Abundant Oxygen Vacancies Research Articles

Core-Shell IrPt Nanoalloy on La/Ni-Co3O4 for High-Performance Bifunctional PEM Electrolysis with Ultralow Noble Metal Loading.

The development of highly efficient and durable bifunctional catalysts with minimal precious metal usage is critical for advancing proton exchange membrane water electrolysis (PEMWE). We present an iridium-platinum nanoalloy (IrPt) supported on lanthanum and nickel co-doped cobalt oxide, featuring a core-shell architecture with an amorphous IrPtOx shell and an IrPt core. This catalyst exhibits exceptional bifunctional activity for oxygen and hydrogen evolution reactions in acidic media, achieving 2Acm-2 at 1.72V in a PEMWE device with ultralow loadings of 0.075 mgIr cm-2 and 0.075 mgPt cm-2 at anode and cathode, respectively. It demonstrates outstanding durability, sustaining water splitting for over 646h with a degradation rate of only 5μVh-1, outperforming state-of-the-art Ir-based catalysts. In situ X-ray absorption spectroscopy and density functional theory simulations reveal that the optimized charge redistribution between Ir and Pt, along with the IrPt core-IrPtOx shell structure, enhances performance. The Ir-O-Pt active sites enable a bi-nuclear mechanism for oxygen evolution reaction and a Volmer-Tafel mechanism for hydrogen evolution reaction, reducing kinetic barriers. Hierarchical porosity, abundant oxygen vacancies, and a high electrochemical surface area further improve electron and mass transfer. This work offers a cost-effective solution for green hydrogen production and advances the design of high-performance bifunctional catalysts for PEMWE.

Synergistic Dual‐Active Sites Engineering in ZIF‐Derived CoOx/B‐Modified g‐C3N4 for Efficient CO2 Cycloaddition Under Mild Conditions

Abstract The carbon dioxide (CO2) cycloaddition reaction provides an efficient route to achieve resource utilization of CO2. However, the inherent chemical stability of CO2 itself hinders its efficient transformation into cyclic carbonates. Herein, the CoOx/BCN catalyst was successfully prepared by a simple deposition method. The CoOx/BCN exhibited excellent catalytic performance in the CO2 cycloaddition reaction synergistically catalyzed with the nucleophilic reagent KI under solvent‐free and mild reaction conditions (80 °C, 0.8 MPa, 6 h). The yield of cyclic carbonate was 98% and the selectivity was 99%, which was significantly superior to CoOx/CN catalyst (with a cyclic carbonate yield of 73.7%). Furthermore, after six cyclic reactions, CoOx/BCN still maintained a yield of over 93%. It was found that after boron (B) was doped into graphitic carbon nitride (g‐C3N4), the generated ─NB(OH)2 group on CoOx/BCN effectively activated the epoxide. Importantly, the interaction between B‐doped g‐C3N4 and CoOx induced the generation of abundant oxygen vacancies, which provided sufficient active sites for CO2 adsorption and activation. In addition, carbonates were identified as the main reaction intermediates by in situ DRIFTS, and the possible reaction pathways of the CoOx/BCN catalyst were proposed. Therefore, this work provides new idea for the design of catalysts for CO2 cycloaddition.

Metal-Organic Frameworks (MOFs)-Derived Mesoporous Carbon Encapsulated Ultrafine Scandium Oxide Electrocatalyst for Highly Efficient Oxidation of 5-Hydroxymethylfurfural to 2,5-Furandicarboxylic Acid.

