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[Display omitted] Aqueous zinc-ion batteries (AZIBs) are competitive alternatives for large-scale energy-storage devices owing to the abundance of zinc and low cost, high theoretical specific capacity, and high safety of these batteries. High-performance and stable cathode materials in AZIBs are the key to storing Zn2+. Manganese-based cathode materials have attracted considerable attention because of their abundance, low toxicity, low cost, and abundant valence states (Mn2+, Mn3+, Mn4+, and Mn7+). However, as a typical cathode material, birnessite-MnO 2 (δ-MnO 2) has low conductivity and structural instability. The crystal structure may undergo severe distortion, disorder, and structural damage, leading to severe cyclic instability. In addition, its energy-storage mechanism is still unclear, and most of the reported manganese oxide-based materials do not have excellent electrochemical performance. Herein, we propose a copper-doped Cu 0.05 K 0.11 Mn 0.84 O 2 ·0.54H 2 O (Cu 2 -KMO) cathode, which exhibits a large interlayer spacing, a stable structure, and accelerated reaction kinetics. This cathode was prepared using a simple hydrothermal method. The AZIB assembled using Cu 2 -KMO showed high specific capacity (600 mA h g−1 at 0.1 A g−1 after 75 cycles). The dissolution-deposition energy storage mechanism of Cu-KMO in AZIBs with double electron transfer was revealed using ex situ tests. The good electrochemical performance of the Cu 2 -KMO cathode fabricated by the doping strategy in this study provides ideas for the subsequent preparation of manganese dioxide using other strategies. [ABSTRACT FROM AUTHOR]

Defect engineering is an effective strategy for modifying the energy storage materials to improve their electrochemical performance. However, the impact of oxygen defect and its content on the electrochemical performances in the burgeoning aqueous NH4+ storage field remains explored. Therefore, for the first time in this work, an oxygen-defective ammonium vanadate [(NH4)2V10O25·8H2O, denoted as Od-NHVO] with a novel 3D porous flower-like architecture was achieved via the reduction of thiourea in a mild reaction condition, which is a facile method that can realize the intention to regulate the oxygen defect content, with the capability of mass-production. The as-prepared OdM-NHVO with moderate oxygen defect content can deliver a stable specific capacitance output (505 F g−1, 252 mAh g−1 at 0.5 A g−1 with ∼80% capacitance retention after 10,000 cycles), which benefits from extra active sites, unimpeded NH4+-migration path and relatively high structure integrity. In contrast, low oxygen defect content will lead to the torpid electrochemical reaction kinetics while too high content of it will reduce the charge-storage capability and induce structural disintegration. The superior NH4+-storage behavior is achieved with the reversible intercalation/de-intercalation process of NH4+ accompanied by forming/breaking of hydrogen bond. As expected, the assembled flexible OdM-NHVO//PTCDI quasi-solid-state hybrid supercapacitor (FQSS HSC) also exhibits high areal capacitance, energy density and reliable flexibility. This work provides a new avenue for developing materials with oxygen-deficient structure for application in various aqueous non-metal cation storage systems.

Defect engineering is an effective strategy for modifying the energy storage materials to improve their electrochemical performance. However, the impact of oxygen defect and its content on the electrochemical performances in the burgeoning aqueous NH4 + storage field remains explored. Therefore, for the first time in this work, an oxygen-defective ammonium vanadate [(NH4)2V10O25O, denoted as Od-NHVO] with a novel 3D porous flower-like architecture was achieved via the reduction of thiourea in a mild reaction condition, which is a facile method that can realize the intention to regulate the oxygen defect content, with the capability of mass-production. The as-prepared OdM-NHVO with moderate oxygen defect content can deliver a stable specific capacitance output (505 F g2O, denoted as Od-NHVO] with a novel 3D porous flower-like architecture was achieved via the reduction of thiourea in a mild reaction condition, which is a facile method that can realize the intention to regulate the oxygen defect content, with the capability of mass-production. The as-prepared OdM-NHVO with moderate oxygen defect content can deliver a stable specific capacitance output (505 F g-1, 252 mAh g-1 at 0.5 A g-1-migration path and relatively high structure integrity. In contrast, low oxygen defect content will lead to the torpid electrochemical reaction kinetics while too high content of it will reduce the chargestorage capability and induce structural disintegration. The superior NH4 +-migration path and relatively high structure integrity. In contrast, low oxygen defect content will lead to the torpid electrochemical reaction kinetics while too high content of it will reduce the chargestorage capability and induce structural disintegration. The superior NH4 +-storage behavior is achieved with the reversible intercalation/deintercalation process of NH4 + accompanied by forming/breaking of hydrogen bond. As expected, the assembled flexible OdM-NHVO//PTCDI quasi-solid-state hybrid supercapacitor (FQSS HSC) also exhibits high areal capacitance, energy density and reliable flexibility. This work provides a new avenue for developing materials with oxygen-deficient structure for application in various aqueous non-metal cation storage systems. [ABSTRACT FROM AUTHOR]

Polar materials, with intrinsic polarization effects, present significant potential for photo(electro)catalysis. However, the available natural polar materials in this field are quite scarce, due to the requisite structural non‐centrosymmetry. Defect engineering emerges as a promising avenue for tuning material symmetry, yet achieving the transition from centrosymmetric to non‐centrosymmetric structures and optimizing associated polarization effects remains challenging. This study demonstrates symmetry breaking in centrosymmetric 3R‐delafossite AgFeO2 through ordered oxygen defects introduction, yielding substantial macroscopic polarization. The transition is achieved via annealing post‐treatment of co‐precipitation‐hydrothermal AgFeO2 samples, with precision in oxygen defects control by tailoring annealing conditions. Experimental characterizations reveal ordered interstitial oxygen and disordered oxygen vacancies. Density functional theory calculations indicate a higher propensity for the formation of disordered oxygen vacancies compared to ordered ones, while ordered interstitial oxygen is more easily formed than its disordered counterpart. Resultant macroscopic polarization enhances photoelectrochemical performance, with photocurrent density increasing from 0.79 to 2.95 µA cm−2. Coupling macroscopic and spin polarization via external electric and magnetic fields further enhances photocurrent density (≈18.44 µA cm−2). These findings provide reference cases and strategies for applying polarization effects in photo(electro)catalytic technology. [ABSTRACT FROM AUTHOR]

Doping inorganic acid ions represents a promising pathway to improving the photocatalytic activity of TiO2, and oxygen vacancy has been regarded as the determinant factor for photocatalytic activity. A series of samples doped with Cl−, NO3−, and SO42− was prepared via a simple sol–gel method. Two different oxygen vacancies in the crystal layer of NO3−/TiO2 and Cl−/TiO2 were found, and those are [Ti3+]-V0-[Ti3+] and [Ti3+]-Cl, respectively. The photocurrent of NO3−/TiO2 with [Ti3+]-V0-[Ti3+] is significantly greater than that of Cl−/TiO2 with [Ti3+]-Cl. The least oxygen vacancy is in the gel layer of SO42−/TiO2, and the negligible photocurrent is due to difficulty in forming a stable sol. Furthermore, the process conditions for the application of TiO2 were investigated in this work. The optimal process parameters are to adjust the solution to pH = 3 during sol–gel preparation, to adopt 550 °C as the calcination temperature, and to use an alkaline electrolyte, while the rest of the preparation conditions remain unchanged. This work reveals a new avenue for designing efficient photocatalysts for air pollutant degradation. [ABSTRACT FROM AUTHOR]

Oxygen defect engineering is a reliable and efficient approach to modulate the electronic structure of metal oxides for the improvement of catalytic efficiency. In this work, carbon nitride supported titanium dioxide nanoparticle, with the space group of I41/amd, was prepared using a high temperature synthesis route. Transmission electron microscope study revealed that titanium dioxide particle were dispersed uniformly on the carbon nitride network. The X-ray photoelectron spectroscopy analysis predicted the formation of oxygen defects in the matrix of titanium oxide, and it also indicated the presence of titanium ions with mixed valence states. The synthesized hybrid system was evaluated as an electrocatalyst for the electrochemical detection of epinephrine using cyclic voltammetric and square wave voltammetric techniques. A custom-made device was also fabricated using synthesized hybrid material for the purpose of evaluating the electrochemical sensing of epinephrine in a pharmaceutical sample. [ABSTRACT FROM AUTHOR]

