Decomposition Products Research Articles

Simulation-Based Investigation on Thermal Propagation in Li-ion Battery Modules with regard to the Thermal Management System

Abstract Thermal propagation in Li-ion battery systems is affected by a wide range of influencing factors including chemical cell properties as well as thermal transport phenomena. Due to the dependence on thermal surroundings it is crucial to regard the entire battery system including peripheral components when assessing thermal runaway and propagation risks. This study proposes a simulation-based approach to support design and dimensioning of potential safety measures. It is based on a chemical model for the thermal runaway decomposition reactions combined with 3D thermal simulations. This is applied on exemplary ten cell battery pack in order to investigate on effects on heat transfer during thermal propagation. Insulation and cooling systems are included in the simulation environment for that purpose. It is found that propagation behavior significantly depends on their positioning within in pack and on thermal boundary conditions. Placing too many barriers may exacerbate hazardous situations instead of mitigating them due to heat accumulation effects. Cooling systems are shown to be able to support thermal runaway mitigation strategies but their effectiveness is limited by thermal transport inside the battery cells.

Role of Metal-Oxide Interfaces in Methanol Decomposition: Reaction of Methanol on CeO2/Ag(111) Inverse Model Catalysts.

Metal-oxide interfaces play a critical role in catalytic processes, such as methanol adsorption and decomposition reactions. In this work, we investigated methanol reactions on the inverse model CeO2/Ag(111) catalyst surfaces, i.e., submonolayer CeO2 films on Ag(111), under ultrahigh vacuum (UHV) conditions to specially address the role of CeO2-Ag interface in the catalytic methanol decomposition reactions. Using scanning tunneling microscopy (STM), low-energy electron diffraction (LEED), and synchrotron radiation photoemission spectroscopy (SRPES), we found that, at the submonolayer ceria coverages, the CeO2 nanoislands exhibit a hexagonal CeO2(111) lattice with fully oxidized Ce4+ on Ag(111). At higher ceria coverages, multilayer ceria nanoislands form on the Ag(111) surface instead of a well-ordered film. A combination of temperature-programmed desorption (TPD) and SRPES reveals that methanol adsorbs dissociatively on the CeO2/Ag(111) surfaces at 110 K, resulting in the formation of methoxy groups. These methoxy groups subsequently decompose via two pathways: (i) interaction with lattice oxygen to produce formate species at 230 K, which then decompose to CO, and (ii) direct dehydrogenation of methoxy to formaldehyde. Notably, the surface with submonolayer CeO2 film on Ag(111) demonstrates low-temperature reactivity (440 K) for methoxy dehydrogenation to formaldehyde, which occurs at a much lower temperature, compared to the surface of multilayer CeO2 on Ag(111) surface (530 K). This finding emphasizes that the CeO2-Ag(111) interfaces provide unique active sites for methoxy dehydrogenation reactions.

Unlocking the Value of Phosphogypsum Waste: Steam Calcination for Efficient Decomposition and Resource Recovery

ABSTRACT Phosphogypsum is a waste by-product of phosphate fertilizer production. It contains calcium sulfate (CaSO4.xH2O), which can be decomposed to produce calcium oxide (CaO) and sulfur dioxide (SO2). Steam calcination is a process that uses steam to decompose CaSO4. This study represents the first comprehensive investigation of steam calcination applied to phosphogypsum, comparing its performance to pure CaSO4 at various temperatures (1050–1200 °C) and steam molar ratios (0, 4%, and 30%). The results showed that steam calcination can significantly lower the calcination temperature of both CaSO4 and phosphogypsum. The presence of steam can significantly accelerate the decomposition reaction of pure CaSO4 and phosphogypsum when compared to decomposition in nitrogen or air. It was found that the decomposition reaction in steam follows the contracting cylinder reaction model in the case of CaSO4 and the first-order reaction model for the phosphogypsum. Additionally, the activation energy for the steam calcination of CaSO4 and phosphogypsum were found to be 421.2 kJ/mol and 418.6 kJ/mol, respectively, which are lower than the activation energy for the calcination in oxyfuel combustion products (O2, CO2, SO2, and H2O gases) 531.4 kJ/mol demonstrating its potential for enhanced energy efficiency. As a result, steam calcination emerges as a promising sustainable solution for valorizing phosphogypsum while reducing energy consumption and greenhouse gas emissions.

