Mbpy/CQD catalysts with different compositions also enhance the kinetics of alcohol oxidation; they have a greater electrochemically active surface area (ECSA) and more development activity for alcohol oxidation than do the Pt/CQD catalysts. For the oxidation of all the selected small alcohol molecules, e.g., methanol, ethanol and isopropanol, the Pt/Cubpy/CQD catalyst composites also mostly exhibited improved catalytic activity, outstanding stability, and lower onset potential (Eonset) and CO tolerance. The favorable performance of the prepared composite catalysts is attributed to their superior ECSA owing to the suitable mixed surface of metal and functional groups of electrodeposited Pt, Mbpy, and CQD on the catalytic composites. Consequently, these as-prepared Pt/Mbpy/CQD composites, which are promising oxidative heterogeneous catalysts, can be used as active and stable catalysts for alcohol oxidation in alkaline solutions.

Achieving High-Capacity Cathode Presodiation Agent Via Triggering Anionic Oxidation Activity in Sodium Oxide.

Compensating for the irreversible loss of limited active sodium (Na) is crucial for enhancing the energy density of practical sodium-ion batteries (SIBs) full-cell, especially when employing hard carbon anode with initially lower coulombic efficiency. Introducing sacrificial cathode presodiation agents, particularly those that own potential anionic oxidation activity with a high theoretical capacity, can provide additional sodium sources for compensating Na loss. Herein, Ni atoms are precisely implanted at the Na sites within Na2O framework, obtaining a (Na0.89Ni0.05□0.06)2O (Ni-Na2O) presodiation agent. The synergistic interaction between Na vacancies and Ni catalyst effectively tunes the band structure, forming moderate Ni-O covalent bonds, activating the oxidation activity of oxygen anion, reducing the decomposition overpotential to 2.8V (vs Na/Na+), and achieving a high presodiation capacity of 710 mAh/g≈Na2O (Na2O decomposition rate >80%). Incorporating currently-modified presodiation agent with Na3V2(PO4)3 and Na2/3Ni2/3Mn1/3O2 cathodes, the energy density of corresponding Na-ion full-cells presents an essential improvement of 23.9% and 19.3%, respectively. Further, not limited to Ni-Na2O, the structure-function relationship between the anionic oxidation mechanism and electrode-electrolyte interface fabrication is revealed as a paradigm for the development of sacrificial cathode presodiation agent.

Zinc oxide morphology-dependent CuOx-ZnO interactions and catalysis in CO oxidation and CO2 hydrogenation

CuO/ZnO catalysts with different ZnO morphologies, i.e. nanoplates (p-ZnO) and nanorods (r-ZnO), have been prepared to test for CO oxidation and CO2 hydrogenation. Strong morphology-dependent CuOx-ZnO interactions were observed, which are tightly associated with the ZnO morphology. p-ZnO predominantly exposing polar {002} facets greatly promote the CuOx-ZnO interactions, contributing to the stabilities of CuOx/ZnO catalysts in both reactions. Experimental evidences reveal that CuO-ZnO interfaces act as the active sites in CO oxidation. CuO/p-ZnO catalyst with stronger CuO-ZnO interactions can facilitate the generations of fine CuO and interfacial Cu(I) species, responsible for the adsorption and reactivity of CO and subsequently the high (intrinsic) activity in CO oxidation. However, CuO/ZnO catalysts undergo in situ restructuring to generate Cu/ZnO in CO2 hydrogenation, whose catalytic performance is determined by the key step of CO2 activation. Consequently, Cu/r-ZnO catalyst possessing more surface basic sites exhibits better catalytic performance. These results greatly deepen the fundamental understanding of Cu-based catalysts in both reactions and broaden the concept of morphology-dependent catalysis of oxide-based nanocrystal catalysts that varies with the reactions catalyzed.

