Zn Catalysts Research Articles

Rational Design of a Co/MnO-Embedded 2D Nitrogen-Doped Carbon/Carbon Nanotube Hybrid Catalyst for Efficient Oxygen Catalysis and High-Capacity Zn–Air Batteries

Rational Design of a Co/MnO-Embedded 2D Nitrogen-Doped Carbon/Carbon Nanotube Hybrid Catalyst for Efficient Oxygen Catalysis and High-Capacity Zn–Air Batteries

Value-added bioproducts by bioethanol dehydrogenation to acetaldehyde through Cu and Zn modified biochar catalysts

ABSTRACT In this study, the efficiency of a series of biochar-supported Cu catalysts, biochar-supported Zn catalysts, and biochar-supported Cu-Zn catalysts was determined through bioethanol dehydrogenation to the high-value chemical, acetaldehyde. Each metal, with weight percentages of 10, 20, and 30, and the combination of Cu-Zn, including 10 wt% of Cu and Zn, 15 wt% of Cu – 5 wt% of Zn, and 15 wt% of Cu and Zn, were fully loaded onto biochar using an incipient wetness impregnation technique. Subsequently, all biocatalysts were subjected to bioethanol dehydrogenation reactions in a temperature range of 200–400 °C. The optimum metal loading for the catalyst was found to be the combination of 15 wt% Cu and 15 wt% Zn. This catalyst resulted in a reasonable acetaldehyde yield of 56.2%, an initial bioethanol conversion of 57.3%, and a very high acetaldehyde selectivity of 98.1% at a mild reaction temperature of 300 °C and ambient pressure. These results were attributed to the optimal concentration of weak-medium acid and medium base sites. Active acid and base sites were identified through temperature-programmed desorption of ammonia (NH3-TPD) and temperature-programmed desorption of carbon dioxide (CO2-TPD), respectively. Furthermore, the reaction stability test of the best biocatalyst (15Cu-15Zn/BB) was proven by maintaining this reaction at the same temperature (300 °C) for 10 h. However, the catalytic performance slightly decreased due to the coke formation of Cu species.

Electrocatalytic Synthesis of Urea

Many industrial chemical processes involve a high-energy demand (often still derived from fossil fuels). Urea is an important chemical for the agricultural industry, which accounts for 70% of the global nitrogen-containing fertilizer usage. Currently, urea is produced by the reaction of liquid NH3 and CO2 [1] in a process known as the Haber-Meiser process. Despite its importance, this process suffers from high energy demand and CO2 emissions, mainly due to the NH3 synthesis step (Haber- Bosch process), which relies on fossil fuel resources. Making urea with electrochemical methods has recently gained interest from the scientific community as this approach provides a way to reduce the high CO2 emissions currently associated with urea production. Among the various nitrogen sources explored for urea electrosynthesis, nitrate (NO3-) is attractive because of its high solubility in water, low dissociation energy and potential to mitigate NO3 − contaminations in water. Even though the mechanism of urea synthesis via CO2 and NO3 - coupling is still controversial and not broadly studied, most reports implicate CO* and NH2* surface intermediates in urea synthesis.[2] Cu is an attractive electrocatalyst as it can reduce CO2 to CO and further products and it is also an active catalyst for the reduction of nitrate to ammonia Previous reports on Cu and Cu-based materials showed that urea can be obtained from NO2 -.[3,4] Early research by Shibata et al. with various catalysts demonstrated that the highest faradaic efficiency towards urea from NO3 - was achieved with a Zn catalyst.[5] In this presentation, I will show our latest results on the development of Cu bimetallic catalysts ( CuRh) for urea electrosysnthesis from CO2 and NO3 -[6,7].

Synergistic effects on Cu, Zn and Al-based catalyst: tracking the change of active sites during glycerol dehydration

Synergistic effects on Cu, Zn and Al-based catalyst: tracking the change of active sites during glycerol dehydration

Catalytic Activation of Bis(2,2,2‐trifluoroethyl) phosphite with Hf(IV) for the Synthesis of Mixed Dialkyl Phosphites

We developed a second‐generation of Lewis acid catalyst enabling selective and user‐friendly phosphonylation of diverse alcohols. This one‐pot method utilizes P(III) reagent bis(2,2,2–trifluoroethyl) phosphite under mild conditions. Exploring the influence of metal selection in Lewis acid catalysts revealed four highly active complexes for alcohol phosphonylation: Zn(II), Al(III), Zr(IV), and Hf(IV). Notably, Hf(IV) displayed superior selectivity compared to the previously developed Zn(II) catalyst.