Bell Test of Quantum Entanglement in Attosecond Photoionization

Attosecond physics enables the study of ultrafast coherent electron dynamics in matter upon photoexcitation and photoionization, revealing spectacular effects such as hole migration and coherent Auger dynamics in molecules. In the photoionization scenario, there has been a strong focus on probing the physical manifestations of internal quantum coherence within the individual parent ion and photoelectron systems. However, quantum correlations between these two subsystems emerging from attosecond photoionization events have thus far remained much more elusive. In this work, we design theoretically and model numerically a direct probe of quantum entanglement in attosecond photoionization in the form of a Bell test. We simulate from first principles a Bell test protocol for the case of noble gas atoms photoionized by ultrashort, circularly polarized infrared laser pulses in the strong-field regime predicting robust violation of the Bell inequality. This theoretical result paves the way for the direct observation of entanglement in the context of ultrafast photoionization of many-electron systems. Our work provides a novel perspective on attosecond physics directed toward the detection of quantum correlations between systems born during attosecond photoionization and unraveling the signatures of entanglement in ultrafast coherent molecular dynamics, including in the chemical decomposition pathways of molecular ions. Published by the American Physical Society 2024

Engineering Stable Decomposition Products on Cathode Surfaces to Enable High Voltage All‐Solid‐State Batteries

Sulfide solid electrolytes such as Li6PS5Cl hold high promise for solid state batteries due to their high ionic conductivity; however, their oxidation potential of ~2.5 V is not compatible with high voltage Ni‐rich cathodes such as LiNixCoyMn1−x−yO2 (x≥0.8). Here, we devise an effective, conformal and thin coating on the cathode active material guided by density functional theory, which suppresses the oxidative decomposition of Li6PS5Cl as shown by experiment. The nanometric coating on nickel‐rich NMC85 enabled capacity retention of 82% after 200 cycles (2.8‐4.3 V vs Li+/Li) using Li6PS5Cl as the solid electrolyte. In comparison, cells with an uncoated CAM only displayed 56% capacity retention. The coated‐NCM85 cells also demonstrate much better rate performance and higher capacity. The enhanced performance is due to the formation of a stable amorphous cathode‐electrolyte interphase accruing from the decomposition products of the LiPO2F2 precursor (as predicted by DFT), which protect the sulfide electrolyte from oxidation. The coating fabricated in this cost‐effective process showed superior performance to state‐of‐the‐art coatings such as LiNbO3. This work highlights the importance of rationally designing stable coating materials based on their potential decomposition products and confirms the suitability of a low‐cost and conformal coating to enable sulfide electrolyte‐based all‐solid‐state batteries.

Engineering Stable Decomposition Products on Cathode Surfaces to Enable High Voltage All-Solid-State Batteries.

Sulfide solid electrolytes such as Li6PS5Cl hold high promise for solid state batteries due to their high ionic conductivity; however, their oxidation potential of ~2.5 V is not compatible with high voltage Ni-rich cathodes such as LiNixCoyMn1-x-yO2 (x≥0.8). Here, we devise an effective, conformal and thin coating on the cathode active material guided by density functional theory, which suppresses the oxidative decomposition of Li6PS5Cl as shown by experiment. The nanometric coating on nickel-rich NMC85 enabled capacity retention of 82% after 200 cycles (2.8-4.3 V vs Li+/Li) using Li6PS5Cl as the solid electrolyte. In comparison, cells with an uncoated CAM only displayed 56% capacity retention. The coated-NCM85 cells also demonstrate much better rate performance and higher capacity. The enhanced performance is due to the formation of a stable amorphous cathode-electrolyte interphase accruing from the decomposition products of the LiPO2F2 precursor (as predicted by DFT), which protect the sulfide electrolyte from oxidation. The coating fabricated in this cost-effective process showed superior performance to state-of-the-art coatings such as LiNbO3. This work highlights the importance of rationally designing stable coating materials based on their potential decomposition products and confirms the suitability of a low-cost and conformal coating to enable sulfide electrolyte-based all-solid-state batteries.

Normalizers of Sylow subgroups in finite reflection groups

Let W be a finite reflection group, either real or complex, and S l a Sylow l -subgroup of W. We prove the existence of a semidirect product decomposition of N W ( S l ) in terms of the unique parabolic subgroup of W minimally containing S l and known decompositions of normalizers of parabolic subgroups. In the real setting, the description follows from the existence of Sylow l -subgroups stable under the Coxeter diagram automorphisms of finite reflection groups with no proper parabolic subgroup containing a Sylow l -subgroup.

