Oxide Microspheres Research Articles

Hollow Zinc Oxide Microsphere–Multiwalled Carbon Nanotube Composites for Selective Detection of Sulfur Dioxide

This work reports the first utilization of anthocyanin extracted from black rice (Oryza sativa L.) grains as a structure-directing agent for the synthesis of hollow zinc oxide (ZnO) spheres via a simple solvothermal reaction and their subsequent modifications with various amounts of multiwalled carbon nanotubes (MWCNTs). Following hybridization with MWCNTs, some MWCNTs are observed to penetrate into the inner cavities of the spheres, while ZnO nanoparticles are formed on the surface of some MWCNTs. When employed as a sulfur dioxide (SO2) sensor, the ZnO-MWCNT (15:1) composite displays a high response of 156 to 70 ppm of SO2 at an optimum temperature of 300 °C as well as good selectivity to SO2 with the response to 50 ppm of SO2 gas being 3 times higher than those to other gases, such as CO, CO2, methanol, toluene, hexane, and xylene. Interestingly, the sensing behavior of this composite is strongly influenced by the proportion of MWCNTs. Specifically, n-type sensing behavior is observed for both ZnO-MWCNT (10:1) and (15:1) composites, while p-type behavior is observed for the ZnO-MWCNT (5:1) composite. The switch in sensing behavior suggests the major contribution of p-type MWCNTs to the electronic and sensing properties of the ZnO/MWCNT composites. The density functional theory (DFT) simulations on the adsorption of SO2 on the ZnO/CNT system reveal that the SO2 molecule only chemically interacts with the O adatom of ZnO (i.e., oxygen atom adsorbed on the surface of ZnO) to form sulfur trioxide (SO3), and charge transfer is observed from ZnO to CNT, which enhances the change in resistance of the composite sensor upon exposure to SO2 gas.

Constructing hydrangea-like hierarchical zinc-zirconium oxide microspheres for accelerating fluoride elimination

The design and synthesis of scientific and rational adsorbents is an effective method for improving adsorption properties. Herein, innovative 3D hydrangea-like hierarchical porous zinc-zirconium oxide microspheres (HPZZ) were synthesized through a simple hydrothermal reaction and calcination process for enhanced fluoride adsorption in aqueous solutions. Benefiting from its distinctive structural and component advantages, the newly designed adsorbent delivered superior adsorption performance (107.41 mg/g), which outperformed most reported metal oxide-based adsorbents. The adsorption kinetics and isotherm data were precisely fitted by pseudo-second-order and Langmuir models. Furthermore, coexisting anions had insignificant effects on the HPZZ. More importantly, the adsorption mechanism between the HPZZ and fluoride could be attributed to electrostatic interactions, complexation, and ion exchange. Interestingly, the exhausted adsorbent could be regenerated for four cycles. A practical application test verified that the HPZZ was a rapid and effective adsorbent for groundwater purification. Therefore, this work brings a novel active material for fluoride decontamination, with the current work providing great significance in environmental research.

3D Hollow rGO Microsphere Decorated with ZnO Nanoparticles as Efficient Sulfur Host for High-Performance Li-S Battery

Lithium-sulfur battery (LSB) will become the next generation energy storage device if its severe shuttle effect and sluggish redox kinetics can be effectively addressed. Here, a unique three-dimensional hollow reduced graphene oxide microsphere decorated with ZnO nanoparticles (3D-ZnO/rGO) is synthesized to decrease the dissolution of lithium polysulfide (LiPS) into the electrolyte. The chemical adsorption of ZnO on LiPS is combined with the physical adsorption of 3D-rGO microsphere to synergistically suppress the shuttle effect. The obtained 3D-ZnO/rGO can provide sufficient space for sulfur storage, and effectively alleviate the repeated volume changes of sulfur during the cycle. When the prepared S-3D-ZnO/rGO was used as the cathode in LSB, an initial discharge specific capacity of 1277 mAh g−1 was achieved at 0.1 C. After 100 cycles, 949 mAh g−1 can still be maintained. Even at 1 C, a reversible discharge specific capacity of 726 mAh g−1 was delivered.

