Low Activation Energy Research Articles

ZIF‐67 Derived Co‐LDH Nanocubes for Oxygen Evolution Reaction

AbstractTo address the substantial energy needs of the quickly evolving modern civilization, efforts are still needed to provide sustainable renewable energy sources. The electrocatalytic Oxygen evolution reaction (OER) is one of the essential technologies used in the various hydrogen production techniques. ZIF‐67 nanocubes (ZIF‐67 NCs) were synthesized in an aqueous solution and used as sacrificial templates. Cobalt nitrate hexahydrate was added under water bath conditions, resulting in the evolution of numerous small layered layers of cobalt hydroxide. This ultimately led to the formation of multilayered, three‐dimensionally crosslinked Co‐LDH with a porous networked cubic morphology. Hydrolysis of Co2+ at different concentrations produces different degrees of weak acidic environments, and the loose LDH on the cubic structure of the best catalyst, Co‐LDH‐1, exposes more active cobalt sites for the OER, which results in a high electrochemically active surface area, with an overpotential of 354 mV and a Tafel slope of 79.06 mV dec−1 at a current density of 10 mA cm−2, and good stability and low activation under alkaline condition also has good stability and low activation energy. It provides us an easy and practical plan for logically creating ZIF‐derived hydroxide materials, leading to the development of affordable and effective electrocatalysts.

Synchronous improvement in mechanical properties and dielectric performance of poly(silylene arylether arylacetylene) by introducing trifluoromethyl groups

AbstractPoly(silylene arylether arylacetylene) (PSEA) resin is a promising material for preparing an advanced wave‐transparent composite because of excellent thermal stability and good dielectric properties. Herein, a novel poly(silylene arylether arylacetylene) resin with trifluoromethyl groups (PSEAF) was synthesized by Grignard coupling reaction, and the effects of the incorporation of trifluoromethyl groups on various properties of PSEAF resin and quartz fiber reinforced composites were investigated. Compared to PSEA, the PSEAF resin exhibits better solubility and processability, and lower apparent activation energy for curing reactions. After thermal curing reactions, the PSEAF resin converts to an amorphous crosslinked network with the temperature at 5% weight loss (Td5) around 470 °C. The cured PSEAF resin possesses improved mechanical properties and dielectric properties. The flexural strength arrives at 64.4 MPa, and the dielectric constant (ε) and dielectric loss (tanδ) at 30 MHz are 2.75 and 4.3 × 10−3, respectively. Besides, the quartz fiber reinforced PSEAF composite simultaneously shows ε of 3.3, theoretical wave transmittance |T|2 of 91.4% at 7 GHz, and flexural strength of 350 MPa.

Reversible Glass‐Crystal Transition in a New Type of 2D Metal Halide Perovskites

AbstractCrystalline metal halide perovskites (MHPs) have ushered in remarkable advancements across diverse fields, including materials, electronics, and photonics. While the advantages of crystallinity are well‐established, the ability to transition to a glassy state with unique properties presents unprecedented opportunities to expand the structure‐property relationship and broaden the application scope for 2D MHPs. Up until now, the exploration of amorphous analogs for MHPs is confined to high‐pressure conditions, limiting in‐depth studies and practical applications. In this context, a new type of 2D MHPs is synthesized by incorporating halogen substituted organic cations, resulting in a remarkable combination of low melting temperature and inhibited crystallization. This new type of 2D MHPs can be effectively melt‐quenched into a glassy state except for (DMIEA)3Pb2I7 (DMIEA = N, N‐dimethyl iodoethylammonium) counterpart. Analysis of the crystallization activation energy for (DMIPA)4Pb3I10 (DMIPA = N, N‐dimethyl iodopropylammonium) reveals a low crystallization activation energy of 60.7 ± 4.0 kJ mol−1, which indicates a fast glass‐crystal transition. The type of atypical 2D MHP showcases facile and reversible switching between glassy and crystalline states and opens up novel possibilities for applications, such as nonvolatile memory, optical communication, and neuromorphic computing.

