Decomposition Products Research Articles

Promising urea electrosynthesis by C-N coupling on copper-based single-atom alloys

Electrochemical synthesis of urea holds a significant importance in the energy landscape, however, the lack of efficient electrocatalysts is the main bottleneck. In this study, 40 single-atom alloys (SAAs) based on Cu(100) and Cu(111) surfaces have been systematically investigated as electrocatalysts for CO2 and N2 co-reduction to produce urea utilizing first-principles calculations. A promising single N and C coupling pathway is uncovered on Cu-based SAAs, besides conventional NCON, CO2, COOH, and CO pathways. CuHf(100) displays a high efficiency in N-N decomposition, C-N coupling, and low reaction limiting potential. Furthermore, CuHf(100) and CuSc(100) have been identified as superior electrocatalysts for efficient urea electrosynthesis. This work provides potential reaction mechanisms with specific single N species, but also a universal strategy for the surface engineering of transition metal-based catalysts in electrocatalytic urea synthesis reactions.

A multi-step discharge/charge model of Li[sbnd]O2 batteries coupled with electrolyte decomposition and carbon electrode corrosion reactions

Electrolyte decomposition and electrode corrosion stand as two primary side reactions in lithium‑oxygen (LiO2) batteries during their discharge/charge cycles. In this work, a comprehensive LiO2 battery model combining multi-step lithium peroxide (Li2O2) formation, electrolyte decomposition, and electrode corrosion is proposed. Based on this model, the deposition behaviors and cycling performance of the LiO2 battery under deep discharge/charge cycles are investigated. The stop of discharge is mainly ascribed to the loss of active surface area for the battery using tetraethylene glycol dimethyl ether (TEGDME) electrolyte, while both O2 transport limitation and active surface area loss lead to the discharge termination for battery using dimethyl sulfoxide (DMSO) electrolyte. The incomplete decomposition of Li2O2 and lithium carbonate (Li2CO3) clogs electrode pores, leading to a continuous decline in the discharge capacity of the LiO2 battery. For the TEGDME-based battery, the undecomposed Li2CO3 gradually dominates the deposition with cycles, wherein electrode corrosion becomes the primary source of the undecomposed Li2CO3 after 3 cycles. For the DMSO-based battery, undecomposed Li2O2 is always a dominant trigger for battery discharge capacity degradation, although electrode corrosion remains a key contributor to Li2CO3 generation. Despite the DMSO-based battery exhibiting lower rates of electrolyte decomposition and electrode corrosion, it demonstrates poorer cyclic performance than the TEGDME-based battery due to the generation of more toroidal Li2O2. Moreover, when the charging cut-off voltage is reduced to 4.2 V, discharge capacity diminishes more rapidly due to the increased accumulation of undecomposed Li2O2, despite suppressed Li2CO3 deposition. Finally, the results confirm that thick electrodes lead to deteriorating cycling performance, stemming from increased discharge/charge overpotential and extended discharge/charge times, thus intensifying the side reactions.

Introducing Bi2S3 Interlayer to Synergistically Modify Mo Back Contact and Regulate Bulk Defects in Kesterite Solar Cells.

A suitable interlayer between the Mo back electrode and kesterite absorber layer has been proven to have a positive effect on limiting the bulk defects of the absorber by the constitute diffusion. Here, a thin Bi2S3 layer is used as the back-interface intermediate layer for the first time, this innovative approach allows for simultaneous modification of the back contact and reduction of bulk defects, resulting in improving the power conversion efficiency of the kesterite device from 9.66% to 11.8%. The evaporated Bi2O3 thin films turn into the Bi2S3 interlayers after sintering the Cu2ZnSnS4 precursor thin films. The Bi2S3 interlayer can inhibit the decomposition reaction of back contact and suppress the formation of the secondary phases. It can also optimize the Fermi level offset and promote the separation of the photoinduced carriers, resulting from its characteristic of high work function. Besides, a small part of the Bi element can diffuse into Cu2ZnSn(S, Se)4 film and induce the crystal growth and restrain Zn-related defects, which is attributed to forming the low melting-point liquid BiSex phase during the high-temperature selenization process. The conclusions highlight the bifunction of the thin Bi2S3 intermediate layer, which can provide a new approach to improve the photoelectric conversion efficiency of kesterite solar cells.

