Zn Sites Research Articles

Recent progress in understanding the nature of active sites for methanol synthesis over Cu/ZnO catalysts

Copper-zinc-alumina (Cu/ZnO/Al2O3) has been utilized as the leading catalyst for industrial methanol synthesis via hydrogenation of CO and CO2 for more than 50 years. Understanding the nature of active Zn sites at the atomic level is vital for gaining insight into the reaction mechanism and rational design of more efficient Cu/ZnO catalysts for methanol synthesis but remains greatly challenging and has been intensively debated for decades. In this mini-review, we first describe the fundamental insights obtained from well-defined model catalysts and then summarize the recent experimental evidence with respect to dynamic structural and electronic changes in the active Zn phase under realistic working conditions by in situ/operando microscopy/spectroscopy and surface site titration using probing molecules. In the following, we discuss the catalytic mechanism of diverse active structures by theoretical calculations and simulations. Therefore, the critical role of interfacial sites between metallic Cu and ZnO, especially those with oxygen defects, in methanol synthesis via CO2 hydrogenation is emphasized. Finally, we discuss the technical challenges and perspectives in understanding the origins of this Cu-ZnO synergy and rational design of next-generation Cu-based methanol synthesis catalysts.

Plasma-deposited reactive species assisted synthesis of colloidal zinc-oxide nanostructures

A surface-wave microwave discharge is applied to deposit reactive oxygen and nitrogen species (RONS) into the liquid subsequently used as a medium for laser ablation of a Zn metallic target. It is shown that during laser ablation in plasma-treated liquids the H2O2 concentration decreases, while in deionized water (DIW) significant H2O2 is produced. Meanwhile, the pH—initially adjusted by applying reductive metals—increases in the acidic liquids and decreases in the alkaline ones. During months of storage the pH of colloids stabilize around pH 6, which insures the long-term stability of RONS. It is demonstrated that in DIW metallic Zn NPs are created, which gradually oxidize during storage, while in the plasma-treated liquids ZnO NPs are produced with the mean size of 18 nm. In the alkaline plasma-treated liquid the NPs form large aggregates, which slows the dissolution of NPs. In the acidic and neutral solutions besides NPs nanosheets are also formed, which during storage evolve into nanosheet networks as a result of the dissolution of NPs. The band gap of the colloidal ZnO is found to decrease with the formation of aggregates and nanosheet networks. The ZnO NPs ablated in plasma-treated liquids exhibit a high-intensity visible emission covering the green-to-red spectral region. The photoluminescence spectra is dominated by the orange-red emission—previously not detected in the case of laser-ablated ZnO NPs and attributed to the interstitial Zn and oxygen sites—and the yellow emission, which can be attributed to the OH groups on the surface. It is shown that during months of storage, due to the dissolution of NPs and formation of nanosheets, the intensity of the visible emission decreases and shifts to the blue-green spectral region.

Preferential heteroatom substitution into ZnIn2S4 nanosheets boosts photocatalytic hydrogen production

Interior modification through preferential substitution of heteroatoms in 2D materials can rescue surface reactive sites for enhanced charge kinetics and photo-activity. Here, Ru and Ni heteroatoms were successfully incorporated in ZnIn2S4 (ZIS) nanosheets via a simple hydrothermal technique. Ru-ZIS photocatalysts exhibited improved photo–water splitting activity (26,400 µmol. h−1g−1) and good stability than that of Ni-ZIS and pristine ZIS under simulated sunlight, which may be related to the increase in reactive sites with Ru substitution, optimized adsorption-free energy of the reaction intermediates and charge kinetics. Ru substitution influenced Zn site availability and thus coordinated bonding with surrounding S ions. Ru-ZIS showed excellent hydrogen evolution performance and minimal change in Gibbs free energy (ΔGH, ∼0 eV). By analyzing the density of states, both Ru and S sites had greater H* intermediate absorption abilities. This study elaborates on the effect of preferential heteroatom substitution on photocatalytic performance and has widespread applications.

