Excellent Catalytic Performance Research Articles

New method for the preparation of hierarchical nanotube K0.3xMnxCe1-xOδ catalysts and their excellent catalytic performance for soot combustion

A series of nanofibrous K-Mn-Ce composite oxide catalysts were prepared via a centrifugal spinning method for the first time, and their physicochemical properties were studied. The prepared K0.3xMnxCe1-xOδ metal oxide catalyst, which is a composite of CeO2 and cryptopotassium manganese-type K2-xMn8O16, exhibits a hierarchical nanotube structure with uniform nanoneedles on its surface. During the process of soot oxidation, CeO2 utilizes its unique oxygen storage and release capacity to supply oxygen species. Simultaneously, the excellent redox properties of K2-xMn8O16 effectively promote valence cycling of the active components and produce more active oxygen species. This synergistic effect effectively enhances the intrinsic activity of the catalysts. Among the prepared catalysts, K0.15Mn0.5Ce0.5Oδ exhibits the highest catalytic performance, with 10% (T10), 50% (T50), and 90% (T90) soot conversion temperatures of 267 °C, 309 °C, and 338 °C, respectively, and shows good stability and water and sulfur resistance. Based on their simple preparation, low cost, and good catalytic performance, K0.3xMnxCe1-xOδ composite metal oxide catalysts have good potential in catalytic soot combustion applications.

In Situ Carbon-Confined MoSe2 Catalyst with Heterojunction for Highly Selective CO2 Hydrogenation to Methanol.

The synthesis of methanol from CO2 hydrogenation is an effective measure to deal with global climate change and an important route for the chemical fixation of CO2. In this work, carbon-confined MoSe2 (MoSe2@C) catalysts were prepared by in situ pyrolysis using glucose as a carbon source. The physico-chemical properties and catalytic performance of CO2 hydrogenation to yield methanol were compared with MoSe2 and MoSe2/C. The results of the structure characterization showed MoSe2 displayed few layers and a small particle size. Owing to the synergistic effect of the Mo2C-MoSe2 heterojunction and in situ carbon doping, MoSe2@C with a suitable C/Mo mole ratio in the precursor showed excellent catalytic performance in the synthesis of methanol from CO2 hydrogenation. Under the optimal catalyst MoSe2@C-55, the selectivity of methanol reached 93.7% at a 9.7% conversion of CO2 under optimized reaction conditions, and its catalytic performance was maintained without deactivation during a continuous reaction of 100 h. In situ diffuse infrared Fourier transform spectroscopy studies suggested that formate and CO were the key intermediates in CO2 hydrogenation to methanol.

Resonant structure substrate anchors Pt to form ordered alloys for efficient oxygen reduction reaction

Platinum-based ordered alloys have excellent catalytic performance for the cathodic oxygen reduction reaction (ORR) in fuel cells. However, these alloys exhibit a lower degree of ordering and larger crystal grains after heat treatment. Herein, a series of cyanamide group molecules (cyanamide, dicyandiamide, melamine) was employed as substrates to modify Pt-based alloys by promoting the binding between metal ions, leading to the preparation of ∼ 4 nm PtM (M = Co, Fe, Ni) ordered alloys after heat treatment. Among them, the PtCo ordered alloy prepared using hydrolyzed cyanamide with a unique resonance structure exhibits a high degree of order (93.1 %), and its mass activity of 0.915 A mgPt-1 at 0.9 V is superior to that of Pt/C. The theoretically calculated adsorption energies of these alloys demonstrate that the resonance structure of the cyanamide substrate is beneficial for alloy formation, thereby facilitating ordered alloy synthesis.

