While defects are unavoidable in crystals and often detrimental to material performance, they can be a key ingredient for inducing functionalities when tailored. Here, we demonstrate that an A-site-deficient perovskite Y$_{1/3}$TaO$_3$ exhibits room-temperature ferroelectricity in a $Pb2_1m$ phase, enabled by ordered vacancies coupled with TaO$_6$ octahedral rotations. Defect-ordered perovskites are frequently trapped in centrosymmetric incommensurate states due to competing structural instabilities; we circumvent this by favoring rotational over polar instability through compositional selection. Unlike canonical improper ferroelectrics that are \textit{ferrielectric}, the vanishing dipoles on vacancy layers in Y$_{1/3}$TaO$_3$ allow for a net ferroelectric alignment of local dipoles, resulting in enhanced polarization. Upon heating, Y$_{1/3}$TaO$_3$ transforms to a paraelectric incommensurate phase at $\simeq$750 K, whose atomic arrangement mirrors the domain topology observed in hybrid improper ferroelectrics. Superspace analysis of the modulated phase reveals a route to improve room-temperature polarization, achieved through epitaxial strain, as confirmed by our lattice-dynamics calculations. This defect-ordering strategy should be generalizable to other improper ferroelectrics, including magnetoelectric multiferroics, providing a pathway to amplify otherwise limited macroscopic polarization.

Microwave heating has emerged as an effective method for selectively heating target materials and promoting rapid chemical reactions. Understanding the relationship between structural features and physical properties of catalysts is crucial for optimizing microwave catalysis. This study investigated molybdenum disulfide (MoS2), a typical microwave-absorbing material capable of converting electromagnetic energy into thermal energy, by examining MoS2 samples with different morphologies. Comprehensive comparison revealed that defect-rich MoS2 nanoflowers exhibited superior microwave heating performance among the tested samples. This enhanced performance was attributed to the synergistic effects of defect engineering, which enhances microwave absorption through localized dipoles, and the unique nanoflower morphology, which promotes multiple reflection and absorption of microwaves between nanoflower layers. These findings highlight the critical role of morphology and defects in modulating the microwave response of MoS2 and provide valuable insights for designing efficient microwave-responsive catalysts.

With the increasingly stringent requirements for the treatment of industrial nitrogen oxides (NOx), ammonia selective catalytic reduction (NH3-SCR) has emerged as the most widely adopted denitrification technology in industrial settings. A series of CeNbOx nano-catalyst with varying Nb compositions were synthesized via the solvothermal method for NH3-SCR. All the CeNbOx samples presented considerable NOx conversion, exceeding 80 % within a broad temperature window of 200-350 degrees C. In addition, the optimal sample shown high stability and strong resistance to SO2/H2O at 225 degrees C. The influence of Nb element on structural properties of the CeNbOx samples was investigated and elucidated using multiple characterization techniques. The NH3-SCR process was further studied by in situ infrared Fourier transform spectroscopy (in situ FTIR), temperature-programmed reduction with H2 (H2-TPR) and X-ray photoelectron spectroscopy (XPS), which revealed that the improved NOx conversion can be attributed to the role of Nb in suppressing the crystal growth of CeO2, promoting the adsorption of oxygen species, increasing the distribution of Ce and improving the redox ability.