Green electrochemical synthesis of 2,5-furandicarboxylic acid (FDCA) from biomass is an essential alternative for the substitution of petroleum-based terephthalic acid. The rational design and application of high-performance electrocatalysts are the key to advance this technique. In this work, mesoporous carbon encapsulated ultrafine Sc2O3 nanoparticles are reported as a new, highly efficient and selective electrocatalyst that realizes the concurrent electrochemical oxidation of biomass-derived 5-hydroxymethylfurfural (HMF) to FDCA coupled with hydrogen evolution. The performance of the optimum electrocatalyst, Sc2O3@C-900, is suppressed its counterparts, including the mesoporous Sc2O3 and the state-of the art electrocatalyst, Ni(OH)2, NiOOH, and some other noble metal electrocatalysts. The high performance is attributed to the ultrafine Sc2O3 nanoparticles with abundant oxygen vacancies, and the mesoporous carbon layer synergistically promotes electrochemical oxidation by accelerating the adsorption and confinement of key intermediates for electro-oxidation, and facilitating the transportations of reactants/products within/out of the electrocatalyst. Moreover, experiments including the electrochemical and in situ measurements, as well as theoretical studies, provide insights into the origin of high efficiency and the preference of the diformylfuran (DFF) pathway.

Interfacial Charge Transfer Modulation via Phase Junctions and Defect Control in Spaced TiO2 Nanotubes for Enhanced Photoelectrochemical Water Splitting

Anodic titanium oxide (TiO2) nanotubes have garnered significant interest as photoelectrodes for photoelectrochemical (PEC) water splitting; however, their intrinsic structural and crystallographic limitations often lead to suboptimal PEC efficiency. Herein, spaced TiO2 nanotubes (SPNTs) with enhanced intertubular spacing are utilized as photoelectrodes to improve light penetration and harvesting. Amorphous SPNTs are subjected to annealing under various atmospheric and thermal conditions to induce phase transitions, forming anatase, rutile, and anatase–rutile heterojunctions. The highest PEC performance is achieved with SPNTs annealed at 600°C in an argon atmosphere (Ar‐600), exhibiting the formation of anatase–rutile heterojunctions and abundant oxygen vacancies (VO). These features facilitate rapid charge transfer, enhancing PEC activity. Notably, Ar‐600 demonstrates a photocurrent density of 0.34 mA cm−2 at 1.23 V vs. reversible hydrogen electrode (RHE), an incident photon‐to‐current efficiency of 48% at 360 nm, a charge carrier density of 2.5 × 1019 cm−3, and the lowest charge transfer resistance (Rct) of 556 Ω. These values represent a 2.1‐fold increase in photocurrent and a fourfold reduction in Rct compared to conventional close‐packed TiO2 nanotubes. Furthermore, the Ar‐600 electrode achieves a hydrogen production amount of 105.4 μL cm−2 after 3 h of PEC operation, highlighting its potential for practical solar‐to‐hydrogen conversion.

Light-assisted activation of oxalic acid by Ni2Fe-LDH with coordinatively unsaturated Fe sites for antibiotics degradation: Mechanism insight and application assessment.

Light-assisted activation of oxalic acid by Ni2Fe-LDH with coordinatively unsaturated Fe sites for antibiotics degradation: Mechanism insight and application assessment.

Sodium percarbonate fuel-driven magnetic micromotor for rapid detection and efficient removal of tetracycline: Synergistic effect of oxygen vacancy and dissolved oxygen.

Sodium percarbonate fuel-driven magnetic micromotor for rapid detection and efficient removal of tetracycline: Synergistic effect of oxygen vacancy and dissolved oxygen.

Improved AC Drain Bias Stability in In-Zn-O TFTs with an Hf-Doped Heterobilayer Structure.

