Decomposition Barrier Research Articles

Volatilization Characteristic of Chloride Salts During the Production of Fired Brick Under Different Atmospheres

The behavior of chloride (Cl) salts in high-temperature environments is critical for various industrial processes, including waste treatment and material synthesis. However, the influence of different atmospheric conditions on the volatilization and interaction of Cl salts with clay minerals remains poorly understood. Previous studies have primarily focused on individual salt types under limited conditions, leaving a gap in the comprehensive understanding of how atmosphere composition affects Cl salt volatilization at high temperatures. This work addresses this gap by systematically investigating the volatilization behaviors of NaCl, KCl, and CaCl2 in different atmospheres (air, N2(g), NH3(g), and H2O(g)) across temperatures from 750 to 1050 °C. The results revealed significant differences in volatilization rates, with H2O(g) atmosphere significantly enhancing Cl volatilization, especially for NaCl and KCl, while CaCl2 showed notably lower volatilization. N2(g) and NH3(g) atmospheres exhibit a similar, moderate effect on Cl volatilization, while the air atmosphere suppressed Cl volatilization due to the formation of stable oxide structures. Thermodynamic simulations confirmed the formation of HCl(g) as the primary volatile species, with metal cations forming stable silicates and feldspar compounds with clay minerals. DFT calculations highlighted that H2O(g) lowers the energy barrier for chloride salt decomposition, accelerating volatilization by weakening the bond between metal cations and Cl ions. These findings provide valuable insights into the impact of atmospheric conditions on the volatilization of Cl salts in high-temperature environments.

Thgraphene with High Polysulfide Anchoring Ability and Catalytic Performance for Advanced Na-S Batteries: A First-Principles Study.

The sodium-sulfur (Na-S) batteries, with advantages such as high energy density, high specific capacity, and low cost, have attracted significant attention in the field of rechargeable batteries in recent years. However, their practical application still faces many challenges. In this study, we employ first-principles calculations to investigate the performance of a 2D carbon allotrope, thgraphene, as an anchoring material in Na-S batteries. Our studies reveal that thgraphene possesses the modest adsorption strength (0.70-1.75 eV) toward S8/Na2Sn species, which is beneficial for inhibiting the dissolution and shuttle effect of sodium polysulfides. Furthermore, thgraphene demonstrates excellent bifunctional catalytic activity, displaying reduced Gibbs free energy barrier (0.58 eV) for sulfur reduction reaction (SRR) and lower Na2S decomposition barrier (0.76 eV); thus, it would greatly enhance the electrode reaction kinetics during the charge/discharge processes. Additionally, we find that applying certain strain can not only maintain the adsorption strength of S8/Na2Sn species but also improve the sulfur reaction activity. These theoretical findings provide an avenue for the potential application of thgraphene in Na-S batteries.

First-Principles Studies on the Design of Tungsten-Based Platinum Electrocatalyst for Hydrogen Evolution Reaction in Alkaline Environment

Hydrogen production has gained prominence as a clean and sustainable energy source, with water electrolysis emerging as a key method for generating hydrogen gas. Platinum (Pt), although extensively used as a cathode electrocatalyst in both acidic and alkaline media electrolyzers due to its moderate hydrogen binding energy, utilization in the Anion Exchange Membrane (AEM) system suffers from low catalytic activity. OH and H2O adsorption energy must be strong enough for facile water dissociation while H binding must be ideal to prevent H desorption from being the bottleneck. In this work, first-principles calculations were used to design Tungsten (W)-based Pt catalyst to effectively control the adsorption energies and aim for a superior alkaline HER catalyst compared to the bulk Pt catalyst. Owing to the weak OH and H2O binding energy on the conventional Pt slab, two methodologies were employed to precisely control adsorption strength of each intermediate. Nanoscale engineering of catalysts, modelled as Pt55 icosahedral nanocluster, was employed where the interaction of all the adsorbates with the surface was increased, lowering the activation barrier for water decomposition. Another approach is through monolayer deposition of Pt on the W simulated as Pt/W(110) slab where the heterogeneous surface induced strain effect and ligand effect. With the discrepancy of the crystal structures of two metals, strain effect was seen more dominant, where adsorbate-induced strain effect also played a significant role in fine-tuning the the adsorption energies of each adsorbate in a favorable direction. Lastly, pursuing the synergistic effect of both methods, W@Pt core-shell nanoparticle structure was formed which did not show enhanced catalytic activity. Since such fine-tuning of adsorption energies of varied intermediates is normally done by engineering a complex heterogeneous surface to execute for bifunctional active sites, this work will provide insights to control the adsorption energies with a simple metal monolayer surface. Figure 1

