Decomposition Pathways Research Articles

Study on pyrolysis process and mechanism of organic coating of waste polyesterimide enameled wire based on density functional theory

The pyrolysis treatment of waste polyesterimide enameled wire offers significant advantages such as continuous processing, non-hazardous nature, and high resource recovery rate. However, research on its pyrolysis process and mechanism remains insufficiently explored. In this study, techniques including thermogravimetry (TG), Fourier transform infrared spectroscopy(FT-IR), pyrolysis–gas chromatography-mass spectrometry(Py-GC/MS) were employed to investigate pyrolysis temperature, weight loss rate, pyrolysis and kinetic parameters, composition and distribution of pyrolysis products, and changes in functional groups under different temperatures and heating rates. The pyrolysis of polyesterimide enameled wire can be divided into three stages: volatilization of specific components (314.8 °C,1.6 %), rapid decomposition of polyesterimide (435.2 °C, 44.7 %), and generation of small organic molecules with the fixation of pyrolytic carbon (750 °C, 9.0 %). The main components of the pyrolysis gas products include aromatic compounds, ethers, aromatics, ketones, and carbon dioxide. At 400 °C, a substantial amount of pyrolysis gas products and free radicals are produced, with an increase in aromatic hydrocarbons. The carbon distribution in the pyrolysis products mainly focuses on C6-C10 and C11-C15, and many organic compounds such as benzoic acid, phenol, and aniline are generated. Based on density functional theory, the bond dissociation energies in the polyesterimide were calculated. This clarified the possible thermal decomposition pathways of the polyesterimide and provided the energy barrier values, elucidating the generation mechanism of pyrolysis products during thermal decomposition. The copper atom in specific location reduces the negative ESP of O and increases the positive ESP of H in EPI, which makes H more likely to attach to O. The presence of Cu increases the ESP range and promote the pyrolysis process. This study provides a theoretical basis for the high-value recycling of waste polyesterimide enamelled wire.

Recent Progress in Liquid Electrolytes for High‐Energy Lithium–Metal Batteries: From Molecular Engineering to Applications

AbstractLithium–metal batteries (LMBs) have garnered significant interests for their promising high gravimetric energy density (Eg) ∼ 750 Wh kg−1. However, the practical application of the LMBs is plagued by the high reactivity and large volume change during charging–discharging of the lithium–metal anode (LMA), seriously deteriorating the battery safety and cycle life. Great efforts have been devoted to tailoring the electrolytes to favor the Li–metal electroplating by uniformizing the deposition morphology and by suppressing the side reactions between electrolytes and LMA. The aggressive chemistries of both the LMA and its high‐voltage counterpart give new electrolyte components more opportunities, especially designing via molecular engineering. Here, a comprehensive and in‐depth overview of the scientific challenges, fundamental mechanisms, and particularly historical strategies of designing new molecules for electrolyte components including solvents, salts, and additives. Their important roles in tuning the Li+ solvation structure, interface composition, decomposition pathways, and the resultant electrochemical performance of LMBs are also presented. Finally, novel insights and promising research directions from the practical application viewpoints are proposed for future electrolyte designs for high‐voltage LMBs.

Study of the potential energy surface of reactions in a system containing <i>i</i>-propyl and <i>n</i>-propyl radicals

The energy pathways of possible decomposition and isomerization reactions of iso-propyl (i-C3H7) and n-propyl (n-C3H7) radicals have been studied by computational methods of quantum chemistry. B3LYP, M062X, MP2, and CBS-QB3 methods are used to localize stationary points on the potential energy surface of a system containing propyl radicals. A number of intermediate compounds formed during the isomerization and decomposition of propyl radicals have been identified, and information has been obtained on their structure and thermochemical parameters. Based on the results of the research, a diagram of the energy levels of the system under consideration was constructed.

Thermal Decomposition of 2-Cyclopentenone.