This work reports the use of the metal‐support interaction strengthening through defect engineering and single atom adsorption to the supports to increase the catalytic activities of metals. Specifically, the plasma treated TiO2 nanowires with the Ir nanoparticle growth and the Sr single atom adsorption (the Ir@Sr‐p‐TiO2 NWs) are synthesized and demonstrated to be efficient catalysts for OER and HER. They only need overpotentials of 250 and 32 mV to drive 10 mA cm−2 for OER and HER, respectively. Their OER and HER activities are much higher than the commercial IrO2 and Pt/C. The high activities of the Ir@Sr‐p‐TiO2 NWs mainly arise from the strengthened metal‐support interactions between the Ir nanoparticles and the p‐TiO2 NWs, achieved by the plasma generated oxygen defects (Vo·) and the Sr adsorption on the p‐TiO2 NWs. Analysis and DFT calculations indicate that the Vo· and Sr adsorption can promote the charge transfer from the p‐TiO2 NWs to the Ir nanoparticles, optimizing the adsorptions of the OER and HER intermediates on the O‐ and H‐covered Ir nanoparticles. Additionally, the strong metal‐support interactions can increase the stabilities of the Ir NPs against the chemical corrosions, increasing the OER and HER durabilities of the Ir@Sr‐p‐TiO2 NWs. [ABSTRACT FROM AUTHOR]

Advanced energy storage technologies have been developed to achieve safe, high-capacity, and stable cathode materials for aqueous Zn-ion batteries. Vanadium oxide has lately become a popular cathode material thanks to its advantages of a sufficient operating voltage window and a highly reversible redox reaction. However, vanadium pentoxide has certain drawbacks, such as poor electrical conductivity and slow ion diffusion. To resolve these problems, V2O5 sheets with amorphous carbon were synthesized by an ultrafast (within one minute), lower temperature (180 ℃), one-step and large-scale combustion synthesis method. We demonstrate the introduction of carbon improves the conductivity and increases the content of low-valence vanadium, resulting in higher electrochemical activity and lower polarization of V2O5/C. Moreover, the introduction of C increases the concentration of oxygen defects in V2O5, further enhancing its conductivity and providing higher active sites for electrochemical reactions, thereby increasing its battery capacity. The synthesized V2O5/C sample exhibited a specific capacitance of 220 mAh g−1 (compared to 180 mAh g−1 for V2O5) in aqueous electrolytes at 4 A g−1, demonstrating a high specific capacity of 85.5% after 500 cycles with nearly 100% Coulomb efficiency. These results indicate improved specific capacitance and cyclic stability. [ABSTRACT FROM AUTHOR]

Herein, Co 3 O 4 /Ce 1-x La x O 2-δ nanocatalysts were established for methane combustion, integrating the sacrificial MOF-template method and deposition-precipitation technique. A favored La-insertion into CeO 2 matrix created smaller-sized Ce 1-x La x O 2-δ sosoloid with more defective structure due to the enhanced transformation of Ce4+ to Ce3+, helping in the intimate contact with Co 3 O 4. This lessened the particle sizes of Co 3 O 4 and alleviated the hybridization strength of Co3+ 3d and O 2p orbitals, which optimized the mobility of surface lattice oxygen and reducibility of Co 3 O 4 , and enriched Co3+ species to attack C–H bonds. Moreover, the transmission of gaseous oxygen and/or activated oxygen of Ce 1-x La x O 2-δ to Co 3 O 4 was expedited, availing the compensation of oxygen vacancies on reduced Co 3 O 4 to regain dissociation centers for methane. Expectedly, the combined function of Co3+/Co2+, Ce4+/Ce3+ and O/O V redox couples allowed Co 3 O 4 /Ce 0.6 La 0.4 O 2-δ with preferable methane removal efficiency to its counterparts, accompanied with desirable recyclability and long-term stability. • La–Ce–O solid solution was deliberately designed by a sacrificial MOF-template route. • The intimate contact and synergy between Co 3 O 4 and Ce 1-x La x O 2-δ were established. • The stripping of O latt from Co3+-O pairs was enhanced and more Co3+ sites were given. • The redox cycles of Co3+/Co2+, Ce4+/Ce3+ and O/O V couples were better accomplished. • Co 3 O 4 /Ce 0.6 La 0.4 O 2-δ featured superior CH 4 combustion activity to its counterparts. [ABSTRACT FROM AUTHOR]

Doping inorganic acid ions represents a promising pathway to improving the photocatalytic activity of TiO2, and oxygen vacancy has been regarded as the determinant factor for photocatalytic activity. A series of samples doped with Cl−, NO3−, and SO42− was prepared via a simple sol–gel method. Two different oxygen vacancies in the crystal layer of NO3−/TiO2 and Cl−/TiO2 were found, and those are [Ti3+]-V0-[Ti3+] and [Ti3+]-Cl, respectively. The photocurrent of NO3−/TiO2 with [Ti3+]-V0-[Ti3+] is significantly greater than that of Cl−/TiO2 with [Ti3+]-Cl. The least oxygen vacancy is in the gel layer of SO42−/TiO2, and the negligible photocurrent is due to difficulty in forming a stable sol. Furthermore, the process conditions for the application of TiO2 were investigated in this work. The optimal process parameters are to adjust the solution to pH = 3 during sol–gel preparation, to adopt 550 °C as the calcination temperature, and to use an alkaline electrolyte, while the rest of the preparation conditions remain unchanged. This work reveals a new avenue for designing efficient photocatalysts for air pollutant degradation.

As a class of nanomaterials with natural enzyme-like characteristics, nanozymes have shown their great potential in various applications. Reducible metal oxides featured with defect structures, and single-atom catalysts with isolated metal sites are regarded as two of the most promising nanozymes. However, the strategies to construct highly performed nanozymes by combining these advantages are rarely reported. Herein, we report the coordination-unsaturated single-atomic Cu species supported on sintered CeO2, which combines the advantages of defect engineering and single-atom catalysis, exhibiting a largely enhanced peroxidase (POD)-like activity. The high-temperature calcination induces the transformation of inert Cu1O4 species into coordination-unsaturated Cu1O3 sites. This novel Cu1O3 active sites with an unsaturated coordination work as a new type of defect sites to greatly activate the isolated Cu atoms and accelerate the dissociation of H2O2 to form hydroxyl radicals (·OH). The obtained nanozyme with a high POD-like activity possesses low cytotoxicity, showing potential applications for the tumor inhibition in vitro and in vivo. [ABSTRACT FROM AUTHOR]

SrTiO3 photocatalysts have been widely applied in overall water splitting reaction for their reasonable redox potential, whereas preventing the defects is crucial to improve the transition of photoexcited carriers influencing the photocatalytic performance. The defects in perovskite-type SrTiO3 were mainly Ti3+ and oxygen vacancies. Thence, little Ta5+ was designed to be doped in the B site for modulating the defect concentration. A series of advanced characterizations demonstrated that Ta5+ is helpful for Al3+ to penetrate the SrTiO3 lattice through lattice distortion, decreasing the Ti3+ defects. Meanwhile, the doping of slight Ta5+ facilitates the decrease in oxygen defect concentration, due to the formation of {Ta5+–O–Al3+}. Photoluminescence spectra and time-resolved fluorescence spectroscopy uncover that the charge carrier separation of SrTiO3 was enhanced by slight Ta5+. However, the excessive Ta5+ greatly promoted form the oxygen defect and Ti3+ species, leading to severe recombination of photogenerated carriers, which significantly reduced the photocatalytic activity. As a result, the optimized sample showed significant improvement in photocatalytic activity compared to the pure SrTiO3. [ABSTRACT FROM AUTHOR]

A series of pure CeO2, ZrO2, and CeZrOx mixed metal oxide catalysts were prepared by a wetness impregnation method and were applied to the dehydrogenation of propane to propylene at 500°C and 0.1 MPa. The prepared catalysts were characterized by thermal gravimetric analysis (TGA), Brunauer, Emmett, and Teller (BET), X‐ray photoelectron spectroscopy (XPS), X‐ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscopes (TEM), Raman spectroscopy, and H2‐TPR. It was observed that the zirconium content of the solid solution of the mixed metal oxide catalyst was 5%–25%, while the zirconium content of the material with phase segregation was higher (50%). The addition of zirconium was proven to decrease the oxygen vacancy concentration on the catalyst surface and change the intensity of (111) crystal of cerium oxide in the catalysts. Among the prepared catalysts, the Ce0.90Zr0.10Ox catalyst with the maximum strength of the (111) crystal plane of cerium oxide exhibited the better catalytic oxidation performance for the dehydrogenation of propane to propylene. Compared with ZrO2 in the blank experiment, the average propane conversion and propylene selectivity of the Ce0.90Zr0.10Ox catalyst were increased by 10.78% and 17.95%, respectively. [ABSTRACT FROM AUTHOR]

