Contactless gas-sensitive photoelectrochemical biosensor for determination of Salmonella typhimurium based on SnO2/CeO2 heterojunction.

Engineering surface oxygen vacancies to steer electron flow for perfluorooctane sulfonate mineralization by visible light.

Efficient and stable catalysts are vital for catalytic ammonia decomposition as a clean hydrogen source. In this study, CeO2 support was modified via high Er doping to exploit the lanthanide contraction effect, enabling a wide range of substitution with Ce-to-Er ratios up to 1 : 0.67 without altering the fluorite structure. Among the prepared catalysts, Ni/CeEr0.44Ox exhibited the highest activity, achieving nearly complete NH3 conversion at 650 °C under a space velocity of 30 000 mL g(cat)-1 h-1, together with excellent long-term stability. Comprehensive characterization revealed that substantial Er incorporation generated abundant oxygen vacancies, strengthened the metal-support interaction, and enhanced the electron density of Ni. These synergistic effects collectively facilitated N-N recombination and desorption, thereby enhancing both activity and durability. This work provides valuable insights into dopant-induced electronic modulation and oxygen vacancy engineering in promoting ammonia decomposition.

Bi-doped SnO2 with abundant oxygen vacancies promotes room-temperature ethanol gas sensing by enhancing surface reactions and electron transfer

Oxygen vacancy-engineered BiOX catalysts: Synergistically boosting redox kinetics and suppressing hydrogen evolution in Iron chromium flow batteries.

Catalytic conversion of CO2 into high-calorie synthetic natural gas (HCSNG) is a desirable pathway for both carbon mitigation and sustainable energy supply. Herein, we report a highly efficient Fe-Co bimetallic catalyst prepared via a simple co-precipitation method. By balancing the C-C coupling and hydrogenation functionality by adjusting the Fe/Co ratio, a high per-pass HCSNG yield of 55.9%, along with negligible olefin formation, was achieved over the Fe-16Co catalyst at 320 °C. This superior performance originates from the highly dispersed Fe and Co active sites with intimate proximity and abundant oxygen vacancies, which promote CO2 adsorption and balance the C-C coupling and hydrogenation functions. Moreover, the Fe-16Co catalyst shows excellent durability over a time on stream of 1000 h, maintaining a relatively stable hydrocarbon distribution. This work offers an effective strategy for sustainable HCSNG synthesis and carbon-neutral fuel production.

Herein, a simple and environmentally benign synthetic strategy is developed to construct a hydrazine-regulated Bi/S co-doped CeVO4 trimetallic sulfur-oxide photocatalyst (Bi/S-CeVO4). The resulting material features abundant oxygen vacancy (Vo) defects and stabilized multivalent Ce3+/Ce4+ and V4+/V5+ states, which synergistically enhance photocatalytic hydrogen evolution reaction (PHER) performance under visible light irradiation. Band structure analyses indicate that Bi/S co-doping effectively modulates the electronic structure of CeVO4, leading to improved photocatalytic performance toward PHER. The coexistence of multivalent Ce3+/Ce4+ and V4+/V5+ species provides efficient electron-hopping pathways, facilitating photogenerated charge separation and transfer while prolonging carrier lifetime. In addition, Vo defects served as catalytic sites for water-molecule adsorption and activation, further accelerating surface reaction kinetics. Benefiting from these synergistic effects, the optimized Bi/S-CeVO4-3, featuring the highest electrochemically active surface area of 0.0015 cm2 and Vo concentration of 24.5%, and suitable ratio of Ce4+/(Ce3++Ce4+) (41.8%) and V4+/(V4++V5+) (38.5%), delivers the highest PHER rate of 1514.7 μmol·h-1, with an apparent quantum efficiency (AQE) x-ray diffraction of 15.28% at 420 nm. Moreover, the catalyst demonstrates excellent stability and durability. This work presents a feasible and effective strategy for electronic structure and defect engineering of CeVO4-based photocatalysts to achieve efficient solar-driven hydrogen evolution.