Hierarchical Hollow Bimetal Oxide Microspheres Synthesized through a Recrystallization Mechanism for High‐Performance Lithium‐Ion Batteries

AbstractBimetal oxide with its intricate nanostructure holds great potential for high‐performance electrode materials in lithium‐ion batteries (LIBs). Herein, a facile strategy for the fabrication of hierarchical hollow Co3O4/ZnCo2O4 microspheres is developed, involving a simple solvothermal synthesis and subsequent thermal annealing in air. An aggregation‐dissolution‐in situ recrystallization structure evolution and growth mechanism is proposed. Benefiting from the unique hierarchical hollow structure with rational porosity, synergistic effect of bimetal components, and better electrical conductivity, the as‐synthesized Co3O4/ZnCo2O4 hierarchical hollow microstructure shows outstanding lithium storage properties. As a result, a superior rate capability (842 mA h g−1 at a current density of 4 A g−1) and an excellent cycle life (754 mA h g−1 after 800 cycles at a current density of 2 A g−1) are obtained. The presented strategy could be applicable to the synthesis of mixed metal oxide hierarchical hollow structures with rational porosity for high‐performance LIBs.

PH-responsive silk fibroin-based CuO/Ag micro/nano coating endows polyetheretherketone with synergistic antibacterial ability, osteogenesis, and angiogenesis

Polyetheretherketone has been widely used for bone defect repair, whereas failures may happen due to implant loosening and infection. Thus, PEEK implant with multi-function (osteogenesis, angiogenesis, and bacteria-killing) is essential to solve this problem. Herein, copper oxide microspheres (µCuO) decorated with silver nanoparticles (nAg) were constructed on porous PEEK surface via silk fibroin. In vitro studies highlighted the pH controlled release ability of this coating. It liberated a high dose of Cu2+ and Ag+ at low pH environment (pH 5.0), leading to 99.99% killing of planktonic bacteria and complete eradication of sessile bacteria, avoiding biofilm formation. Under physiological environment (pH 7.4), a lower amount of leaked metal ions induced promoted ALP production, collagen secretion, and calcium deposition, as well as NO production, which indicated potentiated osteogenesis and angiogenesis. In vivo results displayed the highest new bone volume around, and the appearance of new bone inside porous structure of, PEEK implant with this coating in rabbit tibia, signified the abilities of this coating to promote bone regeneration and osseointegration. Our study established solid support for implants with this coating to be a successful bone defect repair solution. Statement of SignificanceIn this study, CuO/Ag micro/nano particles were incorporated into the porous surface of PEEK through polydopamine and silk fibroin layers. The design of this coating conferred pH-controlled release behavior to Cu2+ and Ag+. High dose of metal ions were released at pH 5.0, which presented synergistic antibacterial ability and killed 99.99% of planktonic bacteria. Low concentration of metal ions were controlled by this coating at physiological environment, which potentiated osteodifferentiation of Ad-MSC in vitro and led to complete integration of implant with bone tissue in vivo.

Synthesis of Flower-Like Co9S8/Reduced Graphene Oxide Nanocomposites and Their Photocatalytic Performance

The novel flower-like Co9S8/reduced graphene oxide (rGO) microsphere nanocomposites were synthesized using wet chemical method in combination with a spray drying technique. The structures and morphologies of as-synthesized Co9S8/rGO nanocomposites were characterized by X-ray diffractometer (XRD), scanning electron microscopy (SEM) and transmission electron microscope (TEM). The results reveal that Co9S8 is homogeneously dispersed on the surface of rGO microspheres. The significantly enhanced photocatalytic activity of Co9S8/rGO nanocomposites in comparison with a pure Co9S8 was investigated by the degradation of methylene blue (MB) using ultraviolet (UV) spectroscopy. The photodegradation ratios of MB using flower-like Co9S8/rGO nanocomposites with a Co9S8 mass ratio of 67.3, 35.3 and 55.6 wt% are about 86.7, 92.0, and 98.7%, respectively, after irradiation for 80 min. By comparing the nanocomposites and pure flower-like Co9S8, the pure Co9S8 showed less photocatalytic activity upon the degradation of MB than the nanocomposites. It can be attributed to the improved electron–hole pair separation and enhanced adsorption due to the presence of rGO microspheres.

