Single-atom cu sites with engineered oxygen vacancies boost electrocatalytic urea production from CO2 and nitrate.

Sputtered ternary NiMoCu electrodes enabling 70% energy efficiency for overall alkaline hydrogen production under practical conditions.

High-entropy composition design offers an effective approach to overcome the sluggish oxygen evolution reaction (OER) kinetics of lanthanum-based perovskite oxides. By incorporating a wider variety of metal cations into the B-site sublattice, the configurational entropy increases accordingly. Following this high-entropy compositional strategy, low-entropy LaCoO3, medium-entropy La(FeCoNi)O3, and high-entropy La(MnFeCoNiCu)O3 were successfully synthesized via a facile sol-gel combustion method. The construction of the high-entropy perovskite oxide (HEPO) was found to substantially alter the morphology, crystal structure, and electronic environment, leading to reduced particle size, modulated B-site metal valence states, and enriched oxygen vacancies. These modifications collectively induce synergistic effects among multiple B-site metal active sites and promote the participation of lattice oxygen through the introduction of surface oxygen defects, thereby activating the oxygen-mediated (LOM) pathway of OER. Remarkably, the as-prepared HEPO exhibited superior OER performance in alkaline media, achieving a low overpotential of 303 mV at 10 mA cm-2, a small Tafel slope of 43 mV dec-1, and excellent stability over 100 h of continuous operation. This work provides valuable insights into the role of B-site configurational entropy in perovskite oxides and highlights the potential of high-entropy design strategies for developing advanced OER electrocatalysts.

Defect-induced magnetism (DIM) in otherwise nonmagnetic wide-band oxides had recently been explored in order to prepare oxide dilute magnetic semiconductor (O-DMSs) as the next-generation spintronic materials. In this context, effect of morphology-dependent surface-disorder and cationic-site defects in tailoring ferromagnetic behaviour and Raman vibrational modes were investigated systematically in series of indium (In)-substituted SnO 2 thin films fabricated by pulsed laser deposition (PLD) in oxygen-deficient Argon (Ar) atmosphere. Surface morphology of the SnO 2 :In films had been changed as nanospheres (NSs), nanoflowers (NFs), nanoflakes (NFLs) and nanowires (NWs) with varying Ar pressure of 1, 10, 100 and 1000 Pa respectively. With increase of deposition pressure, crystallite size and thickness of the film decreased whereas surface disorder had enhanced considerably. Spectroscopic evidence revealed that both Sn vacancy ( V Sn ), oxygen vacancy ( V O ) defects were stabilized with enhanced surface disorder with the films. ESR spectroscopy indicated the presence of two major paramagnetic defect centres comprising Lande g -factor ~ 2.003, assigned to singly ionized V O + defect whereas other ‘ g ’ value about 1.89 were due to V Sn defects or its complex with Vo defects. Being enriched with substantial paramagnetic defects, In-doped SnO 2 films exhibited enhanced high- T C ferromagnetism. NWs of In:SnO 2 exhibited superior ferromagnetic signal with magnetic moment ~ 11.1 emu/cm 3 and Curie temperature ~ 570 K. We attribute RKKY type magnetic interaction between magnetic of isolated V Sn or associated defects complex like ( V Sn - Vo ) mediated through the holes introduced due to In Sn defects as the origin of FM in In:SnO 2 thin films. Therefore, the study depicts the promotion of cation vacancy defects by monitoring growth atmospheric conditions can be an effective way to achieve the oxide-based dilute magnetic semiconductors (O-DMSs) for spintronics applications.

The reverse water-gas shift (RWGS) reaction is crucial for CO2 utilization toward carbon neutrality. However, its efficiency under mild conditions is limited by low-temperature activity and rapid deactivation from metal sintering in conventional catalysts, including the cost-effective but thermally unstable Cu-based systems. In this work, the introduction of Mn into CuZnAl catalysts was demonstrated to significantly enhance their performance in the low-temperature RWGS reaction by promoting more oxygen vacancy formation. MnCuZnAl-Red catalysts achieve superior 26% CO2 conversion and 98% CO selectivity at 400 °C, with a CO formation rate of 422 mmol gcat-1 h-1. Characterization confirms that Mn enhances CO2 adsorption and activation by generating abundant oxygen vacancies. In-situ Fourier infrared (FT-IR) spectroscopy reveals a surface associative pathway. This work highlights Mn's role in enhancing RWGS activity through tailored oxygen chemistry.