Conventional photocatalytic systems rely on light irradiation to activate catalytic reactions, which significantly limits their practical applicability under real environmental conditions. Herein, a W/S codoped Bi2O4 oxysulfide (WBiOS) is developed for pollutant reduction under dark conditions. By introducing the W cation and S anion, the electronic structure of Bi2O4 is reconstructed, accompanied by the formation of abundant oxygen vacancies (Ov) and dual Bi3+/5+ and W4+/6+ redox couples. The Bi3+/5+ and W4+/6+ species establish efficient electron-transfer pathways, while the Ov acts as an electron-trapping center and active sites, thereby accelerating electron transport and surface reaction kinetics. Benefiting from these synergistic effects, optimized WBiOS-2 with n(Bi3+)/n(Bi3+ + Bi5+) (39.46%) and n(W4+)/n(W4+ + W6+) (30.64%) exhibits the largest electrochemically active surface area (1.87 mF cm-2). It achieves complete reduction of 100 mL of 20 ppm 4-nitrophenol, methylene blue, nitro compounds, and Cr(VI) within 16, 8, 6, and 14 min, respectively, using NaBH4 as the reducing agent, with corresponding kinetic rate constants of 0.17, 0.13, 0.18, and 0.19 min-1, respectively. WBiOS-2 demonstrates sustained performance toward mixed pollutants across a wide pH range and maintains structural stability during cyclic operation. This work provides a promising strategy for the design of oxysulfide catalysts for environmental remediation.

Li-rich layered oxides (LRs) are promising candidates for high-capacity cathodes in next-generation lithium-ion batteries (LIBs). However, their commercialization faces challenges such as rapid capacity fading, voltage decay, and irreversible oxygen release. In this study, we develop an innovative interface engineering driven by bicarbonate pyrolysis, which constructs a coherent spinel-phase surface layer, generates abundant oxygen vacancies, and facilitates near-surface metal ion doping (K+, Na+, or Mg2+) on LRs. These enhancements work synergistically to significantly boost the electrochemical performance of the cathode. Notably, the optimized KHCO3-treated sample (SK-LR) exhibits outstanding cycling stability, retaining 94.9% of its capacity after 500 cycles at 1C and 98.9% after 100 cycles at 0.1C, compared to only 67.8% and 85.5% retention for the pristine cathode. Furthermore, SK-LR achieves a high energy density of 1110.5Wh kg-1, along with superior rate capability and thermal stability. Through ex/in situ characterizations and theoretical calculations, this interface engineering is evidenced to be effectively stabilize lattice oxygen by increasing oxygen vacancy formation energy from 3.87 to 5.34eV, enhancing crystal structure via strengthened Mn─O bonds, and optimizing Li+/e- transport kinetics. This work presents effective interfacial engineering to develop ultra-stable Li-rich cathodes, offering a viable pathway for advancing high-energy density LIBs.

Photothermoelectric (PTE) detectors have attracted extensive attention due to the advantages of no external bias, negligible 1/f noise, and low fabrication cost for arrayed and miniaturized devices, and they circumvent the bandgap limitation of traditional photon detectors. However, the practical application of current mainstream PTE materials remains severely hindered by their poor high-temperature stability, especially in harsh scenarios including high-temperature monitoring and industrial waste-heat detection. In this work, CaTiO3 is selected as the PTE material owing to its outstanding high-temperature stability, excellent chemical stability, non-toxicity, and low cost. Nevertheless, intrinsic insulating CaTiO3 possesses neither efficient optical absorption nor favorable thermoelectric properties. Herein, abundant oxygen vacancies are introduced to endow CaTiO3 with broad-spectrum optical absorption via the formation of defect energy levels within the bandgap. Meanwhile, La doping was employed to improve its thermoelectric performance. As a result, the La0.2Ca0.8TiO3 sample achieves a responsivity of ≈300mAW-1 and a noise level below 5 × 10-9WHz-1/2 across a broad spectral range when only intrinsic resistance is considered. It well meets the application needs of harsh civilian environments with no strict requirement for response speed. This work offers a feasible strategy for developing high-performance PTE detectors applicable to high-temperature and harsh working conditions.

