Excellent Catalytic Activity Research Articles

Borate ester hybrid photothermal nanofluid derived from C3N4/MoS2 catalyzed esterification for efficient organic-inorganic synergistic lubrication

The inferior dispersion stability and simple functionality of MoS2-based nanofluids restrict their efficient application in lubrication. Herein, a novel nanofluid composed of C3N4/MoS2, 3-isocyanatopropyltrimethoxysilane, and C3N4/MoS2-catalyzed product (polyethylene glycol-borate ester, PEG-BA) was proposed. C3N4 nanosheets could induce the formation of regular MoS2 nanospheres. The resulting C3N4/MoS2 showed excellent catalytic activity for the esterification of PEG-BA. The C3N4/MoS2 @PEG-BA nanofluid exhibited favorable dispersion stability in PEG600 with no stratification for ≥ 82 days. The addition of 3.0 wt% C3N4/MoS2 @PEG-BA nanofluid could significantly reduce friction coefficient (30.7 %) and wear scar diameter (28.9 %). The excellent lubrication properties of the nanofluid are attributed to the synergistic lubrication effect of C3N4/MoS2 and PEG-BA. Furthermore, the nanofluid exhibits remarkable photothermal conversion performance in both oil and air mediums.

Solar-driven photocatalytic nitrogen fixation on transition metal-doped covalent organic frameworks: First-principles study

Designing highly efficient single-atom catalysts for converting nitrogen into ammonia under ambient temperature conditions holds significant importance. Current research predominantly focuses on electrocatalytic nitrogen fixation, but compared to that, photocatalytic nitrogen fixation requires only sunlight as an energy source, making it more environmentally friendly and cost-effective. Developing efficient nitrogen reduction reaction (NRR) photocatalysts presents a promising yet highly challenging task. Two-dimensional (2D) covalent organic frameworks (COFs) have garnered interest because of their elevated surface area and regular pore structure. This study employs density functional theory calculations to investigate the potential of NRR photocatalysts using the 2D COF TMT-TFPT-COF (TT-COF) supported with 18 different transition metal atoms (TM = Rh, Nb, Os, Mo, Ru, Pt, Ni, Co, V, Cu, Fe, Re, W, Cr, Ta, Mn, Pd, Ti). Through a four-step selection process, the most promising photocatalyst is identified. The results indicate that a single Re atom loaded onto TT-COF (Re@TT-COF) displays the optimal nitrogen fixation performance, demonstrating excellent catalytic activity and selectivity with a limiting potential of only −0.30 V. Furthermore, its good light absorption efficiency, suitable band edge position, and significant photo-generated electron potential enable spontaneous nitrogen fixation. Our study provides useful guidance for the rational design of COF-based NRR photocatalysts with high activity, stability, and selectivity.

Study on the performance of Co–Ni sulfide electrocatalysts supported by different fibroin-based carbon precursors

Research on sustainable energy sources is crucial for alleviating environmental issues and addressing energy security concerns. This study investigates the utilization of various silk precursors in the hydrogen evolution reaction. Waste silk fabric, regenerated silk fibroin film, porous silk fibroin, silk cocoon and degummed silk fibroin were used as precursors to prepare HER electrocatalysts. To investigate the influence of precursor form on catalytic perform9ance, a comparative analysis of the morphology, structure and composition of different materials was conducted. Among various catalysts, waste silk fabric based catalysts exhibit the most excellent catalytic activity, with an overpotential of 113 mV at 10 mA cm−2 and a Tafel slope of 30.9 mV/dec. Even After 1000 cycles of testing, it still maintains excellent catalytic activity. This study provides insights into the influence of precursor forms on the electrochemical performance of biomass carbon-based catalysts, aiming to inspire further research in this field.

A magnetic nanocatalyst based on Bronsted acid and Lewis acid centers for the efficient synthesis of polycyclic melting 1,5-benzodiazepines