Structural implications of ionic conduction in LaAlO3–Ce0.8Gd0.2O2-δ composite solid electrolyte

Investigations were done on the combinations of perovskites and fluorite structured composite electrolyte materials to check the possible enhancement of the ionic conductivity. For this purpose, the compounds, LaAlO3 (LAO) and Ce0.8Gd0.2O2-δ (CGO) were mixed in the weight ratios of 3:1, 2:2, and 1:3 to develop cost-effective composite electrolyte materials. Conductivity spectroscopy techniques were used to examine the dc electrical transport properties. Thermal properties were investigated using thermogravimetry analysis. Fourier transform spectroscopy was employed for bond structural study, while an X-ray diffractometer pattern analysis was employed to ensure the formation of composite structure. Scanning electron microscopy and energy dispersive X-ray spectroscopy studies confirm dense microstructure by a suitable weight proportion of component, homogeneous grain dispersion, and elemental confinement. The electrical behavior of composite electrolytes was demonstrated by electrochemical impedance spectroscopic analysis methods, which instigate the highest value of the conductivity of the order of 0.14x10−2 S cm−1 and lower activation energy value (0.72 eV) at temperature 700 °C for composite with LAO-CGO weight ratio of 1:3.

Ultra‐deep and fast oxidative desulfurization by IL‐POM immobilized on bar‐shaped green fiber toward the high efficiency

The Keggin‐type P‐Mo‐W polyoxometalate‐based ionic liquids ([VimAm]Br‐POM, POM is PMo6W6O40) were facilely supported on the green fiber (CA) to obtain a kind of bar‐shaped catalyst. The [VimAm]Br‐POM@CA showed an outstanding oxidative desulfurization performance for model oil and real oils with H2O2 as oxidant, mainly due to the dual role of the [VimAm]Br‐POM with the high activity and its excellent dispersion on CA. The dibenzothiophene (DBT) in model oil could be almost completely removed with [VimAm]Br‐POM@CA‐2 in 60 min at 60 °C without adding other extractants, in which [VimAm]Br acts as this role. Meanwhile, the influences of reaction temperature, molar ratio of H2O2/S, catalyst dosage, and different sulfur‐containing compounds were also investigated. Interestingly, the pretty low activation energy (0.1875 kJ/mol) has been achieved, and no significant loss of activity even after being reused for 5 cycles. The combination of IL‐POM and CA is an efficient strategy to obtain a newly kind desulfurization catalyst, with remarkable results on catalytic efficiency and reuse ability at the same time.

The ionic conductivity and electrochemical performance of Alginate-PVA based polymer electrolyte with Li+ charge carriers for supercapacitor

This study presents the synthesis and characterization of solid polymer blend electrolytes (SPBEs) using alginate (Alg) and polyvinyl alcohol (PVA) as host polymers, incorporating lithium bis(trimethanesulfonyl)imide (LiTFSI) as the ion-providing salt for potential application in EDLCs. The surface morphology of the SPBEs was revealed using scanning electron microscopy (SEM), while thermal gravimetric analysis (TGA) demonstrates enhanced thermal stability, characterized by reduced weight loss and a shift toward higher decomposition temperature. Complexation between Alg-PVA and LiTFSI was indicated by Fourier-transform infrared spectroscopy (FTIR), as evident by the transitions and intensity changes in FTIR bands corresponding to functional groups. Increasing LiTFSI content reduces bulk resistance, with Alg-PVA containing 20 wt% LiTFSI (Li-20) showing maximum room temperature ionic conductivity (3.31 × 10-4 S cm−1) and the lowest activation energy (0.05 eV). Transport properties, analyzed using the Arof-Noor (A-N) method, reveal that ionic conductivity in SPBEs is governed by ionic mobility and ions’ diffusion coefficient. Sample Li-20 displays predominantly ionic transport with a transference number (tion) 0.98 and electrochemical stability up to 2.55 V. The EDLC, employing activated carbon electrodes and the most conductive electrolyte, demonstrates notable performance features, including specific capacitance (87.51F/g at 2 mV/s, assessed from CV), energy density (25.17 Wh kg−1), and power density (1038.92 W kg−1). Testing at various current densities reveals the highest specific capacitance values associated with the lowest current density, measuring 51.15F/g for the EDLC cell based on the Li-20 sample.