Single bischofite precursor droplet evaporation: Modeling and simulation covering the effects of decomposition reactions and environmental variables

Spray pyrolysis is an excellent method to realize high value utilizing industrial waste bischofite. Interacting droplet evaporation characteristics under the combined influence of ambient pressure, temperature, and decomposition reactions are a prerequisite for constructing spray pyrolysis devices. Therefore, this work established a comprehensive heat and mass transfer model during the multi-component droplet evaporation incorporating decomposition reaction. It also delved into the interplay between temperature and pressure, elucidating their combined influence on the decomposition process during evaporation. The results suggest that raising either temperature or pressure alone can speed up the decomposition process; raising both will more successfully increase the rate of decomposition conversion. In addition, a set of non-dimensionless parameters, mth/ml (mass transfer contribution rate) and Qth/Qd (heat transfer contribution rate), are proposed to characterize the contribution of the decomposition reaction to the evaporation process. Under the actual spray pyrolysis conditions, the mass transfer contribution rate, mth/ml, which is varied in a range of 2 %–70 %, indicating the important role of decomposition reaction during the mass transfer process. The maximum value of the heat transfer contribution rate Qth/Qd is less than 10 %, indicating the dominant role of evaporation in the heat transfer process. Based on the analysis, a theoretical direction for modeling may be provided.

Comprehensive investigation into thermal stability of AB-type bio- carbonate hydroxyapatite synthesized via heat-treated bovine bone

This study investigates the thermal stability and structural changes of AB-type carbonate-hydroxyapatite (AB-type CHA) prepared from heat-treated bovine bone occurring during calcination at 1000, 1100, 1200, and 1300 °C. The structural phase changes and morphological properties of the calcined AB-type CHA samples were assessed by SEM/EDX, XRD, FTIR, and Raman spectroscopy. The findings highlighted that the decomposition of AB-type CHA undergoes three stages: Dehydroxylation, formation of A-type carbonate-hydroxyapatite (A-type CHA), and decomposition. Pure AB-type CHA was stable in a vacuum atmosphere, and no decomposition occurred at temperatures up to 1000 °C. Dehydroxylation and formation of A-type CHA occurred at 1100 °C. The AB-type CHA partially decomposed at a temperature of 1200 °C. A-type CHA, tricalcium phosphate (α-TCP), and tetracalcium phosphate (TTCP) were the main products of the decomposition reactions, and tricalcium phosphate (β-TCP) was also detected in the system. After sintering at 1300 °C, the AB-type CHA was completely decomposed and converted into α-TCP, β-TCP, and TTCP.

Synthesis and Characterization of Cobalt (II) And Zinc (II) Complexes with Diphenylcarbazone and Dimethylsulfoxide: Exploring Antifungal Properties

This study investigates the synthesis of cobalt (II) and zinc (II) complexes with ligands L1 (diphenylcarbazone) and L2 (dimethylsulfoxide), specifically [CoL2(H2O)2]2H2O, [CoL2L1(H2O)2], [ZnL2(H2O)2]2H2O and [ZnL2L1(H2O)2] . The composition of the resulting complexes is shown to depend on the ratios of the starting materials. Characterization of the complexes was conducted using elemental analysis, X-ray phase analysis, UV-VIS spectroscopy, IR spectroscopy, and thermogravimetric analysis. UV spectroscopy revealed d-d transitions in the cobalt (II) complexes at wavelengths between 460-540 nm, while the zinc (II) complex showed a peak at 238 nm. Thermogravimetric analysis indicated that the final products of thermal decomposition for all compounds are metal oxides. Additionally, the effects of these complexes on the growth of selected fungi, specifically Candida, were examined.

Regulating the Performance of CO2 Adsorbents Based on the Pyrolysis Mechanism of Self-Sacrificial Templating Agents.

Previous research has proven that the pore shape and nitrogen group content of adsorbents play essential roles in determining their carbon dioxide (CO2) adsorption performance. In this article, a series of nitrogen-doped porous carbon materials were prepared for CO2 adsorption by varying the proportion of carbon nitride, the pyrolysis temperature, and the activation ratio of KOH, using chitosan as the carbon source, carbon nitride (g-C3N4 and g-C3N5) as self-sacrificing templating agents, and KOH as the activator. Among the prepared materials, T6-850-1 has the highest specific surface area (SBET) of 2336 m2/g, and T6-750-1 has the highest microporous area (Smicro) and CO2 adsorption capacity (1 bar, 298 K) of 1969 m2/g and 3.49 mmol/g, respectively. The thermal decomposition temperature and products of carbon nitride templates were characterized and tested by thermogravimetric infrared gas chromatography-mass spectrometry (TG-IR-GC-MS), and the thermal decomposition mechanisms of the two carbon nitride templates were investigated. We found that the thermal stability of the template directly affects the pore structure of the final sample as well as the type and quantity of nitrogen species.