Optimizing Reversible Phase-Transformation of FeS2 Anode via Atomic-Interface Engineering Toward Fast-Charging Sodium Storage: Theoretical Predication and Experimental Validation.

Sodium-storage performance of pyrite FeS2 is greatly improved by constructing various FeS2-based nanostructures to optimize its ion-transport kinetics and structural stability. However, less attention has been paid to rapid capacity degradation and electrode failure caused by the irreversible phase-transition of intermediate NaxFeS2 to FeS2 and polysulfides dissolution upon cycling. Under the guidance of theoretical calculations, coupling FeS2 nanoparticles with honeycomb-like nitrogen-doped carbon (NC) nanosheet supported single-atom manganese (SAs Mn) catalyst (FeS2/SAs Mn@NC) via atomic-interface engineering is proposed to address above challenge. Systematic electrochemical analyses and theoretical results unveil that the functional integration of such two type components can significantly enhance ionic conductivity, accelerate charge transfer efficiency, and improve Na+-adsorption capability. Particularly, SAs Mn@NC with Mn-Nx coordination center can reduce the decomposition barrier of Na2S and NaxFeS2 to further accelerate reversible phase transformation of Fe/Na2S→NaFeS2→FeS2 and polysulfides decomposition. As predicted, such FeS2/SAs Mn@NC showcases outstanding rate capability and fascinating cyclic durability. A sequence of kinetic studies and ex situ characterizations provide the comprehensive understanding for ion-transport kinetics and phase-transformation process. Its practical use is further demonstrated in sodium-ion full cell and capacitor with impressive electrochemical capability and excellent energy-density output.

Regulating the Local Spin States in Spinel Oxides to Promote the Activity of Li-CO2 Batteries.

Due to the high energy barrier, slow reaction kinetics, and complex reaction environments of Li-CO2 batteries, the development of durable and efficient catalysts is essential. Transition metal oxides are promising for their availability, stability, and 3d electronic features, with spin states playing an important role in CO2 activation. In this study, the local spin states are regulated by incorporating Ni into Co3O4 and its impact on activity in Li-CO2 batteries is explored. The results show that Ni atoms with high spin states in Ni0.1Co2.9O4 facilitate electron transfer from the catalyst to the unoccupied orbitals of CO2, providing sufficient active sites for the nucleation and growth of small Li2CO3 crystals. These small crystals have a low decomposition barrier, leading to improved battery efficiency. Therefore, Ni0.1Co2.9O4 shows superior catalytic performance with an overpotential of 0.72V and an energy efficiency of ≈70% after 500h. This work provides insights into the relationship between spin states and CO2 reactions, highlighting a promising avenue for developing high-performance metal-CO2 batteries.

C3H8O2 Isomers: Insights into Potential Interstellar Species.

2-Methoxyethanol, with a formula C3H8O2, was recently identified in the massive protocluster NGC 6334I. However, its structural isomers, 1,2-propanediol and 1,3-propanediol, remain undetected despite extensive searches in the Sgr B2 region. In this study, we explored the potential energy surface of the C3H8O2 system using CCSD(T)/aug-cc-pVTZ//MP2/aug-cc-pVTZ calculations, identifying 11 species, with the geminal diols 2,2-propanediol and 1,1-propanediol as the most stable forms. We examined the gas-phase decomposition barrier of these geminal diols and found that 1,1-propanediol is thermodynamically stable at low temperatures (10-150 K). C3H8O2 isomers with energies below 30 kcal/mol are relevant to the ISM, as they have been identified or tentatively detected in irradiation experiments of ice analogs of CO, H2O, and CH3OH.

Mechanistic Insights on Coverage-Dependent Selectivity Limitations in Vinyl Acetate Synthesis.