Multiwalled carbon nanotubes decorated MnO 2 nanoflowers with hexagonal structure (ɛ-MnO 2 /MWCNTs) were synthesized by one-step co-precipitation method and delivered stable reversible capacity, low charge transfer resistances and high diffusion coefficients during discharge and charge process. The superior zinc-ion storage performance of ɛ-MnO 2 /MWCNTs can be ascribed to the unique morphology and high theoretical capacity of MnO 2 , and high conductivity and stability of MWCNTs. [Display omitted] • The ɛ-MnO 2 /MWCNTs exhibits the excellent Zn2+ storage performance with fast kinetics. • The enhanced electrochemical performance of ɛ-MnO 2 /MWCNTs is ascribed to the synergistic effect of composites. • The structural stability of ɛ-MnO 2 is improved by carbon decoration. As a potential cathode for aqueous zinc-ion batteries, the low electrical conductivity and poor electrochemical kinetics of MnO 2 limit its further development and application. Herein, multiwalled carbon nanotubes decorated MnO 2 nanoflowers with hexagonal structure (ɛ-MnO 2 /MWCNTs) were synthesized by one-step co-precipitation method. The ɛ-MnO 2 /MWCNTs inherit the advantages of highly conductive MWCNTs and nanostructured MnO 2 , thus showing excellent zinc-ion storage capacity. The ɛ-MnO 2 /MWCNTs display high invertible capacity of 335.6 mAh/g at 0.2 A/g after 150 cycles, and long-term capacity of 115.7 mAh/g at 2.0 A/g after 4000 cycles. The results of kinetics tests further reveal that the MWCNTs decoration can reduce polarization of MnO 2 and accelerate its reaction kinetics. Thanks to these merits, the ɛ-MnO 2 /MWCNTs hold great potential for high performance eco-friendly batteries cathode material. [ABSTRACT FROM AUTHOR]

The solvothermal and wet chemical method was developed to synthesized the p-n heterostructures of the thin porous Co 3 O 4 nanosheets with ZnO nanoparticles. The resulting products were analyzed by using various characterization techniques. The results possessed that the presence of a large number of oxygen defects on the surface of Co 3 O 4 -ZnO-7 favors enhancing the NO 2 adsorption. Correspondingly, the formation of p-n heterojunction and the large surface area of the material itself increased the carrier density and exposed more active sites, which collectively boost the sensing performance to NO 2. The sensor showed a high response of 45.7 (S = R a /R g) to 100 ppm NO 2 at room temperature (RT = 25 °C), with a short response/recovery time (1.3/25 s), and the lower detection limit of the sensor reached 30 ppb, with good selectivity, reproducibility and stability. This study will offer the opportunity to develop new sensors with high response and fast response-recovery to NO 2 at room temperature. [Display omitted] • The abundance of oxygen vacancies and heterojunction formation of Co 3 O 4 -ZnO-7 enhance gas-sensing performance to NO 2. • The Co 3 O 4 -ZnO-7 sensor has a high response of 45.7 to NO 2. • The Co 3 O 4 -ZnO-7 sensor has a short response/recovery time (1.3 s/25 s). [ABSTRACT FROM AUTHOR]

Sonodynamic therapy (SDT) has attracted widespread interest in biomedicine, owing to its novel and noninvasive therapeutic method triggered by ultrasound (US). Herein, the Ti3C2 MXene nanosheets (Ti3C2 NSs) are developed as good sonosensitizers via a two-step method of chemical exfoliation and high-temperature treatment. With the high-temperature treatment, the oxygen defect of Ti3C2 MXene nanosheets (H–Ti3C2 NSs) is greatly increased. Therefore, the electron (e−) and hole (h+) generated by US can be separated faster due to the improved degree of oxidation, and then the recombination of e−-h+ can be prevented with the abundant oxygen defect under US irradiation, which induced the sonodynamic efficiency greatly to improve around 3.7-fold compared with Ti3C2 NSs without high-temperature treatment. After PEGylation, the H–Ti3C2-PEG NSs show good stability and biocompatibility. In vitro studies exhibit that the inherent property of mild photothermal effect can promote the endocytosis of H–Ti3C2-PEG NSs, which can improve the SDT efficacy. In vivo studies further display that the increased blood supply by the mild photothermal effect can significantly relieve hypoxia in the tumor microenvironment, showing photothermal therapy (PTT) enhanced SDT. Most importantly, the H–Ti3C2-PEG NSs can be biodegraded and excreted out of the body, showing no significant long-term toxicity. Our work develops the defective H–Ti3C2 NSs as high-efficiency and safe sonosensitizers for photothermal-enhanced SDT of cancer, extending the biomedical application of MXene-based nanoplatforms.

In this work, we prepared cubic nickel oxide (NiO) nanosheets and constructed NiO with oxygen defects induced by halogen Cl ions (NiO-Vo1). Cubic nickel oxide nanosheets were used as catalysts for electrocatalytic oxygen evolution reaction (OER) and oxidation of chiral 2-butanol. Under artificial simulated sunlight, NiO-Vo1 exhibited good photo-electrocatalytic OER activity and catalytic stability. The high catalytic activity is mainly attributed to the activation of nickel active sites by the halide ion-induced oxygen defect and the enhancement of photoinduced electron–hole separation efficiency. Furthermore, the electrocatalytic performance of oxygen-deficient nickel oxide for the oxidation of chiral 2-butanol was investigated. The results show the catalytic activity of NiO-Vo1 for electrocatalytic oxidation of 2-butanol to butanone compared with NiO. Interestingly, there is no significant difference in the electrocatalytic activity of NiO for (R)-(-)-2-butanol and (S)-(+)-2-butanol oxidation. When NiO-Vo1 was used as the catalyst, the catalytic oxidation reaction rate of (R)-(-)-2-butanol alcohol was significantly higher than that of (S)-(+)-2-butanol alcohol. At 1.77 V vs RHE voltage, the (R)-(-)-2-butanol alcohol has obvious oxidation reaction while the (S)-(+)-2-butanol alcohol is almost absent, realizing the selective electrocatalytic oxidation of (R)-(-)-2-butanol alcohol. This may be attributed to the difference in the interaction strength of chiral molecules with the surface defects of NiO after applying a voltage during the catalytic process, resulting in different catalytic activities. Here, our proposed strategy through the synergistic effect of applied voltage and surface defects provides a new approach for chiral molecule synthesis and efficient chiral resolution. The halide ion-induced defect-catalyst provides a new strategy for the preparation of efficient electrocatalytic water splitting OER and alcohol-selective oxidation catalysts. [ABSTRACT FROM AUTHOR]

Electrocatalytic water splitting is an emerging technology for the development of maintainable hydrogen energy. It remains challenging to manufacture a stable, efficient, and cost-effective electrocatalyst that can conquer the slow reaction kinetics of water electrolysis. Herein, A metal-organic framework (MOF) based material is manufactured and productively catalyze the oxygen evolution reaction (OER). The introduction of elemental nickel enhances the catalytic activity of Co-FcDA. The results show that single Ni was well doped in the CoNi-FcDA catalysts and the doping of Ni has a great influence on the OER activity of CoNi-FcDA catalysts. CoNi-FcDA displayed a low overpotential of 241 mV to arrive at the benchmark current density (10 mA cm−2) with a remarkably small Tafel slope of 78.63 mV dec−1. It surpassed the state-of-the-art electrocatalyst for OER, that is, RuO 2 (260 mV and 97.26 mV dec−1) in efficiency as well as instability. Density functional theory (DFT) calculations show that suitable Ni doping at the same time can increase the density of states of the Fermi level, resulting in excellent charge density and low intermediate adsorption energy. These discoveries provide a practical route for designing 2D polymetallic nanosheets to optimize catalytic OER performance. • Elemental Ni is doped and enhances the catalytic activity of Co-FcDA through one pot solvothermal reaction. • The OER overpotentials of CoNi-FcDA at 10 mA cm−2 only required 251 mV. • CoNi-FcDA increases the DOS of the Fermi level, which produce charge density and low intermediate adsorption energy. [ABSTRACT FROM AUTHOR]