Photothermal catalytic dry reforming of methane (PTC-DRM) offers a promising route for greenhouse gas valorization and solar-to-chemical energy conversion. Herein, Zn-doped CeO2 nanorod-supported Ni-Co bimetallic catalysts were synthesized via a hydrothermal and impregnation method for PTC-DRM. Zn doping induces the formation of abundant oxygen vacancies, strengthens the metal-support interaction, and accelerates charge carrier separation and photothermal conversion. The optimized Ni-Co/5Zn-CeO2-NR catalyst displays exceptional activity at 650 °C under illumination, with greatly improved CH4 and CO2 conversions and syngas yields. Light irradiation suppresses the reverse water-gas shift reaction and mitigates graphitic carbon deposition, markedly enhancing catalytic stability. This work establishes Zn-mediated defect engineering as an effective strategy for designing high-performance Ni-based photothermal DRM catalysts.

Oxygen vacancy-mediated photothermal CO2 methanation over Ni/Ce-Zr solid solution catalysts.

HighlightNovel Ti/Ce-IrO2+PbO2 anodes were fabricated via thermal decomposition with Ce and Ir co-doping to enhance electrocatalytic performance.Ce3+/Ce4+redox coupling (31.5%/68.5%) generates abundant oxygen vacancies and refines β-PbO2 crystallites from 536 to 303 nm.Process impact follows calcination temperature > acid etching > Ce doping ratio > coating loading.The optimized preparation parameters were 10% HCl for 1 h + 10% H2C2O4 for 1 h, 4 mol% Ce doping, 14 g m−2 loading, and 425 °C pyrolysis temperature.The optimised anode achieved a 1.6-fold increase in ECSA, the lowest Rct value, and surface-controlled OER kinetics (b≈0.95–0.99).

A sensing system on highly sensitive functional materials is a necessary prerequisite for the reliable detection of organophosphorus pesticides (OPs) in sophisticated matrices. Currently, the limited stability and narrow interlayer spacing of layered MXene pose considerable challenges to its application in electrochemical sensing. Inspired by the defect engineering strategy, a controllable dual-defect UiO-66 functional material (DDU/a-MXene NRs) was synthesized using alkaline MXene nanoribbons as a substrate. The cation intercalation process results in a-MXene NRs enriched with -OH active sites, exposing a wealth of active sites. Moreover, DDU was prepared through a dual-defect strategy of acetic acid (HAc) regulation and Ce doping, which induces oxygen molecules with unsaturated sites and constructs a barrier to prevent the oxidation of a-MXene NRs. As evidenced by the experimental results, the DDU/a-MXene NRs exhibit a hierarchical pore structure and an abundance of oxygen vacancies (Ov), which facilitate the generation of numerous active sites and accelerate substrate mass transfer, resulting in a strong electrochemical signal. The AChE-Chit/DDU/a-MXene NRs/GCE system using chitosan (Chit)-immobilized acetylcholinesterase (AChE) as recognition possesses a wide linear range (10-11 M to 10-6 M) and a low limit of detection (LOD) of 6.12 × 10-13 M. It has been successfully applied to the determination of OPs in complex matrices of fruits and their peels, and validation via liquid chromatography-mass spectrometry (LC-MS) sampling confirms considerable feasibility. This study provides a new solution to improve the stability of MXene and enhance the sensitivity of biosensors, thereby offering practical value in the domains of food security management and environmental monitoring.

RuRhFeCoNiCu high-entropy oxide nanotubes (RuRhFeCoNiCu HEO-NTs) with rich oxygen vacancies were designed to enhance the electrocatalytic performance of nitrate reduction to ammonia (NRA). Benefiting from the abundant oxygen vacancies and the synergistic effect between high-entropy constituent elements, the as-synthesized RuRhFeCoNiCu HEO-NTs exhibit remarkable electrocatalytic activity toward the NRA.