Integration of Fe2N Nanoparticles and FeCo Alloys into N-Doped Carbon Nanotubes as Efficient Oxygen Catalysts for Rechargeable Zn–air Batteries

Integration of Fe₂N Nanoparticles and FeCo Alloys into N-Doped Carbon Nanotubes as Efficient Oxygen Catalysts for Rechargeable Zn–air Batteries

Modulating the electrocatalytic reduction of CO2 to CO via surface reconstruction of ZnO nanoshapes

The electrocatalytic conversion of carbon dioxide (CO2) into valuable chemicals presents a promising strategy for closing the carbon cycle. In this study, we synthesized zinc (Zn) catalysts through hydrothermal methods using either polyvinylpyrrolidone (PVP) or cetyltrimethylammonium bromide (CTAB) as stabilizing agents. These catalysts proved highly efficient in converting CO2 into carbon monoxide (CO). Our findings revealed that ZnO, synthesized with different morphologies—namely, nanoneedles (ZnO-NN) and nanorods (ZnO-NR)—underwent significant electro-reconstruction, ultimately leading to the formation of hexagonal metallic Zn crystals, regardless of their initial characteristics. Utilizing ex-situ operando techniques, we elucidated that metallic Zn serves as the active phase for the CO2-to-CO conversion process. In a comparison, ZnO-NN catalysts demonstrated superior selectivity and stability, achieving 91.3% CO selectivity at a potential of −0.88 V vs. RHE (Reversible Hydrogen Electrode) due to the facile transformation of ZnO to metallic Zn. Remarkably, these catalysts maintained this level of performance for more than 17 h. Conversely, ZnO-NR catalysts exhibited a lower CO selectivity of 62.5% at a relatively higher potential of −0.98 V vs RHE.

Growth and Electrochemical Study of Bismuth Nanodendrites as an Efficient Catalyst for CO2 Reduction.

There is a growing interest in creating cost-effective catalysts for efficient electrochemical CO2 reduction to address pressing environmental issues and produce valuable products. A bimetallic ZnBi catalyst that enhances catalytic activity and stability toward the electrochemical reduction of CO2 is designed. It is based on bismuth nanodendrites grown using a facile, scalable, and low-cost method. The results have shown that the incorporation of bismuth can decrease the charge transfer resistance and facilitate CO2 reduction toward the formation of CO and formate. It was revealed that the ZnBi catalyst exhibited higher catalytic activity compared with that of the pure Zn catalyst for CO2 reduction, with a lower onset potential [-0.75 V vs a reversible hydrogen electrode (RHE) compared with -0.85 V vs RHE for Zn]. In situ electrochemical attenuated total internal reflection Fourier transform infrared spectroscopy was employed to study the reaction mechanism, showing the formation of CO and formate through the adsorbed *COO- intermediates. This study has demonstrated a new approach for the feasible synthesis of high-performance catalysts for large-scale electrochemical CO2 reduction.

Fe2NiO4/FeNiS2 heterostructure-assembled hollow microtubes with numerous intimate interfaces as advanced catalyst for Zn–Air battery

An efficient electrocatalyst based on hollow-structured microtubes assembled by Fe2NiO4/FeNiS2 hetero-structured nanosheets is developed for the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER), as two-half electrochemical reactions at air cathode of the zinc–air battery. The Fe2NiO4/FeNiS2 nanosheets with strong interaction between Fe2NiO4 and FeNiS2 at the heterointerface can tailor the electronic structure towards boosting the catalytic activity. In addition, the hollow structure effectively reduces the charge/mass transfer resistance, while providing a large surface area. Therefore, the bifunctional activity of the proposed catalyst for both the ORR and OER approaches that of the Pt/C and surpasses that of the RuO2. The zinc–air battery with our material as air–cathodic material possesses a desirable power density of 144.22 mW cm−2 and superior cycling performance of over 1,500 cycles (40 min per cycle) at high current density of 2.0 mA cm−2, outperforming almost the latest reports in the literature.