Metal oxide semiconductors are widely used in display technologies due to their high electron mobility, low leakage current, and robust switching characteristics. However, ensuring stability under AC bias stress, which is an inherent condition for practical device operation, remains a critical challenge. In particular, hot carrier effects (HCE) have been identified as a key mechanism for device instability under AC bias stress, as they induce oxygen vacancies (VO) and acceptor-like defect states. In this study, we selected IZO, a material with excellent properties but weak M-O bonds, to improve AC stability. To address this challenge, we propose a heterobilayer channel thin-film transistor (TFT) consisting of an indium-zinc oxide (IZO) bottom layer and a Hf-doped IZO top layer as a solution to enhance AC bias stability as well as electron mobility. The Hf-doped IZO top layer forms strong bonds with oxygen, effectively reducing oxygen vacancies and VO-related defect states, while inhibiting excessive hot carrier accumulation near the drain electrode. Meanwhile, the IZO bottom layer provides an abundance of oxygen vacancies, contributing to enhanced mobility. The fabricated TFT with the IZO:Hf/IZO bilayer channel exhibits a mobility of 7.3 cm2/(V s) and an Ion degradation rate of only 4% after 1000 s, demonstrating excellent device stability under AC drain bias stress. In addition, negligible hysteresis and excellent reproducibility were also achieved even under AC bias conditions. After stress, the threshold voltage shift was only 0.11 V, with a current on/off ratio of 1.8 × 106 and a subthreshold swing of 512 mV/dec. TCAD simulations further validated the heterobilayer structure in improving stability under AC drain bias stress by demonstrating its effectiveness in suppressing defect generation.

Amorphous/crystalline HTiNbO5-X membranes for efficient confined flow synthesis of acetate ester flavours

Ideal laminar membrane reactors (LMR) necessitate the rational construction of 2D nanoconfined channels and regulation of microenvironment. The intrinsic structure-activity relationship of laminar membrane reactors essentially remains unclear. Herein, amorphous/crystalline HTiNbO5-X nanosheets (NS) with abundant oxygen vacancy (VO) are successfully prepared and stacked as 2D sub-nanoconfined membrane flow reactors with different interlayer spacings. When the interlayer spacing is decreased to 11.0 Å, the representative HTiNbO5-X membrane exhibits impressive conversion of ≈ 100% within 26.6 s and turnover number of up to 306.42 for the esterification of benzyl alcohol at 23 °C. The combination of structural characterizations and theoretical calculations reveals that the synergistic effect of VO and sub-nanoscale confinement greatly promotes the adsorption and orbital symmetry matching of reactants, and reduces the overall energy barrier. Furthermore, the HTiNbO5-X LMR is accessible for other alcohol derivatives, indicating the efficient and green synthesis of acetate ester flavours under mild conditions. This work demonstrates the promising potential of the metal oxide nanosheets to create inorganic laminar membrane reactors for continuous organic synthesis.

SERS assay of FTO by coordination modulation of MIL-101(Fe).

SERS assay of FTO by coordination modulation of MIL-101(Fe).

Sm3+-doped Bi2MoO6 with enhanced photocatalytic CO2 reduction performance originated from abundant oxygen vacancies

Sm3+-doped Bi2MoO6 with enhanced photocatalytic CO2 reduction performance originated from abundant oxygen vacancies

Morphology transformation enhances oxidase-like activity of CuCo2O4 to improve its sensing performance via dissociation-coordination mechanism.

Morphology transformation enhances oxidase-like activity of CuCo2O4 to improve its sensing performance via dissociation-coordination mechanism.

Morphology-engineered porous flower-like CoNi-LDO with oxygen vacancies for the production of aromatic amines through waste H2S.

Morphology-engineered porous flower-like CoNi-LDO with oxygen vacancies for the production of aromatic amines through waste H2S.

Cerium Oxide Nanozymes: Exploring Synthesis, Catalytic Activity, and Biomedical Potential.