Surface Plasmon Modulation in Cu3-xP Nanocrystals.

We demonstrate modulation of the surface plasmon resonance in nonstoichiometric copper phosphide nanocrystals using spectroelectrochemical methods. Application of an anodic potential resulted in a blue-shift of the surface plasmon resonance and an incremental increase in its extinction coefficient. Conversely, upon application of a cathodic potential, the surface plasmon band red-shifted and reduced in intensity. These changes were found to be reversible over multiple cycles of anodic and cathodic potential steps. We also discuss how the postsynthetic ligand treatment impacts the surface plasmon peak and the structure of Cu3-xP nanocrystals. For example, the addition of alkylthiols resulted in the chemical decomposition of the nanocrystals. This work demonstrates how the surface plasmon peak in Cu3-xP can be used to probe changes in the structure and carrier density in these nanocrystals.

Fiscal consolidation plans with underground economy

AbstractFiscal consolidation literature often neglects that there are economies characterized by sizable underground sectors, with their mechanisms of response to fiscal policy shocks. Therefore, reliable analyses of fiscal consolidation plans call for the decomposition of Gross Domestic Product in its regular and hidden components. We investigate fiscal consolidation effects in the context of tax evasion for the Italian economy. Results show that a temporary cut in public spending associated with a permanent drop in tax rate yet entails tax evasion reduction. The main underlying mechanism is the strong responsiveness of the underground sector, implying a reallocation of resources toward the regular sector.

Investigation of carbon-black emissions of a tractor biofuel diesel

BACKGROUND: On the one hand, a petroleum-based liquid fuel diesel engine is a reliable basis for tractors and self-propelled agricultural machines, and on the other hand, the current trends make us to think about the environmental component of these diesel engines and besides to remember about reasonable use of non-renewable petroleum motor fuel. In order to reduce the anthropogenic impact on natural ecosystems and to assess the smokiness of exhaust gases from a tractor diesel running on ethanol and rapeseed oil, the paper considers the relevant model of the carbon-black formation inside it. AIM: Development of the relevant model of carbon-black emission in a tractor diesel running on ethanol and rapeseed oil to assess the smokiness of exhaust gases and to reduce anthropogenic impact on natural ecosystems. METHODS: To simulate the processes of formation and burnout of carbon-black particles in a tractor diesel engine, the volume of the combustion chamber was conditionally divided into several areas (soot content indicators in different areas were added up), and the cycle of calculating the exhaust gas smokiness level included several stages (determination of pressure, integral and differential characteristics of heat dissipation, average temperature of the working fluid, fuel supply indicators and fuel evaporation rate, local coefficients of excess air, composition of gases, concentration of decomposition and oxidation products of rapeseed oil and ethanol, the number of carbon-black particles, the mass of dispersed carbon, the rate of transition of particles to the burnout zone). RESULTS: The developed mathematical model is capable of calculating the carbon-black concentration and the main components of the gas mixture in the reaction zone of the combustion chamber, the content of carbon-black in the exhaust gases at various speed and load modes of operation of a tractor diesel engine. It is capable of obtaining valuable information about the dynamics of the main stages of carbon-black formation and burnout in the cylinder of a tractor diesel engine running on ethanol and rapeseed oil. The results of numerical simulation of carbon-black formation and burnout in a tractor diesel cylinder when running on diesel fuel, ethanol and rapeseed oil are obtained and presented. CONCLUSION: Based on the developed relevant model of carbon-black emission in a tractor diesel engine running on ethanol and rapeseed oil, an assessment of its exhaust gas smokiness was carried out, clearly showing a decrease by 3.4–3.8 times in comparison with diesel fuel operation. The presented method for calculating the carbon-black emission of tractor diesel can be used in the multi-area modeling and researches of such in-cylinder processes as heat generation, heat transfer, etc. The accuracy of calculations based on the proposed model is characterized by the perfection of mathematical algorithms describing the rate of fuel evaporation, the development of a fuel flare, the determination of local temperatures, the rate of flame propagation, the local composition of gases in the cylinder, etc.