Abstract The influence of oxygen vacancies on dielectric properties of Ca and Mn co-doped bismuth ferrite, Bi1-xCaxFe1-xMnxO3 (BCFM) ceramics, synthesized by a modified sol-gel technique, has been investigated. X-ray diffraction reveals that the crystal structure transitions from R3c to the Pbnm space group with increasing co-doping concentration. The correlated barrier hopping conduction model applies up to a 10% co-doping concentration, while overlapping large polaron tunneling exists at concentrations above 20%. The dielectric study reveals strong frequency- and temperature-dependent dielectric parameters. The decrease in dielectric constant and loss with frequency is attributed to Maxwell-Wagner polarization, while the relaxation behavior follows a non-Debye mechanism; low dielectric loss at higher frequency indicates good dielectric stability and potential applications in electronic devices. The AC conductivity is lowest for the 5 mole % of Ca and Mn co-doped bismuth ferrite (BCFM-05) sample and exhibits an increasing trend with higher co-doping percentages. Also, the BCFM-05 sample exhibits the lowest dielectric loss. Thus, the optimized sample BCFM-05, with reduced AC conductivity and minimum dielectric loss, exhibits improved dielectric behavior in ceramics.

The development of low-cost and high-performance noble-metal-free catalysts for the oxygen evolution reaction (OER) is central to advancing alkaline water electrolysis. This work introduces a novel "composition-thermal history" design strategy, synergistically combining controlled A-site Sr2+ doping with optimized high-temperature sintering (950°C) in Pr-based perovskite. The resulting Pr0.75Sr0.25Ni0.7Co0.3O3 (PSNC-25) exhibits unprecedented nanostructuring and a maximized concentration of oxygen vacancies, unlocking efficient OER via lattice oxygen-mediated mechanism. Sr-induced lattice distortion drastically reduces oxygen vacancy formation energy from 2.06 to 1.14eV, promoting facile lattice oxygen participation. Thermal engineering stabilizes high-valence Co4+/Ni3+ states and enhances M─O covalency. Electrochemically, PSNC-25 achieves exceptional activity in 1M KOH: a low overpotential of 389mV at 10mA cm-2 and a Tafel slope of 83mV dec-1, significantly surpassing undoped PrNi0.7Co0.3O3 (η10 ＞ 570 mV). It also exhibits robust durability, by > 120 h chronopotentiometry at 10mA cm-2 with only ∼45mV potential drift. This work establishes a rational framework for activating LOM in cost-effective perovskites through dopant-induced electronic modulation and nano-structural control, advancing scalable green hydrogen production.

Abstract Polyolefin waste hydrogenolysis is constrained by high H 2 pressure, heat–mass transfer limitations, and broad product distributions. Here, a tandem hydropyrolysis–hydrogenolysis strategy decouples polymer depolymerization from hydrogenation, enabling selective low‐pressure upgrading of polyethylene (PE) and polypropylene (PP) to jet fuel‐range hydrocarbons (C 8 –C 16 ). Morphology‐tuned Co 3 O 4 catalysts form Co@CoO core–shell structures enriched with oxygen vacancies, facilitating H 2 dissociation and selective C–C cleavage. Under optimized conditions (540°C, 200°C, catalyst‐to‐feedstock mass ratio ( C / F ) of 4, 1.8 bar H 2 ), an 82.6% liquid yield with 83.7% jet‐fuel selectivity was achieved using standard PE powders, while real medical plastics gave 75%–78% yields. PE mainly produced linear alkanes, whereas PP yielded branched products, enabling fuel tuning. Density functional theory calculations show that oxygen vacancies lower the H 2 dissociation barrier and promote non‐terminal C–C bond activation in n ‐butane. This tandem route offers a scalable, non‐noble pathway to jet fuel from polyolefin waste.