Preparation of Fe/P co-doped MMoO4 (M=Co, Cu and Zn) as environmentally friendly oxygen evolution reaction electrocatalyst

Hydrogen production from electrolyzed water has become an ideal new energy source for people to replace traditional fossil energy sources due to its high efficiency and low-carbon characteristics. Therefore, this paper presents preparation of a series of Fe/P co-doped MMoO4 (M=Co, Cu and Zn) catalyst loaded on nickel foam by simple hydrothermal and phosphorization process for the first time. After comparing different molybdate metal salts as precursors, it was demonstrated that the fabricated Fe/P co-doped CuMoO4 target catalysts possessed excellent catalytic performance with an overpotential of only 287 mV at a current density of 100 mA cm−2, faster reaction kinetics and a large active surface area for oxygen evolution reaction (OER). Density functional theory (DFT) calculation shows that the absorption energy of water and the electrical conductivity of the material are enhanced by the co-doping of the Fe and P. The doping of the Fe and P changes the electronic state and coordination environment of the active site, thus enhancing the catalytic activity of the electrode. The experimental results further prove that the doping of the Fe and P makes the active site more exposed and the resistance smaller, thus enhancing the conductivity and activation energy of the material. What is noteworthy is that the electrode also performed well in stability tests, which provided a fabrication solution of new catalyst for green hydrogen production.

Porous CN@MOF derived N, S-doped hierarchical framework carrying Co3Fe7/Fe0.8Co0.2S heterojunction: An efficient bifunctional cathode catalyst for Zn–air battery

The exploiting of bifunctional transition metal electrocatalysts for the oxygen reduction reaction (ORR) and the oxygen evolution reaction (OER) is of significance for the commercialization of rechargeable zinc-air batteries (ZABs). Herein, the N and S atoms-doped hierarchical carbon framework hosting the Co3Fe7/Fe0.8Co0.2S heterojunction is synthesized by employing porous g-C3N4 as framework and spacer, and FeCo-ZIF as metal source followed by sulfidation and pyrolysis. The detailed characterization confirms that the porous g-C3N4 plays a crucial role in improving the dispersion of metal nanoparticles. The obtained FeCo-Sx@NSC-900 catalysts exhibit layered accumulation configuration with uniformly distributed metal nanoparticles. Moreover, the typical carbon@metal nanoparticles and heterojunction structure can be observed from the HRTEM (High-Resolution Transmission Electron Microscopy) and HAADF-STEM (high-angle annular dark-field STEM) analysis results. The optimal FeCo-Sx@NSC-900 catalysts deliver exceptional ORR and OER performance with a potential difference between ORR and OER of merely 0.713 V, which is superior to the commercial Pt/C+RuO2 catalysts and other monometallic catalysts. Additionally, the ZAB assembled with the optimal FeCo-Sx@NSC-900 catalysts as cathode affords a good battery performance with high OCV (1.50 V), large power density (172 mW/cm2), good discharge stability, large specific capacity, and long-term charge/discharge stability (>300 cycles).

Study of the Chemical Activities of Carbon Monoxide, Carbon Dioxide, and Oxygen Traces as Critical Inhibitors of Polypropylene Synthesis.

This study outlines the investigation into how the compounds CO2, CO, and O2 interact with the active center of titanium (Ti) on the surface of MgCl2 and how these interactions impact the productivity of the Ziegler-Natta catalyst, ultimately influencing the thermal stability of the produced polypropylene. The calculations revealed that the adsorption energies of Ti-CO2-CO and O2 were -9.6, -12.5, and -2.32 Kcal/mol, respectively. Using the density functional theory in quantum calculations, the impacts of electronic properties and molecular structure on the adsorption of CO, O2, and CO2 on the Ziegler-Natta catalyst were thoroughly explored. Additionally, the Gibbs free energy and enthalpy of adsorption were examined. It was discovered that strong adsorption and a significant energy release (-16.2 kcal/mol) during CO adsorption could explain why this gas caused the most substantial reductions in the ZN catalyst productivity. These findings are supported by experimental tests showing that carbon monoxide has the most significant impact on the ZN catalyst productivity, followed by carbon dioxide, while oxygen exerts a less pronounced inhibitory effect.