Abstract Understanding how distinct nitrogen functionalities regulate metal sites remains a central challenge in the rational design of carbon-supported catalysts for hydrogenolysis reactions. Here, we disentangled the structural and electronic roles of pyridinic-N and pyrrolic-N in nitrogen-doped carbon-supported Ni catalysts by systematically tuning nitrogen speciation and investigating the hydrogenolysis of C–O bonds in diphenyl ether (DPE), a representative lignin-derived aryl ether. An optimized nitrogen-doped carbon-supported Ni catalyst (denoted as Ni/NC35) achieved complete DPE conversion under mild conditions (180 °C, 0.5 MPa H2, 1 h) with high selectivity toward cyclohexane and cyclohexanol. Comprehensive characterization and DFT calculations revealed that the appropriate incorporation of pyridinic-N and pyrrolic-N strengthened the metal–support interaction and effectively suppressed Ni nanoparticle aggregation, while synergistically regulating the electronic structure of Ni through both direct Ni–N coordination and non-coordinated modulation of neighboring Ni atoms, thereby promoting the formation of highly active electron-deficient Ni species. These electron-deficient Ni sites led to a modest increase in the energy barrier of C–O bond cleavage but significantly lowered the barriers for H2 dissociation and benzene formation, thereby enhancing the catalytic activity for DPE hydrogenolysis. The findings were consistent with the significantly higher activity of DPE hydrogenolysis and benzene hydrogenation over Ni/NC35 compared to the undoped catalyst (Ni/NC0). This work elucidates the key role of pyridinic-N and pyrrolic-N in structural optimization and electronic regulation of Ni-based catalysts and provides clear design principles for engineering non-noble metal catalysts for selective hydrogenolysis of lignin-derived aryl ethers.

A series of novel Ce-modified MnCoAl layered double oxides (Ce/MCA LDOs) were prepared using solvothermal and impregnation methods for NH3-SCR denitration. Various characterizations, such as X-ray diffraction (XRD), scanning electron microscope (SEM), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), and H-2 temperature-programmed reduction (H-2-TPR) were used to investigate their structural properties and the mechanism of ammonia selective catalytic reduction (NH3-SCR). The incorporation of Ce was found to effectively integrate into the LDO framework and enhance the catalytic activity over a wide temperature window. Moreover, the thermal stability and resistance of H2O and SO2 were evaluated. In situ DRIFTS studies revealed that the reaction follows both the "Langmuir-Hinshelwood" (L-H) and "Eley-Rideal" (E-R) mechanisms. This work provides systematic insights into the design of LDO-based catalysts, demonstrating their potential for practical application in denitration.

In situ X-ray absorption fine structure (XAFS) spectroscopy was employed to elucidate the structural evolution of Pd/CeO2 catalysts during SO2-induced sulfurization. Linear combination fitting of Ce L3-edge XANES spectra quantified the Ce4+ → Ce3+ transformation, revealing fundamentally different sulfurization mechanisms for bare versus Pd-promoted CeO2. At 500 °C, bare CeO2 exhibited surface-limited sulfurization with Ce3+/(Ce3+ + Ce4+) reaching 0.18, while Pd/CeO2 achieved 0.68, demonstrating bulk oxygen participation. Temperature-dependent measurements (200-500 °C) confirmed thermal activation of the sulfurization process, with higher temperatures enabling deeper lattice penetration. Complementary Pd L3-edge XANES revealed that Pd maintained its oxidized state throughout SO2 exposure, excluding PdS formation. S K-edge analysis confirmed exclusive SO42- formation via direct oxidation without intermediate species. These findings establish that Pd catalyzes oxygen mobility within the CeO2 lattice, transforming sulfurization from a surface-confined to a bulk-accessible process while preserving the fluorite structure. The resulting cerium sulfate oxide (Ce2O2SO4) exhibits enhanced stability against re-oxidation in Pd/CeO2, contrasting with the partial reversibility observed for bare CeO2.

It is well known that interactions between the support and metal particles, called metal-support interactions, considerably affect the activity of supported metal catalysts. Two representative consequences of these interactions are the formation of lattice defects at the metal-support perimeter and the change in the charge state of metal particles. However, the identification of control parameters for tuning metal-support interactions is not simple because many factors can affect metal-support interactions. Herein, a model Pt/TiO2 catalyst based on an epitaxial TiO2 thin film was developed and the distribution of oxygen defects and the charge state of Pt on this catalyst were investigated using scanning transmission electron microscopy, electron energy loss spectroscopy, X-ray photoelectron spectroscopy, and first-principles calculations. Results showed that oxygen vacancies are easily formed just below Pt nanoparticles. Moreover, it was revealed that Pt nanoparticles supported on TiO2 (101) are negatively charged. Oxygen vacancies promote charge transfer to Pt nanoparticles, and Pt becomes more negatively charged than that on stoichiometric TiO2. This study demonstrates that the charge state of Pt is affected by the presence of oxygen vacancies on the support, providing an important guideline for controlling metal-support interactions to develop catalysts with desired properties.