Developing improved catalysts for sustainable chemical processes often involves understanding atomistic origins of catalytic activity, selectivity, and stability. Using density functional theory and steady-state kinetic analyses, we probe the elementary steps that form decomposition products that limit selectivity in vinyl acetate (VA) synthesis on Pd surfaces covered with acetate species. Acetate formation and coupling with ethylene control the VA formation catalytic cycle and steady-state coverage, but acetate and ethylene can separately decompose to form CO2. Both decompositions involve initial C-H activations at acetate vacancies, followed by additional C-H activations and eventual C-O formations and C-C cleavages involving reactions with molecular oxygen. Acetate decomposition paths with non-oxidative kinetically-relevant steps exhibit similar free energy barriers to oxidative paths. In contrast, the non-oxidative ethylene path involving an ethylidyne intermediate exhibits a much lower barrier than paths with oxidative kinetically-relevant steps. Ethylene decomposition is very facile at low coverages but is more coverage-sensitive, leading to similar decomposition and VA formation barriers at coverages accessible at steady state, which is consistent with moderate VA selectivity in measurements and ethylene vs. acetate decomposition contributions assessed from regressed kinetic parameters. These insights provide a detailed framework for describing VA synthesis rates and selectivity on metallic catalyst surfaces.

Breaking the Passivation Effect for MnO2 Catalysts in Li−S Batteries by Anion‐Cation Doping

AbstractTransition metal oxides (TMOs) are recognized as high‐efficiency electrocatalyst systems for restraining the shuttle effect in lithium‐sulfur (Li−S) batteries, owing to their robust adsorption capabilities for polysulfides. However, the sluggish catalytic conversion of Li2S redox and severe passivation effect of TMOs exacerbate polysulfide shuttling and reduce the cyclability of Li−S batteries, which significantly hinders the development of TMOs electrocatalysts. Here, through the anion‐cation doping approach, dual incorporation of phosphorus and molybdenum into MnO2 (P,Mo‐MnO2) was engineered, demonstrating effective mitigation of the passivation effect and allowing for the simultaneous immobilization of polysulfides and rapid redox kinetics of Li2S. Both experimental and theoretical investigations reveal the pivotal role of dopants in fine‐tuning the d‐band center and optimizing the electronic structure of MnO2. Furthermore, this well‐designed configuration processes catalytic selectivity. Specifically, P‐doping expedites rapid Li2S nucleation kinetics by minimizing reaction‐free energy, while Mo‐doping facilitates robust Li2S dissolution kinetics by mitigating decomposition barriers. This dual‐doping approach equips P,Mo‐MnO2 with robust bi‐directional catalytic activity, effectively overcoming passivation effect and suppressing the notorious shuttle effect. Consequently, Li−S batteries incorporating P,Mo‐MnO2‐based separators demonstrate favorable performance than pristine TMOs. This design offers rational viewpoint for the development of catalytic materials with superior bi‐directional sulfur electrocatalytic in Li−S batteries.

Breaking the Passivation Effect for MnO2 Catalysts in Li-S Batteries by Anion-Cation Doping.

Transition metal oxides (TMOs) are recognized as high-efficiency electrocatalyst systems for restraining the shuttle effect in lithium-sulfur (Li-S) batteries, owing to their robust adsorption capabilities for polysulfides. However, the sluggish catalytic conversion of Li2S redox and severe passivation effect of TMOs exacerbate polysulfide shuttling and reduce the cyclability of Li-S batteries, which significantly hinders the development of TMOs electrocatalysts. Here, through the anion-cation doping approach, dual incorporation of phosphorus and molybdenum into MnO2 (P,Mo-MnO2) was engineered, demonstrating effective mitigation of the passivation effect and allowing for the simultaneous immobilization of polysulfides and rapid redox kinetics of Li2S. Both experimental and theoretical investigations reveal the pivotal role of dopants in fine-tuning the d-band center and optimizing the electronic structure of MnO2. Furthermore, this well-designed configuration processes catalytic selectivity. Specifically, P-doping expedites rapid Li2S nucleation kinetics by minimizing reaction-free energy, while Mo-doping facilitates robust Li2S dissolution kinetics by mitigating decomposition barriers. This dual-doping approach equips P,Mo-MnO2 with robust bi-directional catalytic activity, effectively overcoming passivation effect and suppressing the notorious shuttle effect. Consequently, Li-S batteries incorporating P,Mo-MnO2-based separators demonstrate favorable performance than pristine TMOs. This design offers rational viewpoint for the development of catalytic materials with superior bi-directional sulfur electrocatalytic in Li-S batteries.