Simple sonochemical synthesis of SrCuO2 assisted GCN nanocomposite for the sensitive electrochemical detection of 4-AAP

The present study demonstrates the development of an electrochemical sensor to detect and quantify 4- Aminoantipyrene (4-AAP), using strontium copper oxide (SrCuO2) microspheres and graphitic carbon nitride (GCN) as a composite in the modified graphite electrode. The SrCuO2 is synthesized by sonochemical method and GCN was prepared using pyrolysis method. Field emission scanning electron microscopy (FESEM), X-ray diffraction spectroscopy (XRD) techniques are used in the characterization of the synthesized materials. Subsequently, the well characterized GCN and SrCuO2 are deposited onto a graphite (Gr) surface and used as transducer material in the fabrication of the electrode. Electrochemical characterization of the as fabricated electrode was carried out with the help of electrochemical impedance spectroscopy (EIS). The results validated the conducting nature of SrCuO2 and GCN. In Comparison with the unmodified electrode, the proposed Gr/SrCuO2/GCN electrochemical sensor, displayed enhanced electrocatalytic behavior towards 4-AAP. The sensor's analytical performance is calibrated and evaluated by cyclic voltammetry (CV) and Differential pulse voltammetry (DPV). The sensor exhibited exceptional characteristics like wide linear range, low detection limit. In addition, the proposed sensor also showed an excellent repeatability, good reproducibility and superior stability. Finally, the real sample analysis results indicated an acceptable recovery range that endeavored the use of the proposed sensor to monitor 4-AAP.

To effectively drive the conversion of sulfur with electroactive niobium tungsten oxide microspheres for lithium−sulfur battery

Abstract Realizing high energy density is the desirable target of the research and development for lithium−sulfur battery. However, the demands of high sulfur content in composite, high sulfur loading in electrode, and low electrolyte usage are likely excessive for reaching both high gravimetric and volumetric capacities of sulfur cathode with conventional inactive hosts of sulfur. Herein, in order to effectively drive the conversion of sulfur, niobium tungsten oxide (Nb18W16O93) microspheres are adopted as electroactive host in the similiar electrochemical window to sulfur. As expected, Nb18W16O93 shows good electrochemical activity for lithium storage, and strong adsorption toward polysulfides. In particular, the in-situ electrochemically lithiated oxide in the discharge process can serve as good electrocatalyst and lithium-transfer bridge, facilitating the conversion of both the solid sulfur and soluble polysulfides. Correspondingly, the new lithium-transfer mechanism on Nb18W16O93 endows the sulfur cathode a high areal capacity (19.19 mAh cm−2) under both high sulfur loading (16.94 mg cm−2) and low electrolyte/sulfur ratio (4.5 μL mg−1). In addition, the sulfur-based composite with high tap density (1.56 g cm−3) shows a desired volumetric capacity (1605.3 mAh cm−3-composite), almost 1.9 times of that for the conventional S/carbon composite. This work provides a new perspective for understanding the electroactive hosts in lithium−sulfur battery.