ABSTRACT Frustrated Lewis pairs (FLPs) have attracted extensive attention in heterogeneous catalysis due to their distinctive ability to efficiently dissociate small molecules and accelerate reaction kinetics, yet challenges remain for low‐cost large‐scale applications. Herein, FLPs are first successfully fabricated in low‐cost silicate minerals, with the inherent surface hydroxyl groups (‐OH) of the latter serving as Lewis base (LB) sites. Simultaneously, H 2 ‐mediated deoxygenation induces oxygen vacancies (O V ), modulating the electronic states of adjacent Zn sites and transforms them into Lewis acid (LA) sites. Density functional theory (DFT) calculations are carried out to elucidate the optimal spatial distance between LA and LB sites and the charge transfer behavior, thereby furnishing atomic‐scale insights into the effective construction of FLPs. Coupled with in‐situ H 2 characterizations, the efficient dissociation of H 2 into H + and H − is directly visualized, thus affording abundant active hydrogen species for the subsequent reaction. Furthermore, FLPs can serve as shallow energy levels to facilitate the separation and migration of photogenerated carriers. The CO formation rate in photocatalytic reaction of the Zn 2 SiO 4 catalyst modified with FLPs is 2.3‐fold higher than that of the pristine FLPs‐free Zn 2 SiO 4 catalyst. This work provides a strategy for FLPs in low‐cost silicate minerals facilitating photocatalytic CO 2 hydrogenation.

Memristors are promising candidates for artificial synapses in neuromorphic computing systems, yet their performance is often limited by nonlinear conductance modulation in oxide-based memristors. This work systematically investigates the modulation mechanism governing conductive filament (CF) rupture behavior utilizing distributed barrier layers based on finite element simulations. Our initial electro-thermal simulations of a HfO2-based memristor with a single-layer Al2O3barrier (SLB) thickness (h= 0, 3, 6, 12 nm) showed only limited improvement in synaptic linearity. In contrast, the introduction of a (HfO2/Al2O3)nmultilayer barrier (MLB) structure fundamentally alters the switching dynamics. Simulations reveal that appropriately increasing the number of layers (n) promotes a transition from continuous to spatially discrete oxygen vacancy migration pathways. This engineered disorder expands the CF rupture region from a localized position to multiple interfaces, thereby reducing the electric field and temperature peaks and driving the set and reset process from abrupt to gradual switching. The optimized MLB device (n= 4) exhibits significantly enhanced synaptic linearity and analog switching characteristics, closely emulating biological synapse behavior. Furthermore, system-level validation using this device model achieved an accuracy of 94.34% in handwritten digit recognition. This work elucidates the physical mechanism by which MLBs enhance conductance linearity, providing a novel design strategy for high-performance memristive synapses.

The acceleration of industrialization has driven the increased emission of volatile organic compounds (VOCs), posing significant threats to both the ecological environment and public health. The deficiency of reactive oxygen species fundamentally restricts the low-temperature catalytic toluene combustion in transition-metal oxide catalysts. Herein, we report a strategy for intelligently designing active Cu+-Ov-Ti ensembles by coupling isolated Cu with adjacent oxygen vacancy, which can synergistically activate chemisorbed O2 into reactive superoxide species (O2-). The defective Cu/TiO2-x catalyst exhibited remarkable catalytic performance for toluene oxidation, achieving a T90 of 225 °C, significantly 100 °C lower than that of the pristine Cu/TiO2 catalyst. The low coordination geometry and electron transfer within Cu+-Ov-Ti ensembles synergistically activated O2 to form the Cu-(O-O)ad-Ti bridged superoxide O2- intermediate with an elongated O═O bond. In addition, the distinctive Cu-(O-O)ad-Ti bridging structure with localized electrons facilitated the chemisorbed O2 dissociation into electrophilic monatomic O- species, which subsequently nucleophilically attack the methyl C-H of toluene. These benzyl alcohol-derived Ph-CH2-O- intermediates can be readily and flexibly converted into reactive benzaldehyde and benzoic acid species, which were available for subsequent aromatic ring-opening reactions. This study not only advances mechanistic insights into the Cu+-Ov-Ti ensembles and electrophilic O- species in toluene catalytic oxidation but also establishes a design Cu+-Ov-Ti principle for engineering efficient VOC elimination catalysts.