Interaction of H2S with perfect and O-covered Pd(100) surface: A first-principles study

Using density functional theory (DFT) calculations, we investigated the dissociative mechanism of H2S adsorption and its dissociation on both clean and oxygen covered Pd (100) surface. For adsorption mechanism, the site preference was considered for H2S and HS monomers on both surfaces. The results suggest that H2S is energetically adsorbed on high symmetry sites, particularly the hollow site, on clean surface and top site on O-covered Pd (100) surface. Chemisorption of HS is stronger than H2S at the favorable hollow site on clean surface and O-covered surface. The energy barriers for S–H bond-breaking during the first H2S dehydrogenation are 0.35, 0.07, 0.32, and 0.16 eV, while for second dehydrogenation are 0.32 and 0.30 eV, respectively. On the oxygen-covered surface, the H2S adsorption site transitions from bridge to the top site and their energy barrier for first-order decomposition is 0.05 eV, significantly lesser than that observed on a clean surface. To examine more, the electronic densities of states as well as d-band center model were used to characterize the interaction of adsorbed H2S with the surfaces. Overall, our findings show that H2S decomposition on these surfaces is exothermic and relatively easy, but the presence of surface oxygen hinders the breaking process of H–S bond due to kinetic and thermodynamic factors.

Fast co-pyrolysis characteristics of polyethylene terephthalate and epoxy resin from waste wind turbine blades

The present study systematically investigated the fast co-pyrolysis characteristics of epoxy resin and polyethylene terephthalate (PET) derived from waste wind turbine blades, with the aim of uncovering the possible synergistic effect in co-pyrolysis. The co-pyrolysis of epoxy resin and PET was beneficial to the formation of pyrolytic char, while the generation of small molecule gaseous products was restrained to a certain degree. The kinetic results revealed that the presence of epoxy resin dramatically reduced the energy barrier for PET decomposition into terephthalic acid (TPA) and vinyl benzoate via a cyclic transition state, finally resulting in an obvious reduction in the activation energy of the pyrolysis reaction. Remarkably, the activation energy for co-pyrolysis sharply decreased to around 150 kJ/mol at a low conversion rate. The co-pyrolysis presented a significant impact on the further transformation of primary pyrolysis products via decarboxylation, deoxygenation, decarbonylation, isomerization, and so on, thus contributing to the selective production of specified chemicals. Furthermore, the plausible reaction pathways and synergistic mechanisms between co-pyrolysis of epoxy resin and PET were discussed thoroughly.

Alkali Metals Activated High Entropy Double Perovskites for Boosted Hydrogen Evolution Reaction.

An efficient and facile water dissociation process plays a crucial role in enhancing the activity of alkaline hydrogen evolution reaction (HER). Considering the intricate influence between interfacial water and intermediates in typical catalytic systems, meticulously engineered catalysts should be developed by modulating electron configurations and optimizing surface chemical bonds. Here, a high-entropy double perovskite (HEDP) electrocatalyst La2(Co1/6Ni1/6Mg1/6Zn1/6Na1/6Li1/6)RuO6, achieving a reduced overpotential of 40.7mV at 10mA cm-2 and maintaining exemplary stability over 82 h in a 1m KOH electrolyte is reported. Advanced spectral characterization and first-principles calculations elucidate the electron transfer from Ru to Co and Ni positions, facilitated by alkali metal-induced super-exchange interaction in high-entropy crystals. This significantly optimizes hydrogen adsorption energy and lowers the water decomposition barrier. Concurrently, the super-exchange interaction enhances orbital hybridization and narrows the bandgap, thus improving catalytic efficiency and adsorption capacity while mitigating hysteresis-driven proton transfer. The high-entropy framework also ensures structural stability and longevity in alkaline environments. The work provides further insights into the formation mechanisms of HEDP and offers guidelines for discovering advanced, efficient hydrogen evolution catalysts through super-exchange interaction.