The thermal decomposition of 2-cyclopentenone, a cyclic oxygenated hydrocarbon that occurs in the pyrolysis of biomass, has been studied in a combined experimental and theoretical approach. Gas-phase pyrolysis was performed at temperatures ranging from 1000 to 1400 K in a pulsed, microtubular reactor. Products were identified by FTIR spectroscopy following their isolation in a low-temperature argon matrix. The following products were identified: carbon monoxide, ketene, propenylketene, vinylacetylene, ethylene, propene, acrolein, acetylene, propyne, and propargyl radical. Computational results identify three different decomposition channels involving a H atom migration, and producing prop-2-enylketene (Pathway 1), prop-1-enylketene (Pathway 2), and a second conformation of prop-2-enylketene (Pathway 3). A fourth decomposition pathway involves simultaneous rupture of two C-C bonds forming a high energy cyclopropenone intermediate that further reacts to form ethylene, acetylene, and carbon monoxide. Finally, a fifth pathway to the formation of acrolein and acetylene was identified that proceeds via a multistep mechanism, and an interconversion from 2-cyclopentenone to 3-cyclopentenone was identified computationally, but not observed experimentally.

Degradation of Atrazine in Water by Dielectric Barrier Discharge Combined with Periodate Oxidation: Enhanced Performance, Degradation Pathways, and Toxicity Assessment.

The widespread occurrence of atrazine (ATZ) in water environments presents a considerable risk to human health and ecosystems. Herein, the performance of dielectric barrier discharge integrated with periodate (DBD/PI) for ATZ decomposition was evaluated. Results demonstrated that the DBD/PI system improved ATZ decomposition efficiency by 18.2-22.5% compared to the sole DBD system. After 10 min treatment, the decomposition efficiency attained 82.4% at a discharge power of 68 W, a PI dosage of 0.02 mM, and an initial ATZ concentration of 10 mg/L. As the PI dosage increased, the decomposition efficiency exhibited a trend of initially increasing, followed by a decrease. Acidic conditions were more favorable for ATZ removal compared to alkaline and neutral conditions. Electron paramagnetic resonance (EPR) was adopted for characterizing the active species produced in the DBD/PI system, and quenching experiments revealed their influence on ATZ decomposition following a sequence of 1O2 > O2-• > IO3• > OH•. The decomposition pathways were proposed based on the theoretical calculations and intermediate identification. Additionally, the toxic effects of ATZ and its intermediates were assessed. This study demonstrates that the DBD/PI treatment represents an effective strategy for the decomposition of ATZ in aquatic environments.

Decomposition and Growth Pathways for Ammonium Nitrate Clusters and Nanoparticles.

Understanding the formation and decomposition mechanisms of aerosolized ammonium nitrate species will lead to improvements in modeling the thermodynamics and kinetics of aerosol haze formation. Studying the sputtered mass spectra of cation and anion ammonium nitrate clusters can provide insights as to which growth and evaporation pathways are favored in the earliest stages of nucleation and thereby guide the development and use of accurate models for intermolecular forces for these systems. Simulated annealing Monte Carlo optimization followed by density functional theory optimizations can be used reliably to predict minimum-energy structures and interaction energies for the cation and anion clusters observed in mass spectra as well as for neutral nanoparticles. A combination of translational and rotational mag-walking and sawtooth simulated annealing methods was used to find optimum structures of the various heterogeneous clusters identifiable in the mass spectra. Following these optimizations with ωB97X-D3 density functional theory calculations made it possible to rationalize the pattern of peaks in the mass spectra through computation of the binding energies of clusters involved in various growth and dissociation pathways. Testing these calculations against CCSD(T) and MP2 predictions of the structures and binding energies for small clusters demonstrates the accuracy of the chosen model chemistry. For the first time, the peaks corresponding with all detectable species in both the positive and negative ion mass spectra of ammonium nitrate are identified with their corresponding structures. Thermodynamic control of particle growth and decomposition of ions due to loss of ammonia or nitric acid molecules is indicated. Structures and interaction energies for larger (NH4NO3)n nanoparticles are also presented, including the prediction of new particle morphologies with trigonal pyramidal character.