Iron-Doped carbon supported nickel selenide heterogeneous materials for Dual-Function water electrolysis catalysts

Developing efficient, economical, and resource-abundant dual-function electrocatalysts for water splitting is crucial. In this study, uniform growth of NiSex nanocrystals on Fe-doped XC-72 carbon (NS/XC-Fe) was achieved through a solvothermal method, resulting in the formation of a composite material with outstanding performance. NS/XC-Fe exhibits excellent catalytic performance for both oxygen evolution reaction (OER) (261 mV, 10 mA·cm−2) and hydrogen evolution reaction (HER) (275 mV, 10 mA·cm−2) under alkaline conditions, owing to the introduction of iron and the construction of heterogeneous interfaces. Additionally, NS/XC-Fe exhibited excellent stability during the 24 h polarization test. Density Functional Theory (DFT) calculations indicated that the introduction of iron optimized the catalyst’s H adsorption capability, while the construction of heterogeneous interfaces lowered the energy barrier of the rate-determining step. This demonstrates the significant potential of NS/XC-Fe as an electrocatalyst, providing new insights for the design and synthesis of efficient bifunctional electrochemical water splitting catalysts.

Efficient catalysis of acetylene semi-hydrogenation through synergistic action of supported ionic liquid-nickel catalyst

In the semi-hydrogenation of acetylene, nickel-based catalysts offer a promising alternative to precious metal palladium catalysts. Despite the positive hydrogenation activity of nickel-based catalysts, there is still room for improvement in terms of their selectivity and stability. In this study, a simple incipient wetness impregnation method was employed to prepare Ni(OAC)2-IL/Al2O3 catalyst and its performance in the selective hydrogenation of acetylene was investigated. It was found that under the conditions of 170 °C and a space velocity of 600 h−1, the 3 % Ni(OAC)2-IL/Al2O3 catalyst achieved a 95.3 % acetylene conversion with an 85.6 % ethylene selectivity. Furthermore, the catalyst exhibited outstanding stability over a 100 hour test. TEM, XPS and C2H4-TPD experiments showed that the Ni species were encapsulated in the ionic liquids (ILs), and the interaction between the metal ions, nickel, and the ILs ensured a high dispersion and stability of the actives on the carriers, and the electronic effect between the ionic nickel and the ionic liquids increased the electron cloud density of the Ni, which improved the catalyst selectivity, which is the main reason for its excellent catalytic performance.

Synthesis of InZrOx nanosheets and its application in CO2 hydrogenation to methanol

Synthesis of methanol via CO2 hydrogenation is a very important reaction. In recent years, the In2O3 based catalysts were proved to be a sort of promising catalysts to accelerate this reaction, which have aroused extensive attention. However, design of novel In2O3 based catalysts that can efficiently produce methanol from CO2 hydrogenation at low temperature is still in great need. Herein we fabricated the InZrOx nanosheets via a simple solvothermal method, which had peculiar surface structure and plenty of oxygen defects. The InZrOx nanosheets displayed excellent low temperature catalytic performance in a slurry reactor. The methanol selectivity (90 %) and activity (1.4 mmol gIn-1h−1) were achieved at 180 °C, which are 2.3 and 1.6 times than that of the counterpart nanoparticles, respectively. Water as a clean and cheap reaction solvent played a crucial role, which participated in the kinetic process of the catalysis. The particular catalyst structure and the solvent effect of water accounting for the outstanding reaction results.

Efficient hydrodeoxygenation of methyl palmitate over NiMo/ZrO2 catalyst with electron transfer between Ni and Mo

The hydrodeoxygenation of biomass into high quality fuels is one of the effective technologies to produce green diesel and solve the environmental pollution of fossil fuels at source. In this work, the catalytic performances of NixMoy/ZrO2 catalysts for methyl palmitate hydrodeoxygenation were evaluated, and the characterization results were combined to understand their role of physicochemical and structural properties in modulating the specific selectivity of alkanes. Under mild reaction condition (270 °C, 3 MPa), the Ni1Mo1/ZrO2 catalyst showed the best hydrodeoxygenation reactivity (conversion: 99.4%) and alkane selectivity (95.0%, hexadecane: 73.6%) of methyl palmitate. It was found that the electron transfer from Mo to Ni in Ni1Mo1/ZrO2 catalyst promoted the active site Ni anchoring and H2 molecules activation, which were associated with the better hydrodeoxygenation activity. In addition, the highest oxygen vacancies and Mo5+ content in Ni1Mo1/ZrO2 catalyst benefited the adsorption and breaking capacity of CO/C-O bonds and hexadecane yield. The Ni1Mo1/ZrO2 catalyst maintained excellent catalytic performance and structural stability after a long-term test of 60 h, which could be efficiently applied for hydrodeoxygenation of methyl palmitate.