Difference in hot deformation behavior of a Ni–Fe based superalloy through cast-wrought and additive manufactured processes

Traditional cast-wrought superalloys have been challenging in cogging due to element segregation. However, additive manufacturing technology is anticipated as a novel method for producing low-segregation superalloys. A set of isothermal compression tests were conducted on a Ni–Fe based superalloy GH4169 in various processing conditions, including as-cast and as-homogenized alloy produced by triple melting (Alloy TMC and TMH), as well as additive manufactured alloy (Alloy AM). Flow stresses were examined to develop activation energy maps and processing maps. Additionally, microstructure evolutions were observed to investigate the mechanisms of recrystallization nucleation and grains refinement during hot deformation. Under specific deformation conditions, three alloys have developed to varying refinement stages. As Zener-Hollomon parameter Z decreases, the nucleation mechanism shifts from continuous to discontinuous dynamic recrystallization. Alloy TMH exhibits enhanced hot workability compared to TMC, which is attributed to its lower activation energy Q and more limited instability region. Q value of Alloy AM is slightly higher than that of TMH; however, it demonstrates a wider processing window. Utilizing AMed superalloys for hot deformation not only provides advantages in low segregation and fine grains, but also simplifies the process sequences. This is expected to break through the current technical bottleneck associated with higher performance superalloy turbine disks.

Single‐Atom Catalysts Based on the Mo2CO2 MXene for CO Oxidation

AbstractThrough density functional theory calculations, the mechanism of CO oxidation to CO2 on single‐atom catalysts consisting of an atom of Ti, Fe, or Zn deposited on the surface of the Mo2CO2 MXene is investigated. In the case of Fe@Mo2CO2, a mechanism resembling that of Termolecular Langmuir–Hinshelwood (TLH) is thermodynamically and kinetically favored, displaying very exothermic CO2 formation, low activation energies, and easy CO2 desorption. On Ti@Mo2CO2, the dissociation of CO2 is almost barrierless and much more likely to occur than CO2 desorption, barring the usage of this surface as a catalyst for CO oxidation. Finally, on Zn@Mo2CO2, a hybrid Langmuir–Hinshelwood/Eley–Rideal (LH/ER) mechanism is thermodynamically and kinetically feasible. Here, after the first CO2 forms, with an energy barrier of only 0.62 eV, the second CO2 is formed spontaneously, and the Zn–CO2 interactions are weak enough to allow desorption. The calculated thermodynamic quantities and reaction rates at T = 300 K indicate that Fe@Mo2CO2 should be quite active toward CO oxidation, followed by Zn@Mo2CO2, while the Ti‐based model is inactive. The results add to the evidence that establishes single transition metal atoms adsorbed on MXene surfaces as cheap and easily obtainable catalysts that offer the best of both bare and functionalized MXenes.