Anion‐Reduction‐Catalysis Induced LiF‐Rich SEI Construction for High‐Performance Lithium‐Metal Batteries

AbstractThe practical application of lithium‐metal batteries (LMBs) remains impeded by uncontrollable Li dendrite growth and unstable solid‐state electrolyte interphase (SEI) on lithium‐metal anodes. Constructing the inorganic‐rich SEI is considered as an effective strategy to realize the dense Li deposition and inhibit interfacial side reactions, thereby improving the lifespans of LMBs. Herein, an anion‐reduction‐catalysis mechanism is proposed to design a LiF‐rich SEI utilizing 2D tellurium (Te) nanosheets as catalysts, which are homogenously implanted on the substrate. Lithiophilic Te nanosheets can induce uniform Li nucleation and deposition through in situ lithiation reactions, while the resulting product Li2Te can reduce the energy barrier for anion decomposition and promote the generation of LiF in the SEI. Consequently, Li dendrite growth and interfacial side reactions are effectively suppressed, enabling long‐cycle‐life LMBs. The Te‐modified electrode in half‐cells delivers superior cycle life exceeding 500 cycles and a high average Coulombic efficiency of 97.8% at 5 mAh cm−2. The high‐energy‐density (405 Wh kg−1) pouch cells pairing the Te‐modified Li anodes with high‐mass‐loading LiNi0.9Co0.05Mn0.05O2 (NCM90) cathodes exhibit stable cycling performance with a high average Coulombic efficiency of 99.3% in carbonate electrolytes. This work provides a promising anion catalyst design for LiF‐rich SEI and paves the way for developing high‐energy‐density LMBs.

Highly Reversible Sodium‐ion Storage in A Bifunctional Nanoreactor Based on Single‐atom Mn Supported on N‐doped Carbon over MoS2 Nanosheets

AbstractConversion‐type electrode materials have gained massive research attention in sodium‐ion batteries (SIBs), but their limited reversibility hampers practical use. Herein, we report a bifunctional nanoreactor to boost highly reversible sodium‐ion storage, wherein a record‐high reversible degree of 85.65 % is achieved for MoS2 anodes. Composed of nitrogen‐doped carbon‐supported single atom Mn (NC‐SAMn), this bifunctional nanoreactor concurrently confines active materials spatially and catalyzes reaction kinetics. In situ/ex situ characterizations including spectroscopy, microscopy, and electrochemistry, combined with theoretical simulations containing density functional theory and molecular dynamics, confirm that the NC‐SAMn nanoreactors facilitate the electron/ion transfer, promote the distribution and interconnection of discharging products (Na2S/Mo), and reduce the Na2S decomposition barrier. As a result, the nanoreactor‐promoted MoS2 anodes exhibit ultra‐stable cycling with a capacity retention of 99.86 % after 200 cycles in the full cell. This work demonstrates the superiority of bifunctional nanoreactors with two‐dimensional confined and catalytic effects, providing a feasible approach to improve the reversibility for a wide range of conversion‐type electrode materials, thereby enhancing the application potential for long‐cycled SIBs.

Asymmetrical TiSSe Monolayers as Catalytic Materials for Lithium-Sulfur Batteries: A DFT Study

Asymmetrical Janus TiSSe monolayers as cathode materials for lithium-sulfur batteries were studied by first-principles calculations, encompassing adsorption, catalytic, and conductive properties. The polarization effect, arising from the asymmetric arrangement of constituent elements, results in variability in adsorption energy and bonding processes across S/Se surfaces. The moderate adsorption energy of Lithium Polysulfides (LiPSs) on the TiSSe monolayer effectively mitigates the shuttle effect. The bond formation process investigated by charge transfer, physical/chemical adsorption, and projected crystal orbital Hamiltonian population (pCOHP), revealed its emergence in the early lithiation stage. The Gibbs free energies for the reduction reaction of sulfur on the S/Se surface demonstrate a significant enhancement in the transformation kinetics. The low decomposition and diffusion energy barriers for lithium atoms on the S/Se surface of the TiSSe monolayer indicate its catalytic potential in facilitating sulfur redox transformation. The TiSSe monolayer exhibits metallic properties before and after polysulfide absorption, thereby enhancing electron transport capacity in Li-S batteries. Therefore, the Janus TiSSe monolayer presents a new perspective for the selection of battery adsorption materials in lithium-sulfur batteries.