A new approach to the preparation of CdMoO4 nanopowders with methylene blue oxidation activity evaluation

The scheelite-type CdMoO4 nanopowders were prepared through calcination of an oxalate precursor in static air at 500 °C for 2h. The oxalate precursor was analyzed by Fourier transform infrared spectroscopy (FTIR) and thermal gravimetric analysis (TGA). The as-synthesized cadmium molybdate was characterized by Raman spectroscopy (RS), X-ray diffraction (XRD), Scanning electron microscopy (SEM), and Energy dispersive X-ray spectroscopy (EDX). Its catalytic activity was tested by the oxidation reaction of methylene blue (MB) dye in the presence of hydrogen peroxide. The obtained results showed that CdMoO4 nanopowders have very high catalytic activity with a yield of 98 % during a period of 2h under alkaline conditions at pH 11.

In-situ formed stable Pt nanoclusters on ceria-zirconia solid solutions induced by hydrothermal aging for efficient low-temperature CO oxidation

Pt nanoclusters (PtC) on the surface of ceria-zirconia solid solutions exhibit superior low-temperature CO oxidation activity compared to Pt single atoms (Pt1). However, the redispersion behavior of the PtC to Pt1 lowers the efficiency of CO Oxidation. In this work, the stable surface hydroxyl groups were constructed by high-temperature hydrothermal aging treatment. Specifically, the Pt1 catalyst (Pt/CZOe-SA) prepared by atom trapping was subjected to high-temperature hydrothermal treatment to obtain the stable PtC catalyst (Pt/CZOe-HT) with in-situ formed PtC. The experimental results showed that PtC with 2–3 nm size could achieve excellent low-temperature activity and thermal stability. In addition, the ab initio molecular dynamics and density functional theory calculations revealed the specific evolution process of dynamic dispersion for PtC with or without hydroxyl groups from the femtosecond scale, suggesting that the hydroxyl groups limited the dispersion of PtC in the form of “energy fence”. The hydrothermal treatment not only introduced high-temperature stable hydroxyl groups to improve the stability of the in-situ formed PtC, but also optimized the ratio of Pt1 and PtC, and then enhanced the low-temperature activity by the synergistic effect between Pt1 and PtC. The present work can provide theoretical guidance for developing high-performance and high-stability Pt-based catalysts.

Construction of Mesoporous Aluminosilicate Thin Films on ITO Electrodes for Immobilizing a Cationic Ru(II) Water Oxidation Catalyst

Aluminosilicate (Al‐SiO2) thin films with vertically aligned mesochannels were successfully synthesized on ITO electrodes and employed for the immobilization of a cationic Ru(II) water oxidation catalyst without requiring linker groups. Optimal synthesis conditions yielded uniform mesoporous Al‐SiO2 films with tunable Al content, high surface area (568 m2/g), 3.94 nm pore size, and 155 nm thickness. Electrochemical studies confirmed the presence of the immobilized Ru complex undergoing diffusion‐controlled Ru(III/II) and Ru(IV/III) electron transfer. The Ru loading reached 4.71 nmol/cm2 at Si/Al = 9.6, with higher Al content enhancing loading amounts via cation exchange. The Ru‐modified electrode exhibited high electrocatalytic water oxidation activity, achieving 75.3% Faradaic efficiency and a turnover number of 298.6 for O2 evolution for 1 hour. This work provides a new approach to construct porous environments on an electrode surface to immobilize positively charged transition‐metal complexes as catalysts, offering potential applications in the development of electrocatalytic systems for energy conversion.

Selectively photocatalytic oxidation of methane to methanol promoted by Charge-Polarized Zn-Ti pairs