A new nanozyme with peroxidase-like activity for simultaneous phosphoprotein isolation and detection based on metal oxide affinity chromatography: Monodisperse-porous cerium oxide microspheres

Monodisperse-porous cerium oxide (CeO2) microspheres obtained by a new method were used for simultaneous phosphoprotein isolation and detection for the first time. The synthesis method, “staged sol-gel templating protocol” provided monodisperse-porous CeO2 microspheres 5.0 μm in size, with the specific surface areas and the pore volumes up to 80 m2/g and 0.41 cm3/g, respectively. CeO2 microspheres were directly used as a metal oxide affinity chromatography (MOAC) sorbent without any post-functionalization protocol. The isolation/enrichment of phosphoproteins from complex biological samples such as milk and human serum was performed using CeO2 microspheres as the sorbent, with the purities up to 99%. In batch MOAC runs, the equilibrium adsorption capacities of 105.3 and 82.4 mg phosphoprotein/g sorbent were obtained for α-casein and β-casein, respectively. CeO2 microspheres also exhibited peroxidase-like activity and were proposed as a new nanozyme for colorimetric determination of phosphoprotein concentration in complex samples. Maximum substrate consumption rate and Km were determined as 384.6 μM/min and 2885.8 μM, respectively, according to Michealis-Menten model. The peroxidase-like activity of CeO2 microspheres linearly decreased with the increasing phosphoprotein concentration while no appreciable change in this magnitude was observed with the increasing non-phosphoprotein concentration. This behavior was explained by the increase in the pseudospecific phosphoprotein adsorption onto CeO2 microspheres with the increasing phosphoprotein concentration. Similar linear tendencies between peroxidase-like activity and phosphoprotein concentration observed in the complex samples such as human serum and milk allowed the determination of phosphoprotein concentration up to 300 and 400 μg/mL, respectively, using CeO2 microspheres as the nanozyme. This study provided a new, unique material having a dual function termed as isolation and detection of large phosphorylated molecules without applying any post-functionalization protocol.

Graphene Oxide-Crospolyvinylpyrrolidone Hybrid Microspheres for the Efficient Adsorption of 2,4,6-Trichlorophenol.

Microspheres of the graphene oxide and crospolyvinylpyrrolidone composite (GO–PVPP) were prepared via suspension polymerization and investigated for the adsorption of 2,4,6-trichlorophenol (2,4,6-TCP) from wastewater. The microspheres were thoroughly characterized using scanning electron microscopy, infrared spectroscopy, N2 physisorption, elemental analysis, X-ray diffraction, and thermogravimetric analysis. The GO–PVPP microspheres comprised GO sheets on the surface and demonstrated good thermal stability, good swelling rate, and excellent adsorption capacity of 2,4,6-TCP (up to 466.77 mg/g). The adsorptions were determined as a function of pH, temperature, adsorbent loading, adsorption time, and initial content of 2,4,6-TCP in the solutions. The sorption kinetics was satisfactorily modeled using the pseudo-second-order rate equation, and the sorption equilibrium can be described using the Freundlich model. The 2,4,6-TCP adsorption by GO–PVPP was shown to be endothermic and spontaneous. The reusability of GO–PVPP was also demonstrated by the adsorption and desorption cycles.

Development and deployment of 141Ce fiducial marker sources for supplementing nuclear diagnostic procedures

A facile method to prepare 141Ce based fiducial marker sources was developed to put forward an alternate to 99mTc markers routinely used during nuclear imaging procedures. Cerium oxide microspheres were prepared as source substrate by ‘internal gelation process’. ‘State-of- the art’ analyzing tools were used for characterizing the substrate. Neutron irradiation of microspheres in ‘Dhruva’ reactor was optimized. Post irradiation and quality evaluation, the sources were enclosed in an in-house developed portable device. 141Ce sources containing 37–59 MBq (1.0–1.6 mCi) of 141Ce were supplied to three nuclear imaging centres. Newly developed 141Ce fiducial markers could successfully supplement real time SPECT imaging procedures.