Bimetallic Mn-Ce oxides modified α-Fe2O3 nanorods for low temperature catalytic thermal desorption of naphthalene in soil

Developing highly active catalytic thermal desorption system is of great significance to soil remediation in a sustainable manner. Herein, Mn-Ce oxides modified α-Fe2O3 nanorods were fabricated for catalytic thermal desorption of naphthalene. When N2 was injected at 500 mL/min and heated at 180 °C for 5 min, the removal rate of naphthalene in soil by Ce-Mn/α-Fe2O3 reached a maximum of 99.96 %, and the corresponding removal rate achieved 32.1 %. Such excellent catalytic performances can be attributed to the mutual conversion of oxidation valence states of MnOx, CeO2, and Fe2O3, which enhance the oxygen mobility of the catalyst surface, resulting in abundant oxygen vacancies and acidic sites. Combined with the tests of GC–MS and FT-IR, the degradation intermediates were identified and a probable reaction pathway was proposed. This study provides an economical and efficient strategy for the enhancement of catalytic thermal desorption, showing crucial practical significance for PHAs remediation in soil.

Interfacial engineering of TiO2@Bi-BiOBr by constructing hierarchical core–shell heterojunction to boost charge transfer for photothermal CO2 reduction

CO2 reduction by a sustainable pathway such as photothermal catalysis is highly demanded currently, high carrier recombination rate still severely limits the performance of photothermal catalysis. Constructing heterojunction interfaces with high exposed area is an effective strategy to solve the problem of carrier recombination. However, fine control of the interface structure is still highly challenging. Herein, Density functional theory (DFT) calculations were constructed to reveal that metallic Bi leads to more densities of states (DOS) generation at the conduction band edge in Bi-BiOBr, which argues that photogenerated electrons are more likely to be delivered to metallic Bi. A TiO2@Bi-BiOBr hollow hierarchical core–shell heterojunction was designed, providing a highly exposed interface and Bi between interfaces. Such structure endows the catalyst with excellent photothermal catalytic performance, achieving a CO yield of 30.4 μmol·h−1·g−1. The highly improved performance is attributed to interfacial thermoelectrons transfer boosted by the construction of TiO2@BiOBr heterojunction as well as metal Bi. And a possible CO2 reduction pathway is proposed, which is consistent with the Carbine pathway. This study provides an exciting idea for the modulation of photoelectron transfer at catalyst interfaces.

Imidazole-based organic polymer frameworks as metal- and halogen-free heterogeneous platforms for efficient CO2 cycloaddition

Developing effective metal- and halogen-free heterogeneous catalysts for the CO2 cycloaddition remains a challenge. In this study, novel imidazole-based hyper-crosslinked polymers (HCP-BZ, HCP-BP and HCP-TBZ) with abundant N sites were constructed via a one-pot polymerization, and employed as heterogeneous catalysts for the CO2 cycloaddition reaction. The special skeletal pore structure with abundant hierarchical pore structures and uniformly distributed active sites were demonstrated by various characterization technologies. The optimal HCP-TBZ(16:1) exhibits a good CO2 selective adsorption performance with a CO2 adsorption capacity of 2.23 mmol/g and CO2/N2 adsorption selectivity of 41 at 273 K and 0.1 MPa. Additionally, the resulting catalyst HCP-TBZ(16:1) achieves an excellent catalytic performance with 96 % yield and 99 % selectivity without metal, halogen, cocatalyst and solvent additions (120 °C, 1.0 MPa CO2, 5 h). Moreover, the HCP-TBZ(16:1) also exhibits a satisfactory catalytic activity under the mild conditions (70 °C, 1.0 MPa CO2), and can effectively catalyze the cyclic carbonate preparation from the dilute CO2 (15 %CO2/85 %N2). The comparable catalytic activity and the determined structural stability, reusability and universality make the prepared imidazole-based HCPs a potential heterogeneous catalyst candidate for the CO2 cycloaddition. This study will provide some guidance for developing metal-free and halogen-free CO2 adsorption and conversion platforms.