Peripheral P doping in Zn1/NC single-atom catalyst to enhance propane dehydrogenation reaction

Although Zn-based catalysts are widely used for propane dehydrogenation (PDH), the positively charged Zn is susceptible to reduction to metallic state under harsh conditions, which ultimately leads to its vaporization and thus irreversible deactivation. Moreover, the understanding of the structure-performance relationship of Zn-based catalysts in PDH remains limited. In this work, the effect of peripheral P doping on PDH over atomically dispersed Zn catalysts with different N/C coordination numbers (Zn1-NnC4-n-P, n = 2–4) is investigated by density functional theory (DFT) calculations. The results show that the peripherally P-doped Zn1-N2C2 catalyst exhibits improved performance and stability compared to the undoped Zn1-N2C2. It is revealed that there is a linear relationship between the energy barrier of the first dehydrogenation step of C3H8 and the H affinity of the active site. Furthermore, the peripheral P doping contributes to the stabilization of the tetra-coordination structure of Zn during catalysis, which in turn lowers the energy barrier for the second dehydrogenation step of C3H8. The experimental results are in good agreement with theoretical predictions. This work provides useful insights for the rational design of efficient SACs for PDH via doping strategy.

Single-Atom Zn Catalyst Derived from ZIF-8 for One-Step CO Hydrogenation to Dimethyl Ether

Single-Atom Zn Catalyst Derived from ZIF-8 for One-Step CO Hydrogenation to Dimethyl Ether

Highly efficient and active Co-N-C catalysts for oxygen reduction and Zn–air batteries

Highly efficient and active Co-N-C catalysts for oxygen reduction and Zn–air batteries

Selective oxidation of veratryl alcohol to veratraldehyde using more active catalyst in a continuous reactor

Verataldehyde (3,4-dimethoxybenzaldehyde) was used as a precursor for various industrial applications, such as flavouring agents, odorants, and pharmaceuticals. The major approach of this study is to convert veratryl alcohol to veratraldehyde, and the whole reaction was carried out in a continuous-process reactor. A bimetallic catalyst was prepared by the wet impregnation method in four different ratios by varying the metal percentage (Mn-10 % and Zn-5–20 %). These metals were incorporated into the activated carbon, which has a high mesoporous nature and was prepared from the used waste surgical mask. The catalysts were subjected to analysis and characterization. Textural characteristics, morphology, chemical properties, and stability of the catalyst were ascertained by utilizing X-ray diffraction, Brunauer-Emmett-Teller, N2 adsorption–desorption isotherm, Fourier transform infrared spectroscopy, and a transmission electron microscope. By varying the continuous reactor parameters such as pressure, temperature, WHSV−1, and reaction time, the catalysts were optimised to achieve the maximum conversion and selectivity of the veratryl alcohol. The AC-Mn (10 %)/Zn (15 %) catalyst was carried out under ideal conditions: 90 °C, 5 mL of TBHP as the solvent, 15 bar of pressure, and 3.2 g of catalyst proven a greater result in the reaction with a conversion and selectivity of 98 %. The stability and reusability of the catalyst were confirmed by delivering a 95.8 % yield even after five reaction runs. A continuous reaction study can provide valuable inputs for the commercial exploitation of veratryl alcohol (VA) to veratraldehyde (VAld). Again, catalytic support was synthesised utilising waste products, and the metal components are cost-effective as compared to noble metals.

Versatile electrochemical manufacturing of mixed metal sulfide/N-doped rGO composites as bifunctional catalysts for high power rechargeable Zn–air batteries

Electrodeposition was used for direct synthesis of nitrogen-dopged reduced graphene oxide (NrGO) and mixed transition metal sulfides (NCMS). The resulting NCMS/NrGO composite exhibits excellent OER/ORR peroformance as Zn–air battery cathode.

Chemical fabrication and synergistic mechanism of N-doped carbon modified with FeP as catalysts for flexible rechargeable Zn–air batteries

A 3D porous N-doping Paulownia-derived carbon modified with FeP nanoparticles (FeP@NPW) was used as an air cathode for flexible rechargeable Zn–air batteries. The flexible rechargeable ZAB based on FeP@NPW exhibits outstanding cycle stability and durability.

A highly efficient catalytic method for the synthesis of phosphite diesters.

In contrast to conventional methods that rely on stoichiometric activation of phosphonylating reagents, we have developed a highly efficient catalytic method for the synthesis of phosphite diesters using a readily available phosphonylation reagent and alcohols with environmentally benign Zn(ii) catalysts. Two alcohols could be introduced consecutively on the P center with release of trifluoroethanol as the sole byproduct, without any additive, under mild conditions. The products could be oxidized smoothly to access phosphate triesters. A range of alcohols, including sterically demanding and highly functionalized alcohols such as carbohydrates and nucleosides, can be applied in this reaction.

Cobalt-containing ZIF-derived catalysts for Zn–air batteries

The synthetic and modification parameters of cobalt-containing ZIF-derived catalysts for Zn–air batteries with different amounts of metal.