MOF derived cobalt-phospho-boride for rapid hydrogen generation via NaBH4 hydrolysis

Developing effective transition metal catalysts that can replace precious metal-based catalysts for hydrogen generation from the hydrolysis of chemical hydride has attracted extensive interest. This study focuses on synthesizing cobalt phospho-boride (CoPB) within a metal-organic framework (MOF) framework using hydrothermal and chemical reduction methodologies. Incorporating boron and phosphorous into Co-MOF enhances the hydrogen generation rate, reaching 1.8 L/min/g and 3.6 L/min/g for CoB-MOF and CoPB-MOF, respectively, during NaBH4 hydrolysis. Along with the nanostructured morphology of MOF, the electron modulation around Co-sites due to the presence of P and B creates a synergic effect to produce this high H2 generation rate and very low activation energy of 20.7 kJ/mol. The kinetic studies on NaBH4 hydrolysis reaction revealed zero-order kinetics with respect to NaBH4 concentration for CoPB-MOF, where porous morphology renders facile movement of BH4− ions to the active sites. The heat treatment at 773 K in the N2 atmosphere did not show any significant fall in the activity of CoPB-MOF, thus showcasing its robust nature. Moreover, the present catalyst also displayed recycling behavior with no signs of deactivation.

Topological proton regulation of interlayered local structure in sodium titanite for wide‐temperature sodium storage

AbstractDeveloping high‐capacity and high‐rate anodes is significant to engineering sodium‐ion batteries with high energy density and high power density. Layered Na2Ti3O7 (NTO), with an open crystal structure, large theoretical capacity, and low working potential, is recognized as one of the prospective anodes for sodium storage. Nevertheless, it suffers from sluggish sodiation kinetics and low (micro)structure stability triggered by a high Na+ diffusion barrier and weak adhesion of [Ti3O7] slabs. Herein, the interlayered local structure of NTO is regulated to solve the above issues, in which parts of interlayered Na+ sites are substituted by H+ (Na2−xHxTi3O7 [NHTO]). Theoretical calculations prove that the NHTO offers lower activation energy for Na+ transports and low interlayer spacings with alleviated Na–Na repulsion and relatively flexible [Ti3O7] slabs to reduce fractural stress. In situ and ex situ characterizations of (micro)structure evolution reveal that NHTO goes through transformation between H‐rich and Na‐rich phases, resulting in high structure stability and microstructure integrity. The optimal NHTO anode delivers a high capacity of 190.6 mA h g−1 at 0.5 C after 300 cycles and a superior high‐rate stability of 90.6 mA h g−1 at 50 C over 10,000 cycles at room temperature. Besides, it offers a capacity of 50.3 mA h g−1 after 1800 cycles at a low temperature of −20°C and 195.7 mA h g−1 after 500 cycles at a high temperature of 40°C at 0.5 C. The developed topologically interlayered local structure regulation strategy would raise the prospect of designing high‐performance layered anodes.

Insight into interface chemistry of metal oxides anchored on biowaste-derived support for highly selective glycolysis of waste polyethylene terephthalate

The unprecedented rise of polyethylene terephthalate (PET) waste demands sustainable solutions like catalytic glycolysis, a promising recycling technology that mitigates environmental harm. Herein, we synthesized a series of novel Mo-Zn@SiO2 catalysts for PET glycolysis, derived from readily available rice husk ash via the wetness impregnation method. The optimum Mo-Zn@SiO2 exhibits exceptional activity, achieving complete PET conversion and a 90.4 % yield of bis(2-hydroxyethyl) terephthalate (BHET) – one of the highest performances reported for heterogeneous catalysts. Density functional theory (DFT) calculations suggest that the formation of the ZnMoO4 phase optimizes reactant and product adsorption energies, enhancing Lewis acidity and facilitating depolymerization. Kinetic studies reveal a low apparent activation energy (139.27 kJ/mol) for BHET production at 175–190 °C. Additionally, the catalyst demonstrates excellent recyclability, maintaining activity after five cycles. This work presents a viable and efficient strategy for PET waste valorization using a low-cost, readily available, and easily synthesized catalyst.