For its high specific discharge capacity and low working voltage, lithium vanadate is considered a promising anode material. However, inherent low conductivity and unsatisfactory cycle performance limit its further application. In this work, doping at the V site does not destroy the crystal structure of lithium vanadate but also increases the lattice volume. Moreover, the increased content of oxygen defect in the presence of redox reaction effectively improves the electrochemical properties of lithium vanadate. At the same time, the enhancement of hydrophilicity effectively improves the migration rate of ions. Among all LiLa x V 3-x O 8 samples, LiLa 0.01 V 2.99 O 8 (LVO-La-10) demonstrates better rate and cycle performance. LVO-La-10 delivers specific discharge capacities of 93.5 mAh g1 at 0.5 C, and 42.8 mAh g−1 at 7 C, which is 17.4 and 16.7 mAh g−1 larger than that of lithium vanadate, respectively. Moreover, the capacity retention rate of LVO-La-10 (87.8%) is still higher than that of lithium vanadate (75.8%) at the rate of 0.2 C after 100 cycles. This work exhibits that increasing the lattice volume and oxygen defect of lithium vanadate effectively improves its electrochemical performance. [ABSTRACT FROM AUTHOR]

Erbium-doped silicon oxide thin films with different erbium contents are prepared by RF sputtering. It is found that the oxygen-related defects in the prepared films can sensitize Er3+ ions both in the photoluminescence and electroluminescence processes. When Er content is low, the injected electrons in the films will excite the oxygen-related defects in the silicon oxide with a non-radiative recombination, and then excite Er3+ ions by energy transfer. Meanwhile, when Er content is high, Er3+ ions can be both excited by hot electron collision and energy transfer. [ABSTRACT FROM AUTHOR]

Herein, p+‐silicon/air‐annealed manganese copper ferrite (MCF oxide) thin film/indium tin oxide (ITO) stacking photodetectors, capable of detecting light illuminations ranging from the visible to near‐infrared region, are fabricated. The MCF oxide photodetectors composed of earth‐abundant and eco‐friendly metal oxides are fabricated by radio‐frequency (RF) magnetron sputtering. The optical and photoconductive characteristics are investigated by photoluminescence (PL) spectrum, ultraviolet–visible spectroscopy (UV–vis), X‐ray diffractometer (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). Defect levels within the wide bandgap of MCF oxide semiconductor enable high sensitivity ranging from visible to near‐infrared illuminations. The device exhibits a fast photoresponse less than 10 ms, a high photosensitivity of 163, and a responsivity of 1.26 A W−1 under a bias voltage of −2 V. The device not only demonstrates peak performances under 800 nm illumination, but also exhibits considerable photosensitivity under visible light illuminations of 630, 532, and 450 nm. The noticeable performances make air‐annealed MCF oxide thin film device a viable candidate for next‐generation photodetectors. [ABSTRACT FROM AUTHOR]

Ag/CeO 2 /SBA-15 hybrid photocatalysts were synthesized and their catalytic activities were investigated in the photodegradation of Congo red (CR) under different conditions. The results of X-ray diffraction (XRD) analysis, Rietveld refinement, X-ray photoelectron spectroscopy (XPS) analysis, and DRS-UV–vis characterization confirmed that oxygen defects were created in CeO 2 layer and its concentration decreased on increasing of ceria loading of the catalysts. Ag0/Ag+ and Ce3+/Ce4+ couples coexisted in the Ag/CeO 2 /SBA-15 catalysts, resulting from the electrons transferring from Ag0 nanoparticles (AgNPs) to Ce4+ around the oxygen defects in CeO 2. The values of surface Ag0/Ag+ and Ce3+/Ce4+ ratios were correlated well with the variation of oxygen defect concentration and the photocatalytic activity. The catalysts with the lower CeO 2 content, i.e. 5–10 wt%, exhibited the better photocatalytic activity due to the formation of a greater number of oxygen defects and more electrons transferring between AgNPs and CeO 2. CR could be photodegraded with a higher conversion under acidic than basic condition, following the first order kinetics. A four-stage reaction mechanism consisting of the primary, secondary, aromatic ring opening, and mineralization steps was proposed. This work also confirms that the combination of computer simulation technique for the crystalline structure refinement with the catalytic experiments can gain new insights into the reaction mechanism and help to better understand the photocatalytic behaviors. [Display omitted] • Oxygen defects were created in the crystalline structure of ceria. • Electron transfer from Ag0 nanoparticles to CeO 2 takes place in Ag/CeO 2 /SBA-15; • Correlation of Ag0/Ag+ and Ce3+/Ce4+ ratios and oxygen defect concentration with their photoactivity was established. • CR could be photodegraded with a greater degree under acidic than basic condition. • A 4-stage CR photodegradation pathway was proposed. [ABSTRACT FROM AUTHOR]

Abstract The alkaline zinc-based batteries with high energy density are becoming a research hotspot. However, the poor cycle stability and low-rate performance limit their wide application. Herein, ultra-thin CoNiO2 nanosheet with rich oxygen defects anchored on the vertically arranged Ni nanotube arrays (Od-CNO@Ni NTs) is used as a positive material for rechargeable alkaline Ni–Zn batteries. As the highly uniform Ni nanotube arrays provide a fast electron/ion transport path and abundant active sites, the Od-CNO@Ni NTs electrode delivers excellent capacity (432.7 mAh g−1) and rate capability (218.3 mAh g−1 at 60 A g−1). Moreover, our Od-CNO@Ni NTs//Zn battery is capable of an ultra-long lifespan (93.0% of initial capacity after 5000 cycles), extremely high energy density of 547.5 Wh kg−1 and power density of 92.9 kW kg−1 (based on the mass of cathode active substance). Meanwhile, the theoretical calculations reveal that the oxygen defects can enhance the interaction between electrode surface and electrolyte ions, contributing to higher capacity. This work opens a reasonable idea for the development of ultra-durable, ultra-fast, and high-energy Ni–Zn battery.

Exploiting suitable photocathodes to achieve high photocurrent and long-term endurance is still a great challenge in photoelectrocatalytic CO 2 reduction (PEC CO 2) reactions. Herein, an In-doped Bi 2 O 3 decorated oxidized copper foam (CBIO/CF) self-standing photoelectric cathode is well designed by the self-assembly process without an externally added binder. Via sunlight-promoted strategy, CBIO/CF with a unique 3D hierarchical nanoflower structure displays a superior faradaic efficiency of 90.0 % towards HCOOH over a wide potential window from −0.87 ∼ −1.17 V RHE and reaches 97.8 % at −0.87 V RHE with a partial current density of 14.41 mA cm−2. The in-situ Fourier transform infrared spectroscopy (FTIR) analysis demonstrates the abundant oxygen defects induced by In doping boost CBIO/CF absorbing substantive intermediate species related with formate generations, and porous structure accelerating mass transportation. Moreover, the well-designed staggered p-n heterojunctions of Cu 2 O and In-doped Bi 2 O 3 on the surface of catalysts favor the generation and separation of electron/hole pairs and contribute to the photocatalytic reduction of CO 2 under a bias voltage. This work paves the way for rational regulation of self-supporting photoelectrode for PEC CO 2 to HCOOH with suitable conduction band valence bands and high performance and stability. [Display omitted] • The self-standing CBIO/CF catalyst with 3D hierarchical nanoflower structure offers abundant active sites for PEC CO 2 reduction. • The p-n hybrid heterojunctions of CBIO/CF photocathode result in high separation efficiency of carriers and holes. • The Cu 2 O/Cu foam electrode substrate provided superconductive highway to transfer electrons. • The CBIO photocathode exhibits enhanced CO 2 reduction to HCOOH with FE of 97.8 % at −0.87 V RHE with a J HCOO - of 14.41 mA cm−2 [ABSTRACT FROM AUTHOR]