Investigations of the Laser Ablation Mechanism of PMMA Microchannels Using Single-Pass and Multi-Pass Laser Scans.

CO2 laser machining is a cost effective and time saving solution for fabricating microchannels on polymethylmethacrylate (PMMA). Due to the lack of research on the incubation effect and ablation behavior of PMMA under high-power laser irradiation, predictions of the microchannel profile are limited. In this study, the ablation process and mechanism of a continuous CO2 laser machining process on microchannel production in PMMA in single-pass and multi-pass laser scan modes are investigated. It is found that a higher laser energy density of a single pass causes a lower ablation threshold. The ablated surface can be divided into three regions: the ablation zone, the incubation zone, and the virgin zone. The PMMA ablation process is mainly attributed to the thermal decomposition reactions and the splashing of molten polymer. The depth, width, aspect ratio, volume ablation rate, and mass ablation rate of the channel increase as the laser scanning speed decreases and the number of laser scans increases. The differences in ablation results obtained under the same total laser energy density using different scan modes are attributed to the incubation effect, which is caused by the thermal deposition of laser energy in the polymer. Finally, an optimized simulation model that is used to solve the problem of a channel width greater than spot diameter is proposed. The error percentage between the experimental and simulation results varies from 0.44% to 5.9%.

The effect of dithionite and its decomposition products on redox mediators used in the cyclic voltammetry of nitrogenase enzymes

Cyclic voltammetry is a powerful tool to study enzyme mechanisms. Over the last decade voltammetry has been applied to probe aspects of nitrogenase catalysis. One aspect that is often overlooked is the effect of dithionite (S2O42‐, DTH) that is routinely added to purification and storage buffers to protect nitrogenase and anaerobic enzymes alike (e.g hydrogenase) from oxygen. Dithionite has extremely complex chemistry with a myriad of decomposition products. Here we sought to systematically investigate the effect of dithionite and some of its decomposition products on the voltammetry of different redox mediators independently and in conjunction with nitrogenase. We found the major decomposition product sulfite (SO32‐) gives rise to reductive catalysis, which cannot be distinguished from enzyme catalysis, particularly with cobaltocenium mediators. We provide recommendations on how to identify and avoid interpreting ‘pseudo’ catalysis in lieu of enzyme catalysis by DTH and reinforce the requirement to remove DTH prior to performing cyclic voltammetry experiments.

The interface interaction and thermal sensitivity of nitrogen-rich energetic co-particles: A reactive molecular dynamics simulation study

Composite explosives are the ultimate used form of energetic materials in weapon systems and aerospace or deep-sea explorers. Among them, the energetic co-particles which combine high-energy crystals with low-sensitivity energetic crystals, is a excellent way to balance energy and safety for energetic materials. In this work, a kind of nitrogen-rich octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine(HMX) / 2,6-diamino-3,5-dinitropyrazine-1-oxide (LLM-105) co-particles were investigated using molecular modeling methods. Different ratios of HMX/LLM-105 co-particles were constructed by combining different high-energy HMX surfaces with low-sensitivity LLM-105 surfaces. Reactive molecular dynamics simulations (RMD) were carried out on the co-particle models to investigate the thermal sensitivity, as well as classical molecular dynamics simulations were performed to investigate the interfacial interactions. The results show that strong attractive forces including van der Waals and electrostatic interactions exist along the crystalline interfaces, and the thermal decomposition reactions were greatly influenced by the composition of the co-particles. Finally, recommended ratio of HMX/LLM-105, which has enough attractive interaction to enhance the interface, high energy as well as good thermal stability was selected. This research is of significance on the design of advanced insensitive energetic composites.

Lithium salt preprocessing calcination strategy for a more stable layered structure of lithium-rich manganese-based cathodes

The poor cycling performance of lithium-rich manganese-based (LMR) cathodes limits their practical applications. The stability of the layered structure is closely related to the cycling performance. The high-temperature solid-state reaction between transition metal oxides (TMOs) and lithium salts promotes the formation of the layered structure, which determines the quality of the layered structure. Considering the influence of physicochemical changes of the lithium salt on the formed layered structural stability, in this work, the calcination strategy includes a short period of holding time near the melting point of Li2CO3, referred to as the lithium salt preprocessing calcination strategy, which allows the molten Li2CO3 to be fully contacted with TMOs at relatively low temperatures, alleviating the problem of Li in the thermal decomposition products of Li2CO3 not easily further reacting with TMOs. Compared to the conventional calcination procedure, this new calcination strategy reduces the oxygen vacancy concentration as well as the relative Mn3+ content on the surface of the cathodes, which significantly improves the cycling performance. In addition, the shortening of the constant high temperature calcination time effectively reduces the production energy consumption, which provides a reference for the future efficient and low-cost synthesis of electrode materials with excellent cycling performance.