Catalytic activity of Co/γ-Al2O3 catalysts for decomposition of ammonia to produce hydrogen

This paper aims to study the performance of Co/meso-Al2O3 catalysts for ammonia decomposition to produce hydrogen. High-performance Co/meso-Al2O3 catalysts were prepared using a sequential metal loading approach. The synthesized catalysts were analyzed by several techniques including X-ray diffraction (XRD), N2 physisorption analysis, temperature-programmed reduction (H2-TPR), temperature-programmed desorption (NH3-TPD) and transmission electron microscope (TEM). The effect of metal loading, decomposition temperature and weight hourly space velocity (WHSV) on the catalyst activity were studied. Temperature-programmed desorption (NH3-TPD) analysis showed the coexistence of weak acidic sites and strong acidic sites in the synthesized catalysts, indicative of weak metal–support interaction. The reaction activation energy of the catalysts followed the order of 26Co-CAT(A) < 9Co-CAT(A) < 16Co-CAT(A) < 5Co-CAT(A) < CAT(A). Particularly, 26 Co-CAT(A) exhibited significantly lower activation energy compared to the other catalyst, which was in line with its catalytic activity. This observation indicated that the cobalt loading in 26 Co-CAT(A) resulted in relatively weaker metal-support interactions, leading to lower desorption energy and thus allowing higher NH3 conversion at lower temperatures. These findings offer valuable insights for the development and optimization of advanced Co-based catalysts, facilitating the sustainable and efficient application of ammonia decomposition.

Preparation of LiLaZrMO (M= Ga/Al) solid electrolytes for thermal batteries

Thermal batteries (TBs) are ideal power sources for high temperature environment due to their high specific energy, long storage time, and quick activation. However, the common molten salt electrolytes (MSE) suffer from overflow under overload or high spin state, which could lead to short circuit of the batteries. To address this issue, LiLaZrMO (LLZMO, M = Ga/Al) doped with different elements are prepared. The doping elements result in the phase change of LiLaZrO (LLZO) from tetragonal to cubic, alters the distribution of Li atoms and increases the ion transport bottleneck sizes. In particular, LiLaZrGaO (LLZGO) has the lowest activation energy (0.3 eV) and the highest total conductivity (2.57 × 10−2 S cm−1 at 500 °C) owing to the larger bottleneck and unique Li+ transport channel. TB with LLZGO provides the highest discharge specific capacity of 368.5 mAh g−1 and lowest internal resistance (0.23 Ω cm−2). Compared with the ones using LiF–LiCl–LiBr MSE, TB with LLZGO solid electrolyte (SE) also shows superior performance in pulse discharge capabilities due to the stable internal resistance as well as the fluctuation free characteristics. Therefore, LLZGO SE holds great potential as viable alternative to MSEs in TBs.

Microenvironment regulation breaks the Faradaic efficiency-current density trade-off for electrocatalytic deuteration using D2O

The high Faradaic efficiency (FE) of the electrocatalytic deuteration of organics with D2O at a large current density is significant for deuterated electrosynthesis. However, the FE and current density are the two ends of a seesaw because of the severe D2 evolution side reaction at nearly industrial current densities. Herein, we report a combined scenario of a nanotip-enhanced electric field and surfactant-modified interface microenvironment to enable the electrocatalytic deuteration of arylacetonitrile in D2O with an 80% FE at −100 mA cm−2. The increased concentration with low activation energy of arylacetonitrile due to the large electric field along the tips and the accelerated arylacetonitrile transfer and suppressed D2 evolution by the surfactant-created deuterophobic microenvironment contribute to breaking the trade-off between a high FE and large current density. Furthermore, the application of our strategy in other deuteration reactions with improved Faradaic efficiencies at −100 mA cm−2 rationalizes the design concept.