High-entropy oxides (HEOs) is a new type of catalyst that has emerged in recent years. High-entropy oxides, which is doped by a variety of metal cations and form a single-phase solid solution with a uniquely stabilized structure, is a strong contender for ideal catalysts due to their elemental versatility and designability. However, high-entropy oxides (HEOs) had not yet emerged in the field of gas-phase catalysis, here we reported the selection of five metal salts Zn(NO 3) 2 ·6H 2 O, Cu(NO 3) 2 ·3H 2 O, Co(NO 3) 2 ·6H 2 O, Ni(NO 3) 2 ·6H 2 O and Fe(NO 3) 3 ·9H 2 O, a high-entropy oxide FeNiCuZnCoO x was successfully prepared and uniformly loaded on activated carbon using wet chemistry, it was applied to the catalytic oxidation and removal of SO 2 in industrial flue gas, and the structural mechanism of HEOs affecting desulfurization capacity was described. The oxygen vacancy structure produced by the typical lattice distortion effect of high-entropy oxides greatly improved the catalytic activity of activated carbon, and the desulfurization capacity was significantly improved, in which the maximum saturated adsorption reached 40.93 mg/g at 293 K. [Display omitted] Catalytic oxidation mechanism of KAC-HEOs. • Successfully prepared HEOs loaded on activated carbon and applied them to the catalytic oxidation and removal of SO 2 in industry for the first time. • Explained the mechanism of catalytic oxidation and removal of SO 2 using the unique oxygen defect structure of HEOs. • Solved the problem of loading agglomeration by chemical treatment, so that the HEOs was uniformly dispersed and the desulfurization capacity was enhanced. [ABSTRACT FROM AUTHOR]

Development of next-generation electrode materials for battery-like supercapacitors has paid unique impetus from both energy density and power density perspectives. This report provides a facile synthetic route for the preparation of nickel–cobalt oxalate (NiCo2C2O4). The material exhibits a specific capacitance (specific capacity) value of 1009 F g–1 (126 mAh g–1) at a current density of 1 A g–1. Further, the inclusion of g-C3N4 during the synthesis resulted in the formation of a nanoporous NiCo2C2O4/g-C3N4 composite, where the sheet-kind NiCo2C2O4 was uniformly decorated onto the graphitic carbon nitride (g-C3N4) thin sheets. Interestingly, the developed nanoporous NiCo2C2O4/g-C3N4 composite delivers a high specific capacitance (specific capacity) of 1263 F g–1 (158 mAh g–1) at 1 A g–1. In addition, the nanoporous composite network showed a high specific energy of about 35.54 Wh kg–1 at the specific power of 226.36 W kg–1. The electrochemical studies unveil that the materials stored charge through both surface redox and intercalation redox (battery-like) processes. The higher specific capacity of the composite could be attributed to the synergistic coupling between Ni and Co ions, high oxygen defect content, and the improved redox process of Ni/Co ions facilitated by the g-C3N4 support. In addition, a hybrid device was developed using NiCo2C2O4/g-C3N4 and activated charcoal (AC) as positive and negative electrodes, respectively. The hybrid device exhibited an extended voltage window of 1.5 V, and a good rate capability along with a maximum specific energy value of 18.4 Wh kg–1 at the specific power value of 732 W kg–1. [ABSTRACT FROM AUTHOR]

Developing efficient electrode material with rational design and structure remains a crucial and great challenge for the significant improvement of high-performance hybrid supercapacitors (HSCs). Particularly, the performance of the HSCs can be largely enhanced by designing the battery-type Faradaic material with well-defined morphology and defective engineering. Here, a facile and effective strategy is utilized to develop oxygen-deficient flower-like three-dimensional NiMoO 4−δ (O d -NMO) nanomaterial via hydrothermal process and following thermal-treatment under an inert-gas atmosphere. The presence of oxygen deficiency in the O d -NMO is evaluated utilizing various spectroscopy techniques by comparing the pristine NiMoO 4 (P-NMO) heat treated under an ambient atmosphere. The electrochemical studies indicate that the oxygen defect sites in the O d -NMO electrode have a considerable role in the betterment of supercapacitive performances. Hence, the O d -NMO electrode provides a large specific capacity of 789 mA h g−1 at 1 A g−1 with an excellent rate capability than the P-NMO (579 mA h g−1). Besides, the fabricated HSC based on O d -NMO flower and activated carbon as the positive and negative electrodes, delivers a specific capacitance as high as 153 F g−1 and accomplishes a large energy density (47.76 W h kg−1) and power density (51.69 kW kg−1) with improved long-term stability. [ABSTRACT FROM AUTHOR]

Herein, we report the synthesis of novel worm like structured SnO2 nanoparticles photocatalysts by chemical precipitation route from sodium stannate in the absence of a precipitating agent. The physico-chemical characteristics of the synthesized SnO2 were studied using powder X-ray diffraction (PXRD), Diffuse Reflectance Spectroscopy (DRS), Photoluminescence (PL), and High resolution transmission electron microscope (HRTEM) studies. PXRD and HRTEM analysis reveals the formation of amorphous SnO2 in the tetragonal crystal structure. XPS and PL characterization affirmed the presence of oxygen defects in SnO2, which could be due to Sn2+ present in the lattices. The optical band gap calculated using Kubelka-Munk method to be 3.8 eV. Photocatalytic studies of the prepared SnO2 catalyst showed 92% of Rhodamine-B (RhB) degradation in 120 min under UV irradiation. The enhanced dye degradation activity is attributed to oxygen defects in the SnO2 catalyst, which are responsible for the enhanced charge separation and inhibition of electron-hole pair recombination by trapping photogenerated electrons.

This work reports a strategy that integrates the carbon nanotube (CNT) supporting, ultrathin carbon coating and oxygen defect generation to fabricate the RuO 2 based catalysts toward the pH-universal hydrogen evolution reaction (HER) with high efficiencies. Specifically, the CNT supported RuO 2 nanoparticles with ultrathin carbon loricae and rich oxygen vacancies at the surface (C@OV-RuO 2 /CNTs-325) have been synthesized. The C@OV-RuO 2 /CNTs-325 shows superior activities and excellent durability for the HER. It only requires overpotentials of 36.1, 18.0, and 19.3 mV to deliver -10 mA cm -2 in the acidic, neutral, and alkaline media, respectively. Its HER activities are comparable to that of the Pt/C in the acidic media but higher than those of the Pt/C in the neutral and alkaline media. The C@OV-RuO 2 /CNTs-325 shows excellent HER durability with no activity losses for > 500 h in the acidic, neutral or alkaline media at -250 mA cm -2 . The density-functional-theory calculations indicate that the CNT supporting, the carbon coating, and the OVs can modulate the d-band centers of Ru, increasing the HER activities of C@OV-RuO 2 /CNTs-325, and stabilize the Ru atoms in the catalyst, increasing the durability of the C@OV-RuO 2 /CNTs-325. More interestingly, the C@OV-RuO 2 /CNTs-325 shows great potential for practical applications toward overall seawater splitting., (© 2024 Wiley‐VCH GmbH.)

Solid-oxide electrolysis cells are a clean energy conversion device with the ability to directly electrolyze the conversion of CO 2 to CO efficiently. However, their practical applications are limited due to insufficient CO 2 adsorption performance of the cathode materials. To overcome this issue, the A-site cation deficiency strategy has been applied in a layered perovskite PrBaFe 1.6 Ni 0.4 O 6-δ (PBFN) cathode for direct CO 2 electrolysis. The introduction of 5% deficiency at the Pr/Ba site leads to a significant increase in the concentration of oxygen vacancies (nonstoichiometric number δ of oxygen vacancies increased from 0.093 to 0.132), which greatly accelerates the CO 2 adsorption performance as well as the O 2- transport capacity toward the CO 2 reduction reaction (CO 2 RR). CO 2 temperature-programmed desorption indicates that A-site cation-deficient (PrBa) 0.95 Fe 1.6 Ni 0.4 O 6-δ (PB95FN) shows a larger desorption peak area and a higher desorption temperature. PB95FN also exhibits a greater presence of carbonate in Fourier transform infrared (FT-IR) spectroscopy. The electrical conductivity relaxation test shows that the introduction of the 5% A-site deficiency effectively improves the surface oxygen exchange and diffusion kinetics of PB95FN. The current density of the electrolysis cell with the (PrBa) 0.95 Fe 1.6 Ni 0.4 O 6-δ (PB95FN) cathode reaches 0.876 A·cm -2 under 1.5 V at 800 °C, which is 41% higher than that of PB100FN. Moreover, the PB95FN cathode demonstrates excellent long-term stability over 100 h and better short-term stability than PB100FN under high voltages, which can be ascribed to the enhanced CO 2 adsorption performance. The PB95FN cathode maintains a porous structure and tightly binds to the electrolyte after stability testing. This study highlights the potential of regulating oxygen defects in layered perovskite PrBaFe 1.6 Ni 0.4 O 6-δ cathode materials via incorporation of cation deficiency toward high-temperature CO 2 electrolysis.