Solution-plasma treatment for synthesizing Ketjenblack-supported Pt (1 1 1) nanocatalysts with ultra-low overpotential for Li-O2 batteries

Reducing the loading of noble metals to achieve high catalytic activity is key to enhancing the performance and reducing the cost of lithium-oxygen (Li-O2) batteries. In this study, a highly dispersed platinum (111) catalyst supported on Ketjenblack (p-Pt/KBs) is synthesized using a novel approach that involves the interaction between solution and nonthermal plasma (SNP). The influence of different glow discharge voltages on morphology and performance of catalytic materials is investigated. The results show that the electrocatalyst prepared at 400 V has uniform Pt (111) nanocrystals embedded on Ketjenblack, achieved through plasma-induced decomposition of H2PtCl6 followed by nucleation and growth. The designed catalyst, when used as the cathode catalyst in Li-O2 batteries, demonstrates lower polarization losses with an overall overpotential of only 0.24 V compared to commercial platinum on carbon (Pt/C). The plasma effect results in significantly increased defects and grafted oxygen-containing functional groups on the support surface, providing abundant active sites conducive to anchoring of Pt nanoparticles (NPs) onto the scaffold and promoting their electronic coupling. Moreover, dominant mesopores offer ample triple-phase active zones that facilitates lithium-ion transport and rapid oxygen diffusion, further lowering energy barrier for Li2O2 decomposition and reducing the charge overpotential.

Strain effect on TaSe2/Te2 monolayer as adsorption substrate in lithium–sulfur battery

Lithium-sulfur (Li–S) batteries, with their high theoretical specific capacity and energy density, are considered a promising alternative to current energy storage technologies. However, their practical application is hindered by the polysulfide shuttle effect, which leads to capacity fade and reduced coulombic efficiency. In this study we employs density functional theory (DFT) to explore the use of two-dimensional (2D) metallic transition metal dichalcogenides (TMDs), tantalum diselenide (TaSe2) and tantalum ditelluride (TaTe2), as anchoring materials for lithium polysulfides (LiPSs). Our findings reveal that these TMD monolayers exhibit a balanced binding affinity towards LiPSs, ranging from 1.20ev to 3.34eV (TaSe2) and from 2.35ev to 3.74eV (TaTe2). Notably, the decomposition barriers for Li2S on TaSe2 and TaTe2 are significantly lower than those of bulk Li2S with a value of 1.62eV and 1.54eV, suggesting these materials can facilitate rapid charge-discharge processes. The introduction of strain, simulating the expansion during lithiation, demonstrates that these monolayers maintain their adsorption capabilities, a crucial attribute for practical applications, with a increased decomposition barriers of 2.4eV(TaSe2) and 2.51eV(TaTe2). The catalytic activity of these monolayers for the sulfur reduction reaction (SRR) was evaluated, showing a spontaneous conversion mechanism for lithium-sulfur clusters, which is expected to enhance the overall performance of Li–S batteries. This study presents TaSe2 and TaTe2 as innovative and promising candidates for advanced Li–S battery applications, offering a perspective in addressing the critical challenges associated with the polysulfide shuttle effect.

Dry Reforming of Methane on Ni/LaZrO2 Catalyst under External Electric Fields: A Combined First-Principles and Microkinetic Modeling Study.