The fabrication of efficient and stable catalysts for peroxymonosulfate (PMS) activation is critical for the remediation of tetracycline (TC), a refractory antibiotic pollutant. MXene-based materials have emerged as promising catalyst platforms, yet their conventional preparation relies on hazardous fluorine-based etchants and complex multi-step procedures. Here, we developed a facile, fluorine-free one-pot CaCl2molten salt etching strategy. This method integrates MAX phase exfoliation with simultaneousin-situanchoring of Ru nanoparticles on MXene, yielding a Ru-Ca@Mo2TiC2MXene (Ru-Ca@MTC) composite. The chelation of dopamine and the intercalation of Ca2+synergistically regulated the material structure, endowing the Ru-Ca@MTC with an iris-like morphology, an expanded interlayer spacing, abundant oxygen vacancies, and uniformly distributed approximately 5 nm Ru active sites. The Ru-Ca@MTC/PMS system demonstrated excellent TC degradation performance, achieving 96% removal within 30 min, and maintained high catalytic activity over a wide pH range (2.74-10.76) with strong resistance to inorganic anions and actual water matrices. Mechanistic studies confirmed that TC degradation was dominated by1O2-based non-radical pathway, driven by Run+/Ru(n+1)+redox cycling and oxygen vacancy-induced PMS electron transfer. Seventeen degradation intermediates were identified, and toxicity assessments verified the significant reduction of TC toxicity after degradation. Additionally, Ru-Ca@MTC showed good reusability with 92.5% TC removal after five cycles. By enabling fluorine-free, one-pot synthesis of noble metal-loaded MXene catalysts, this work offers a simplified, safer, and scalable technical solution for the treatment of antibiotic-contaminated water.

Binder-free and self-supported iron-cobaltite/vertical graphene nanosheets hybrid electrodes are fabricated through a controlled electrodeposition approachfor high-performance aqueous supercapacitors.The deposition process enabled precise tuning of the microstructure while inducing cation redistribution between Co+ 2/Co+ 3 and Fe+ 2/Fe+ 3 states, thereby improving the electrochemical activity of the hybrid electrode. The synergistic interaction between Fe and Co redox centers accelerated faradaic redox reactions, leading to remarkably high specific capacitance. In addition, annealing induced structural ordering, abundant oxygen vacancies significantly enhanced charge-transport kinetics and promoted dominant surface-controlled pseudocapacitive behavior, resulting in superior rate capability and long-term cycling stability. A correlation between microstructure, cation redistribution, oxygen vacancies, and charge-storage performance is established. An asymmetric coin cell assembled using the iron-cobaltite/vertical graphene hybrid electrode as positive electrode and oxidized vertical graphene as the negative electrode operated stably over a wide potential window of 1.5V. The device delivered an areal capacitance of 41 mF/cm2 together with high energy and power densities of 115.2Wh/kg and 1405.8W/kg, respectively. In addition, the assembled device exhibited excellent cycling stability (∼94%) and coulombic efficiency (96%). These findings highlight the potential of electrodeposited iron-cobaltite/vertical graphene hybrid electrodesfor advanced energy-storage applications.