Reducing the reaction temperature required for methanol-to-hydrocarbons (MTH) by microwave (MW)-assisted heating is an efficient strategy to improve the energy efficiency of the reaction. Designing zeolites with excellent MW self-absorption capacity is essential to address such an issue. Herein, we demonstrated a quite simple strategy to prepare HK mixed-type ZSM-5 zeolite (HK-CZ5) by introducing protons into K+ exchanged commercial ZSM-5 zeolite, making it possess both outstanding MW absorption property and accessible Br & Oslash;nsted acid sites. MW-assisted MTH results revealed that MW irradiation effectively reduced the catalytic reaction temperature compared to conventional heating conditions. The mechanism of MW-induced high MTH activity was identified theoretically as the electric field of MW being beneficial to the formation of carbocation intermediates, enabling the catalyst to exhibit excellent activity at relatively low temperatures. Additionally, MW reduced the decomposition temperature of coke species, which facilitated the preservation of the zeolite framework and avoided the loss of active sites, thereby maintaining the high activity of catalyst after multiple regeneration tests. The MW-assisted MTH over HK-CZ5 zeolite at low temperatures provides a practical paradigm and valuable guidance for advancing zeolite-driven acid-catalyzed reactions toward high energy efficiency.

Dry reforming of methane (DRM) requires high heat input, and identifying microwave-responsive catalysts that do not rely on external susceptors remains challenging. Here, we show that LaNiO3-derived catalysts enable susceptor-free microwave-assisted DRM and exhibit faster activation and higher CH4 and CO2 conversions than conventional external heating at an apparent bed temperature of 600 degrees C. Time-resolved XRD, XAFS, and H-2-TPR analyses indicate that microwave irradiation accelerates the reduction of LaNiO3 via a transient La2NiO4 intermediate, followed by formation of Ni/La2O3. In situ dielectric measurements show a sharp increase in dielectric loss during the initial reaction stage, consistent with enhanced microwave coupling during catalyst activation. Under microwave irradiation, whisker-like carbon species are also formed and are suggested to contribute to sustained microwave absorption at later reaction stages, based on the temporal correlation between carbon accumulation and the recovery of dielectric loss. Microwave power-control experiments further suggest that maintaining a moderately reduced state containing La2NiO4 improves heating behavior while sustaining catalytic performance. These results support a structure-dielectric-activity relationship in microwave-assisted DRM and provide guidance for designing susceptor-free catalysts for electrified reforming.

Utilising unexploited methane through its reaction with CO2via the dry reforming of methane (DRM) has attracted attention. However, there are challenges related to catalyst deactivation and energy consumption due to the highly endothermic nature of the DRM; thus, microwave activation has been proposed to increase energy efficiency by directly heating the catalyst while minimising the heating of the reactor. In this study, we clarify the advantages of microwave heating in terms of more reactive coke formation during the reaction and enhanced reactivity under microwave conditions compared with conventional resistive heating. For the latter, steady-state isotopic transient kinetic analysis (SSITKA) was conducted to gain mechanistic insights, which suggested that microwave heating accelerated CO generation steps. This study shows that microwave activation can be advantageous in terms of reaction kinetics for the DRM.Keywords: Dry reforming of methane; Microwave heating; La-Ni oxide catalyst; SSITKA.