Feedstock recycling of single-use garment simultaneously using CO2 and MSW incinerator bottom ash

This study is aimed at proposing a feedstock recycling approach to make value-added monomer from single-use garment like stocking waste (SW) using incinerator bottom ash catalyst (IBAC). SW is made mainly of nylon 6 (>80 wt%) with minor components such as polyurethane. Thermochemical SW decomposition pathways are identified by evolved gas analysis and single-shot pyrolysis analysis, confirming that caprolactam (a value-added chemical re-used for manufacturing nylon 6) is the major product. IBAC is composed mainly of alkaline metal oxides (e.g., CaO). The use of IBAC in thermochemical SW conversion at 500 °C under CO2 atmosphere increases the yield of caprolactam reaching 70.8 wt% (20 % higher than non-catalytic SW conversion (59.2 wt%)). Moreover, the caprolactam yield corrected to the nylon 6 content of SW is 86.8 wt%. The enhancement of caprolactam production by IBAC in CO2 is most likely due to the synergistical effect of IBAC and CO2 on promoting the molecular interaction of amide groups present on SW. It is hoped that this study brings the idea of new applications of concurrently reusing textile waste (e.g., SW) and municipal solid waste-treatment byproduct (e.g., IBAC).

{Co4O4} Cubanes in a conducting polymer matrix as bio-inspired molecular oxygen evolution catalysts

Exploration of efficient molecular water oxidation catalysts for long-term application remains a key challenge for the conversion of renewable energy sources into fuels. Cuboidal {Co4O4} complexes keep attracting interest as molecular water oxidation catalysts as they combine features of both heterogeneous and homogeneous catalysis with bio-inspired motifs. However, the application of many cluster-based catalysts for the oxygen evolution reaction still requires new stabilization strategies. Drawing inspiration from the stabilizing effects of natural polymers, we introduce a conductive polymer-hybrid approach to covalently immobilize {Co4O4} cubane oxo clusters as oxygen evolution catalysts. Polypyrrole is applied as an efficient p-type conducting polymer that promotes hole transfer during the oxygen evolution reaction, resulting in higher turnover frequency compared to the pristine {Co4O4} oxo cluster and heterogeneous Co-oxide benchmarks. The asymmetric coordination of {Co4O4} not only mitigates catalyst decomposition pathways, but also increases the catalytic efficiency by exposing a directed cofacial dihydroxide motif during catalysis.

Exploring the impact of nanoshaped ceria in the methanol decomposition reaction pathway for clean energy production

The effect of facet exposure in ceria nanostructures on the catalytic properties of Pd/CeO₂ during methanol decomposition was investigated. The results showed the structure sensitive nature of this reaction, with the catalytic activity depending on the facet exposed in the ceria nanostructures. Operando DRIFTS-MS and DFT calculations demonstrated that methanol decomposition proceeds mainly via two reaction pathways depending on the exposed nanofacets: the formate and the formaldehyde pathways. The formaldehyde pathway is inhibited on the (111) nanofacets, where only the formate pathway is energetically favoured, in contrast to the (100) and (110) facets. Superior specific catalytic activity was observed in the catalyst with octahedral morphology, attributed to the higher number of oxygen vacancies per unit surface area, which facilitates the decomposition of formates. By gaining a better understanding of the relationship between the shape control of the catalyst, this work contributes to the collective effort of discovering and implementing sustainable low-carbon energy solutions.

Radical versus Non-Radical Reactivity in ortho- and para-Quinonedimethides and Implications for Cycloaddition Mechanisms.

The latent singlet diradical character of the parent ortho-quinonedimethide (o-QDM), as revealed by valence bond calculations, is demonstrated experimentally by trapping with the kinetically stable free radical TEMPO at room temperature. In the absence of TEMPO, the main pathway for decomposition at ambient temperature is not (as previously proposed in the literature) a radical reaction but instead a concerted Diels-Alder dimerization, which through ωB97X-D/aug-cc-pVTZ/SMD//M06-2X-D3/6-31+G(d,p)/SMD calculations is shown to proceed through an ambimodal bispericyclic transition state. The predominantly non-radical reactivity of o-QDM at room temperature differs from that of its isomeric para-quinonedimethide (p-QDM) congener, which self-reacts exclusively through radical pathways. These findings suggest the potential for tunable concerted/stepwise cycloadditions.