NiFeOOH nanosheets are promising non-noble metal catalysts for the oxygen evolution reaction (OER). However, their application is hindered by a high formation energy barrier of the *OOH intermediate. Herein, NiFeOOH hierarchical (Hier-NiFeOOH) nanosheet arrays with abundant oxygen vacancies (Ov) are grown in situ on a nickel foam (NF) substrate. The presence of Ov enhances the exposure of Ni active sites, thereby promoting OH- adsorption. More importantly, the small secondary nanosheets (∼50 nm) enable extensive exposure of the hierarchical nanosheet interfaces, which provide three-dimensionally distributed adsorption sites. Such sites enable coadsorption of the *OOH intermediate via Ni-O bonds and hydrogen bonds. The multisite coadsorption greatly reduces the formation energy barrier of the *OOH intermediate during the OER process. The synergistic effect between the hierarchical nanosheet interfaces and Ov boosts the OER intrinsic activity by 9 times compared with the NiFeOOH nanosheet. Additionally, the small size of secondary nanosheets guarantees a high density of interfaces formed on the primary microsheets. Consequently, the Hier-NiFeOOH/NF electrode delivers overpotentials of 240 mV and 300 mV to achieve current densities of 100 mA cm-2 and 1 A cm-2, respectively, while maintaining excellent stability for over 1000 h at 1 A cm-2. Furthermore, a homemade water electrolyzer assembled with the Hier-NiFeOOH/NF electrode exhibits superior durability during repeated start-shutdown cycles.

Developing cost-effective aqueous rechargeable zinc-manganese batteries with high capacity and long cycle life remains a challenge. In this study, a nanorod-structured Al-doped MnO2 cathode material (PAMO) containing α-MnO2/γ-MnO2 heterophases and abundant oxygen vacancies was prepared through a chemical bath deposition method incorporating polyethylene glycol (PEG) modification. The large specific surface area and abundant pore structure of PAMO facilitate electrolyte permeation and diffusion. Defects at the α/γ-MnO2 heterophase boundary expose numerous active sites, increase the electrochemically active surface area, and enhance diffusion-controlled capacity. The heterogeneous phase interface and abundant oxygen vacancies serve as shortcut pathways for ion diffusion, facilitating rapid ion transport and accelerating electrode reaction kinetics. Al3+ doping reduces the average oxidation state of Mn after cycling, thereby suppressing the dissolution of MnO2. Therefore, the PAMO-based zinc-ion battery exhibits a low redox polarization voltage, a high specific capacity (422 mAh g-1 at 0.1 A g-1), excellent high-rate charge/discharge performance, and long cycle durability. This work pioneers a facile approach for the development of cathode materials for large capacity and long cycle life zinc-manganese batteries through dopant-induced heterophase engineering.

Optimizing loss components by phase engineering is crucial for enhancing the microwave absorption performance of magnetic core-dielectric shell composites. In this work, a series of core-shell structured composites (FTR) were elaborately synthesized by high-temperature hydrogen reduction of Fe3O4@TiO2 precursors and the TiO2 shell content was effectively regulated by varying the dosage of tetrabutyl titanate (TBOT). With the increase of TBOT dosage, the phase composition of FTR composites gradually evolves from Fe/Fe2O3@TiO2 (FTR-2.0) to Fe@TiO2 (FTR-2.5) and Fe@FeTiO3/TiO2 (FTR-3.0, FTR-3.5). FTR-2.5 has the highest Fe content (86.24 wt %) and saturation magnetization (141.7 emu·g-1). Low TBOT dosage leads to TiO2 cracks around the magnetic core after hydrogen reduction, but the remaining shell still encapsulates the magnetic core. In contrast, high TBOT dosage promotes the solid-state reaction between Fe and TiO2 shells, generating thick and dense FeTiO3 shells and abundant hollow spheres. Regarding loss components, FTR-2.5 is dominated by magnetic loss due to its highest metallic Fe content, whereas dielectric loss plays a more prominent role in other FTR composites. Notably, polarization loss prevails in the high-frequency range, including interfacial polarization at the heterogeneous interfaces among Fe, Fe2O3, TiO2, and FeTiO3 and dipole polarization enhanced by abundant oxygen vacancies. Benefiting from the synergistic effects of strong magnetic loss, enhanced multiple polarization, and a continuous impedance matching region, FTR-2.5 achieves a maximum effective absorption bandwidth of 5.92 GHz at a thickness of 1.95 mm. This work provides insights into the phase evolution mechanism of Fe3O4@TiO2 during H2 reduction and a reference for improving broadband microwave absorption.