Observing the surface structure and charge dynamics of catalysts during catalytic reactions is crucial for elucidating reaction mechanisms. However, nanoscale characterization of the catalyst structure and charge states in the presence of reactive gases presents experimental challenges. Here, the structures and charge states of a gold nanoparticle (NP) are directly visualized on ceria during redox cycles using electron holography, a method related to transmission electron microscopy. The introduction of oxidizing O2 gas to the microscope led to structural changes on the NP surface and decrease the intrinsic negative charge of the NP. Conversely, under reducing H2 gas, the surface structure and charge state of the NP remained almost unchanged compared to those in vacuum. Systematic analysis revealed that the injection and removal of O2 gas caused reversible changes in the charge state of the NP within the range of a few electrons. The effect of O2 gas on charging of the NP is confirmed by first-principles calculations. These findings demonstrate the potential of electron holography in gas environments for advancing the understanding the reaction mechanisms on heterogeneous catalysts.

Microwaves can selectively and rapidly heat materials upon absorption, offering advantages over conventional heating methods. However, practical applications in oxide materials remain limited due to insufficient understanding of fundamental heating mechanisms and inadequate control of heating characteristics. In this study, we elucidated the heating mechanism of La-Ce-Ni oxides to develop oxide materials with excellent microwave heating properties. We comprehensively investigated the crystal structure, microstructure, electrical conductivity, and dielectric properties of La-Ce-Ni oxides with various compositions. In La-Ce-Ni oxides, the strong CeO2-LaNiO3 interaction induced structural distortions and modified dielectric properties, which predominantly contributed the heating properties under a microwave electric field, rather than electrical conductivity. The dielectric properties, rather than the electrical conductivity, were the primary factors determining the microwave heating performance of this system.

Catalytic dehydration of bioethanol using tungsten polyoxometalate (POM) clusters is a viable method for the sustainable production of ethylene, a valuable industrial chemical. The reaction process of ethanol dehydration on mesoporous-silica-SBA-15 (SBA-15)-supported heteropolyacids (HPAs) involves complex parallel-consecutive pathways, which differ from those involved in pure HPAs systems. Notably, the reaction progresses from the formation of diethyl ether at lower temperatures to the complete generation of ethylene at higher temperatures. To conserve energy, achieving high selectivity for ethylene at lower temperatures is crucial. In this study, we impregnated 12-tungstophosphoric acid into an SBA-15 catalyst, followed by microwave-assisted heating to obtain a catalyst that facilitates the dehydration of ethanol to ethylene. Experimental findings revealed that this catalytic technique achieves a reaction at lower temperatures than conventional thermal catalysis, exhibiting conversion rates and selectivity values exceeding 99%. Additionally, the influence of the substrate on the entire reaction process was elucidated by clarifying the reaction pathways using theoretical calculations.

Local surface plasmon resonance (LSPR) is introduced into traditional photocatalytic systems, which has become a research focus. However, there is still a huge gap in the research of LSPR effect, especially the requirement of ideal plasma carrier has not been fully elaborated and planned. Here, a single crystal Cu2O nanoreactor (Cu2O-V) was synthesized with surface modified silver nanoparticles as an optical antenna for CO2 conversion. The precisely designed Cu2O single crystal structure has a highly ordered atomic arrangement and fewer grain boundary defects, which provides a high-speed electron transport path and greatly improves the stability of Cu+. Meanwhile, the vesicle structure and thin shell array formation of Cu2O-V form a "double light trap", showing prominent LSPR amplification effect. This allows the catalyst to be uniformly immersed in the local electromagnetic field, further increasing the rate of carrier generation and transfer. Finally, under the synergistic action of "double light trap" and LSPR, Ag5 %-Cu2O-V shows first-class performance and excellent stability. A small amount of C2H4 was also detected. This study reveals the effect of a single crystal Cu2O catalyst characterized by a high-speed electron transport channel and vesicle array structure combined with LSPR on the photoreactivity.