Metal Propionate Solutions for High-Throughput Liquid-Assisted Manufacturing of Superconducting REBa2Cu3O7-δ (RE = Y, Gd, Sm, and Yb) Films.

The cost-effective synthesis of a series of metal propionate powders (copper, yttrium, barium, samarium, gadolinium, and ytterbium) is developed through single chemical reactions resulting in five novel crystalline forms. These complexes are valuable precursors for the preparation of epitaxial REBa2Cu3O7-δ (REBCO) superconducting films (here, RE = Y, Sm, Gd, and Yb) through the innovative transient liquid-assisted growth (TLAG) process based on chemical solution deposition (CSD). TLAG-CSD shows impressive results with YBa2Cu3O7-δ (YBCO), obtaining critical current densities of 2.6 MA/cm2 (77 K) on 500 nm films at unprecedented growth rates (50-2000 nm/s), boosting unprecedented high-throughput industrial production. With a cardinal concern on designing the pyrolysis toward optimal nanocrystalline films for TLAG, an analysis of the thermal behavior of the synthesized precursors is essential. Decomposition pathways for each metal propionate are established, and compatibility with TLAG-CSD is corroborated. Metal-organic solutions for these REBCO systems are successfully prepared, and their rheological properties and thermal behavior are analyzed. This work demonstrates homogeneous nanocrystalline films through propionate-based REBCO precursor solutions, including several rare-earth ions, which display exemplary chemical and microstructural characteristics crucial for TLAG, and provides a base for a wide variety of CSD-based functional oxides.

Ab Initio Kinetic Pathway of Diborane Decomposition on Transition Metal Surfaces in Borophene Chemical Vapor Deposition Growth.

The chemical vapor deposition (CVD) method holds promise for the scalable and controlled synthesis of high-quality borophene. However, the current lack of an atomistic understanding of intricate kinetic pathways from precursors to borophene impedes process optimization. Here, we employ first-principles simulations to systematically explore the pyrolytic decomposition pathways of the most used precursor diborane (B2H6) to borophene on various transition metal surfaces. Our results reveal that B2H6 on various metal substrates exhibits different dissociation behaviors. Meanwhile, the activity of the examined metal substrates is quite anisotropic and surface direction-dependent, where the estimated overall catalytic activity order of these metals is found to be Pd ≈ Pt ≈ Rh > Ir ≈ Ru ≈ Cu > Au ≈ Ag. Our study provides atomistic insights into the dissociation kinetics of diborane precursors on various transition metal surfaces, serving as a guide for experimental growth of borophene.

Key role of sulfur in sulfidated zerovalent iron during persulfate activation for the dynamic equilibrium of oxidative radicals including SO4•- and •OH

Surface sulfidation has been widely investigated to effectively enhance the utilization and selectivity of iron electrons for enhanced pollutant reduction. However, there is relatively less knowledge on whether sulfidation facilitates the catalytic oxidation process and the mechanism of enhancement. Therefore, in this study, the role of surface sulfidation in modulating the oxidant decomposition pathway and reactive oxygen species generation was investigated with the sulfidated zerovalent iron (S-ZVI) activated persulfate (PS) system. The results revealed that sulfur on the surface of S-ZVI not only facilitates PS activation to generate more SO4•-, but also acts as an essential in the dynamic equilibrium between SO4•- and •OH. Specifically, the S-ZVI surface sulfide first forms sulfur monomers during catalysis, which promotes electron transfer to accelerate Fe3+ to Fe2+ cycling, prompting the generation of more SO4•- also generates SO32−. Then, SO32− is further reacted with •OH to generate the [O−-O-SO3-] intermediate of SO4•-, which leads to a dynamic equilibrium of SO4•- and •OH, mitigating the further conversion of SO4•- to •OH. These findings unveiled the dynamic variation of sulfur on the surface of S-ZVI during PS activation, elevating new insights for the sulfate radical-based efficient degradation.