Heterointerfaces in composite electrodes play critical roles in catalytic performance, but methods for precise optimization of them are still lacking and remain challenging. Here, we propose an innovative ion-directional migration strategy to achieve precise optimization of heterointerfaces in a composite electrode of a solid oxide electrolysis cell (SOEC) for ultraefficient CO2 electrolysis. Specifically, a composite electrode composed of Sr2Fe1.5Mo0.5O6-δ perovskite and Ru0.05Ce0.95O2 fluorite with a Ru loading of only 0.89 wt % (denoted as SFM-005Ru@CeO2) is elaborately designed. Thermal treatment induces directed migration of Ru ions from the fluorite phase to the perovskite-fluorite heterointerfaces and subsurfaces of Sr2Fe1.5Mo0.5O6-δ, enabling precise optimization of the oxygen vacancy concentration and the electronic environment of Fe cations inside the perovskite phase at the subsurface, thereby markedly enhancing O2-/e- conductivity and CO2 reduction reaction (CO2RR) activity. Impressively, a SOEC supported by an La0.8Sr0.2Ga0.8Mg0.2O3-δ (LSGM, 140 μm) electrolyte and employing the SFM-005Ru@CeO2 composite with a precisely optimized heterointerface as the cathode delivers an ultrahigh current density of 3.80 A cm-2 @1.5 V at 800 °C for direct CO2 electrolysis, superior to all previously reported electrodes. It also shows excellent stability over 200 h under harsh operating conditions (750 °C, 1.6 A cm-2). This work opens up a new avenue to improve the performance of composite materials in various catalytic systems through precise heterointerface engineering.

A Mn-doped Fe3O4 (Mn-Fe3O4) nanozyme was synthesized using a one-step solvothermal method. Compared to pristine Fe3O4, Mn-Fe3O4 exhibits unique oxidase (OXD)-like activity and enhanced peroxidase (POD)-like activity. The superior catalytic performance arises from the incorporated Mn species and the associated oxygen vacancies facilitate oxygen adsorption and activation, establishing an efficient self-cascade catalytic system. In this system, hydrogen peroxide (H2O2) generated in-situ through OXD-like catalysis can trigger mimic-POD reactions. A dual-mode antioxidant detection platform was subsequently constructed using melatonin (MT) as a proof of concept, with 3,3',5,5'-tetramethylbenzidine (TMB) serving as the substrate for the Mn-Fe3O4 nanozyme. The colorimetric mode enables rapid visual screening by monitoring the oxidation of TMB to a blue-colored product, achieving a detection limit of 0.13 µM. The electrochemical mode features the novel utilization of mesoporous silica nanochannels for the selective enrichment of oxidized TMB (oxTMB), enabling highly sensitive quantification of MT with a detection limit as low as 0.6 nM. The assay applied to commercial tablets shows excellent recovery and reproducibility. This work combines engineered nanozymes with nanofilm-modified electrodes, offering an innovative approach for constructing advanced multimodal sensing systems.