Dry reforming of methane (DRM) reaction has great potential in reducing the greenhouse effect and solving energy problems. Herein, the DRM reaction mechanism and activity on Ni16/LaZrO2 catalyst under electric fields were comprehensively investigated by combining density functional theory calculations with microkinetic modeling. The results showed that La doping increases the interaction between Ni and ZrO2 by Ni cluster transfer of more electrons. The adsorption strength of species followed the order Ni16/ZrO2 > Ni16/LaZrO2, which is consistent with the results for the d-band center but opposite to the metal-support interaction. The best DRM reaction path on Ni16/LaZrO2 was the CH2-O pathway, which is different from the CH-O pathway on Ni(111) and Ni16/ZrO2. Both positive and negative electric fields of strong and weak metal-support interactions reduced the energy barrier of DRM reaction. Importantly, our results showed that the more dispersed and smaller Ni12/LaZrO2 model by considering the dispersing effect induced by La doping, which displayed very different results from that of Ni16/LaZrO2: reduced the energy barrier for methane decomposition, thereby promoting DRM reaction activity. Microkinetic results showed that the carbon deposition behavior of DRM becomes weaker on Ni16/LaZrO2 due to the suppression of methane decomposition in the presence of La doping compared to Ni16/ZrO2, but the opposite result is obtained on Ni12/LaZrO2. The order of DRM reactivity was Ni16/LaZrO2 < Ni16/ZrO2 < Ni12/LaZrO2, which is consistent with the experiment observations. The conversion of methane and CO2 was higher in positive electric fields than in negative electric fields at low temperatures, but the results were opposite at high temperature. Negative electric fields can improve the carbon deposition resistance of Ni-based catalysts compared to positive electric fields. The degree of rate control analysis showed that CHx* oxidation also plays an important role in the DRM reaction. We envision that this study could provide a deeper understanding for guiding the widespread application of electric field catalysis.

Novel phase of the Na-N system in the N-rich region under high pressure

The study of the Na-N system in the N-rich region under high pressure enriches the structural types of polynitrogen structure: four novel structures (P1-NaN7, Cm-NaN7, C2-NaN8, and R 3‾-NaN8) are proposed. The layered structure of the Cm-NaN7 and R 3‾-NaN8 phase consisting of the N16 and N18 ring respectively are first proposed in the Na-N system under high pressure. The Cm-NaN7 and R 3‾-NaN8 phase not only can be stabilized to the ambient conditions, but also the Cm-NaN7 phase can decompose and release energy at 325 K, while the R 3‾-NaN8 phase can be stable to at least 1000 K. The research shows that the different decomposition barriers and charge transfer are important reasons for the difference of decomposition temperature. The Cm-NaN7 phase is semiconductor phase with a band gap of 0.06 eV, while the R 3‾-NaN8 phase is metal phase. Furthermore, the excellent energy density, detonation pressure, and detonation velocity of the Cm-NaN7 and R 3‾-NaN8 phase make them as potential candidates in the application of high energy density materials.

Deciphering the Catalytic Mechanism of Peroxidase-like Activity of Iron Sulfide Nanozymes.

Iron sulfide nanomaterials represented by FeS2 and Fe3S4 nanozymes have attracted increasing attention due to their biocompatibility and peroxidase-like (POD-like) catalytic activity in disease diagnosis and treatments. However, the mechanism responsible for their POD-like activities remains unclear. Herein, taking the oxidation of 3,3,5,5-tetramethylbenzidine (TMB) by H2O2 on FeS2(100) and Fe3S4(001) surfaces, the catalytic mechanism was investigated in detail using density functional theory (DFT) calculations and experimental characterizations. Our experimental results showed that the catalytic activity of FeS2 nanozymes was significantly higher than that of Fe3S4 nanozymes. Our DFT calculations indicated that the surface iron ions of iron sulfide nanozymes could effectively catalyze the production of HO• radicals via the interactions between Fe 3d electrons and the frontier orbitals of H2O2 in the range of -10 to 5 eV. However, FeS2 nanozymes exhibited higher POD-like activity due to the surface Fe(II) binding to H2O2, forming inner-orbital complexes, which results in a larger binding energy and a smaller energy barrier for the base-like decomposition of H2O2. In contrast, the surface iron ions of Fe3S4 nanozymes bind to H2O2, forming outer-orbital complexes, which results in a smaller binding energy and a larger energy barrier for the base-like decomposition of H2O2. The charge transfer analysis showed that FeS2 nanozymes transferred 0.12 e and Fe3S4 nanozymes transferred 0.05 e from their surface iron ions to H2O2, respectively. The simulations were consistent with the experimental observations that the FeS2 nanozymes had a greater affinity for H2O2 compared to that of Fe3S4 nanozymes. This work provides a theoretical foundation for the rational design and accurate preparation of iron sulfide functional nanozymes.