Biosynthesis of mechanically recyclable 3D-Cu2O@megacatalyst for Fenton-like catalysis of tetracycline and the mechanistic insights

Treating sewage waters contaminated with persistent organic pollutants (POPs) presents a pressing environmental concern, mandating, affordable, implementable and sustainable remediations. Supported catalysts, wherein metal nanoparticles are grafted onto inert supports to endow porosity, reactant access, performance and catalyst re-use are emerging as sustainable catalytic platforms. Herein, size-controllable, mechanically recyclable 3D-Cu2O@megacatalyst of ∼81 ± 5 cm2, ∼37 ± 3 cm2 and ∼1 ± 0.6 cm2 were biofabricated by exploiting the innate metal binding feature of pristine eggshells. The as-fabricated Cu2O@megacatalyst was utilized for the Fenton-like treatment of POPs, with exceptional activities against diverse molecules: antibiotic (tetracycline (TC)), textile dye (methylene blue) and pharmaceutical precursor (4-nitrophenol) with the degradation efficiencies of 95.6 %, 96.8 % and 93.4 %, respectively. Optimization studies revealed that our megacatalyst can function consistently in the presence of various oxidising agents, free radical scavengers, wide pH, temperatures and inorganic and organic contaminants. The catalyst demonstrated stability and catalytic efficiency in different real-time water matrices: ultrapure water-95.6 %, tap water-84 %, lake water-86 %, and river water-91 %. Furthermore, plausible reaction mechanism and decomposition pathways for TC degradation were assessed using GC-MS, while evaluating the toxicity using ECOSAR and oxygen uptake assay, which revealed less toxic reaction intermediates and end products. Overall, our results provide new insight into the sustainable development of a generalized highly stable, scalable, ultra-efficient and mechanically recyclable Fenton-like supported catalyst for the detoxification of POPs in sewage waters.

Activated charge transfer by interfacial S−O “bridge” at MnIn2S4/WO3 for eliminating kanamycin: Z-scheme mechanism, pathways and toxicity assessment

In the realm of heterojunction photocatalysis, the efficiency of carrier separation and overall photocatalytic reactions are significantly influenced by the accompanying resistance at the interface as well as the pathway of charge transfer. Herein, a covalently linked Z-scheme MnIn2S4/WO3 heterojunction with interfacial S−O bonds was synthesized through simple calcination and hydrothermal strategies. This tight heterostructure exerted the collaborative impact of interfacial covalent bonding in a Z-scheme model, and its significant role in facilitating the separation of charge carriers was investigated. 19 wt% WO3 combined MnIn2S4 (MIS/WO-19) delivered a remarkable degradation efficiency of 97.4 % for kanamycin, which was 8.8 times higher than that of pure MnIn2S4. The formation of S−O linkages between MnIn2S4 and WO3 was confirmed through experimental analyses and theoretical modeling. The proposed Z-scheme charge transfer pathway was examined by integrating quenching experiments, ESR tests, and DFT computations. This distinctive S−O bond, acting as a specialized “bridge”, in combination with the Z-scheme pathway, efficiently promoted the migration and segregation of photo-induced charges, leading to a notable enhancement in the degradation of kanamycin. Furthermore, the decomposition pathways of kanamycin were investigated through a collaborative approach involving mass spectrometry and DFT simulations, and a toxicity analysis of the intermediates was conducted by the computational toxicology.

Facile boosting catalytic thermal decomposition of ammonium perchlorate from 3D porous nano Co3O4@ZnO composites

The design of efficient catalysts for the pyrolysis of ammonium perchlorate (AP) is important for the performance of composite solid propellants. Co3O4@ZnO heterojunction composites were fabricated by hydrothermal and calcination treatments and used to promote the thermal decomposition of AP. The influences of the Co/Zn molar ratio on the catalytic performance and the content of decomposition products of AP were investigated by various techniques such as TEM, XPS, BET, EIS, and TG-IR. The results revealed that the Co/Zn = 3 sample exhibited excellent performance with the high-temperature decomposition (HTD) temperature of AP reduced from 410°C to 295 °C and the apparent activation energy decreased to 98.7 kJ/mol in the case of 2 wt% addition, attributed to the construction of a heterojunction with abundant active sites enhancing the charge transfer capability between the Co3O4 and ZnO. The decomposition pathway of AP is influenced by the catalyst components, and the Co/Zn = 3 nanostructures demonstrated outstanding catalytic performance by accelerating the decomposition of HClO4 and the conversion of NH3, and promoting the production of N2O, NO, and NO2. This work provides a feasible strategy for the development of Co3O4@ZnO catalysts with excellent catalytic activity towards AP.