Revealing Active Sites and Reaction Pathways in Direct Oxidation of Methane over Fe-Containing CHA Zeolites Affected by the Al Arrangement.

Fe-containing zeolites are effective catalysts in converting the greenhouse gases CH4 and N2O into valuable chemicals. However, the activities of Fe-containing zeolites in methane conversion and N2O decomposition are frequently conflated, and the activities of different Fe species are still controversial. Herein, Fe-containing aluminosilicate CHA zeolites with Fe species at different spatial distances affected by the arrangement of framework Al atoms were synthesized in a one-pot manner in the presence or absence of Na. The arrangement of framework Al atoms was identified by 27Al and 29Si MAS NMR spectra and thermogravimetry-differential thermal analysis (TG-DTA) curves. Ultraviolet (UV)-vis, X-ray absorption spectroscopy (XAS), and NO adsorption fourier transform infrared spectroscopy (FTIR) spectra were adopted to analyze Fe speciation. The higher proportion of Fe species in the 6 MR of Fe-CHA zeolites in the presence of Na was confirmed by the NO adsorption FTIR spectrum. The activities of proximal and distant Fe sites in reactions including direct oxidation of methane to methanol, methanol to hydrocarbon, and N2O decomposition were compared at different temperatures to provide the corresponding active sites and reaction pathways. The distant, isolated Fe and isolated proton were more active in the direct oxidation of methane to methanol and tandem conversion of methanol to hydrocarbon reactions than the proximal, isolated Fe and paired protons, respectively. Additionally, proximal, isolated Fe sites afforded higher activity in N2O decomposition. These findings guide the design of highly active catalysts in methane oxidation, methanol to hydrocarbon, and N2O decomposition reactions, addressing energy and environmental concerns.

Non-Adiabatic Excited-State Time-Dependent GW (TDGW) Molecular Dynamics Simulation of Nickel-Atom Aided Photolysis of Methane to Produce a Hydrogen Molecule

Methane photolysis is a very important initiation reaction from the perspective of hydrogen production for alternative energy applications. In our recent work, we demonstrated using our recently developed novel method, non-adiabatic excited-state time-dependent GW (TDGW) molecular dynamics (MD), how the decomposition reaction of methane into a methyl radical and a hydrogen atom was captured accurately via the time-tracing of all quasiparticle levels. However, this process requires a large amount of photoabsorption energy (PAE ∼10.2 eV). Moreover, only one hydrogen atom is produced via a single photon absorption. Transition metal atoms can be used as agents for photochemical reactions, to reduce this optical gap and facilitate an easier pathway for hydrogen production. Here, we explore the photolysis of methane in the presence of a Ni atom by employing TDGW-MD. We show two possibilities for hydrogen-atom ejection with respect to the location of the Ni atom, towards the Ni side or away from it. We demonstrate that only the H ejection away from the Ni side facilitates the formation of a hydrogen molecule with the quasiparticle level corresponding to it having an energy close to the negative ionization potential of an isolated H2 molecule. This is achieved at a PAE of 8.4 eV which is lower compared to that of pristine methane. The results obtained in this work are an encouraging step towards transition metal-mediated hydrogen production via photolysis of hydrocarbons.

Single-atom Barium Promoter Enormously Enhanced Non-noble Metal Catalyst for Ammonia Decomposition.

As a well-established topic, single-atom catalyst has drawn growing interest for its high utilization of metal. However, researchers prefer to develop various active metals with single-atom form, the intrinsic roles of single-atom promoters are usually underrated, which are significant in boosting reaction activity. In this work, Ba single atoms were in situ prepared in the Co-Ba/Y2O3 catalyst with crystallized BaCO3 as the precursor under the ammonia decomposition reaction condition. The optimized Co-Ba/Y2O3 catalyst achieves extremely high H2 production rate of 138.3 mmolH2·gcat-1·min-1 at very low temperature (500 °C, GHSV = 840,000 mL·g-1·h-1) and Co-Ba/Y2O3 exhibits excellent durability during the 350 h test, which realizes the highest activity among all non-noble catalysts, and reaches or even exceeds numerous reported Ru-based catalysts. Both Y2O3 and Co demonstrate positive interactions with Ba, which significantly facilitates the dispersion of Ba species at high temperatures (≥ 600 °C). Ba single atoms significantly enhance the charge density of Co and form additionally active Co-O-Ba-Y2O3 interfacial sites, which alleviates hydrogen poisoning and decreases the reaction barrier of the N-H bond activation of *NH. The exploration of atomically dispersed promoters is groundbreaking in heterogeneous catalysis, which opens up a whole new domain of catalytic material.