Constructing 3D Zincophilic Skeleton in Nitrogen-Doped Carbon Hybrid Fibers for Dendrite-Free Zn Anodes.

The Zn dendrite growth and side reactions are two major issues for the practical use of Zn metal anodes (ZMAs). Herein, an N-doped carbon-based hybrid fiber with the 3D porous skeleton and the zincophilic Cu nanoparticles (denoted as Cu@HLCF) is developed for stable ZMAs. The zincophilic Cu particles in the skeleton work as the active sites to facilitate uniform Zn nucleation. Meanwhile, the abundant pores in the framework of the hybrid fibers provide a large space to relieve the structural stress and suppress the dendrite growth. Moreover, the good mechanical characteristics of the hybrid fiber ensure its high potential applications for flexible electronics. Theoretical analysis results disclose the strong interaction between Zn and Cu sites, and experimental results demonstrate the low voltage hysteresis, high reversibility, and dendrite-free behavior of the Cu@HLCF host for Zn plating/stripping. Moreover, the solid-state Zn-ion battery (ZIB) assembled with a Cu@HLCF/Zn anode shows the prominent flexibility, impressively reliability, and outstanding cycling capability. Therefore, this work not only provides a novel design for the efficient and stable Zn metal anode but also promotes the development of flexible power sources for flexible electronics.

Aromatic‐rich oil production from catalytic co‐pyrolysis of pine sawdust and LDPE with bifunctional biochar by different preparation methods

AbstractBackgroundCatalytic co‐pyrolysis of biomass with waste plastics can produce high‐quality chemicals, making it a potential alternative to fossil fuels. The production of aromatic‐rich oil was achieved in this work by the catalytic co‐pyrolysis of pine sawdust and low‐density polyethylene (LDPE) using a series of biochar (BC) made using different preparation methods. Zinc chloride (ZnCl2) was employed to activate the BC during the preparation process, owing to its optimal activity for the co‐pyrolysis intermediates. The study compared the effects of BCs activated using different treatment methods on the yield and fractions of pine sawdust and LDPE co‐pyrolysis in a fast pyrolysis tube furnace at 650 °C.ResultsThe study indicates that the ZnCl2 BC, prepared from pine sawdust by fast pyrolysis (F‐AC), exhibited the best aromatic catalytic activity. The selectivity to aromatic hydrocarbons was 72.53%, and the content of BTEX (benzene, toluene, ethylbenzene, and xylene) was 32.17%.ConclusionThe Diels–Alder reaction and aromatization were made more effective due to the Zn sites and large pore structure in F‐AC. Using Fourier transform infrared, scanning electron microscopy and X‐ray photoelectron spectroscopy analysis, it was found that F‐AC contained more oxygen (O)‐containing groups in abundance, which improved its adsorption capacity for reaction intermediates. At the same time, the porous structure and high SSA of BC provided a region for the reaction intermediate to interact with the active center containing O‐containing groups. This enhanced the synergy between biomass and plastics and raised the selectivity of aromatic hydrocarbons. It provides a reference for the application of carbon‐based materials in the co‐pyrolysis of biomass and waste plastics. © 2024 Society of Chemical Industry (SCI).

Highly Stable Polyaniline-Based Cathode Material Enabled by Phosphorene for Zinc-Ion Batteries with Superior Specific Capacity and Cycle Life.