Ferroelectric materials with the typical perovskite structure are widely used in capacitors, ultrasonic devices, oil drilling, transducers, and other fields. Lead-lanthanum-zirconium-titanate ceramics co-doped with Sn and Ba, have been widely investigated. However, there is little attention has been focused on the dielectric properties of barium-lanthanum-zirconium-titanate. Thus, in this work, Sn doped Ba0.955La0.03Zr0.02Ti0.98O3 ferroelectric ceramics were prepared via a classical high-temperature solid state reaction. Scanning Electron Microscopy (SEM) was used to observe the surface appearance of ceramics. The X-ray diffraction (XRD) patterns at room temperature, indicate that the ceramics are well crystallized. Impedance properties and dielectric properties reflect the characteristic of typical high temperature dielectric relaxation behavior. The conductive activation energy and the relaxation activation energy are obtained through the calculation of the Arrhenius law. The fitting results show that the dielectric relaxation behavior at high-temperature, was related to the oxygen defect. The electrical modulus verified the partial short-range carrier migration, also contribute to the high-temperature dielectric properties. [ABSTRACT FROM AUTHOR]

The influence of proton radiation on the achiral structural transition at 180° domain walls in tetragonal ferroelectric BaTiO3 is theoretically studied in this work. The proton-induced oxygen vacancy in ferroelectrics is predicted using the Monte Carlo Simulations, which increases with the increase of the proton fluence and the energy of the incident proton. A model based on the LGD is developed to investigate the influence of oxygen vacancy which is considered as a defect dipole on the achiral structural transition of Bloch–Néel type of domain wall. Under the proton radiation, the Bloch-type of domain wall shows the character of asymmetric because of the coupling of the polarization and the electric field, while the proton radiation just changes the magnitude of the polarization in the Néel-type of domain wall. [ABSTRACT FROM AUTHOR]

The structural and chemical properties of biogenic silica obtained from rice husk using an acid treatment were determined in order to explore its potential as a support in the synthesis of catalysts for the remediation of contaminants in water. Using thermogravimetric analysis (TG-DTG) the total amount of silanol groups on the surface was quantified and by means of DRIFT spectroscopy and TPR-NH 3 analysis, the amount of silanol groups present (isolated, geminal and vicinal) were identified and quantified. The silica structure was confirmed by XRD and a silica content of 99.3% was determined by XRF. The zeta potential measurements revealed an isoelectric point at pH 5.4. Finally, the presence of non-bridging oxygen centers – NBO type oxygen defects on the surface of the biogenic silica was identified by DRIFT and EPR spectroscopy techniques. New knowledge is uncovered aimed at the future exploration of rice husk silica produced by a more environmentally friendly method, as a potential support in the synthesis of catalysts. [Display omitted] • Silica rice husk has potential as a support in the synthesis of catalysts. • DRIFT spectroscopy and NH 3 -TPD allow quantification of silanol groups in biosilica. • Silica rice husk contains isolated, geminal, and vicinal silanol groups. • Zeta potential negative in biosilica is favorable in catalyst synthesis processes. • The chemical activation allows the generation of oxygen defects in biosilica. [ABSTRACT FROM AUTHOR]

[Display omitted] • By optimizing the internal electronic structure and exposing more active sites. • The synergistic effect of heterogeneous atoms and oxygen defects. • The unique hexagonal morphology is more favorable to the exposure of active sites. • The highly active and stable bifunctional cobalt oxide-based catalysts. Undesirable conductivity and insufficient electrocatalytic activity are the current bottlenecks of cobalt tetroxide from achieving efficient water electrolysis. Herein, by optimizing the internal electronic structure and the controlled design of the morphology, we design a unique hexagonal Mn-Co 3 O 4 -200 nanostructure that exhibits superior water electrolysis performance with low overpotentials and excellent long-term durability under strongly alkaline conditions, outperforming many other previously reported cobalt oxide-based compounds. Theoretical combined with characterization analysis indicates that introduced Mn atoms induce an increase in the high spin-orbital occupancy of Co2+ to optimize free energy of the OOH*→O 2 step, which excites the catalytic activity of the Co sites, resulting in a substantial increase in the catalytic activity of the Mn-Co 3 O 4. Furthermore, we briefly summarize the catalytic activity variation pattern of several catalysts with different microscopy morphologies and innovatively propose a more intuitive means to evaluate their exposed active areas. Compared with other morphologies, the special hexagonal morphology with abundant pores and large effectively exposed catalytic surface area can promote the exposure rate of active centers, mass transfer of electrolytes and diffusion of hydrogen and oxygen in the electrocatalytic process, thus accelerating the rate of electrocatalytic reactions. [ABSTRACT FROM AUTHOR]

Oxygen defects, surface acidity and catalytic activity of Keggin-type phosphotungstic acid dispersed on SBA-15 mesoporous catalyst were investigated. When the catalyst was calcined at different temperature, oxygen defects resulted from removal of terminal oxygen from W=O bond or cleavage of corner sharing W–Oc–W bond in the Keggin structure via dehydration or/and suface dehydroxylation. The catalyst contained both Lewis (L) and Brønsted (B) acid sites and their amount varied with the calcination temperature which could be correlated well with the conversion of 4,6-dibenzothiophene (4,6-DMDBT) in a model diesel using H2O2 as oxidant. L acid sites served as active sites for 4,6-DMDBT adsorption via electron donation-acception pathway and B acid sites helped oxygen transferring from peroxotungstate complex to sulfur atom in the adsorbed 4,6-DMDBT, benefiting the sulfone formation. [ABSTRACT FROM AUTHOR]

High‐performance electrocatalysts have been deeply investigated and widely explored to improve the energy conversion efficiency in advanced electrochemical technologies. As a vital rare‐earth oxide, CeO2 has shown great promise in catalysis for its feasible redox feature, high oxygen storage capacity, abundant surface oxygen defects, and structural robustness. The structural characteristics will boost the electrocatalytic activity and durability of CeO2‐based hybrids. In this Review, relevant research results focusing on recent hybrid materials between CeO2 and other functional species, including metal, metal oxides/hydroxides, metal sulfides and phosphides, towards the oxygen evolution reaction (OER), hydrogen evolution reaction (HER), and nitrogen reduction reaction (NRR) are summarized. This Review also highlights the key role of CeO2 and the structural design strategies in the hybrid electrocatalysts, including ion doping, interface and defect engineering, electronic structure optimization, and morphology control for catalytic output enhancement. Lastly, some scientific challenges and perspectives have been proposed, aiming to promote the development of other CeO2‐based hybrids for energy related electrocatalysis. [ABSTRACT FROM AUTHOR]

• In-situ surface-confined intergrowth mechanism is proposed for synthesis process. • Highly compacted V o -TiO 2 @C anode was rapidly synthesized by one-pot method. • Ultra-long cycling life up to 10,000 cycles is gained with high capacity retention. • High Na+ diffusion coefficients are obtained for highly compacted structure. TiO 2 as the promising anode material candidate of sodium-ion battery suffers from poor conductivity and slow ion diffusion rate, which severely hampers its development. Highly compacted TiO 2 /C microspheres without inner pores/tunnels are synthesized by a very facile one-pot rapid processing method based on novel in-situ surface-confined inter-growth mechanism. This highly compacted TiO 2 /C microspheres exhibit an excellent electrochemical performance of reversible Na+ storage despite with relatively large particle/aggregation size from submicrometer to micrometer. An outstanding cycling stability extending to 10,000 cycles is gained with a high retention capacity of 140.5 mAh g−1 at a current rate of 2 A g−1. An ultra-high reversible capacity of 362 mAh g−1 close to its theoretic specific capacity is obtained at a current rate of 0.05 A g−1. The successful combination of highly compacted structure with large particle size, excellent electrochemical performance as well as rapid cost-effective preparing process might provide a potential industrial approach for efficiently synthesizing electrode materials for Na ion batteries. [ABSTRACT FROM AUTHOR]