Single‐atom Barium Promoter Enormously Enhanced Non‐noble Metal Catalyst for Ammonia Decomposition

As a well‐established topic, single‐atom catalyst has drawn growing interest for its high utilization of metal. However, researchers prefer to develop various active metals with single‐atom form, the intrinsic roles of single‐atom promoters are usually underrated, which are significant in boosting reaction activity. In this work, Ba single atoms were in situ prepared in the Co‐Ba/Y2O3 catalyst with crystallized BaCO3 as the precursor under the ammonia decomposition reaction condition. The optimized Co‐Ba/Y2O3 catalyst achieves extremely high H2 production rate of 138.3 mmolH2·gcat−1·min−1 at very low temperature (500 °C, GHSV = 840,000 mL·g−1·h−1) and Co‐Ba/Y2O3 exhibits excellent durability during the 350 h test, which realizes the highest activity among all non‐noble catalysts, and reaches or even exceeds numerous reported Ru‐based catalysts. Both Y2O3 and Co demonstrate positive interactions with Ba, which significantly facilitates the dispersion of Ba species at high temperatures (≥ 600 °C). Ba single atoms significantly enhance the charge density of Co and form additionally active Co‐O‐Ba‐Y2O3 interfacial sites, which alleviates hydrogen poisoning and decreases the reaction barrier of the N‐H bond activation of *NH. The exploration of atomically dispersed promoters is groundbreaking in heterogeneous catalysis, which opens up a whole new domain of catalytic material.

Combining APCS-MLR model to evaluate the distribution and sources of rare earth elements in a large catchment

Rare earth elements (REEs), functioning as indicators for environmental tracking, revealing the impacts of human activities on changes in aquatic ecosystems. However, systematic research on the geochemical characteristics of REEs in large river basins remains relatively scarce. Therefore, this research investigates the geochemical properties of REEs within the Yangtze River basin, analyzing the quantity and spatial distribution of REEs in surface aquatic environments across the upstream, midstream, and downstream segments of the Yangtze River, and quantitatively assessing their sources. Results indicate that the REE concentration in the upstream and downstream areas are significantly higher than in the midstream, with average concentrations of 0.69 μg/L, 0.56 μg/L, and 0.39 μg/L, respectively. REEs in the Yangtze River basin are enriched in light rare earth elements (LREEs), exhibiting a slight negative cerium (Ce) anomaly and a pronounced positive europium (Eu) anomaly. The Ce anomaly correlates with pH levels, and the Eu anomaly is largely attributed to the selective chemical decomposition and solubilization of feldspar minerals. Correlation analysis indicates that REE sources are related to manganese (Mn). Utilizing the Absolute Principal Component Scores-Multiple Linear Regression (APCS-MLR) model, the principal sources of REEs are further determined to be mineral sources (36.80%), industrial sources (45.61%), and mixed sources (17.59%). Further analysis suggests that mining and dissolution of Mn-bearing feldspar minerals, along with the discharge of industrial wastewater, considerably influence REE concentrations in the basin. This study reveals the anthropogenic and natural factors influencing the distribution of REEs in the Yangtze River basin, laying a foundational framework for investigating how human activities affect the dispersion of REEs in aquatic environments.

Selective Oxidation of Polyesters via PdCu-TiO2 Photocatalysts in Flow.

Catalytic upcycling of plastic wastes offers a sustainable circular economy. Selective conversion of the most widely used polyester, polyethylene terephthalate (PET), under ambient conditions is practically attractive because of low energy consumption and carbon footprint. Here, we report selective, aerobic conversion of PET in a flow reactor using TiO2 photocatalyst modified with atomic Pd and metallic PdCu (Pd1Cu0.4-TiO2) under ambient conditions. We demonstrate that atomically synergistic Pd1Cu0.4-TiO2 exhibits a formate evolution of 4707 μmol g-1 h-1 with a selectivity of 92.3% together with trace COx released. Importantly, we show that this corresponds to 10-103 times greater activity than reported photocatalytic systems. We confirm that synergy between atomic Pd and metallic PdCu boosts directional charge transfer and oxygen-induced C-C cleavage and inhibits product decomposition. We conclude that photocatalytic waste plastic-to-chemical conversion is sustainable via targeted engineering of atomically synergistic catalysts and reaction systems.