In this study, 3-(Triethoxysilyl)propyl chloride (CPTES) was used to modify the surface of magnetic nanoparticles Fe3O4@SiO2, and aminomethylphosphonic acid (AMPA) was further anchored on the surface. Then, Ce (III) was used as the ligand to immobilize the surface of the modified material with N/O as the donor. Magnetic nanocatalysts (Fe3O4@SiO2@CPTES@AMPA@CeCl3) were successfully prepared. The prepared catalysts were characterized by infrared spectroscopy (FT-IR), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), transmission electron microscopy (TEM), nitrogen absorption-desorption experiment (BET), vibrating sample magnetometer (VSM), energy dispersive spectroscopy (EDS) and inductively coupled plasma atomic emission spectrometry (ICP-AES). A synergetic effect of Brønsted and Lewis acid (AMPA and CeCl3) of the magnetic nanocatalyst was examined to active carbonyl, imine or enamine bonds for the synthesis of polycyclic fused 1,5-benzodiazepine with quaternary carbon centers or quinoxaline ring in a one-pot method. It was found that this catalyst exhibited excellent catalytic activities (TON up to 111368, TOF up to 110232 h−1) and high selectivities in the synthesis of fused 1,5-benzodiazepine compounds (22 examples, 85–96 % yields). The mechanism for the synthesis of polycyclic fused 1,5-benzodiazepine catalyzed by Fe3O4@SiO2@CPTES@AMPA@CeCl3 was proposed. The nanocatalyst was readily recovered by simple magnetic decantation and can be recyclable without obviously reducing catalytic activity up to seven times.

Sponge-like tungsten phosphide-ruthenium constructed by ultrafast quasi-solid state microwave for wide pH hydrogen generation

Transition metal phosphides (TMPs) are typical of emerging hydrogen evolution reaction (HER) catalysts, but tedious synthesis approach limits its practical applications. Herein, sponge-like tungsten phosphide with ruthenium (Ru/WP) is synthesized by a simple and rapid (20 s) quasi-solid state microwave approach. The synthesized Ru/WP possesses porous morphology with rich interconnected channels to accelerate the energy transport and expose ample active sites. In addition, the strong electronic interactions promote the reaction kinetics between Ru and WP. Thus, the prepared Ru/WP owns excellent catalytic activity in alkaline freshwater/seawater, acid and neutral electrolyters, with low overpotentials of 36/24, 48, and 69 mV to provide 10 mA cm−2 for HER. In alkaline electrolyte, the overall water decomposition requires only 1.57 V to reach 10 mA cm−2 with satisfactory stability. The rapid microwave quasi-solid state synthesis strategy provides a novel direction for developing metal phosphides in the energy sector.

Regulating the microstructure and catalytic activity of metal selenides via calcination strategy for lithium-sulfur battery

Metal selenides obtain a series of advantages such as high electronic conductivity, excellent catalytic activity and facile fabrication approach, which are considered as promising catalysts in lithium sulfur (Li-S) battery. Traditional research based on metal selenides focuses on designing novel/complex microstructures or composites, however, the catalytic ability can be greatly affected by internal properties such as defect or vacancy. In this work, hollow nickel-cobalt layered double hydroxide (NiCo-LDH) is first fabricated and applied as a precursor to fabricate NiCoSe, and Se vacancy accompanied with crystal phase, microstructure and catalytic activity can be regulated by simply adjusting selenization atmosphere and temperature. Involving the application of NiCoSe in Li-S battery, the optimum fabrication parameter is perform the selenization at 600 °C under argon/5 % hydrogen, and the battery can exhibit a high discharge specific capacity of 1042.8 mAh g−1, excellent cycling performance of 500 cycles with a decay rate of 0.083 % at 1 C. This work highlights the importance of calcination process and also provides reference for further modifying the microstructure and performance of metal selenides in Li-S battery.

Construction of 2D porous g-C3N4 by steam reforming with the introduction of Fe clusters forming Fe-Nx to enhance photo-Fenton catalytic activity

In this study, the Fe clusters were anchored onto 2D porous g-C3N4 nanosheets to synthesize Photo-Fenton catalysts Fe-CNS with highly and uniformly dispersed Fe-Nx active sites via a supramolecular thermal polymerization and subsequent impregnation strategy. The obtained Fe-CNS composites exhibited excellent Photo-Fenton catalytic activity and stability even under high pH and anion conditions, suggesting Fe clusters doping into 2D porous g-C3N4 nanosheets host through Fe-Nx coordination structures enhanced the separation efficiency of light-generated charge carriers, promoted Fe3+/Fe2+ redox cycle, accelerated the activation of H2O2 and improved the stability of Fe species and leading to a remarkable Photo-Fenton synergistic effect. Among these Fe-CNS composites, Fe-CNS with doping amount of 7 % Fe species shows superior Photo-Fenton activity for the elimination of Tetracycline (TC), and the corresponding k value is 0.04729 min−1, which is 25.4 times superior to that of photocatalytic oxidation TC of bulk g-C3N4, indicating that the strategy on changing Fe doping amount yielded opportunity to optimize Photo-Fenton combined action between Fe clusters and g-C3N4 nanosheets host. The degradation mechanism of TC using Fe-CNS composites in the Photo-Fenton system has been further elucidated by considering that the embedded Fe clusters in the N-rich 2D g-C3N4 nanosheets form abundant Fe-Nx active sites.