Photocatalysis offers an intriguing route for selective oxidation of CH4 to CH3OH under mild conditions. However, owing to the ultra-high stability of CH4 and the diversity of oxidative products, the activity of CH4 oxidation and the selectivity of CH3OH are still far from satisfactory. Herein, we report a dual-cocatalyst of Au and bimetallic oxide (Zn2Ti3O8) nanoparticles (NPs) modified TiO2 nanotube (Au/Zn2Ti3O8/TiO2) for highly active and selective photocatalytic oxidation of CH4 to CH3OH with O2 at room temperature. The introduction of Zn2Ti3O8 NPs is skillfully exploited the epitaxies of ZIF-8 on the surface of protonated titanate nanotubes (H-TNTs) and the followed thermal treatment with air. During photocatalytic CH4 oxidation, 1.7 %Au/Zn2Ti3O8/TiO2-4 achieved a formation rate of liquid oxygenates of 1200 μmol·gcat.–1·h−1 with a CH3OH selectivity of 91.5 %, which were much higher than those over 1.7 %Au/TiO2 and 1.7 %Au/ZnO. Mechanism investigation confirmed the presence of the strong electron interaction between Au NPs, Zn2Ti3O8 NPs and TiO2 nanotubes in 1.7 %Au/Zn2Ti3O8/TiO2-4, which intensified the charge polarization between Zn sites and Ti sites. These charge-polarized Zn-Ti sites were not only beneficial to the adsorption and activation of CH4, but also accelerated the further transformation of CH3OOH to CH3OH, as well as inhibited the excessive oxidation of CH3OH.

Electrocatalysis of hydrogen and oxygen electrode reactions in alkaline media by Rh-modified polycrystalline Ni electrode

Developing novel electrocatalysts for energy conversion applications is of utmost importance for reaching the energy security of modern society. Here we present a comprehensive investigation of rhodium-modified polycrystalline nickel as an electrocatalyst for hydrogen and oxygen electrode reactions in alkaline media. The surface modification of nickel electrodes was achieved by facile galvanic displacement (up to 30 s) from a highly concentrated acidic Rh3+ solution. The results demonstrate a significant enhancement in the electrocatalytic activity for both hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) on the Rh-modified Ni electrodes, positioning galvanic displacement as a viable approach to engineering advanced electrocatalysts for clean energy applications. On the other hand, the hydrogen oxidation (HOR) and oxygen reduction reaction (ORR) activities of the Rh-modified electrodes are lower compared to polycrystalline platinum. It is suggested that semiconducting Rh2O3 has a detrimental role on the HOR and ORR performance, while the activities of HER and OER, dominantly taking place on metallic Rh and conductive RhO2, are very high. This research sheds light on the mechanisms underlying the enhanced electrode kinetics on Rh-modified Ni electrodes and provides insights into the development of efficient and cost-effective electrocatalysts for renewable energy technologies.

Mn/CeO2 contains enriched surface lewis acid sites and pore structures accelerated catalytic oxidation of propane at low temperature

The development of highly efficient non-precious metal catalysts for the low-temperature catalytic oxidation of volatile organic compounds (VOCs) is a critical imperative in VOCs control. In this study, a series of highly active CeMnOx catalysts with Mn-doped CeO2 were investigated. The catalysts (WHSV=30,000 mL g−1 h−1) exhibited the highest catalytic propane oxidation activity (T90 = 230 °C) and excellent stability over 600 h, When the Mn:Ce ratio was 2.5. The introduction of Mn doping resulted in modifications to the pore structure of CeO2, leading to an increase in specific surface area and enhanced gas transfer kinetics. Additionally, it induced surface electronic defects and elevated the concentration of acidic sites, thereby facilitating the adsorption and activation of propane. Consequently, these improvements contributed to an enhanced catalytic performance of the catalyst. The in-situ DRIFTS infrared spectra revealed that Mn doping reduced the activation energy of the reaction and facilitated the conversion of acetone groups as well as decomposition of carboxylic acid groups.