MOF-74 derivatives spinel CuCo2O4/C with d-band center modulation for accelerating ammonium perchlorate thermolysis

As one of main components of solid propellant, ammonium perchlorate (AP) shows slow sluggish decomposition kinetics with unconcentrated heat release. In the past, researchers have done a lot of work using spinel oxides as combustion modifiers to improve the combustion performance of AP. However, AP decomposition process is very complicated, and the relationship between intrinsic activity of cobalt-based spinel catalysts and AP combustion process is still unclear. In this paper, a series of cobalt-based spinel structure catalysts, MCo2O4/C, were prepared by pyrolysis of cobalt-containing bimetal MOF-74 and used as AP combustion catalysts. All of them showed excellent catalytic performance, among which CuCo2O4/C had the best catalytic activity. It effectively reduces the activation energy of the reaction, speeds up the reaction rate, and reduces the peak temperature of the AP decomposition reaction by 161.2 ℃, and the reaction rate k is 10.28 times of Co3O4/C. XPS and NH3-TPD tests indicate that substitution CoTd2+ with Cu2+ increases the ratio of Co3+/Co2+ and enhance interaction between NH3 and catalyst. The essential reason is that Cu–O-Co corner sharing effect changes electron distribution and enhances CoOh3+ Lewis acidity accompanied with the proximity of d-band center to EF by density functional theory calculations.

Selective hydrogenation of furfural to furfuryl alcohol over copper-cobalt bimetallic catalyst

Cu-based catalysts have been widely studied as selectively hydrogenated furfural. However, due to the weak hydrogenation activity of the mono-metal copper-based catalyst, the interaction with furfural is usually weak, and the accessibility of the active site is severely limited. A micro-doping strategy was proposed in this study to solve these problems. Trace amounts of cobalt metal are doped into copper using equal volume impregnation. Compared with the Cu/MgO catalyst, the bimetallic CuCo/MgO-0.04 catalyst changes metal particles' size and valence and regulates the catalyst surface's electronic environment. Electron transfer occurs between Co and Cu, and many active sites are generated for adsorption and activation of CO double bonds, and hydrogenation reactions occur with adjacent H protons to improve the selectivity of furfuryl alcohol. CuCo/MgO-0.04 catalyst has excellent catalytic performance of 100 % furfural conversion and 99.4 % furfural alcohol selectivity. Combined with experimental data, kinetic studies, and theoretical calculations, it was confirmed that the d-band center shifted up in the catalyst doped with trace metal cobalt, which optimized the adsorption energy and configuration of furfural and reduced the reaction barrier more effectively. This study provides a strategy to support the partial doping of highly dispersed Cu nanoparticles with a small amount of Co metal. It achieves excellent catalytic properties and chemical selectivity in selective hydrogenation reactions.

Preparation of Cs/CuAl-LDO@Al2O3@Fe3O4 magnetic catalysts and reaction mechanism of the side-chain alkylation of toluene to styrene