Formulation and Characterization of Moringa Oleifera Nano Particles

The synthesis of copper oxide nano particles (CuO NPs) using moringa oleifera leaves extract as a green reducing agent has gained significant interest due to its eco-friendly and cost-effective nature. Moringa oleifera leaves extract acts as a reducing agent and capping agent simultaneously, making it a promising alternative to traditional methods. The size, shape, and optical properties of the synthesized CuO NPs can be controlled by varying the concentration of moringa oleifera leaves extract and reaction time. The synthesized CuO NPs exhibit excellent antimicrobial, antioxidant, antiviral, anti-inflammatory and catalytic activities, making them suitable for various applications in bio medicine, wastewater treatment, and energy storage. Overall, the green synthesis of CuO NPs using moringa oleifera leaves extract holds great potential for sustainable and green nanotechnology. FTIR and UV Studies carried out in which it showed that drug-drug and drug-excipients are compatible.

Sub-nanometric ruthenium clusters prepared by solid-state dispersion for catalytic selective aerobic oxidation of aromatic alcohols

The selective aerobic oxidation of alcohols to corresponding aldehydes is one of the most important challenges in the green chemical industry. In this work, Ru/Al2O3-SSD catalyst with highly dispersed metallic ruthenium clusters (average particle size of 0.97 nm) was prepared by solid-state dispersion (SSD) for efficient selective aerobic oxidation of aromatic alcohols to aldehydes. Compared with the counterpart catalyst Ru/Al2O3-IM prepared by wet impregnation (IM), this catalyst has smaller metal particles (0.97 nm vs. 3.4 nm), resulting in a special electronic structure, and exhibits much higher TOF (234 h−1 vs. 98 h−1) in the aerobic oxidation reaction of benzyl alcohol at 80 °C. The catalyst also shows excellent catalytic activity in the preparation of vanillin by selective aerobic oxidation of vanillyl alcohol at 100 °C, delivering a vanillin yield of 99%. The solid-state dispersion strategy provides an efficient and facile way for the fabrication of high-performance sub-nanometric metal catalysts.

Co/CoSe heterojunction as bifunctional oxygen electrocatalysts for rechargeable Zinc–Air batteries

The construction of suitable heterostructures in materials can tune the Fermi energy levels and electron transport rates of materials to achieve attractive oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) properties. In this study, a catalyst anchored in nitrogen-doped carbon nanowires (NCNW) with a heterogeneous interface of Co and CoSe is constructed to realize high-performance ORR and OER bifunctional catalysis. These Co and CoSe heterostructure interfaces can optimize the adsorption of intermediates. The Co/CoSe@NCNW catalyst performs excellent ORR catalytic activity (E1/2 = 0.89 V), and good OER activity (potential at 10 mA/cm2, Ej = 10 = 1.55 V). More importantly, the material shows excellent performance in rechargeable zinc-air batteries (ZABs). The open-circuit voltages of 1.47 and 1.50 V and the peak power densities of 122.56 and 74.49 mW/cm2 in liquid and solid electrolytes, respectively, are superior to those of the ZABs prepared from noble metals. Consequently, the construction of heterogeneous structures can convincingly boost the commercialization of rechargeable ZABs, and be extended to other fields involving ORR and OER.

Atomically Engineered Defect-Rich Palladium Metallene for High-Performance Alkaline Oxygen Reduction Electrocatalysis.

Defect engineering is a key chemical tool to modulate the electronic structure and reactivity of nanostructured catalysts. Here, it is reported how targeted introduction of defect sites in a 2D palladium metallene nanostructure results in a highly active catalyst for the alkaline oxygen reduction reaction (ORR). A defect-rich WOx and MoOx modified Pd metallene (denoted: D-Pd M) is synthesized by a facile and scalable approach. Detailed structural analyses reveal the presence of three distinct atomic-level defects, that are pores, concave surfaces, and surface-anchored individual WOx and MoOx sites. Mechanistic studies reveal that these defects result in excellent catalytic ORR activity (half-wave potential 0.93V vs. RHE, mass activity 1.3AmgPd-1 at 0.9 V vs. RHE), outperforming the commercial references Pt/C and Pd/C by factors of ≈7 and ≈4, respectively. The practical usage of the compound is demonstrated by integration into a custom-built Zn-air battery. At low D-Pd M loading (26µgPdcm-2), the system achieves high specific capacity (809mAhgZn -1) and shows excellent discharge potential stability. This study therefore provides a blueprint for the molecular design of defect sites in 2D metallene nanostructures for advanced energy technology applications.