Highlights: Ultra-thin CoNiO2 nanosheet with rich oxygen defects anchored on the vertically arranged Ni nanotube arrays (Od-CNO@Ni NTs) is successfully constructed. The Od-CNO@Ni NTs electrode delivers extraordinary electrochemical performance. The theoretical calculations reveal that oxygen defects effectively improve the electrochemical kinetics and the surface electronic state structure of Od-CNO @ Ni NTs, thus exhibiting strong OH − adsorption capacity.The alkaline zinc-based batteries with high energy density are becoming a research hotspot. However, the poor cycle stability and low-rate performance limit their wide application. Herein, ultra-thin CoNiO2 nanosheet with rich oxygen defects anchored on the vertically arranged Ni nanotube arrays (Od-CNO@Ni NTs) is used as a positive material for rechargeable alkaline Ni–Zn batteries. As the highly uniform Ni nanotube arrays provide a fast electron/ion transport path and abundant active sites, the Od-CNO@Ni NTs electrode delivers excellent capacity (432.7 mAh g−1) and rate capability (218.3 mAh g−1 at 60 A g−1). Moreover, our Od-CNO@Ni NTs//Zn battery is capable of an ultra-long lifespan (93.0% of initial capacity after 5000 cycles), extremely high energy density of 547.5 Wh kg−1 and power density of 92.9 kW kg−1 (based on the mass of cathode active substance). Meanwhile, the theoretical calculations reveal that the oxygen defects can enhance the interaction between electrode surface and electrolyte ions, contributing to higher capacity. This work opens a reasonable idea for the development of ultra-durable, ultra-fast, and high-energy Ni–Zn battery. [ABSTRACT FROM AUTHOR]

Bifunctional oxygen catalyst is an important component in the cathode for rechargeable zinc‐air batteries. MnO2 catalysts have aroused intense interests owing to their promising activity for oxygen reduction reaction (ORR), which, however, is still not comparable to precious metal catalysts. To improve the ORR catalysis and meet the requirement for a bifunctional oxygen catalyst, MnO2 nanosheets are modified with Co, Ni or Fe via a facile solution‐based method. Among the modified samples, Co−MnO2 presents improved catalysis for both ORR and oxygen evolution reaction (OER). The modification introduces additional active sites for OER and induced more oxygen defects to further facilitate the ORR. Zn‐air batteries with the Co−MnO2 air cathode showed a higher peak power density of 167 mW cm−2, a lower potential gap of 0.75 V and a higher round‐trip efficiency of 63 % (5 mA cm−2) compared to MnO2 without modification. Good cycling stability of the battery is also achieved. The proper amount of cobalt species in the MnO2 is vital for achieving a balance between high performance and durable cycling. [ABSTRACT FROM AUTHOR]

• The OD-ZnO/C composites were engineered with defect-rich and defect-poor surfaces. • The OD-ZnO/C-N 2 -600 exhibited a high quantum yield of 0.13% under Vis-NIR. • The OD-ZnO/C-N 2 -600 showed superior stability compared to OD-ZnO/C-Air-500. • Both CO 2 – and HCOO– are the key intermediates on the surface of OD-ZnO/C-N 2 -600. • Both CO 2 activation and charge carrier mobility are critical in CO 2 photoreduction. Photocatalytic CO 2 reduction with H 2 O over wide bandgap semiconductor-based photocatalysts is significantly limited by the low light utilization efficiency and poor activation of CO 2 /H 2 O molecules on the photocatalyst's surface. Herein, we demonstrate that oxygen-deficient ZnO/carbon dot (OD-ZnO/C) hybrid, rationally engineered with synergistically enhanced CO 2 /H 2 O activation ability and increased light utilization efficiency, showed excellent full spectrum (UV, visible and NIR light)-driven CO 2 photoreduction. Under UV–Vis-NIR, Vis-NIR and NIR light separately, the optimized sample demonstrated high quantum yields of 0.26%, 0.13% and 0.05% for CO production, yields which are considerably superior to the reported values in the literature. The synergistic effects between OD-ZnO and carbon dots for visible- and NIR-driven CO 2 reduction were systematically investigated. Experimental results showed that both the defect-induced sub-band in OD-ZnO and the upconverting emission from the carbon dots effectively increased the light utilization efficiency within the UV–Vis to NIR region, and the heterojunctions formed between OD-ZnO and carbon dots promoted the efficient separation of charge carriers. Meanwhile, the defect-rich surface ensures the efficient adsorption and activation of CO 2 /H 2 O into the key intermediate CO 2 –, formate, and hydroxyl species, which are effectively converted under light illumination from UV–Vis to NIR region. Based on the combined results of the CO 2 photoreduction analysis and the material characterization, plausible CO 2 photoreduction pathways under visible and NIR light irradiation are proposed. [ABSTRACT FROM AUTHOR]

The experimental results obtained in the study on the possibility of sensitizing titanium dioxide (polymorphic anatase phase) to the visible region of the spectrum by doping and co-doping with impurities of non-metals in order to create effective photocatalysts for the decomposition of organic compounds have been analyzed. The presence of impurity atoms appears to result in a change in the electronic structure of the titanium dioxide matrix, in the appearance of “impurity bands” and in the narrowing of the energy gap of titanium dioxide. Such a modification is accompanied by an extension of the spectral range of sensitivity of photoactive solids to the longwavelength region of the spectrum and, therefore, can be used to improve the catalytic properties of these materials. Spectral manifestations of carbon impurities in titanium dioxide in the form of carbide and carbonate, as well as sulfur in the forms of sulfite, sulfide, and sulfate, have been studied by the density functional theory method. A Ti14H22O39 cluster model was chosen for the titanium dioxide matrix. The calculations were carried out in the framework of the cluster approximation, using functional B3LYP and basis set 6-31G (d, p). Comparison of the results of quantum chemical calculations with the available experimental data shows that the impurity sulfur and carbon atoms in titanium dioxide, which are in different coordination states and different oxidation states, appear in different spectral ranges. This circumstance makes it possible to elucidate the structure of the samples based on the experimental spectra. A change in the coordination and oxidation states of impurity atoms leads to spectral shifts and splitting of peaks, which can reach 1.5 eV (XPS). The presence of admixtures of non-metals leads to a change in color (deepening in the case of sulfide or carbide) of the samples, appearing in the corresponding UV spectra. [ABSTRACT FROM AUTHOR]

Summary Noncorrosive K2SO4 is found to be able to activate the chestnut shell carbon to oxygen‐enriched porous carbons. Chestnut shells are activated by K2SO4. The structure, texture, chemical state of surface of samples and morphology are analyzed via X‐ray diffraction, X‐ray photoelectron spectroscopy, Raman spectra, transmission electron microscopy and scanning electron microscopy, respectively. With the optimum amount of K2SO4 (m(K2SO4)/m(C) = 1.8), higher specific surface area (SSA, 1412 m2 g−1) and total pore volume (0.75 m2 g−1) are obtained. The prepared carbon samples exhibit a hierarchical textural structure making up of micropores, mesopores and macropores. More importantly, a large amount of oxygen defects, as high as 37.7%, and a small amount of sulfur element (0.31%‐0.79%) are successfully introduced on the surface of the carbons. The activation mechanism of K2SO4 is also investigated via thermogravimetry analysis (TGA) and differential scanning calorimetry (DSC), which put it down to the high‐temperature redox reaction between C and K2SO4. Owing to the high SSA, the composition of pore, and the abundant surface defects, the activated porous carbons originated from chestnut shell carbon possess highly enhanced capacitive properties. At 0.1 A/g, the specific capacitance reaches 265 F/g, and retains 92% of its starting value after 10 000 cycles at 10 A/g. In general, K2SO4 is a promising noncorrosive alternative to the conventional KOH activator. [ABSTRACT FROM AUTHOR]