Aqueous zinc-ion batteries (ZIBs) are regarded as a type of promising energy-storage device because of their high safety and low cost, and polyaniline (PANI) is normally employed as a cathode material for ZIBs owing to its unique electrochemical properties and high environmental stability. However, a low specific capacity and a short cycle life limit the development and applications of PANI-based electrodes. Herein, we have developed a novel type of highly stable PANI-based cathode material enabled by phosphene (PR) for aqueous Zn-PANI batteries through in situ chemical oxidative polymerization. The introduction of PR nanoflakes not only inhibits the degradation of PANI and generates more active sites for Zn2+ storage but also enables a synergistic effect of the Zn2+ insertion/extraction and P-Zn alloying reaction. This promotes a high reversible specific capacity of 240.2 mAh g-1 at 0.2 A g-1 and excellent rate performance for the PR/PANI nanocomposite cathode material. Compared to the pristine PANI cathode material, the PR/PANI nanocomposite cathode material is more suitable for the Zn-PANI battery, thanks to its higher specific capacity and better cycle stability. This study provides an innovative approach for developing the next generation of reliable PR-based electrode materials for aqueous energy-storage devices.

Role of Histidine 310 in Amydetes vivianii firefly luciferase pH and metal sensitivities and improvement of its color tuning properties.

Firefly luciferases emit yellow-green light and are pH-sensitive, changing the bioluminescence color to red in the presence of heavy metals, acidic pH and high temperatures. These pH and metal-sensitivities have been recently harnessed for intracellular pH indication and toxic metal biosensing. However, whereas the structure of the pH sensor and the metal binding site, which consists mainly of two salt bridges that close the active site (E311/R337 and H310/E354), has been identified, the specific role of residue H310 in pH and metal sensing is still under debate. The Amydetes vivianii firefly luciferase has one of the lowest pH sensitivities among the group of pH-sensitive firefly luciferases, displaying high bioluminescent activity and special spectral selectivity for cadmium and mercury, which makes it a promising analytical reagent. Using site-directed mutagenesis, we have investigated in detail the role of residue H310 on pH and metal sensitivity in this luciferase. Negatively charged residues at position 310 increase the pH sensitivity and metal sensitivity; H310G considerably increases the size of the cavity, severely impacting the activity, H310R closes the cavity, and H310F considerably decreases both pH and metal sensitivities. However, no substitution completely abolished pH and metal sensitivities. The results indicate that the presence of negatively charged and basic side chains at position 310 is important for pH sensitivity and metals coordination, but not essential, indicating that the remaining side chains of E311 and E354 may still coordinate some metals in this site. Furthermore, a metal binding site search predicted that H310 mutations decrease the affinity mainly for Zn, Ni and Hg but less for Cd, and revealed the possible existence of additional binding sites for Zn, Ni and Hg.

Zn Single-Atom Catalysts Enable the Catalytic Transfer Hydrogenation of α,β-Unsaturated Aldehydes.

Highly active nonprecious-metal single-atom catalysts (SACs) toward catalytic transfer hydrogenation (CTH) of α,β-unsaturated aldehydes are of great significance but still are deficient. Herein, we report that Zn-N-C SACs containing Zn-N3 moieties can catalyze the conversion of cinnamaldehyde to cinnamyl alcohol with a conversion of 95.5% and selectivity of 95.4% under a mild temperature and atmospheric pressure, which is the first case of Zn-species-based heterogeneous catalysts for the CTH reaction. Isotopic labeling, in situ FT-IR spectroscopy, and DFT calculations indicate that reactants, coabsorbed at the Zn sites, proceed CTH via a "Meerwein-Ponndorf-Verley" mechanism. DFT calculations also reveal that the high activity over Zn-N3 moieties stems from the suitable adsorption energy and favorable reaction energy of the rate-determining step at the Zn active sites. Our findings demonstrate that Zn-N-C SACs hold extraordinary activity toward CTH reactions and thus provide a promising approach to explore the advanced SACs for high-value-added chemicals.