Vaterite-based in situ surface modification and process-dependent biocompatibility of laser sintered polypropylene

Polypropylene (PP) rapidly gains scientific attention as fatigue-resistant and lightweight tissue repair and implant material, while emerging laser-sintering based methods for PP processing further allow unlimited versatility of PP specimens and often reduced numbers of process steps, substituting traditional manufacturing approaches. Generally, PP is considered biocompatible for a variety of medical applications while showing superior long-term stability, however, thermoplastic processing of polypropylene may induce the formation of cytotoxic degradation products, necessitating its cytotoxicological assessment. In the present study, PP specimens have been fabricated using warm, quasi-isothermal and complementary cold, non-isothermal powder bed fusion (PBF), allowing processing PP at ambient powder bed temperature of 25 °C for minimizing thermal exposure and the formation of decomposition products. The surface of manufactured specimens has been modified with hybrid coatings consisting of mesoporous inorganic microcrystals of vaterite laden with model biomacromolecules, i.e., fluorescently labelled dextran, demonstrating the stable coating and attachment of dextran-loaded vaterite crystals independent of the applied PBF processing regime. Vaterite coating is degradable and enables the opportunity to endow the surface of PP with sustained release functionalities. Both coated and uncoated specimens demonstrated excellent biocompatibility independent of the applied processing regime, as evaluated in an ex ovo shell-less hen's egg model.

A high-efficiency pre-lithiation strategy for Li-ion capacitor achieved by the synergistic effect of pre-lithiation and solid electrolyte interface film modification

The cathodic pre-lithiation process, currently considered the most feasible resolution to address the irreversible depletion of Li+ in dual carbon-based lithium-ion capacitors (LICs), encounters obstacles in widespread adoption due to its substantial dosage requirement, rising decomposition potential and the damage related to its decomposition residues. Hence, in this study, the successful utilization of Li2NiO2 for LIC pre-lithiation is accomplished, leveraging the synergistic effect between Li2NiO2 and lithium difluoro oxalate borate (LiDFOB). It's noteworthy that the full capacitor, entirely composed of commercial materials (activated carbon/hard carbon) and supplemented with 20 wt% LNO +2 wt% LiDFOB, exhibits remarkable energy densities of 98.53 Wh kg−1 at a power density of 31 W kg−1 and 19 Wh kg−1 at a power density of 4.65 kW kg−1. Moreover, the full capacitor displays commendable performance, demonstrating superior capacitive behavior and excellent high-current cycling proficiency. Besides, electrochemical evaluations and structural analyses unveil that LiDFOB, via solid electrolyte interface (SEI) modification, enhances the utilization of Li+ sourced from Li2NiO2 thus avoiding the abuse of pre-lithiation reagents, while the LNO decomposition products contribute substantially to additional capacitance. The synergistic effect of pre-lithiation reagent and SEI modification underpin the outstanding performance witnessed in the full capacitor.

Challenges in XPS Analysis of PEO‐LiTFSI‐based Solid Electrolytes: How to Overcome X‐ray‐Induced Photodecomposition

AbstractThe cycle life of poly(ethylene oxide) (PEO) batteries containing lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) is hindered by interfacial (electro)chemical electrolyte decomposition, a process traditionally examined via X‐ray photoelectron spectroscopy (XPS). Our research presents a critical examination of X‐ray induced photodecomposition, commonly misinterpreted as (electro)chemical electrolyte decomposition, in PEO‐LiTFSI systems and those with NCM cathodes. We provide novel insights into this X‐ray induced photodecomposition process and show that it is particularly pronounced when LiTFSI is dissolved and not in its pure state. Most importantly, we reveal that cryogenic measurement conditions can almost completely mitigate this photodecomposition. This insight not only deepens the understanding of photodecomposition within XPS analyses but also provides a transformative approach to the accurate characterization of electrolyte materials in lithium batteries.