Mulberry-like hollow rGO microspheres decorated with CoO nanoparticles as efficient polysulfides anchoring for Li-S batteries

Lithium-sulfur batteries (LSB) became recently one of the most promising next-generation energy storage devices due to their high energy density and low cost. However, its large-scale commercial application is hindered by severe shuttle-effect and insulation of the sulfur. Herein, in order to overcome these disadvantages, mulberry-like three-dimensional hollow reduced graphene oxide microspheres modified with cobalt oxide nanoparticles (CoO/MGra) were designed as sulfur host. CoO/MGra possesses not only excellent electrical conductivity but also provides sufficiently large space for the storage of sulfur. The three-dimensional hollow structures can also significantly alleviate the volume expansion of sulfur during the cycling process. At the same time, the shuttle effect is suppressed due to the efficient chemical adsorption towards lithium polysulfide by CoO nanoparticles. As a result, excellent cycle stability (1010 mAh g−1 after 150 cycles at 0.2C) and outstanding rate performance (745 mAh g−1 at 3C) are achieved when using the S-CoO/MGra cathode.

Oxygen vacancies boosting ultra-stability of mesoporous ZnO-CoO@N-doped carbon microspheres for asymmetric supercapacitors

Long-term cycling stability of pseudocapacitive materials is pursued for high-energy supercapacitors. Herein, the mesoporous zinc-cobalt oxide heterostructure@nitrogendoped carbon (ZnO-CoO@NC) microspheres with abundant oxygen vacancies are self-assembled through a hydrothermal method combined with an annealing post-treatment. The multifunctional polyvinyl pyrrolidone (PVP) is used as a structure-directing agent, the precursor of NC and the initiator of abundant oxygen vacancies in zinc-cobalt oxide microspheres. XPS demonstrates the generation of surface oxygen vacancies resulted from the reduction effect of conductive NC, and further confirms the weaker interaction between the metal ions and oxygen atoms. As a result, the electrode based on ZnO-CoO@NC in 2 mol L−1 KOH shows enhanced capacitive performance with an excellent cycle stability of 92% retention of the initial capacitance after 40,000 charge-discharge cycles at 2 A g−1, keeping the morphology unchanged. The assembled asymmetric supercapacitor, graphene//ZnO-CoO@NC, also performs good cyclic stability with 94% capacitance retention after 10,000 cycles at 2 A g−1. The remarkable electrochemical performance of the self-assembled ZnO-CoO@NC composite is attributed to the mesoporous architecture, abundant oxygen vacancies, conductive ZnO scaffold for CoO crystals forming heterostructure of ZnO-CoO and the high conductive NC layer covering outside of the multi-metal oxide nanoparticles. Hence, the ZnO-CoO@NC holds great promise for high-performance energy storage applications.

Carbon-templated strategy toward the synthesis of dense and yolk-shell multi-component transition metal oxide cathode microspheres for high-performance Li ion batteries

Development of efficient strategies for the synthesis of multicomponent microspheres applicable to cathodes in lithium ion batteries is in urgent need. This paper presents ‘drop and dry’ method for synthesizing dense and yolk-shell multicomponent transition metal oxide microspheres. The infiltration of ethanol solution containing several metal precursors into highly porous carbon template microspheres through repetitive drop and dry process and subsequent heat treatment under oxygen atmosphere result in dense and yolk-shell microspheres. The first target cathode material is LiMn1.5Ni0.5O4, which operates at high voltage. After infiltration of Li, Mn, and Ni salts into the pores of the carbonaceous microspheres, stepwise heat treatment under low oxygen flow rate yields dense LiMn1.5Ni0.5O4 microspheres exhibiting non-aggregation characteristics and narrow size distribution. In comparison, one-step oxidation of carbon microspheres containing metal salts under high oxygen flow rate results in yolk-shell LiMn1.5Ni0.5O4 microspheres. The dense and yolk-shell microspheres exhibit stable cycle performance and capacities of 113 and 111 mA h g−1 are delivered after 1200 cycles at 10 C rate, respectively. In addition, discharge capacities of 69 and 44 mA h g−1 for yolk-shell and dense microspheres, respectively, are delivered at a high current density of 50 C.