Structure growth, stability and adsorption properties of (AgZn3)n clusters

ABSTRACT Recently, an effective syngas catalyst composed of AgZn3 clusters is reported, in which the CO and H2 generation may occur at the Zn sites and the hollow sites between Ag and Zn. Hence, the atomic model of the AgZn3 is worth established to further investigate the catalytic mechanism. Here, we take advantage of the genetic algorithm with the density functional theory to unbiasedly search configurations of (AgZn3)n (n = 1–6) clusters. It is found that (AgZn3)n clusters evolve from hollow cages to close-packed structures, with Zn atoms gradually occupying the core positions. The Eb and Δ2E analyses show that the (AgZn3)3 has a higher stability than that of its neighbors. The AIMD simulations demonstrate that the (AgZn3)3 shows a favorable stability at 700 K. The molecular orbitals reveal that 21 valence electrons of the (AgZn3)3 fill superatomic orbits resulting in an electronic configuration of 1S21P61D102S21F1. The adsorptions of CO on the bridge sites of (AgZn3)3 are much higher in energy than the top adsorptions, but the red shift of the stretching frequency of C-O is more obvious in the former. Our results are verified that the Zn sites and bridge sites between Ag and Zn are active sites for CO.

Scalable and economical production of oxygen deficient vanadium oxide with tunable vacancies concentration for bendable zinc ion batteries

Although vanadium oxides have high theoretical capacity and low cost, their practical application in aqueous zinc ion batteries (AZIBs) is bottlenecked by sluggish diffusion kinetics and capacity decline. Herein, the oxygen-deficient V2O5-x·nH2O (defined as VOd) with tunable oxygen vacancy concentration has been obtained via an economic and scalable method. The introduction of oxygen vacancies not only provides extra sites for Zn2+ storage, but also reduces the electrostatic barrier for Zn2+ intercalation, resulting in enhanced capacity and cycling stability. As a result, VOd cathode with proper amount of oxygen defect exhibits a high capacity of 415 mAh g−1 and energy density of 294 Wh kg−1 at 0.2 A g−1, estimating a roughly chemical costs of $64/kWH for VOd cathode. Besides, the VOd exhibits excellent stability at 20 A g−1 with average capacity decay of 0.004 % per cycle for 5000 cycles. Moreover, the bendable quasi-solid VOd//Zn battery maintains stable capacity of 200 mAh g−1 at 2 A g−1 even when repeatedly bending to straight angles. Therefore, the economical production of VOd cathode and construction of bendable quasi-solid battery provides a feasible way to boost the construction of efficient flexible energy storage devices and broadened application of AZIBs.

Integrating four-, five- and six-coordinated Zn catalytic centers in an ionic-type zinc catalyst for the coupling of CO2 with epoxides

Effectively converting greenhouse gas CO2 into value-added chemicals, without the need for cocatalysts or solvents, is a vital objective in order to attain carbon neutrality and promote sustainable development. However, achieving this goal continues to pose significant challenges. In this study, the in-situ formed octadentate N5O3 tripodal ligand (H3L) reacts with ZnBr2 and ZnI2 to produce two ionic-type zinc catalysts, [Zn2(L)]2[ZnBr4]·4CH3OH (IZ-1) and [Zn2(L)]I·CH3OH (IZ-2), respectively. In the [Zn2(L)] subunit, the two Zn ions exhibit non-symmetry and are coordinated with the N5O3 ligand in a five- and six-coordinate mode, respectively. Due to the coexistence of Lewis acidic Zn sites and nucleophilic Br- ions, IZ-1 shows remarkable catalytic performance in the cycloaddition of CO2 with epoxides. Under cocatalyst- and solvent-free conditions, it achieves an excellent yield of cyclic carbonates, reaching up to 99 %. The ionic-type zinc catalyst can be readily recovered and reused at least for five times without a noticeable loss in catalytic activity. Mechanistic investigation demonstrates that the improved activity of IZ-1 is attributed to the synergistic effect of Lewis acidic Zn centers and nucleophilic Br-. Moreover, the broad substrate scope of IZ-1 further highlights its versatility and applicability in the cycloaddition reaction.