A series of Cs/CuAl-LDO@Al2O3@Fe3O4 magnetic catalysts with varied CuAl-LDO contents were prepared by growing CuAl-LDH layers on the surface of Al2O3@Fe3O4 magnetic cores, impregnated with Cs and followed by calcination. The as-synthesized catalysts were characterized by XRD, N2 adsorption-desorption, SEM, TEM(EDS), XPS, NH3-TPD, CO2-TPD, and VSM techniques. The catalytic performance and reusability of the catalysts for the side-chain alkylation of toluene with formaldehyde were evaluated in a micro-high-pressure reactor, and the reaction mechanism was further studied. The results showed that the Al2O3@Fe3O4 magnetic core of the catalyst was about 110 nm, and the CuAl-LDO formed a staggered lamellar structure with a shell thickness of around 30–45 nm. The magnetic catalyst demonstrated excellent catalytic performance and reusability for the side-chain alkylation of toluene with formaldehyde in one-step to styrene. As-synthesized magnetic Cs/CuAl-LDO@Al2O3@Fe3O4 catalyst with CuAl-LDO content of 20 wt% delivered toluene conversion of 7.97% under optimized conditions, while the styrene selectivity and the selectivity of side-chain alkylation were 90.17% and 98.36%, respectively. The reaction mechanism showed that the benzene ring of toluene was stably adsorbed on the Al3+ acid sites of the CuAl-LDO layers. The C–H group of the side-chain of toluene formed carboanions and protons under the action of the Cuδ+–Oδ– base sites. Formaldehyde formed a transition state of adsorbed formaldehyde under the action of Cuδ+ acid sites. Finally, these adsorbed states and intermediate species accomplished the side-chain alkylation of toluene with formaldehyde to styrene in one-step under the synergic action of acid-base sites. The synergistic effects of suitable acid-base sites and lamellar spatial structures in the catalyst were the key to styrene formation with high selectivity.

Hollow Cu/CoS2 Nanozyme with Defect-Induced Enzymatic Catalytic Sites and Binding Pockets for Highly Sensitive Fluorescence Detection of Alkaline Phosphatase.

Along with an ever-deepening understanding of the catalytic principle of natural enzymes, the rational design of high-activity biomimetic nanozymes has become a hot topic in current research. Inspired by the active centers of natural enzymes consisting of catalytic sites and binding pockets, a Cu-doped CoS2 hollow nanocube (Cu/CoS2 HNCs) nanozyme integrating substitution defects and vacancies is developed through a defect engineering strategy. It is shown that the vacancies and substitution defects in the developed Cu/CoS2 HNC nanozymes serve as binding pockets and catalytic sites, respectively. The construction of this key active center and the accelerated electron transfer from the Co/Cu redox cycle significantly improve the substrate affinity and catalytic efficiency of the Cu/CoS2 HNCs nanozymes, which results in the excellent catalytic performance of the Cu/CoS2 HNC nanozymes. Using the superior enzymatic activity of Cu/CoS2 HNCs, a fluorescence detection platform for alkaline phosphatase (ALP) is established, which is a wider detection range and lower limit of detection (LOD) than previous work. This work broadens the family of nanozymes and provide a new idea for the development of novel nanozymes with high enzyme activity, as well as a guideline for the construction of highly sensitive fluorescent sensors.

Heterogeneous CuS QDs/BiVO4@Y2O2S Nanoreactor for Monitorable Photocatalysis.

Exploration of multifunctional integrated catalysts is of great significance for photocatalysis toward practical application. Herein, a 1D confined nanoreactor with a heterogeneous core-shell structure is designed for synergies of efficient catalysis and temperature monitoring by custom encapsulation of Z-scheme heterojunction CuS quantum dots/BiVO4 (CuS QDs/BiVO4) and Y2O2S-Er, Yb. The dispersed active sites created by the QDs with high surface energy improve the mass transfer efficiency, and the efficient electron transport channels at the heterogeneous interface extend the carrier lifetime, which endows the nanoreactor with excellent catalytic performance. Meanwhile, real-time temperature monitoring is realized based on the thermally coupled levels 2H11/2/4S3/2→4I15/2 of Er3+ using fluorescence intensity ratio, which enables the monitorable photocatalysis. Furthermore, the nanoreactor with a multidimensional structure increases effective intermolecular collisions to facilitate the catalytic process by restricting the reaction within distinct enclosed spaces and circumvents potential unknown interaction effects. The design of multi-space nanoconfined reactors opens up a new avenue to modulate catalyst function, providing a unique perspective for photocatalytic applications in the mineralization of organic pollutants, hydrogen production, and nitrogen fixation.