• Atomic layer Co 3 O 4-x nanosheets (1 nm) are synthesized. • Robust OER and ORR activities are achieved for atomic layer Co 3 O 4-x nanosheets. • Rechargeable ZAB performance of Co 3 O 4-x nanosheets is 1.7 fold than Pt/C-IrO 2. Stable and efficient bifunctional electrocatalyst for air electrode is still of challenge for rechargeable zinc-air batteries (ZABs). Here, we report an atomic layer oxygen defect cobalt oxides (Co 3 O 4-x) nanosheets (1 nm) as efficient electrocatalyst for oxygen reduction reaction (ORR) and oxygen evolution reaction (OER). Due to the atomic layer nanosheets, more oxygen defects are formed during plasma treatment enabling effective OER catalysis with overpotential of only 309 mV, which is lower compared to benchmarking IrO 2 (313 mV). Meanwhile, a Pt-like ORR activity is achieved for Co 3 O 4-x due to the atomic layer nanosheets with highly exposed active sites and loosened binding strength between Co3+ and O 2 /OH−. The battery performance of Co 3 O 4-x nanosheets is 1.7 times higher than that of Pt/C-IrO 2 based ZABs. Besides, Co 3 O 4-x nanosheets exhibit undetectable degradation in battery performance after galvanostatic discharge-charge with 5 mA cm−2 for 150 h implying the superior stability of the atomic layer Co 3 O 4-x nanosheets. All-solid-sate ZABs fabricated from Co 3 O 4-x nanosheets perform an impressive power density of 57 mW cm−2 and stable galvanostatic discharge-charge voltage for 2 h demonstrating that Co 3 O 4-x nanosheets can be utilized as air electrode for practical application. [ABSTRACT FROM AUTHOR]

The recombination of interface charges hindered photocatalytic nitrogen fixation (NRR), but the introduction of surface oxygen defects (O V) and the construction of heterojunctions were found to effectively separate charges at the interface and enhance NRR efficiency. Here we successfully constructed the δ-Bi 2 O 3 /Bi 2 WO 6 (BBWO-3) heterojunction with a core-shell similar structures and O V -rich via a solvothermal method, where the δ-Bi 2 O 3 nanosheets were grown in-situ on the surface of Bi 2 WO 6 (BWO) hollow microspheres. The optimized BBWO-3 achieved a nitrogen fixation yield of 65.6 μmol−1·g−1 Cat under simulated sunlight, which was 6 times that of δ-Bi 2 O 3 and 2.8 times that of Bi 2 WO 6 , without needing sacrificial agents. The enhanced photocatalysis activity was attributed to O V and the formation of direct Z-Scheme heterojunction with core-shell similar structures, achieving effective spatial separation of photogenerated charges and providing a dedicated pathway for charge migration. At the meanwhile, since the bending of the band, an internal electric field (IEF) was formed from δ-Bi 2 O 3 to BWO at the interface, which accelerate the dynamics of charge transfer. Moreover, the mechanism of the NRR was elucidated based on density functional theory (DFT) and in-situ XPS. This study provides a new idea for the construction of O V -rich core-shell similar structures direct Z-Scheme heterojunction photocatalysts. [Display omitted] • The direct Z-Scheme δ-Bi 2 O 3 /Bi 2 WO 6 heterojunction with a core-shell similar structure was constructed. • The introduction of oxygen defects provided abundant active sites and reactant adsorption sites for NRR. • The delocalized electrons moved from δ-Bi 2 O 3 to BWO and formed an internal electric field (IEF). • The photocatalytic nitrogen fixation yield of BBWO-3 was 65.6 μmol−1·g−1 Cat. [ABSTRACT FROM AUTHOR]

[Display omitted] • ALD HfO 2 films grown under different oxidation conditions were examined. • Simply modified ALD process enables the defect passivation at the atomic layer level. • Leakage current density significantly decreased compared with conventional ALD. • Proposed ALD process is suitable for application on heat-sensitive substrates. HfO 2 films grown via atomic layer deposition (ALD) at low temperature generally exhibit high impurity content, reduced density, and increased oxygen defects, resulting in degraded electrical properties. To overcome this issue, this study applied an in-situ defect passivation technique at low temperature, modifying the ALD oxygen source feeding step to suit heat-sensitive substrates. The electrical properties of the ALD HfO 2 film grown at 80 °C are improved when the oxygen source feeding step is repeated twice, and especially the leakage current density is significantly decreased, which is approximately 1/7 smaller at an electric field of 1 MV/cm compared to the film grown via the conventional ALD process at 80 °C. This improvement in the electrical properties can be attributed to decreased carbon impurities and oxygen defects and increased film density. A simple modification of the oxygen source feeding step during the ALD process can effectively reduce defects within the ALD HfO 2 films at the atomic layer level, even when grown at low deposition temperatures. [ABSTRACT FROM AUTHOR]

Constructing efficient, durable, and economical catalysts to promote hydrogen production from hydrous hydrazine (N 2 H 4 ·H 2 O) is crucial, but still a great challenge. Herein, noble-metal-free Cr(OH) 3 -modified Ni nanoparticles (NPs) (2.7 nm) supported on defect-rich carbon-doped mesoporous TiO 2 nanosheets (C-TiO 2) were prepared for the first time via a simple and green wet-chemistry approach, in which the amount of oxygen defect in C-TiO 2 can be easily regulated by adjusting the amount of carbon doping. Significantly, the defect rich Ni-Cr(OH) 3 /C-TiO 2 catalyst presented 100% H 2 selectivity, ultrahigh catalytic activity, and remarkable durability for N 2 H 4 ·H 2 O dehydrogenation, with a turnover frequency (TOF) value of 266 h−1 at 323 K, more than 6-fold improvement than that of the Ni-Cr(OH) 3 /TiO 2 (41 h−1), which is among the highest values reported so far for noble-metal-free catalysts. The superior catalytic efficiency and durability are mainly owing to the small-sized and electron-rich of Ni NPs induced by the oxygen defects in C-TiO 2 , where the more oxygen defects, the better the catalytic activity. Furthermore, the catalyst also showed outstanding catalytic efficiency (TOF = 577 h−1) and robust durability for complete dehydrogenation of hydrazine borane (N 2 H 4 BH 3) at 323 K. This work provides inspiration for the construction of defect engineering and new insights for the development of low-cost and efficient heterogeneous hydrogen production catalysts. [Display omitted] • Cr(OH) 3 -modified Ni NPs supported on defect-rich C-TiO 2 were synthesized via a simple wet-chemistry method. • The oxygen defect concentration of C-TiO 2 can be controlled by easily adjusting the carbon doping amount. • The more oxygen defects, the better the catalytic activity. • TOF values of Ni-Cr(OH) 3 /C-TiO 2 for N 2 H 4 and N 2 H 4 BH 3 dehydrogenation are 266 and 577 h−1 at 323 K, respectively. [ABSTRACT FROM AUTHOR]

In this study, a non-activated ion-doped full-spectrum emission phosphor for white light-emitting diode (WLED) lighting is proposed using oxygen defect engineering. The YMZn 3 AlO 7 (M = Ca, Sr, Ba) phosphors with "114″ structure were prepared via a high-temperature solid-state reaction. Under excitation with 373 nm ultraviolet (UV) light, YSrZn 3 AlO 7 in YMZn 3 AlO 7 (M = Ca, Sr, Ba) exhibited the highest emission intensity and formed a wide yellow emission band centred at 563 nm. The full width at half maximum of the YSrZn 3 AlO 7 phosphor was 172.6 nm. A theoretical model based on the designed oxygen vacancies was proposed to determine the self-activated luminescence mechanism. Density functional theory calculations revealed that oxygen vacancies lead to the generation of new energy levels. Electron paramagnetic resonance experiments further confirmed that the luminescence originated from oxygen vacancies. Eventually, a warm WLED device ((x, y) = (0.4057, 0.4359)) with a correlated color temperature of 3814 K and a relative color rendering index of 83 was successfully prepared using the YSrZn 3 AlO 7 phosphor and a 365 nm UV LED chip. These results suggest that YSrZn 3 AlO 7 is a promising WLED phosphor and provide new insights into the application of self-activated phosphors in WLED. A novel self-activated YSrZn 3 AlO 7 phosphor has been prepared and its luminescence mechanisms have been analyzed. [Display omitted] • A novel self-activated YSrZn 3 AlO 7 phosphor (FWHM = 172.6 nm, QE = 56.9%) was prepared. • The influence of oxygen vacancies on band structure was investigated. • The mechanism of self-activated luminescence of YSrZn 3 AlO 7 phosphor was discussed. • A WLED device (R a = 83) was prepared using YSrZn 3 AlO 7 phosphor and 365 nm UV chip. [ABSTRACT FROM AUTHOR]