In situ coupling metallophilic Zn sites and interfacial LiCl stabilizer to achieve one-step reversible hydrogen storage in Li/Na dual-cation borohydride

Dual-cation borohydrides composed of alkali or alkaline-earth metals attract considerable attention for hydrogen storage, thanks to their high hydrogen capacity and low eutectic melt point; however, they still suffer from high-temperature-dependent dehydrogenation and poor reversibility. In-situ catalyzation and nanoconfinemnt are effective for easing these problems, but a simple and efficient method is required to achieve their coulping. Here inspired from the structural stabilization and performance improvement roles on anodes of metal batteries by constructing metallophilic Zn sites and interfacial LiCl layers, we develop a 0.62LiBH4-0.38NaBH4 system with ZnCl2 as reactive additives by one-step ball milling. In-situ evolved LiCl and Zn(BH4)2 are surprisingly identified as interfacial stabilizers and metastable phases to disperse borohydride particles and to trigger hydrogen release below 100 °C, respectively. Further formed Zn from the decomposition of Zn(BH4)2 acts as catalytic nucleation sites to promote the one-step and reversible (de)hydrogenation of LiBH4 and NaBH4, without producing high chemical potential intermediates, benefiting from the strong affinity of Zn towards Li and Na. These factors contribute to a cyclic stability of nearly 70 %, the highest for dual-cation borohydrides reported so far. The present work provides new insights and a feasible scheme for developing promising borohydride-based storage systems towards practical application.

First-principles study of electronic and magnetic properties in site dependent Fe-doped chalcopyrite ZnSnAs2semiconductors: Comparison with those of Mn- and Cr-doped ZnSnAs2

The electronic and magnetic properties of Fe-doped ZnSnAs2 within chalcopyrite structures have been studied by first-principles calculations using the density functional theory (DFT) full-potential linearized augmented-plane-wave method and the plane-wave pseudopotential methods. The band gap of ZnSnAs2 was determined to be 0.816 eV using the modified Beck-Jonson (mBJ) exchange potential. When Fe dopants substitutionally replace Sn atoms, half-metallic ferromagnetism is observed in ZnSnAs2 where in the spin-down band at the Fermi level is entirely unoccupied. The magnetic exchange interaction between two Fe atoms substituting Zn and Sn sites in the supercell with different geometries has been studied. The total energy difference (ΔE) between the antiferromagnetic (AFM) and ferromagnetic (FM) configurations suggests that Fe atom occupation of Zn sites in ZnSnAs2 leads to a predominantly AFM state, while the Fe atom occupation of Sn sites prefers the FM state.

Modulating the Catalytic Properties of Polyoxovanadates with Transition-Metal-Complex Units for Selective Oxidation of Sulfides.

Selective oxidation of sulfides to sulfoxides is of great significance in the synthesis of pharmaceuticals, desulfurization of fuels, and detoxification of sulfur mustard chemical warfare agents. Designing selective catalysts to achieve the efficient transformation of sulfides to sulfoxides is thus highly desired. Herein, we report three transition metal-complex-functionalized polyoxovanadates, [Zn2(BPB)2][V4O12]·0.5BPB·H2O (1), [Ni(BPB)(H2O)][V2O6]·2H2O (2), and [Co(HBPB)2][V4O12] (3) (BPB = 1,4-bis(pyrid-4-yl)benzene)), and explore their applications for selective oxidation of sulfides using H2O2 as an oxidant. All three compounds were catalytically effective for the oxidation of methyl phenyl sulfide to methyl phenyl sulfoxide, with 1 being best-performing with complete conversion and a selectivity of 96.7%. In the selective oxidation of a series of aromatic and aliphatic sulfides to corresponding sulfoxides, 1 also showed satisfactory performance; in particular, the chemical warfare agent stimulant 2-chloroethyl ethyl sulfide can be completely and selectively oxidized to the nontoxic 2-chloroethyl ethyl sulfoxide within 20 min at room temperature. Catalyst 1 can be recycled and reused at least six times with uncompromised performance. The perfect performance of 1 is attributed to the synergistic effect of coordinatively unsaturated V and Zn sites in bimetallic oxide, as revealed by comparative structural and catalytic studies.

Highly efficient nitrogen fixation over S-scheme heterojunction photocatalysts with enhanced active hydrogen supply.