Cerium oxide (CeO2) nanozymes have emerged as a novel class of nanozyme materials distinguished by their tunable valence states (Ce3+/Ce4+) and abundant surface oxygen vacancies (OVs), demonstrating exceptional chemical stability, cost-effectiveness, and scalable manufacturability. Precise control of reaction temperature or implementation of carrier-mediated crystal growth strategies effectively enhances nanoparticle dispersion and mitigates aggregation. This review systematically summarizes recent advancements in CeO2 nanozymes: First, it elaborates on cutting-edge synthetic methodologies, encompassing self-supported strategies (calcination, hydrothermal, and sol-gel) and carrier-mediated approaches (small-molecule compounds, macromolecular compounds, and nanomaterials), with comparative analysis of their respective merits and limitations. Second, the catalytic mechanism is comprehensively elucidated, particularly focusing on the modulation of electron transfer kinetics and surface adsorption energies in metal/nonmetal hybrid systems. By optimizing oxygen vacancy concentration to regulate Ce3+/Ce4+ redox cycling dynamics, significant enhancement in redox efficiency and catalytic stability can be achieved, enabling precise enzyme-like activity regulation. Furthermore, the review comprehensively summarizes breakthrough applications in multidimensional biomedical fields, including precision tumor therapy, intelligent antibacterial systems, inflammatory microenvironment regulation, and ultrasensitive biosensing. This work establishes a theoretical framework for structure-activity relationship-guided rational design of high-performance CeO2 nanozymes and delineates their potential translational applications in precision medicine.

Surface reductive acid etching for the fabrication of abundant oxygen vacancies into CuCo2O4 for enhanced toluene oxidation

Surface reductive acid etching for the fabrication of abundant oxygen vacancies into CuCo2O4 for enhanced toluene oxidation

Quenching induced Cu and F co-doping multi-dimensional Co3O4 with modulated electronic structures and rich oxygen vacancy as excellent oxygen evolution reaction electrocatalyst.

Quenching induced Cu and F co-doping multi-dimensional Co3O4 with modulated electronic structures and rich oxygen vacancy as excellent oxygen evolution reaction electrocatalyst.

Mo-V/g-C3N4 with strong electron donating capacity and abundant oxygen vacancies for low-temperature aerobic oxidative desulfurization.

Mo-V/g-C3N4 with varying oxygen vacancy contents were prepared via successive H2 and NaBH4 reduction. The oxygen vacancies could enhance oxygen adsorption while π-conjugated g-C3N4 support could promote surface electron transfer capacity, both facilitating the activation of oxygen into reactive oxygen species superoxide radicals. The catalyst achieves 100% aerobic oxidative desulfurization performance at 80 °C.

Enhancing CO Preferential Oxidation in H2-Rich Stream on Solid Solution CuO_CeO2 Catalyst with Abundant Oxygen Vacancies.

In this study, we propose a strategy for preparing solid solution CuO_CeO2 catalysts derived from Ce-based MOFs for CO preferential oxidation. The support provided by frameworks and the anchoring of amino groups prevent the agglomeration of Cu species during subsequent annealing. Therefore, highly dispersed Cu species are formed, and even some are atomically embedded in the CeO2 lattice. Notably, 99.5% CO conversion and 58.2% CO2 selectivity are achieved at a WHSV of 36,000 mL/(h·gcat) with only 4.41 wt % Cu loading. No decrease in efficiency is observed within 150 h. DFT calculations reveal that the O2 is favorably adsorbed and activated at oxygen vacancies of Cu-Ce-V[O], whereas the CO adsorption is localized at Cu ion sites. Highly dispersed Cu species and neighboring oxygen vacancies provide abundant active sites for CO oxidation via the noncompetitive L-H mechanism. This research offers insights for designing efficient non-noble metal catalysts and understanding the reaction mechanism.

Single-Atom Ru Anchored Mesoporous TiO2 Phase-Junction Promotes Photocatalytic Biomass Conversion.