Temperature dependent conductivity, dielectric relaxation, electrical modulus and impedance spectroscopy of Ni substituted Na[formula omitted]Zr[formula omitted]Ni[formula omitted]Si[formula omitted]PO[formula omitted]

We investigate the structural, dielectric relaxation, electric modulus and impedance behavior of Ni-doped NASICON ceramic Na3+2xZr2−xNixSi2PO12 (x=0.05–0.2) prepared using the solid-state reaction method. The increase in dielectric constant with temperature and decrease with frequency is explained on the basis of space charge polarization using the two-layer model of Maxwell–Wagner relaxation. The dielectric loss peak at lower temperatures follows the Arrhenius-type behavior with frequency having activation energy of 0.27 ± 0.01 eV of dipolar relaxation, suggests similar type of defects are responsible for all the doped samples. The real (ϵ′) and imaginary (ϵ′′) permittivity variation with frequency shows the broad relaxation behavior indicates the non-Debye type of relaxation in the measured temperature range. The permittivity values decrease with the amount of doping due to the increased number of charge carriers upon Ni doping at the Zr site. The impedance variation with frequency at various temperatures shows two types of relaxation for all the samples correspond to grain and grain boundary contribution in total impedance. The grain contributions are observed at higher frequencies, while grain-boundary contributions occur at the lower side of frequencies. The imaginary part of the electric modulus also shows two types of relaxation peaks for all the samples indicating similar activation energy at low temperatures and variable activation energy at higher temperatures. The fitting of the imaginary modulus using KWW function shows the non-Debye type of relaxation. We find that all modulus curves merge with each other at low temperatures showing a similar type of relaxation, while curves at high temperatures show the dispersed behavior above the peak frequency. The a.c. conductivity data are fitted using the double power law confirming the grain and grain boundary contributions in total conductivity. The double power law exponent variation with temperature shows the small polaron hopping conduction over the measured temperature range for all the doped samples.

Microwave driven steam reforming of biomass model tar based on metal organic frameworks (ZIF-67) derived Co/C catalyst

Tar catalytic removal is a key issue in biomass gasification, which is suffering from catalyst coking and sintering. Microwave technology is attractive due to the high activity on polar molecules and ability to lower activation energy. In this study, the Co/C derived from metal-organic frameworks (ZIF-67) was developed as a bifunctional microwave catalyst that can strengthen the interaction between microwave and tar catalytic reforming, and enhance the anti-coking and sintering ability. The effects of the temperature, heating method, tar concentration, and catalyst support on model tar conversion rate were investigated. The operating conditions at 700 °C and tar concentration lower than 20 g/m3 can reach a promising conversion rate over 90.15 % under microwave irradiation. On the one hand, microwave heating groups performed better in conversion rate and coking compared to conventional heating, due to the active species generated from the microwave plasma. On the other hand, Co/C showed better performance in catalytic activity and sintering stability, due to the highly dispersion of cobalt nanoparticles and the confinement effect of carbon nanotubes on the catalyst surface. These findings proposed a novel approach for efficient biomass tar removal under microwave irradiation, and offered a potential tool to further reveal the mechanism in microwave driven tar steam reforming system.

Hydrochar from winemaking industry wastes as solid biofuel: A thermal and kinetic analysis of pyrolysis and combustion

Pyrolysis and combustion behavior of the hydrochar (HY) from co-hydrothermal carbonization (co-HTC) of vine pruning (VP) and exhausted grape marc (EGM) by using vinasse as wet catalytic vector was investigated through thermogravimetric analysis (TGA). For both raw- and co-HTC biomass, different iso-conversional methods were used for kinetic analysis, and the thermodynamic parameters were determined. Overall, even if HY exhibited a lower activation energy compared to EGM and VP during both pyrolysis and combustion, HTC has positive effects on the hydrochar’s structure, which achieved a more thermodynamically stable, structurally ordered, and energetically favorable state. The obtained kinetic and thermodynamic parameters would contribute to the development of biomass thermochemical conversion technologies and the application of hydrochar-based energy systems.