Improved Straw Decomposition Products Promote Peanut Growth by Changing Soil Chemical Properties and Microbial Diversity

The ameliorative effects of straw decomposition products on soil acidification have been extensively studied. However, the impact of chemically treated straw decomposition products on crop productivity and the underlying microbial mechanisms remain unclear. This study aimed to investigate the effects of two dosages of Ca(OH)2-treated straw decomposition products of peanuts on red soil acidity, fertility, and bacterial and fungal diversity through a pot experiment. The pot experiment included four treatments: chemical nitrogen, phosphorus, and potassium (NPK) fertilization alone (CK), NPK chemical fertilization combined with peanut straw decomposition products (PS), NPK chemical fertilization combined with 4% Ca(OH)2-treated peanut straw decomposition products (PS4Ca), and NPK chemical fertilization combined with 8% Ca(OH)2-treated straw decomposition products (PS8Ca). High-throughput sequencing was performed to investigate the effects of these treatments on soil microbial diversity. The treatments with PS, PS4Ca, and PS8Ca significantly increased soil pH, exchangeable base cations, and nutrient content, whereas they decreased the exchangeable acid, especially exchangeable aluminum. The peanut growth improved substantially with the application of straw decomposition products. Specifically, PS4Ca significantly increased the Shannon and Richness indices of fungi. The principal coordinate analysis showed that the soil microbial communities in the straw decomposition product treatments were significantly different from CK. Linear discriminant analysis effect size identified unique bacteria and fungi between treatments. The Mantel test indicated that exchangeable base cations and pH were significantly positively correlated with bacterial communities, whereas available potassium was positively correlated with fungal communities. The partial least squares path modeling revealed that the bacterial communities positively and directly affected all peanut agronomic traits. In contrast, the fungal communities had a negative and direct effect only on peanut 100-pod weight. Therefore, adding Ca(OH)2-treated straw decomposition products could effectively improve crop productivity by alleviating soil acidification, increasing soil nutrients, and subsequently changing microorganisms.

On the path to kinetic solid-state chemistry: Activation energy-controlled stepwise synthesis and crystal structure of LiSc(NCN)2

Rationally designing new materials is a crucial objective in modern solid-state chemistry, employing different synthetic strategies to vary a reaction's energetic aspects and, hence, effectively control its direction. In that context, and aided by density-functional-based enthalpy diagrams, we have developed a solid-state cyanamide metathetic method allowing to synthetically scan its activation energy profile, thus yielding milder reaction conditions and preventing potential product decomposition. This approach has led to the preparation of the ternary cyanamide LiSc(NCN)2 via solid-state metathesis between Na2NCN, ScCl3 and LiCl, essentially by the existence of an intermediate, LixNa1–xSc(NCN)2, and the subsequent stepwise exchange of Na+ with Li+ ions. Both LiSc(NCN)2 and the solid solution crystallize in an orthorhombic crystal structure with Pbcn symmetry, similar to the rest of the LiM(NCN)2 cyanamide family with M = Al, In, Yb and Y. Structural analysis of the coordination environment around the NCN2− group reveals a relaxation in the distortion of this unit and also an inversion of the cyanamide orientation as Na+ ions are progressively replaced with Li+, thus making the formation of the targeted compound highly favorable.

Flame-Retardant Glass Fiber-Reinforced Epoxy Resins with Phosphorus-Containing Bio-Based Benzoxazines and Graphene.

This paper presents a study of the flammability and thermal decomposition products of glass fiber-reinforced epoxy resin (GFRER) with the addition of cardanol-based phosphorus-containing benzoxazine monomer (CBz) and graphene and their combinations in different proportions (up to 20 wt.%). The addition of CBz alone or in combination with graphene resulted in an increase in the limiting oxygen index (LOI) and self-extinguishing in the UL-94 HB test. The flame-retardant samples had better tensile mechanical properties than the sample without additives. The differential mass-spectrometric thermal analysis (DMSTA) of the thermal decomposition products of GFRER without additives and with the addition of CBz and graphene was carried out. CBz addition promoted the thermal decomposition of high-molecular-weight products of epoxy resin decomposition in the condensed phase and at the same time decreased the time of release of low-molecular-weight thermal decomposition products into the gas phase. Graphene addition resulted in an increase in the relative intensities of high-molecular-mass peaks compared to GFRER without additives.