Morphological regulation of Pt/CeO2 and its catalytic dehydrogenation of methylcyclohexane in fixed bed reactor

A series of Pt/CeO2 compounds with hollow spheres (Pt/CeO2–S), wires (Pt/CeO2–W), and particle (Pt/CeO2–P) morphologies were prepared and further used for catalytic liquid organic hydrogen carrier (LOHC) dehydrogenation. The exposure and distribution of different crystal faces affected the nucleation process of crystals and then formed different microscopic morphologies. Compared with Pt/CeO2–W and Pt/CeO2–P, Pt/CeO2–S showed hollow spherical structures with significantly higher oxygen vacancy concentrations and specific surface areas. These structural differences not only affected platinum (Pt) dispersion, but also affected the activity and stability of the catalyst, thus promoting methylcyclohexane (MCH) conversion. The fixed bed reaction showed that Pt/CeO2–S had excellent catalytic activity, with the MCH conversion rate at 97.7 % and hydrogen release rate of 350.50 mmol/g(Pt)/min, and it still maintained stable activity after 72 h. Under the same conditions, the MCH conversion rates for Pt/CeO2–W and Pt/CeO2–P were only 77.23 % and 32.02 %, respectively. Therefore, through the growth pattern and morphology controls of catalyst supports, this was an effective means for improving the dehydrogenation performance of LOHC.

Enhanced selectivity in the production of furans/olefins through ex-situ catalytic pyrolysis over metal-modified TS-1

Catalytic pyrolysis technology is one of the most environmental and efficient approach in converting biomass waste into high-value chemicals and fuels. In this study, the ex-situ catalytic pyrolysis of cellulose to produce furans and olefins was reported using various metal-loaded TS-1 as catalysts. The experimental results showed that the Au/TS-1 exhibited an exceptional catalytic activity in the production of furans and olefins, achieving a selectivity of 49.17 % and 40.65 %, respectively. Ni/TS-1 effectively promoted the formation of ethylene, yielding a selectivity of 97.49 % and a yield of 6.11 C-mol%. Under the optimized conditions: pyrolysis temperature of 550 ℃, catalytic temperature of 600 ℃, and catalyst to cellulose mass ratio of 20:1, the Au/TS-1 catalyst achieved a furans selectivity of 41.91 % with a yield of 11.94 C-mol%, while olefins selectivity and yield were 49.84 % and 18.99 C-mol%, respectively. At this condition, Au/TS-1 still has excellent catalytic activity after 10 cycles and has good catalytic effect towards different biomass feedstocks. Furthermore, the possible mechanism to produce furans and olefins was revealed. This research offers valuable insights for guiding the directed conversion of biomass into value-added chemicals, paving the way for a more sustainable future.

Laccase-mimicking activity of octahedral Mn3O4 nanoparticles and fluorescence of carbon dots as dual-mode signals for the specific detection of arsenic(V) in environmental water samples

The detrimental growth of water pollutants such as heavy metals has become a life-threatening problem in the modern era. Challenges remain in the development of rapid and accurate methods for detecting pentavalent arsenic [As(V)] in environmental water. The octahedral Mn3O4 nanoparticles (NPs) did not display excellent laccase-mimicking catalytic activity, whereas the adsorbed As(V) on the surface significantly enhanced the catalytic activity. Meanwhile, the quinone imine generated from the substrates 2,4-dichlorophenol (2,4-DP) and 4-aminoantipyrine (4-AAP) catalyzed by octahedral Mn3O4 NPs further quenched the carbon dots fluorescence. Thus, it is possible to establish a fast and accurate dual-mode sensor for detecting As(V). The developed dual-mode method of As(V) detection has good sensitivity and selectivity. The limit of detection for As(V) in colorimetric mode is 6.96 μg·L−1, whereas in the fluorescent mode, it is as low as 2.56 μg·L−1. Moreover, the detection data obtained by the dual-mode method can be validated by each other, thereby ensuring the dependability of the sensing system. The constructed dual-mode method with merits of sensitivity, speed and accuracy can offer a powerful tool for As(V) detection in environmental water. Furthermore, the application of laccase-mimicking activity in dual-mode detection provides new strategies for other environmental hazard detection.