TiO2 thermal stress deformation induced to promote photocatalytic CO2 reduction

Semiconductor photocatalytic reduction of CO2 is an effective means to achieve the goal of double carbon. TiO2 has received extensive attention as an excellent photocatalyst, but the adsorption of CO2 on the surface of TiO2 is not stable, which greatly inhibits the yield and selectivity of reduction products. In this work, wollastonite was used to reduce the melting temperature of TiO2 and in turn induce thermal stress deformation on the surface of the TiO2 lattice. Characterization and DFT results certified that the lattice stress deformation caused by the contraction of oxygen vacancy enables TiO2 to obtain better carrier transport efficiency and lower activation energy barrier, and also stabilizes the adsorption state of CO2 on the surface of TiO2 crystal, which effectively improved the reduction yield and selectivity of CO2. The CO yield is increased by 5.1 times, reaching up to 2.09 μmolg-1h−1, and the CO selectivity is as high as 91 %. These findings provide valuable insights for the development of efficient and selective photocatalysts for carbon dioxide transformation and pave the way for novel avenues in this research field.

Probing the cw-Laser-Induced Fluorescence Enhancement in CsPbBr3 Nanocrystal Thin Films: An Interplay between Photo and Thermal Activation.

Perovskite nanocrystals hold significant promise for a wide range of applications, including solar cells, LEDs, photocatalysts, humidity and temperature sensors, memory devices, and low-cost photodetectors. Such technological potential stems from their exceptional quantum efficiency and charge carrier conduction capability. Nevertheless, the underlying mechanisms of photoexcitation, such as phase segregation, annealing, and ionic diffusion, remain insufficiently understood. In this context, we harnessed hyperspectral fluorescence microspectroscopy to advance our comprehension of fluorescence enhancement triggered by UV continuous-wave (cw) laser irradiation of CsPbBr3 colloidal nanocrystal thin films. Initially, we explored the kinetics of fluorescence enhancement and observed that its efficiency (φph) correlates with the laser power (P), following the relationship φph = 7.7⟨P⟩0.47±0.02. Subsequently, we estimated the local temperature induced by the laser, utilizing the finite-difference method framework, and calculated the activation energy (Ea) required for fluorescence enhancement to occur. Our findings revealed a very low activation energy, Ea ∼ 9 kJ/mol. Moreover, we mapped the fluorescence photoenhancement by spatial scanning and real-time static mode to determine its microscale length. Below a laser power of 60 μW, the photothermal diffusion length exhibited nearly constant values of approximately (22 ± 5) μm, while a significant increase was observed at higher laser power levels. These results were ascribed to the formation of nanocrystal superclusters within the film, which involves the interparticle spacing reduction, creating the so-called quantum dot solid configuration along with laser-induced annealing for higher laser powers.

Tuning the Metal-Support Interaction by Modulating CeO2 Oxygen Vacancies to Enhance the Toluene Oxidation Activity of Pt/CeO2 Catalysts.

In this research, a range of Pt/CeO2 catalysts featuring varying Pt-O-Ce bond contents were developed by modulating the oxygen vacancies of the CeO2 support for toluene abatement. The Pt/CeO2-HA catalyst generated a maximum quantity of Pt-O-Ce bonds (possessed the strongest metal-support interaction), as evidenced by the visible Raman results, which demonstrated outstanding toluene catalytic performance. Additionally, the UV Raman results revealed that the strong metal-support interaction stimulated a substantial increase in oxygen vacancies, which could facilitate the activation of gaseous oxygen to generate abundant reactive oxygen species accumulated on the Pt/CeO2-HA catalyst surface, a conclusion supported by the H2-TPR, XPS, and toluene-TPSR results. Furthermore, the results from quasi-in situ XPS, in situ DRIFTS, and DFT indicated that the Pt/CeO2-HA catalyst with a strong metal-support interaction led to improved mobility of reactive oxygen species and lower oxygen activation energies, which could transfer a large number of activated reactive oxygen species to the reaction interface to participate in the toluene oxidation, resulting in the relatively superior catalytic performance. The approach of tuning the metal-support interaction of catalysts offers a promising avenue to develop highly active catalysts for toluene degradation.