Micropore effects on coal pyrolysis process investigated by using reactive molecular dynamics

The micropore structure can serve as the diffusion channels for intermediates and light tar products during coal pyrolysis, which is very important for modulating the desired tar or char products. In this work, the micropore effects on product distribution and the reaction mechanisms during Hailaer coal pyrolysis was explored for the first time from the atomistic simulation point of view by using large-scale ReaxFF MD simulation and the reasonable model with the artificially adding micropore strategy. The results suggest that the micropore structure indeed has a significant impact on the major tar product distribution and competitive reactions during coal pyrolysis process at high temperature. The micropore can promote decomposition reactions through accelerating C–C bond breaking significantly and inhibit the recombination reactions accompanied with the char formation with more carbon in sp2 structure. Based on the oxygen-containing bond behaviors in char products obtained from coal pyrolysis process, it is unraveled that the more micropore exits in coal structure, the more Csp3-O bonds and less Csp2-O bonds in char precursors. Particularly, the light tar products with ring groups are more influenced by micorpore structures than those chain products. Considering that the limitation of current experimental techniques in micropore detection, the strategy sheds new light on the depth investigation of micropore effects on reactions, which can provide complement for experimental observations and tar product modulation.

Kinetic Modeling of Mass Loss during Carbonization of Sodium Carboxymethyl Cellulose (CMC) Aerogels

The carbonization of sodium carboxymethyl cellulose (CMC) aerogels involves complex thermal decomposition processes leading to the formation of carbonaceous residues. Understanding the kinetics of mass loss during carbonization is vital for optimizing the production of CMC carbon aerogels with desired properties. In this study, a mathematical model is presented that describes the kinetics of mass loss during the carbonization process of CMC aerogels. This model considers the temperature and concentration dependence of CMC decomposition reactions and is validated against experimental data obtained at various conditions. The proposed kinetic model elucidates the underlying mechanisms governing mass loss during carbonization, offering valuable insights for the design and optimization of CMC carbon aerogels across diverse applications. Furthermore, the analysis of the experimental data reveals variations in both the reaction order and the rate constant for different concentrations of CMC aerogels, indicating distinct kinetic behavior. These findings contribute to a deeper understanding of the carbonization process and pave the way for tailored synthesis approaches to meet specific application requirements.

Ignition and flow combustion characteristics of hydroxylammonium nitrate - based liquid propellant based on electric method

Hydroxylamine nitrate (HAN)-based liquid propellants are characterized by high energy content and low toxicity ionic monopropellants, offering great potential application prospects in the space engine. This paper proposes an experimental system for electric ignition and combustion of HAN-based liquid propellant. The energy for decomposition, current, and combustion image of HAN-based liquid propellant are measured under different initial voltage, propellant volume, and the initial pressures in Ar and air atmospheres. The results show that the energy for decomposition decreased with an increase in initial voltage, propellant volume, and initial pressure. An increase in the initial voltage accelerates the reaction speed of HAN-based liquid propellant, and the energy for decomposition is approximately 3 J. An increase in the propellant volume decreases the equivalent resistance in the circuit, increasing the current and enhancing the thermal effect of the propellant. The accumulation of decomposition products and heat under high pressure reduced the energy for decomposition; the energy for decomposition is less than 1.5 J for the pressurization condition. Compared with the Ar atmosphere, the energy for decomposition of HAN-based liquid propellant shows better stability in the air atmosphere. The flow combustion device of HAN-based liquid propellant for the flow state is designed. The HAN-based liquid propellant is successfully ignited for different initial voltages and flow rates. The research results provide a reference for the design of space engine for HAN-based liquid propellant based on the electric ignition method.

H2S induced in-situ formation of recyclable metal sulfide-based sorbent for elemental mercury sequestration in natural gas

Enlightened by the phenomenon that hydrogen sulfide (H2S) can readily decompose on metal oxides to generate sulfide species and the obtained metal sulfides are generally adopted as Hg-affine ligands for Hg0 capture, a urea modified copper oxide (U-CuO) was prepared via high-temperature calcination of the mixture of urea and copper nitrate for Hg0 removal in natural gas containing H2S. Benefitted from the decomposition of urea and the release of gaseous decomposition products, the as-synthesized U-CuO was enriched with abundant base sites and lattice oxygen, and characterized with developed textural features, which facilitates the diffusion and adsorption of H2S and subsequent sequestration of Hg0. The Hg0 adsorption capacity and uptake rate of U-CuO under simulated natural gas (N2 + 500 ppm H2S+8% H2O) reached as high as 134.06 mg g−1 and 58.32 μg g−1 min−1, respectively, which largely surpassed those of most CuS-based sorbents for Hg0 immobilization. Besides, U-CuO sorbent also exhibited satisfactory recyclability only through simple thermal treatment, the Hg0 removal efficiency of U-CuO maintained above 97 % even after ten adsorption-regeneration rounds. This preparation strategy not only provides valuable hints to guide the design and synthesis of Hg0 sorbents used for natural gas containing H2S but also inspires further investigation for the cost-effective performance enhancement of Hg0 sorbents.