Photocatalytic N2 fixation is a promising strategy for ammonia (NH3) synthesis; however, it suffers from relatively low ammonia yield due to the difficulty in the design of photocatalysts with both high charge transfer efficiency and desirable N2 adsorption/activation capability. Herein, an S-scheme CoSx/ZnS heterojunction with dual active sites is designed as an efficient N2 fixation photocatalyst. The CoSx/ZnS heterojunction exhibits a unique pocket-like nanostructure with small ZnS nanocrystals adhered on a single-hole CoSx hollow dodecahedron. Within the heterojunction, the electronic interaction between ZnS and CoSx creates electron-deficient Zn sites with enhanced N2 chemisorption and electron-sufficient Co sites with active hydrogen supply for N2 hydrogenation, cooperatively reducing the energy barrier for N2 activation. In combination with the promoted photogenerated electron-hole separation of the S-scheme heterojunction and facilitated mass transfer by the pocket-like nanostructure, an excellent N2 fixation performance with a high NH3 yield of 1175.37 μmol g-1 h-1 is achieved. This study provides new insights into the design of heterojunction photocatalysts for N2 fixation.

Enhanced NO2 sensing performance of metal ion substituted ZnFe2O4 core-shell microspheres: Experiment and DFT study

In this study, ZnFe2O4 core-shell microspheres were substituted by varying metal ions (Cu2+, Co2+, Ce3+) using a solvothermal method without any template combined with the subsequent thermal treatment. The product underwent characterization by employing a variety of techniques such as XRD, SEM, TEM, XPS and UV-Vis. The characterization revealed that the formation mechanism of core-shell microspheres and metal ions do replace corresponding positions in the ZnFe2O4 core-shell microspheres. Gas sensing tests were conducted on the substituted ZnFe2O4 materials and it was found that NO2 sensing performance has been improved to varying degrees because of the addition of metal ions. Specifically, at 120°C, the response value of the Co0.25Zn0.75Fe2O4 sensor was 170 for 5 ppm NO2, which was more than 150 times higher than that of the pristine core-shell microspheres ZnFe2O4 sensor. Theoretical calculations indicate that for the three cations (Cu2+, Co2+, Ce3+) substituting ZnFe2O4, the Zn, Zn, and Fe site are the most easily substituted sites, respectively. The optimal adsorption location for NO2 molecules on ZnFe2O4 is the oxygen site with an adsorption energy of −3.56 eV and an electron transfer amount of −0.9422 e. The study also discussed the mechanism behind the enhanced sensing performance of the Co0.25Zn0.75Fe2O4. The porous shell structure, hollow interior of the microspheres and special internal electron transfer channels made them ideal candidates for gas-sensing applications.

First-principles study on the electronic structure of n-type magnetic semiconductor Ba(Zn 1−x Co x )2As2

We perform systematic first-principles calculations on the electronic structure of n-type magnetic semiconductor Ba(Zn 1−x Co x )2As2 with the facilitation of HSE06 hybrid functional. Supercells are used to consider the doping of Co atoms, and the first-principles band structures are unfolded for clarity. Based on the calculation results, magnetic states are preferred by individual Co atoms doped in Ba(Zn 1−x Co x )2As2 at diluted limit, and carriers are originated mainly from situations where only one Co atom exists in the nearest neighbor Zn sites out of certain doped Co atoms. The origination of carriers can be explained by the density of states and the unfolded band structure, where it is found that the scattering effects from single Co atom is small but quite large when more Co atoms are located at adjacent Zn sites. The large scattering effects of two adjacent Co atoms will alter the band structures near the Fermi-level. Carriers in Ba(Zn 1−x Co x )2As2 mainly originate from the As-4p orbitals, with partial contributions from the Co-3d orbitals. Our work provides new insights into the origin of the n-type carriers in magnetic semiconductors and will inspire the development of new magnetic semiconducting systems.