In-Situ investigation of the catalytic hydrogenation reaction of 4-nitrothiophenol by using single Pt@Au nanowires as a new platform

Investigating the kinetics and mechanisms of catalytic hydrogenation reaction is important for fundamental research and chemical engineering, especially at single nanowire/nanoparticle level. In this work, we constructed a dual-functional single Pt@Au nanowire (Pt@Au NW) reaction platform, which was used for in-situ monitoring the p-nitrothiophenol (4-NTP) catalytic reduction process by using surface-enhanced Raman scattering (SERS) and UV–vis spectroscopy. The conversion of reactants and intermediates as well as the product generation during the reaction process were analyzed carefully, and the influencing factors of temperature and light were also discussed. Moreover, the density functional theory (DFT) was used to further investigate the effect of the single Pt@Au NW on catalytic hydrogenation reaction of 4-NTP. The results show that the single Pt@Au NW can be a good platform for in-situ monitoring catalytic hydrogenation reaction of 4-NTP with excellent catalytic activity, high stability, and good reproducibility, and clarified that trans-dimercaptoazobenzene (trans-DMAB) intermediates were produced that are further converted to the p-aminothiophenol (4-ATP). The work will not only give researchers new insights into the combination of the single nanowire/nanoparticle with spectroscopic techniques, but may also inspire further in-depth studies of multifunctional catalysts for catalytic hydrogenation reaction at single entity level.

Simple generic self-assembly fabrication of transition metal borates on polyaminophenylboric acid modified foam nickel for highly-efficient overall water splitting

Water electrocatalysis for hydrogen production as a prospect strategy to store renewable energy and reduce carbon emissions has attracted great attention, and exploring water electrolysis catalysts has become a research hotspot for widespread industrial water electrolysis application. Very recently, transition metal borates have been demonstrated great potential for electrocatalytic hydrogen or oxygen evolution in alkaline media. However, a generic method for fabricating transition metal borates as bifunctional oxygen catalysts are still challenging. Herein, through a two-step process including poly-aminophenylboronic acid electrodeposition and subsequent electrostatic self-assembly of transitional metal ions, for the first time, to our best knowledge, a simple and generic approach to fabricate polyaminophenylborate transition metal salt modified nickel foam electrodes (PAB-M/NF, M represents transition metal element) was developed for highly efficient water splitting. As a proof of concept, the obtained PAB-Ru/NF exhibited remarkable bifunctional HER and OER catalytic activities and stability in alkaline medium. To drive the HER and OER with a current density of 10 mA cm−2 in 1 M KOH electrolyte, PAB-Ru/NF only required an overpotential of 14 mV and 301 mV, respectively. Moreover, even at a great current density of 250 mA cm−2, PAB-Ru/NF can exhibit very favorable long-term stability for over 35 h. When assembled into an electrolyzer with PAB-Ru/NF as both the anode and cathode, a current density of 10 mA cm−2 can be achieved at a very low cell voltage of 1.50 V. In addition, the other PAB-M/NF catalysts (M including but not limited to Fe, Co and Ni) prepared by the same way also show excellent bifunctional HER and OER catalytic activities and durability. This study provides a prospective and economically feasible generic approach for developing practical bifunctional catalysts for industrial water electrolysis.

Small Organic Molecule‐Assisted Mesoscopic Self‐Assembly of SnO2 Nanoparticles: An Efficient Catalyst for the Synthesis of β‐Nitroaldol

AbstractOver the past few decades, huge number of mesoporous materials have been synthesized by using supramolecular assembly of ionic/non‐ionic surfactants as structure‐directing agents (SDAs). Here, we report a facile synthetic strategy to fabricate self‐assembled SnO2 nanoparticles with well‐defined nanocrystalline spherical morphology and mesoporosity using sodium salicylate as a SDA and stabilizing agent. The mesophases of the materials were investigated by powder X‐ray diffraction, TEM and N2 sorption studies. TEM results show that the mesopores are formed by the assembly of ultrasmall SnO2 NPs with broad range of interparticle voids and N2 sorption studies agreed well with this TEM data. This synthesis strategy facilitated the generation of SnO2 NPs with increased surface area and pores of nanoscale dimensions with a large number of exposed surface‐active sites. The photoinduced electron transfer in these materials was investigated by the fluorescence quenching study with pyranine, which suggested the presence of surface Lewis basicity. The materials showed excellent catalytic activity for the synthesis of β‐nitroaldol through the reaction of benzaldehyde and nitromethane. The heterogeneous nature of the catalyst could be attributed to the high surface area, presence of numerous surface active sites, and structural robustness of the self‐assembled SnO2 nanostructure. The catalysts exhibited negligible loss in activity after several catalytic cycles.