In situ N-doping engineered biochar catalysts for oxidation degradation of sulfadiazine via nonradical pathways: Singlet oxygen and electron transfer

Understanding the structure of non-metallic heteroatom-doped carbon catalysts and the subsequent degradation of new pollutants is crucial for designing more efficient carbon catalysts. Environmentally friendly in situ N-doped biochar catalysts were prepared for peroxymonosulfate (PMS) activation and sulfadiazine (SDZ) degradation. The acid washing process and calcination temperature of catalyst increased π-π* shake up, graphitic N percentage, specific surface area and defects, promoting the transformation of pollutant degradation mechanism from radical pathway to non-radical pathway. 100 % of the SDZ with the initial concentration of 10 mg/L was quickly degraded within 60 min using 0.2 g/L catalysts and 0.5 mM PMS. Excellent catalytic performance was attributed to singlet oxygen and electron transfer-dominated non-radical pathways. The four potential degradation pathways of SDZ were proposed, and toxicity predication indicated that overall biotoxicity of the intermediates during SDZ degradation was decreased. This research deepens our understanding of the mechanisms of non-radical pathways and guides the synthesis of carbon-based catalysts.

The acceleration of the active phase transition of NiCoFe hydroxide by Ta doping to achieve Long-Time seawater electrolysis at Ampere-Level current density

Considering the regional distribution of freshwater resources, acquiring hydrogen by seawater electrolysis has lower cost and feasibility. NiCoFe-based materials have been widely studied due to their excellent catalytic oxidation performance in freshwater. However, the large amount of chloride ions in seawater will severely erode the catalytic site and greatly reduce the catalyst's lifetime. In this paper, a two-dimensional nanosheet quaternary metal hydroxide electrode composed of Ni, Co, Fe, and Ta elements was synthesized via a facile one-step hydrothermal method for efficient oxygen evolution reaction (OER) in seawater electrolysis. Structural characterization and in-situ test revealed that the incorporation of Ta not only optimized the electronic structure of the catalyst but also accelerated the formation of the γ-NiOOH phase, making the active phase is protected from being attacked by Cl- ions during the formation process, enhancing its OER activity while achieving extended durability. The catalyst was operated at an ampere-level of 1 A cm-2 for over one month (800 h), and no significant degradation was observed. This work provides a promising strategy for developing cost-effective, efficient, and stable catalysts for challenging applications in seawater electrolysis.

Magnesium borate whiskers/La2-XCeXZr2O7 catalysts preparation on cordierite honeycomb ceramic surfaces for soot catalytic oxidation͏

Magnesium borate whiskers were used to prepare a hierarchical microstructure on cordierite ceramic substrate through the precipitation-molten salt method. The La2-XCeXZr2O7 catalyst was then loaded onto the magnesium borate whiskers to form the hierarchical microstructure. The Ce-doped catalysts exhibited a significant improvement in the catalytic activity of soot combustion compared to the La2Zr2O7 catalyst. The study employed various techniques to characterize the structural morphology and phase composition, including scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), Fourier transform-infrared spectroscopy (FT-IR), and X-ray diffraction (XRD). The growth of Magnesium borate whiskers (Mg2B2O5) with diameters of 100–200 nm and lengths of 2–5 μm were grown and tightly bonded to the cordierite ceramic substrate to mimic the structure of human respiratory system cilia. This could improve the filtration efficiency of soot in car exhaust. BET analysis showed that the specific surface area of cordierite increased from 0.684 m2/g to 1.363 m2/g after whisker growth. The study confirmed that the whiskers were firmly attached to the cordierite ceramic substrate, as demonstrated by the binding strength experiments. The addition of Ce metal has been found to significantly enhance soot combustion due to the presence of more active oxygen species and superior mobility of lattice oxygen species with more oxygen vacancies. The catalyst's intrinsic redox property was characterized using X-ray photoelectron spectroscopy (XPS) and H2 temperature-programmed reduction (H2-TPR). The semi-quantitative thermogravimetric analysis (TG-DTG) and the temperature-programmed oxidation (TPO) of catalysts showed that Z-La1.9Ce0·1Zr2O7 exhibited the highest catalytic activity for soot combustion, with an ignition temperature of 268 °C, a peak temperature of 418 °C, and a temperature of 90 % soot conversion of 464 °C. Furthermore, cyclic stability experiments demonstrate that the Z-La1.9Ce0·1Zr2O7 catalyst exhibits excellent structural stability and consistent catalytic performance. This distinctive microstructure holds great potential for applications in the field of DPF.