Microwave-assisted hydrothermal synthesis of ZnO@ZrO2 nanohybrid for biomedical and photocatalytic applications

The present study was conducted to synthesize zinc oxide decorated on zirconium oxide (ZnO@ZrO2) nanohybrid synthesized through microwave-hydrothermal (MW-HT) method. Various analytical techniques were used to analyze the morphology, surface properties, constitution of hybrid, and elemental composition. Additionally, the anti-microbial activity of ZnO@ZrO2 nanohybrid was assessed against Gram-positive and Gram-negative pathogenic bacteria, hemolytic, anti-oxidant as well as anti-inflammatory assay. The hexagonal wurtzite phase of the ZnO was revealed by the XRD analysis. The experimental results reveal that the synergetic effect between the Zn and Zr active sites results an excellent biomedical activity. The ZnO@ZrO2 nanohybrid was successfully applied to the photocatalytic degradation of basic fuchsin (BF) dye within short period of time under visible light (VL) radiation. Moreover, the ZnO@ZrO2 nanohybrid exhibited an extraordinary performance for photocatalytic degradation of BF with a pseudo-first order rate constant (k) of ca. 0.1702 min−1, which was 2.5 and 1.8 fold compared to ZnO and ZrO2 photocatalysts. These results indicated that the ZnO@ZrO2 nanohybrid can be used as a potential biomaterial for bioengineering and photocatalytic applications.

Highly dispersed Zn-N, S co-doped carbon for highly efficient electrocatalytic oxygen reduction

Supportive atomic Zn electrocatalysts exhibit excellent stability for oxygen reduction reaction (ORR) due to their fully occupied d orbitals of Zn, but their catalytic activity is not satisfactory. Whereas heteroatom doping can anchor the Zn atoms to achieve higher Zn loading; and additionally serve as auxiliary sites to enhance the catalytic activity of Zn sites. Herein, we present a method for the synthesis of N, S co-doped carbon with highly dispersed Zn (named Zn-NSC). The ORR activity of the Zn-NSC catalysts is optimized by adjusting the pyrolysis temperature and the atomic structure of the dopant molecules. The optimized Zn-NSC demonstrates significantly enhanced ORR electrocatalytic activity, this is attributable to its highly co-doping of N and S heteroatoms that are adjacent to Zn atoms. Specifically, the Zn-NSC3 catalyst exhibits remarkable ORR characteristics with excellent onset voltage (0.97 V vs RHE) and half-wave potential (0.87 V vs RHE), surpassing those of Pt/C (0.97 V and 0.85 V, respectively). Additionally, the Zn-NSC3 can be utilized as efficient cathode for Al-air batteries, achieving a high power density of 119.4 mW cm−2 and satisfactory discharge stability. This work proposes an approach for synthesizing low-cost and efficient ORR electrocatalysts for Al-air battery applications.

Exploring the Performance Improvement for CO2 Chemical Fixation in Zn/ZnMg-MOFs.

A new 3D zinc-based metal-organic framework {[Zn7L2(DMF)3(H2O)(OH)2]·5DMF}n (1) (H6L = 5,5',5″-(methylsilanetriyl) triisophthalic acid) was constructed with an organosilicon-based linker, where H6L is a tetrahedral structure furnished with rich -COO- chelating sites for Zn(II) immobilization. Compound 1 exhibited two types of irregular one-dimensional channels and a three-dimensional skeleton with large specific surface area, making it a promising catalytic platform. Moreover, by incorporation of the second metal ion into the inorganic node of framework 1, isomorphic bimetallic MOF ZnMg-1 was successfully synthesized. ZnMg-1 demonstrated enhanced catalytic activity compared to 1 under identical conditions. Contrast experiments and theoretical calculations indicate that bimetallic active sites play a facilitating role in the chemical fixation of epoxides and CO2. It indicated that efficient chemical fixation of CO2 to cyclic carbonates was obtained over isomorphic MOF catalysts 1 and ZnMg-1.