This research is dedicated to improving the efficacy and durability of graphdiyne (GDY), a novel 2D carbon allotrope, for applications in photocatalytic hydrogen generation. Addressing issues such as the relatively poor stability of GDY in practical applications, we innovatively employed a high-entropy oxide (HEO) to replace conventional copper substrates, successfully preparing an HEO-GDY composite. This was further integrated with Zn0.5Cd0.5S to construct the ZHG-10 photocatalyst. Experimental results demonstrate that ZHG-10 exhibits superior photocatalytic hydrogen evolution activity and cycling stability in comparison to GDY-based catalysts synthesized from Cu or Cu2+ precursors, achieving a hydrogen production rate of up to 7.59mmol/g/h. Photoelectrochemical tests reveal that the multi-element chemical environment of HEO significantly enhances the separation efficiency of photogenerated charge carriers. Kelvin probe force microscopy (KPFM) analysis and density functional theory (DFT) calculations indicate that the multi-metal synergy and lattice distortion effects in HEO introduce numerous defective active sites (e.g., oxygen vacancies), which not only serve as efficient centers for hydrogen adsorption and activation but also significantly optimize interfacial charge transfer pathways. This study elucidates the dual functionality of HEO-GDY in enhancing charge carrier separation and providing abundant active sites, offering a new strategy for developing high-performance and durable GDY-based photocatalytic systems.

Semiconductor-based photocatalysis using TiO2, ZnO, and related materials offers a promising solution for efficient wastewater treatment through light-assisted advanced oxidation processes. In this study, oxygen vacancy (Ov)-rich ZnO micrometer-sized particles (ca. 0.5 μm) are grown on a conductive carbon cloth via a one-step molten salt method. The effects of different coordinating anions added into the molten salt on the morphological characteristics of the resultant ZnO crystallites are studied. The optimized photocatalyst (CC@ZnO-3 min) achieves near-complete degradation of 20 ppm ofloxacin within 2 h under UV irradiation and in the presence of 5 mM KHSO5 (PMS). In the absence of PMS, it removes 26% of total organic carbon (TOC) after 8 h─a 6-fold improvement over commercial ZnO with an average particle size of ca. 0.2 μm, which is also immobilized on carbon cloth with a similar loading mass of ca. 7.0 mg·cm-2. Radical trapping experiments reveal that superoxide (·O2-) and holes play dominant roles in the degradation process. The engineered oxygen vacancies not only enhance charge carrier separation but also significantly improve electron transfer efficiency. This work presents a strategy for developing high-efficiency photocatalysts to address pharmaceutical pollution.

S-scheme heterojunctions enable spatialseparation of photogenerated carriers, but remain constrained by interfacial electron transfer efficiency. Herein, oxygen vacancy defects are locally formed by removing fluorine atoms from the highly oriented (001) crystal plane of TiO2 with fluorine doping. These defects can introduce additional doping energy levels, serving as the bench for S-scheme interfacial electron transfer in CdS/TiO2. As verified by femtosecond transient absorption spectra, in situ irradiated X-ray photoelectron spectra, and theoretical computational simulations, the defect energy levels trap the localized electrons, which participate in the S-scheme interfacial transfer upon photoexcitation. The electron trapping process effectively prolongs the lifetime of photogenerated carriers and retards the charge recombination within each component. Besides, the binding energy shifts and surface potential changes detected by emerging in situ irradiated soft X-ray absorption spectroscopy and in situ irradiated Kelvin probe force microscopy provide conclusive evidence for the CdS/TiO2 S-scheme heterojunction. Benefitting from trap energy level-assisted S-scheme electron transfer mechanism, the optimal CdS/TiO2 composite exhibits superb photocatalytic H2 production performance.

Photothermal materials possess efficient light absorption and light-to-energy conversion capabilities, and have been widely applied in research on seawater desalination and sewage treatment. However, traditional solar desalination faces challenges such as poor salt resistance, low photothermal conversion efficiency, and the inability to effectively remove wastewater discharged from seawater. In this study, we designed a self-floating solar evaporator with a vertically arranged and porous structure. By employing a simple "impregnation-crosslinking-reduction" method, we induced cross-linking in balsa wood/MXene/MnO2 (MMW). Among them, MXene exhibits exceptionally Superior efficiency in photothermal energy conversion and is widely applied as a photothermal material in the field of seawater desalination. Meanwhile, MnO2 nanoflowers, rich in oxygen vacancies, can effectively activate peroxydisulfate (PDS), demonstrating efficient catalytic performance. Within the evaporator, they spontaneously establish a wet, porous internal structure and specialized water pathways. Under such conditions, The system demonstrates a maximum evaporation capacity of 1.90 kg m-2 h-1, along with an evaporation efficiency of 113.4%. Moreover, the evaporator demonstrates high degradation rates(94.09% for 50 mg L-1 methylene blue and 95.31% for 100 mg L-1 Rhodamine 6G). In addition, this evaporator enables salt to be expelled from its interior to the surface via convection,which can acquire freshwater efficiently and sustainably. Furthermore, we used the purified water collected from evaporation to irrigate mung beans, which were able to germinate and grow normally. This work provides a direction for the application of evaporators and offers an alternative approach to addressing water scarcity and enhancing water utilization.