NC Loaded PtM Alloy from M-NC with Ultralow Pt Loading for Oxygen Reduction Reaction

Developing low Pt or non-precious metal catalysts for oxygen reduction reaction (ORR) has becoming necessary in recent years. Herein, PtM alloy anchored on nitrogen-doped carbon (PtM/NC, M=Fe, Co) catalyst with ultralow Pt loading (∼1 wt%) is prepared from the simple two-process pyrolysis, namely from C to M-NC then to PtM/NC. The as-prepared PtM/NC (M=Fe, Co) shows an excellent ORR catalytic performance with the peak potential and half-wave potential of 0.901 and 0.870 V for PtFe/NC, 0.868 and 0.845 V for Pt3Co/NC. The ORR on PtM/NC (M=Fe, Co) is a mainly direct 4-electron reaction pathway (3.75–3.90) in alkaline solution. Moreover, they possess good methanol tolerance and stability. Synergistic effect of Pt and M together with N species result in the excellent ORR catalytic activity of PtM/NC (M=Fe, Co). The negative shift of Pt binding energy caused by both lattice contraction and electron orbital coupling from M is beneficial for reducing the d-band center of Pt, weakening the oxygen binding energy and enhancing the ORR intrinsic activity of Pt. The strong interactions between NC and PtM alloy are beneficial for anchoring PtM nanoparticles, promoting the stability of catalyst. This work provides a new strategy for preparing ultralow Pt loading catalysts.

Efficient calcium sulfite oxidation treatment by a highly active iron-manganese bimetallic metal-organic frameworks (MOFs)

Calcium sulfite (CaSO3) oxidation is the key step in the resource utilization of flue gas desulfurization (FGD) ash waste. However, under natural conditions the oxidation rate of CaSO3 is very low, limiting its conversion into calcium sulfate, an acceptable product for construction material. This study was devoted to the investigation of the synthesis and performance of a bimetallic MOFs with potential catalytic activity, namely, Fe/Mn(BDC)(DMF,F) catalysts. A combination of techniques including SEM, EDS, XRD, FT-IR, etc. were used to characterize the catalysts. The excellent catalytic performance examined in a gas-liquid-solid three-phase oxidation system are due to the special flexible respiratory architecture and homogeneous distribution of active sites, which allows the reactants to fully contact with the catalyst. Mn incorporated in the backbone of the metal-organic framework significantly enriches the catalytic active species that participate in a radical chain reaction with activated SO32- as ·SO3-, which in turn generates the key radical ·SO5- that reacts with SO32- to form SO42-. In the presence of Fe/Mn(BDC)(DMF, F)-13, the oxidation ratio of CaSO3 could reach 90.71%, which is more than 30-fold compared to non-catalytic oxidation and almost 5 times the effects of the single metal Fe(BDC)(DMF, F) catalyst. In addition, the study of kinetics shows that the oxidation rate of Fe/Mn(BDC)(DMF,F)-13 can reach 0.042mmol·L-1·s-1 with an apparent activation energy of 10.86kJ/mol. The oxidation rate is mainly affected by reaction temperature, pH value, catalyst concentration, and air flow rate. This study provides a potentially sustainable way for utilization of CaSO3-containing desulfurization ash.