Performance evaluation of a dynamic electrooxidation systems with magnetically functionalised UiO-66-NH2 and Ti/Sb–SnO2 for methotrexate treatment

Novel conductive MOF magnetic particles Fe3O4@UiO-66-NH2@PANI (FUP) were prepared and combined with Ti/Sb–SnO2 electrodes to construct a dynamic system with improved electrochemical oxidation efficiency. Electrochemical tests revealed that the Ti/Sb–SnO2–FUP electrodes showed a high active specific surface area and low charge transfer resistance. Investigation of the effects of parameters such as dynamic particle loading, magnetic separation time, initial concentration, Na2SO4 dosage and solution pH on the methotrexate (MTX) degradation rate revealed that the degradation rate reached 97.5%. Electron paramagnetic resonance spectroscopy revealed that the Ti/Sb–SnO2–FUP electrodes could produce abundant hydroxyl radicals, possibly due to the unique pore structure of UiO-66-NH2 and the semiconductor structure of aniline. Finally, the decomposition pathway of MTX and ecotoxicity of the intermediates were analysed through LC-MS/MS and Toxicity Estimation Software Tool theoretical calculations combined with genotoxicity experiments. The results showed that Ti/Sb–SnO2–FUP could effectively reduce the toxicity of the intermediates. In this work, a dynamic electrooxidation system was developed using magnetic Ti/Sb–SnO2 electrodes coupled with MOFs, providing a new idea to improve the oxidative degradation efficiency of electrooxidation systems.

Decomposition of tetracycline with peroxymonosulfate activated by an ordered hierarchical pores Fe-N/C catalyst rich in FeNx sites: Insights into singlet oxygen mechanism

FeNx sites show significant superiority in the degradation of antibiotic contaminants, but there are difficulties in successfully constructing highly dispersed FeNx sites. In this work, Fe-N/C catalysts doped with hierarchical ordered pores structure and FeNx active sites were prepared by metal node exchange strategy. Among them, Fe-N/C-2 had more excite species for peroxymonosulfate (PMS) owing to the synergy between Fe and N coordination, which achieved 89.36 % tetracycline (TC) removal rate within 20 min, and its reaction kinetic (k = 0.245 min−1) is 7.66 times more than original PMS system. Moreover, the material exhibited excellent activation performance in a variety of complex water environments, such as the coexistence of multiple anions, strong acids and alkalis (pH = 2.90 ∼ 10.73), and natural organic matter interference. Chemical bond detection confirmed the successful formation of FeNx sites, free radical trapping experiments showed that FeNx was the main catalytic site, and 1O2 was the main active component. Furthermore, the reaction principle of the FeNx site catalyzing the production of 1O2 from PMS was revealed in detail through mechanism exploration. Next, the probable pathways of TC decomposition were elaborated in terms of the intermediates identified by Liquid Chromatograph Mass Spectrometer (LC-MS). This study emphasized the significant potential of synthesizing Fe-N/C catalysts with activated FeNx sites, elucidated mechanism of FeNx in PMS activation, and confirmed its feasibility in TC degradation.

Design of Highly Electrophilic and Stable Metal Nitrido Complexes.