Boosting toluene destruction by engineering surface acidity–alkalinity in defective cobalt oxide catalyst

The surface acidity and alkalinity of catalysts played a decisive role in the destruction of Volatile organic compounds (VOCs). In this study, a series of Co3O4 catalysts were synthesized under different temperatures by calcining metal organic frameworks (MOFs). By controlling the temperature, the organic linkers were effectively eliminated, resulting in catalysts with a high specific surface area due to the preservation of the parent structure of the MOFs. Among the catalysts tested, Co3O4−350 (calcined at 350 °C) demonstrated the highest catalytic activity for toluene oxidation (T90 =231 ℃) and reliable water resistance (3 vol.% water vapor). The efficacy was attributed to the high ratio of reactive oxygen species and high valence Co species, weaken Co−O bond strength as well as high concentration of oxygen vacancies. In situ diffuse reflectance infrared Fourier transform spectroscopy (in situ DRIFTS) demonstrate that acidity–alkalinity is crucial in the adsorption and activation, while oxygen vacancies were found to be essential for deep oxidation.

Revealing the Effect of Anion Regulation in NiCo2X4 (X = O, S, Se, Te) on Photoassisted Methanol Electrocatalytic Oxidation.

Designing nonprecious metal anode catalysts for photoassisted direct methanol fuel cells (PDMFCs) remains a challenge. As a semiconductor catalyst with a spinel structure, NiCo2O4 has good methanol catalytic oxidation activity and photocatalytic activity, making it a highly promising anode non-noble metal catalyst for PDMFCs. However, compared with the noble metal catalyst, the photoelectrocatalytic activity remained to be improved. In this report, an anion regulation strategy was adopted to improve the photoassisted methanol electrocatalytic activity. Using a CoNi-Aspartic (CoNi-Asp) nanorod as the precursor, the anion-regulated NiCo2X4 (X = O, S, Se, Te) was prepared by oxidation, sulfuration, selenization, and telluridation reactions. The regulation of anions and their effects on the electronic structure, intermediate product, and photoelectric catalytic performance of NiCo2X4 (X= O, S, Se, Te) was systematically discussed. Photoelectrochemical characterization and adsorption energy of •OH revealing the volcano-like correlation between the anion in NiCo2X4 (X = O, S, Se, Te) and their photoelectrocatalytic performance. The narrowest band gap (2.239 eV), the highest •OH adsorption energy (-3.32 eV), and the highest ratio of Co3+/Co2+ (2.19) ensure the best photoelectric catalytic performance of NiCo2S4, under the visible light irradiation, the photoresponse current density was 1.9 A g-1, the current density at 0.6 V was up to 21.9 A g-1. After 9 h of stability testing, the current retention rate was 80%. This report sheds an idea for the rational design of non-noble anode catalysts for PDMFCs.

Advanced Progress for Promoting Anodic Hydrogen Oxidation Activity and Anti-CO Poisoning in Fuel Cells

Advanced Progress for Promoting Anodic Hydrogen Oxidation Activity and Anti-CO Poisoning in Fuel Cells

Oxidation of 2,5-bis(hydroxymethyl)furan to 2,5-furandicarboxylic acid with morphology-dependent Au/CeO2 catalysts

2,5-Furandicarboxylic acid (FDCA), a bio-based diacid with a rigid ring, has a similar structure to petroleum-based terephthalic acid. Its co-polyester with ethylene glycol has excellent performance in terms of thermal and mechanical properties. Herein, an Au/CeO2-rod catalyst with rich oxygen vacancies was developed to achieve the efficient oxidation of 2,5-bis(hydroxymethyl)furan (BHMF) to FDCA with a 92 % yield under mild conditions, with the addition of 4 equivalents of Na2CO3 at 80℃ under 2 MPa O2 for 6 h. The large specific surface area of CeO2-rod is beneficial for better dispersion of Au nanoparticles. Meanwhile, the high activity of Au/CeO2-rod can be attributed to that the rod-shaped CeO2 exposed more active (100) facets, resulting in strong metal-support interaction between Au nanoparticles and CeO2-rod. This could generate more Au species with oxidized state and more oxygen vacancies, thus promoting the reactant adsorption and oxygen activation and enhancing the final oxidation activity. The oxidation of 5-hydroxymethyl-2-furancarboxylic acid to FDCA was determined as the rate-determining step in the oxidation of BHMF over the Au/CeO2 catalyst.