Indium-doped BiFeO₃ gas sensors for the high-sensitivity and selective SO₂F₂ detection

A novel gas sensor based on In-doped BiFeO3 was devised to enhance the sensitivity and selectivity for detecting sulfur hexafluoride (SF6) decomposition products, specifically sulfuryl fluoride (SO2F2). The sensor was fabricated using an electrospun technique and hydrothermal approach followed by low-temperature pyrolysis at 250°C, achieving a single-phase BiFeO3 perovskite structure. The In-doped BiFeO3 sensor exhibits remarkable sensitivity (17.8) with a detection limit of 100 ppm for SO2F2 and outstanding selectivity, effectively minimizing responses to the interfering gases. The In-doping into the BiFeO3 results in uniform tubular nanofibers with an increased specific surface (63.53 m2g−1) area, larger pore size (38.17 nm), and reduced grain size. The microstructural enhancements, along with the catalytic activity of In nanoparticles and the formation of p/n junctions facilitating charge transfer and diffusion, lead to the improved sensing capabilities such as lower operating temperatures, higher gas responses, and moderate response/recovery times. This sensor design is tailored for the practical indoor and on-road detection of SO2F2 in industrial applications, contributing to the creation of smart and sustainable urban environments by ensuring a safe and healthy atmosphere.

Dual-species sensor using time-division multiplexed laser absorption spectroscopy for hydrogen sulfide and carbon monoxide measurement in SF6 insulated equipment fault detection

To address the issues of high detection limits, long response times, and susceptibility to cross-interference in the detection of characteristic gases CO and H2S produced by SF6 electrical equipment failures, a dual-species laser sensor prototype for SF6 decomposition products in electrical equipment was developed based on tunable diode laser absorption spectroscopy (TDLAS). The absorption lines of 2334 nm and 1576 nm were selected for CO and H2S, respectively. The concentration inversion was performed using wavelength modulation spectroscopy (WMS) with first harmonic normalization of the second harmonic. The experimental results demonstrate that a rapid response time of ∼30 s is achieved and the sensor has detection accuracies of 0.59 % for CO and 2.09 % for H2S, with minimum detection limits of 0.46 ppb and 14.00 ppb, respectively. The dual-species laser sensor allows for convenient, rapid, and precise detection of CO and H2S, showing promising application prospects in electrical environment monitoring.

The Unimolecular Decomposition Mechanism of Trimethyl Phosphate.

Trimethyl phosphate (TMP), an organophosphorus compound (OPC), is a promising fire-retardant candidate for lithium-ion battery (LIB) electrolytes to mitigate fire spread. This study aims to understand the mechanism of TMP unimolecular thermal decomposition to support the integration of a TMP chemical kinetic model into a LIB electrolyte surrogate model. Reactive intermediates and products of TMP thermal decomposition were experimentally detected using vacuum ultraviolet (VUV) synchrotron radiation and double imaging photoelectron photoion coincidence (i2PEPICO) spectroscopy. Phosphorus-containing intermediates such as PO, HPO and HPO2 were identified. Sampling effects could successfully be obviated thanks to photoion imaging, which also showed evidence for isomerization reactions upon wall collisions in the ionization chamber. Quantum chemical calculations performed for the unimolecular decomposition of TMP revealed for the first time that isomerization channels via hydrogen and methyl transfer (barrier heights of 65.9 and 72.6 kcal/mol, respectively) are the lowest-energy primary steps of TMP decomposition followed by CH3OH/CH3/CH2O or dimethyl ether (DME) production, respectively. We found an analogous DME production channel in the unimolecular decomposition of dimethyl methylphosphonate (DMMP), another important OPC fire-retardant additive with a similar molecular structure to TMP, which are not included in currently available chemical kinetic models.