Various metal oxide catalysts have been utilized to enhance the electrode reaction kinetics in vanadium redox flow battery (VRFB). However, the determining factor governing their catalysis is still insufficiently understood. Herein, selectively doping of Sr and Ce at La site of LaMnO3 perovskite (LSMO and LCMO) was used to modulate chemical environments of Mn ion activity donors, thereby boosting vanadium redox reaction processes. Sr doping increases the valence state of Mn ions, making it easier for Mn ions to take an electron from the electrode and transfer it to V3+ ions, which lowers the reaction energy barrier of V3+/V2+ redox processes. Conversely, Ce doping decreases the Mn valence and increases the oxygen vacancies, boosting the charge transfer and mass transfer of VO2+/VO2+ redox processes. Theoretical calculation further demonstrates that doping Sr and Ce enhances the vanadium ion's ability for charge transfer and adsorption. Compared with pristine VRFB, the VRFB with LSMO- and LCMO-modified anode and cathode, respectively, exhibits an excellent energy efficiency (EE) of 67% at a high current density of 300mAcm-2 and an increased EE of 15% at 150mAcm-2. This study is critical for promoting fundamental understanding and offering a design strategy for achieving superior-performance metal-based electrocatalysts in VRFB.

Metal-oxide interactions are ubiquitous in many technological applications and involve a complex interplay between the oxide support and the metal nanoparticle. Particularly, it has been proposed that in strong metal-support interaction, the defect chemistry affects the metal cluster morphology. Here we develop a physics-guided machine learning framework to decode these interactions using Pt7 and Pt13 representative of planar and tridimensional clusters, analyzing the impact of across oxygen vacancy concentrations of CeO2-x = 0-12.5% (528 configurations). Our models (R2 > 0.97) reveal that polaron swarms, rather than defect concentrations, predominantly control cluster shape and charge through size-dependent pathways. The framework yields quantitative design principles for defect-driven catalyst optimization and provides a general methodology for systematic mechanisms of metal-support interactions across diverse catalyst systems.

Achieving reliable hydrogen sensing at room temperature remains a critical challenge due to the limited carrier transport and unstable surface chemistry of conventional polycrystalline oxides. Here, we demonstrate that precise growth-mode control of epitaxial anatase TiO2 thin films via sputtering atmosphere engineering provides an effective route to overcoming these limitations. By systematically tuning the Ar/O2 ratio, the TiO2 growth mode transitions from a defective island-like mode to a layer-by-layer mode and finally to a stress-induced island. The film deposited at an 8/1 Ar/O2 ratio achieves an ideal combination of perfect crystallinity, an atomically flat surface, and a balanced oxygen vacancy concentration, yielding a clean and well-defined Pd-TiO2 interface upon catalyst deposition. The resulting Pd/TiO2 sensor exhibits exceptional room-temperature hydrogen sensing performance: a strong response of 11.34 to 100 ppm of H2, a low detection limit (5 ppm), excellent selectivity over other battery abuse gases, remarkable humidity resistance, and long-term stability. Comprehensive structural and mechanistic analyses reveal that the superior performance originates from an efficient interface-dominated sensing mechanism, rather than the conventional surface reaction pathway. This work establishes a "structure over stoichiometry" paradigm for developing advanced gas sensors and provides an effective route toward high-reliability, low-power hydrogen safety monitoring.