Preparation and characterization of a novel ethanol gas sensor based on FeYO3 microspheres by using orange peels as bio-templates

The perovskite Iron Yttrium Oxide (FeYO3) microspheres on the basis of bio-templates with orange peels have been successfully obtained by a facile hydrothermal ‘green synthesis’ along with multifarious characterization techniques. The XRD demonstrated that the synthesized sample was single phase FeYO3 with a hexagonal perovskite structure. Moreover, the solid microspheres with relatively rough surfaces were displayed by SEM and TEM. Benefiting from this fact, the sensor based on p-type semiconductor FeYO3 microspheres showed good gas sensing characteristics towards ethanol at the optimum operating temperature of 330 °C with a low detection limit (1 ppm), good repeatability and fast response/recover time, etc. Accordingly, this work supplies a good experimental basis for FeYO3 as a novel semiconductor gas sensing material soon.

Catalytic soot oxidation using hierarchical cobalt oxide microspheres with various nanostructures: Insights into relationships of morphology, property and reactivity

While diesel engines are extensively employed, soot from diesel engines lead to serious air pollution, which should be eliminated through catalytic soot oxidation processes. As Co3O4 represents a practical catalyst for oxidizing soot, it is critical to further investigate relationships of morphology-property-reactivity of Co3O4 catalysts for optimizing design of Co3O4 for soot oxidation. Thus, the present study, as the first attempt, aims to manipulate morphologies of Co3O4 microspheres to exhibit different surficial hierarchical nanostructures for comparing their corresponding catalytic activities. Specifically, four hierarchical Co3O4 microspheres (HCOMs) are fabricated, including Co3O4 with flower morphology (COF), Co3O4 with urchin morphology (COU), Co3O4 with sheet morphology (COS), and Co3O4 with pyramid morphology (COP), for comparisons in catalytic soot oxidation. The results indicate that these HCOMs showed much higher catalytic activities than the commercial spherical Co3O4 nanoparticles and most of reported cobalt-based catalysts as these HCOMs possessed high surface areas and porous nanostructures. In particular, among these HCOMs, COP stood out as the most advantageous HCOM for soot oxidation as COP contained more reactive surface and more superior redox properties than other HCOMs, thereby enabling COP to accelerate soot oxidation. These HCOMs could be also recyclable for soot oxidation over multiple cycles without loss of catalytic activities. These results and findings demonstrate that HCOMs are certainly promising cobaltic catalysts for oxidizing soot, and, through this present study, the relationship between morphologies, properties and catalytic activities can be correlated to provide important insights to design and apply hierarchically nanostructured Co3O4 catalysts for soot oxidation.

Use of a pressurized water treatment to prevent cracking of internal gelation sol-gel microspheres

Pressurized water treatments were investigated as a means to prevent cracking of internal gelation sol-gel microspheres upon drying and heating. A batch of gelled cerium oxide microspheres was prepared, split into two samples that were processed with and without a pressurized water treatment, and dried in air at room temperature. Thermogravimetric analysis was used to compare the mass loss profiles between the two samples and to understand volatile emissions from cerium oxide microspheres during heat treatments up to 600 °C. Microspheres that were processed without a pressurized water treatment lost ~4.6 times more mass upon heating than microspheres that were subjected to a pressurized water treatment. Comparison of the cracking behavior of microspheres prepared with and without a pressurized water treatment indicated that microspheres subjected to a pressurized water treatment were virtually crack-free after heat treatments. Conversely, microspheres processed without a pressurized water treatment, which is typical of traditional washing processes, exhibited extensive cracking. Analysis of residues dried from pressurized water treatment effluents indicated that hexamethylenetetramine and urea, which are excess reactants from the internal gelation process, were removed from gelled microspheres during the pressurized water treatment step. Traditional processing methods for preparing internal gelation microspheres use specific feed solution and gelation parameters to reduce subsequent cracking upon drying and heating. Results from this study indicate that more aggressive gel-forming conditions may be used to produce crack-free microspheres, if a pressurized water treatment step is included after washing and before air-drying.