ConspectusMetal oxo (M═O) and nitrido (M≡N) complexes are two important classes of high-valent transition metal complexes. The use of M═O as oxidants in chemical and biological systems has been extensively investigated. Nature makes use of M═O in enzymes such as cytochrome P450 to oxidize a variety of substrates. Highly oxidizing oxo species have also been synthesized and they have been shown to oxidize organic and inorganic substrates via one-electron oxidation, O atom transfer, and H atom abstraction pathways. In contrast, the oxidation chemistry of M≡N is much less investigated. Although a variety of nitrido complexes are known, most of them are inert and do not show appreciable oxidizing properties, which is not unexpected since the N3- ligand is much more electron-donating than the O2- ligand. In principle, highly electrophilic/oxidizing nitrido complexes may be designed by using weakly coordinating ancillary ligands and/or by increasing the oxidation state of the metal centers. A number of such species have been generated in solution at low temperatures. However, attempts to isolate them are often hampered by their ease of decomposition via bimolecular N···N coupling to generate N2. In some cases, decomposition occurs by intramolecular nitrogenation of the ancillary ligand.In this account, we describe our recent efforts into the design of nitrido complexes that are highly oxidizing but stable enough so they can be isolated and characterized, and their reactivity toward organic substrates can be readily investigated.We have successfully isolated and determined the structure of the first stable manganese(VI) nitrido complex bearing an oxidation-resistant macrocyclic tetraamido TAML ligand, [MnVI(N)(TAML)]- (H4TAML = 3,3,6,6,9,9-hexamethyl-3,4,8,9-tetrahydro-1H-benzo[e][1,4,7,10] tetraazacyclotridecine-2,5,7,10(6H,11H)-tetraone). This complex readily undergoes direct aziridination of alkenes; it also abstracts hydrides from NADH analogues via a Separated CPET mechanism. Coupling of the nitrido ligands to give dinitrogen is a major decomposition pathway for electrophilic nitrido complexes. In order to shut down this pathway, we made use of a bulky trianionic corrole ligand TTPPC (H3TTPPC = 5,10,15-tris(2,4,6-triphenylphenyl)corrole) to prepare manganese nitrido complexes. Remarkably, we were able to isolate and determine the structures of [MnV(N)(TTPPC)]- and its one- and two-electron ligand-oxidized products, [MnV(N)(TTPPC+•)] and [MnV(N)(TTPPC2+)]+ ("TTPPC" has a 3- charge, 'TTPPC+•' has an overall 2- charge and 'TTPPC2+' has an overall 1- charge). Although [MnV(N)(TTPPC2+)]+ is formally a manganese(V) complex, it was found to be the most electrophilic among isolated metal nitrido complexes. The use of the bulky corrole ligand effectively prevents the decomposition of Mn≡N by N···N coupling.A number of luminescent M═O species that possess highly oxidizing excited states are known. We have also developed a strongly luminescent osmium(VI) nitrido complex, [OsVI(N)(L)(CN)3]- (OsN, HL = 2-(2-hydroxy-5-nitrophenyl)benzoxazole), that absorbs visible light to generate a highly oxidizing/electrophilic excited state. The excited state readily reacts with a wide variety of organic and inorganic substrates, many of these reactions are unprecedented. Notably, it reacts with cyclohexane to give an osmium(IV) cyclohexyliminato product, and with benzene to give an osmium(IV) p-benzoquinone iminato species.

Optimizing power output in direct formic acid fuel cells using palladium film mediation: experimental and DFT studies

Low-temperature hydrogen production from environmentally friendly liquid fuels such as methanol, ethanol, and formic acid for miniature fuel cells used in powering portable electronic devices is attracting reasonable attention. In this study, we present the findings from the decomposition of formic acid and subsequent power generation within a microfluid fuel cell. The fuel cell system was engineered to incorporate a palladium membrane at the anode and a modified carbon Torray paper at the cathode. To assess fuel cell performance, we employed chronopotentiometry and cyclic voltammetric electro­chemical techniques. This simple fuel cell could achieve a current peak of 3.17 µW by utilizing 2.50 M HCOOH solution and 2.26 µW with 0.1 M solution, all at room temperature. Finally, to provide a deeper understanding of the reactivity and HCOOH decomposition pathways on various palladium surfaces, we conducted density functional theory (DFT) studies. Our DFT investigations revealed that the Pd(111) surface exhibited more negative adsorption energy compared to other surfaces, suggesting its propensity for a more isomeric crystal morphology. This research underscores the promising potential of low-temperature hydrogen production using safe liquid fuels in microfuel cell applications for portable electronic devices.