Constructing advanced semiconductor nanoreactors is an effective route to boost the efficient photocatalytic conversion of biomasses to high-value-added products. Herein, single-atom anchored flower-like mesoporous TiO2 nanoreactors with tunable anatase-rutile crystalline phases are prepared via a micelle-interface confined co-assembly strategy (Ru0.5/A&R-TNs). This approach not only facilitates the introduction of various monatomic/diatomic (e.g., Ru, Mo, Pd, Pt, etc.) sites but also spontaneously induces the TiO2 phase transformation from anatase to rutile, achieving precise control of two-phase ratios. The interface of the two phases with abundant oxygen vacancies (Ov) facilitates the adsorption and activation of 5-hydroxymethylfurfural (HMF), which exhibits a high photocatalytic HMF oxidation to DFF (selectivity of 90.8%). Based on the optimal phase compositions, the doping of Ru single-atom further exhibits a high atom utilization and suitable electronic structure. Therefore, the Ru0.5/A&R-TNs achieve the cascade conversion from HMF to 5-formyl-2-furoic acid with a selectivity of 75.8%. This research provides innovative ways for single-atom catalyst synthesis, and the mechanism of synergistic catalytic action may provide new guidance for the photocatalytic conversion of high-value-added products from HMF.

Surface Modification of Fe-Based Perovskite Oxide via Sr0.95Ce0.05CoO3−δ Infiltration: A Strategy for Thermochemical Stability

Cobalt-based perovskite oxides exhibit remarkable catalytic activity owing to abundant oxygen vacancies and mixed ionic–electronic conductivity, but they suffer from structural instability. In contrast, iron-based perovskite oxides are thermochemically stable under oxidizing and reducing conditions but are catalytically limited. To combine these complementary properties, a composite perovskite oxide was designed and prepared by infiltrating Sr0.95Ce0.05CoO3−δ (SCC) into Ba0.5Sr0.5Fe0.8Cu0.2O3−δ (BSFC). The SCC precursor solution was dropwise applied to a BSFC|SDC|BSFC symmetric cell and heat treated. Surface morphology and compositional analyses confirmed the distribution of SCC nanoparticles on the BSFC surface. High-temperature X-ray diffraction and Rietveld refinement results revealed that both BSFC and SCC retained the cubic perovskite structure (space group Pm-3m) at room temperature. No phase transition or secondary phase formation was observed during heating from 200 to 800 °C, and the peak shifts are attributed to thermal expansion and possible oxygen loss at elevated temperatures. Upon cooling, the diffraction patterns returned to their initial state, confirming a high-temperature structural stability. XPS analysis showed an increase in the satellite peak intensity associated with Fe3+ after SCC infiltration, and the average oxidation state of Fe decreased from 3.52 (BSFC) to 3.49 (composite perovskite oxide). The O 1s spectra revealed a higher relative content of surface-adsorbed oxygen species in the composite, indicating increased oxygen vacancy formation.

Dual-Functional Schottky-Barrier-Free Plasmonic TiN/TiO2 Photocatalyst for Efficient NH3 and H2 Production.

Titanium nitride has garnered much attention owing to its high charge carrier density and low work function. These merits compensate for the shortcomings of traditional photocatalysts. Herein we report on the synthesis of TiN/TiO2 nanoparticles (NPs) as a new Schottky-barrier-free plasmonic photocatalyst (SBFPP) through the oxidation of commercially available TiN NPs. Our SBFPP possesses abundant oxygen vacancies (OVs) and the ability to generate hot charge carriers. The TiN NPs oxidized at 400 °C for 2 h, which is designated as TiN-2, exhibit broad light absorption and a high OV concentration. Theoretical calculations have revealed that the presence of OVs and nitrogen dopants leads to the formation of defect electronic states in TiO2. Hot electrons from TiN can efficiently migrate to these defect states, hindering the rapid electron-hole recombination. Besides the efficient photocatalytic nitrogen fixation, the TiN-2 NPs also exhibit excellent hydrogen generation performance. Furthermore, the photocatalytic film formed by combining the TiN/TiO2 NPs and a porous poly(vinyl alcohol) film dramatically improves the photocatalytic nitrogen fixation performance, giving an enhancement of ∼4.4 times in comparison with the TiN-2 NPs. This study unveils a promising avenue for the rational design of plasmonic photocatalysts and facilitates the development of practical applications in the field of photocatalysis.