Synthesis and Photocatalytic Activity of Cu2O Microspheres upon Methyl Orange Degradation

Cuprous oxide (Cu2O) microspheres were synthesized through a simple chemical method by using ascorbic acid (AA) as reducing agent at room temperature and short reaction time. The influence of the reducing agent and ammonium hydroxide (NH4OH), as well as reaction time, on the morphology, size, and crystalline phase structure of Cu2O were explored. The obtained materials were characterized by X-ray diffraction, scanning electron microscopy, nitrogen physisorption, and temperature-programmed reduction, whereas the catalytic activity was assessed using the photodegradation of methyl orange (MO). It was found that AA was responsible for the Cu2O nanoparticles self-assembling into Cu2O microspheres after 0.16 h of reaction time. Quantum theoretical calculations revealed that self-assembly is due to the hydrophilic modification of the Cu2O-nanoparticles driven by the parallel-to-surface dehydroascorbic acid chemisorption; likewise, the simulation of a mesoscopic molecular dynamics confirmed that the amphiphilic-like nature of the dehydroascorbic acid-Cu2O complexes leads to nanoparticles’ spherical morphology. The NH4OH concentration affected the porosity and crystalline phase of the microspheres. The porous Cu2O microspheres modified into well-defined Cu0 polyhedrons with the reaction time. The Cu2O microspheres exhibited high photocatalytic activity up to 76% during decolorization of MO. Two catalytic processes were distinguished: the removal of organic compound controlled by the faceting of the particles under dark conditions, and its photodegradation using visible light increased by the porosity of the Cu2O microspheres.

Carbon Nanotubes Coupled with Metal Ion Diffusion Layers Stabilize Oxide Conversion Reactions in High-Voltage Lithium-Ion Batteries.

Creating new architectures combined with super diverse materials for achieving more excellent performances has attracted great attention recently. Herein, we introduce a novel dual metal (oxide) microsphere reinforced by vertically aligned carbon nanotubes (CNTs) and covered with a titanium oxide metal ion-transfer diffusion layer. The CNTs penetrate the oxide particles and buffer structural volume change while enhancing electrical conductivity. Meanwhile, the external TiO2-C shell serves as a transport pathway for mobile metal ions (e.g., Li+) and acts as a protective layer for the inner oxides by reducing the electrolyte/metal oxide interfacial area and minimizing side reactions. The proposed design is shown to significantly improve the stability and Coulombic efficiency (CE) of metal (oxide) anodes. For example, the as-prepared MnO-CNTs@TiO2-C microsphere demonstrates an extremely high capacity of 967 mA h g-1 after 200 cycles, where a CE as high as 99% is maintained. Even at a harsh rate of 5 A g-1 (ca. 5 C), a capacity of 389 mA h g-1 can be maintained for thousands of cycles. The proposed oxide anode design was combined with a nickel-rich cathode to make a full-cell battery that works at high voltage and exhibits impressive stability and life span.

Turning the activity of Cr–Ce mixed oxide towards thermocatalytic NO oxidation and photocatalytic CO2 reduction via the formation of yolk shell structure hollow microspheres

Cr–Ce mixed oxides microspheres will have considerable potential in thermocatalytic NO oxidation and photocatalytic CO2 reduction reaction (CO2RR) if their low porosity and expensive synthetic expenditure can be overcome. To avoid these obstacles, a facile and economical strategy was adopted to synthesize double-shelled hollow Cr–Ce mixed oxide microspheres. The highly active multipurpose catalyst achieved an ultrahigh thermocatalytic NO oxidation efficiency at low temperatures, and provided high yields of CH4 and CH3OH during the photocatalytic CO2RR. For NO oxidation, the optimized catalyst provided over 40% NO removal at 150 °C, which was ascribed to the reduced aggregation of the active subunits and the increased active species availability. Further, the exposed surface could generate an increased content of Cr6+ and Oβ, which played the key role in NO oxidation. For CO2 photocatalytic reduction, the superior behavior originated from the reduced band gap and the effective separation of photoinduced charge carriers. This study opens up new possibilities of using Cr–Ce mixed oxides for application in catalysis.