Enhanced Electrocatalytic Performance of the FePt/PPy-C Composite toward Methanol Oxidation.

A novel FePt/PPy-C composite nanomaterial has been designed and investigated as a methanol oxidation reaction (MOR) electrocatalyst. The FePt nanoparticles with an average diameter of about 3 nm have been prepared by the co-reduction method and then loaded onto the PPy-C composite support. The electrocatalytic performance is affected by the composition of the FePt nanoparticles. The experimental results indicated that the Fe1.5Pt1/PPy-C catalyst exhibited excellent catalytic activity and stability for MOR, with mass activity and specific activity of 1.76 A mgPt-1 and 2.71 mA cm-2, respectively, which are 5.18 and 4.60 times higher than that of the commercial Pt/C catalyst. Density functional theory (DFT) has been employed to simulate the electrical structures of catalyst supports, and the mechanism of the methanol oxidation process has been further analyzed. The heterojunctions of the PPy-C interface could accelerate the electron migration from the electrocatalytic center to the electrodes. The possibility of methanol oxidation has been improved effectively, which can be confirmed by the d-band center and CO adsorption energy on FePt nanoparticles in the DFT calculation results.

Oxygen vacancy–rich K-Mn3O4@CeO2 catalyst for efficient oxidation degradation of formaldehyde at near room temperature

Synthesis of catalysts with high catalytic degradation activity for formaldehyde (HCHO) at room temperature is highly desirable for indoor air quality control. Herein, a novel K-Mn3O4@CeO2 catalyst with excellent catalytic oxidation activity toward HCHO at near room temperature was reported. In particular, the K addition in K-Mn3O4@CeO2 considerably enhanced the oxidation activity, and importantly, 99.3 % conversion of 10 mL of a 40 mg/L HCHO solution at 30 °C for 14 h was achieved, with simultaneous strong cycling stability. Moreover, the addition of K species considerably influenced the chemical valence state of Mn from +4 (ε-MnO2) to +8/3 (Mn3O4) on the surface of CeO2, which obviously changed the tunnel structure and the number of oxygen vacancies. One part of K species is uniformly dispersed on K-Mn3O4@CeO2, and the other part exists in the tunnel structure of Mn3O4@CeO2, which is mainly used to balance the negative charge of the tunnel and prevent collapse of the structure, providing enough active sites for the catalytic oxidation of HCHO. We observed a phase transition from tunneled KMnO2 to Mn3O4 to tunneled MnO2 with the decreasing K+ content, in which K-Mn3O4@CeO2 exhibited higher HCHO oxidation activity. In addition, K-Mn3O4@CeO2 exhibited lower oxygen vacancy formation and HCHO adsorption energies in aqueous solution based on density functional theory calculations. This is because the K species provide more active oxygen species and richer oxygen vacancies on the surface of K-Mn3O4@CeO2, promote the mobility of lattice oxygen and the room-temperature reduction properties of oxygen species, and enhance the ability of the catalyst to replenish the consumed oxygen species. Finally, a possible HCHO catalytic oxidation pathway on the surface of K-Mn3O4@CeO2 catalyst is proposed.

Nanoarchitectonics of hollow Co3O4 through tannic acid etching of ZIF-67 for catalysis of toluene oxidation

Oxide catalysts obtained by derivatization of MOFs as precursors often have excellent results in the catalysis of VOCs. In this study, the Co3O4 catalysts obtained by pyrolysis after tannic acid etching using ZIF-67 as precursor showed excellent toluene catalytic activity. Among them, Co3O4 −1–15 showed the best catalytic activity with T90 = 219 °C (the conversion temperatures of 90 %), which was 20 °C lower than that of Co3O4 -O obtained by direct pyrolysis of ZIF-67. It also exhibits excellent stability and cyclic stability. After tannic acid treatment, Co3O4 −1–15 exposed higher surface Co3+ and Olatt (surface lattice oxygen) content, which were the key factors for its most outstanding catalytic activity. Lattice oxygen mobility and oxygen vacancies were also important factors affecting catalyst activity.