Understanding the ultra-fast dynamics of ferroelectric materials is essential for advancing the development of next-generation high speed electronic and photonic devices. Here, the ultrafast piezoelectric response of cobalt-substituted BiFeO3 (BiFe1-xCoxO3) with x = 0.15, consisting of morphotropic phase boundary of monoclinic M-C and M-A -type phases is investigated. The real-time piezoelectric response in (001)-oriented BiFe0.85Co0.15O3 (BFCO) epitaxial thin film was monitored using the time-resolved X-ray microdiffraction technique under an applied electric field with pulse widths 70 ns and 100 ns. The BFCO thin film yielded a high piezoelectric strain of approximately 0.53 % along [001] direction, with a giant c/a ratio (similar to 1.26) at an electric field of 1.3 MV/cm and a pulse width of 100 ns, with a piezoelectric coefficient (d(33)) of 40 pm/V. This finding is an important step towards the development of a high performance lead-free piezoelectric material for ultrafast operations in advanced technological applications.

Perovskites with Bi or Pb on the A-site host a number of interesting and yet to be understood phenomena such as negative thermal expansion in BiNiO$_3$. We employ hard x-ray photoemission spectroscopy of Ni 2$p$ core-level as well as valence band to probe the electronic structure of BiNiO$_3$ and PbNiO$_3$. The experimental results supported by theoretical calculations using dynamical mean-field theory reveal essentially identical electronic structure of the Ni-O subsystem typical of Ni$^{2+}$ charge-transfer insulators. The two materials are distinguished by filling of the Bi(Pb)-O antibonding states in the vicinity of the Fermi level, which is responsible for the Bi disproportionation in BiNiO$_3$ at ambient pressure and absence of similar behavior in PbNiO$_3$. The present experiments provide evidence for this conclusion by revealing the presence/absence of Bi/Pb $6s$ states at the top of the valence band in the two materials.

The interaction between a metal and a support, which is known as the metal-support interaction, often plays a determining role in the catalytic properties of supported metal catalysts. Herein, we have developed model Pt/CeO2 catalysts, which enabled us to investigate the interface atomic and electronic structures between Pt and the {001}, {011}, and {111} planes of CeO2 using scanning transmission electron microscopy and electron energy-loss spectroscopy. We found that the number of Ce3+ ions around the Pt nanoparticles followed the order {001} > {011} > {111}, which was the opposite order of the generally accepted stability of low index surfaces of CeO2. Systematic first-principles calculations revealed that the presence of Pt nanoparticles facilitated the formation of oxygen vacancies and that the appearance of the Pt delta+ state was preferred when Pt nanoparticles were in contact with CeO2 {001} planes due to direct charge transfer from Pt to CeO2. These results provide important insights into the nature of the metal-support interaction for a comprehensive understanding of the properties of supported metal catalysts.

Transition metal oxides show high activity while still facing the challenges of low mineralization and poor durability in the ozone catalytic oxidation (OCO) of volatile organic compounds (VOCs). Improving the oxygen mobility and low-temperature reducibility of transition metal oxides was found to be an effective way to address the above challenges. Here, highly dispersed Ag was added to Mn3O4 via the co-precipitation oxalate route, and the obtained Ag/Mn3O4 exhibited higher mineralization and stability in benzene catalytic ozonation at room temperature. Compared to Mn3O4, the concentration of CO2 formed from benzene oxidation over Ag/Mn3O4 was significantly increased, from 585.4 ppm to 810.9 ppm, while CO generation was greatly suppressed to only one tenth of its original value (194 ppm vs. 19 ppm). In addition, Ag/Mn3O4 exhibited higher catalytic stability than Mn3O4. The introduction of Ag obviously improved the oxygen mobility and low-temperature reducibility of Mn3O4. Moreover, the highly dispersed Ag also promoted the activity of surface oxygen species and the chemisorption of benzene on Mn3O4. The above physicochemical properties contributed to the excellent catalytic performance and durability of Ag/Mn3O4. This research could shed light on the improvement in VOC mineralization via ozone catalytic oxidation.