Facile Sol-gel Method Research Articles

Sunlight-Driven Photocatalytic Active Fabrics through Immobilization of Functionalized Doped Titania Nanoparticles.

Frequent washing of textiles poses a serious hazard to the ecosystem, owing to the discharge of harmful effluents and the release of microfibers. On one side, the harmful effluents from detergents are endangering marine biota, while on the other end, microplastics are observed even in breastfeeding milk. This work proposes the development of sunlight-driven cleaning and antibacterial comfort fabrics by immobilizing functionalized Zn-doped TiO2 nanoparticles. The research was implemented to limit the use of various detergents and chemicals for stain removal. A facile sol-gel method has opted for the fabrication of pristine and Zn-doped TiO2 nanoparticles at three different mole percentages of Zn. The nanoparticles were successfully functionalized and immobilized on cotton fabric using silane coupling agents via pad-dry-cure treatment. As-obtained fabrics were characterized by their surface morphologies, availability of chemical functionalities, and crystallinity. The sunlight-assisted degradation potential of as-functionalized fabrics was evaluated against selected pollutants (eight commercial dyes). The 95-98% degradation of dyes from the functionalized fabric surface was achieved within 3 h of sunlight exposure, estimated by color strength analysis with an equivalent exposition of bactericidal activities. The treated fabrics also preserved their comfort and mechanical properties. The radical trapping experiment was performed to confirm the key radicals responsible for dye degradation, and h+ ions were found to be the most influencing species. The reaction pathway followed the first order kinetic model with rate constant values of 0.0087 min-1 and 0.0131 min-1 for MB and MO dyes, respectively.

Achieving outstanding mechanical/bonding performances by epoxy nanocomposite as concrete–steel rebar adhesive using silane modification of nano SiO2

Anchoring steel rebar in concrete structures is a common method in the building and construction industry. This research focuses on improving the mechanical/bonding properties of the prepared epoxy nanocomposite adhesive using surface treatment of SiO2 nano fillers by glycidoxypropyltrimethoxysilane (GPTMS). For this purpose, the nano silica particles were silanized via a facile sol–gel method at silane concentrations of 1, 5, 10 and 20X (i.e. X is stoichiometric silane concentration). The nanoparticles were characterized carefully by FTIR, TGA, XRD and XPS techniques. It was found that the highest GPTMS grafting ratio was obtained at silane concentration of 10X. The pure and silanized nanoparticles were added to a two-pack epoxy resin and were compared for tensile and compressive properties. It was found that surface modification of nano silica caused improvement in the strength, modulus, compressive strength and compressive modulus by 56, 81, 200 and 66% compared to the pristine epoxy adhesive and also 70, 20, 17 and 21% compared to the pure nano silica containing adhesive. It also caused 40 and 25% improvement in the pullout strength, 33 and 18% enhancement in the pullout displacement and 130 and 50% in adhesion energy compared to the pristine and raw silica-containing adhesives, respectively.

Enhanced Photocatalytic Coupling of Benzylamine to N-Benzylidene Benzylamine over the Organic-Inorganic Composites F70-TiO2 Based on Fullerenes Derivatives and TiO2.

The organic-inorganic composites F70-TiO2, based on fullerene with carboxyl group derivatives and TiO2 semiconductor, have been designed and constructed to become an optical-functional photocatalyst via the facile sol-gel method. The composite photocatalyst obtained shows excellent photocatalytic activity for the high-efficiency conversion of benzylamine (BA) to N-benzylidene benzylamine (NBBA) with air pressure at a normal temperature under visible light irradiation. By optimizing the composition, the composites with the 1:15 mass ratio of F70 and TiO2, denoted as F70-TiO2(1:15), demonstrated the highest reaction efficiency for benzylamine (>98% conversion) to N-benzylidene benzylamine (>93% selectivity) in this study. However, pure TiO2 and fullerene derivatives (F70) exhibit decreased conversion (56.3% and 89.7%, respectively) and selectivity (83.8% and 86.0%, respectively). The UV-vis diffuse reflectance spectra (DRS) and Mott-Schottky experiment's results indicate that the introduction of fullerene derivatives into anatase TiO2 would greatly broaden the visible light response range and adjust the energy band positions of the composites, enhancing the sunlight utilization and promoting the photogenerated charge (e--h+) separation and transfer. Specifically, a series of results on the in situ EPR tests and the photo-electrophysical experiment indicate that the separated charges from the hybrid could effectively activate benzylamine and O2 to accelerate the formation of active intermediates, and then couple with free BA molecules to form the desired production of N-BBA. The effective combination, on a molecular scale, between fullerene and titanium dioxide has provided a profound understanding of the photocatalysis mechanism. This work elaborates and makes clear the relationship between the structure and the performance of functional photocatalysts.

Synthesis and characterization of highly conductive Ga/Y co-doped LLZO by facile combustion sol-gel method

In this study, garnet material with the composition of Li6.4Ga0.2La3Zr(2-x)YxO12(x = 0,0.1,0.3,0.5) were synthesized by combustion sol-gel method. Phase evolution were studied by X-ray diffraction analysis and Raman. The microstructure and ionic conductivity were investigated by scanning electron microscopy and electrochemical impedance spectroscopy, respectively. Yttrium showed to be effective for promoting Densification while it did not affect the stability of cubic phase structure. However, high amounts of yttrium resulted in the formation of a secondary phase. Adding yttrium also caused microstructural grain growth. Maximum ionic conductivity (1.04 mS.cm−1 at 25 °C) was obtained in Li6.4Ga0.2La3Zr1.7Y0.3O12 sample with relative density of 96.6%. Compared to other reports with similar densities and ionic conductivities, lower sintering temperature and holding time were used in this work. This could be attributed to the effectivity of Ga/Y to promote sintering. Moreover, it may be originated from the good sinterability of combustion sol-gel synthesized powders. This synthesis method's reduced energy and time make it considerable for large-scale production.

Green synthesis of MnCo2O4 nanoparticles grown on 3D nickel foam as a self-supported electrode for oxygen evolution reaction

The development of effective and low-cost catalysts for the oxygen evolution reaction (OER) has become an effective and promising strategy for sustainable energy technologies. In this work, we report a synthesis route for preparing MnCo2O4 nanoparticles on nickel foam (Ni foam) through a facile sol-gel method using Flaxseed (Linum usitatissimum) as a polymerizing agent and subsequent an adapted hydrothermal process. Here, a large surface area was obtained due to the small particle size combined with the absence of binders to promote the adhesion of the active material on the substrate. Thus, this seems to be an interesting strategy to boost electrocatalytic reactions. The structural, microstructural, and surface properties of MnCo2O4 electrodes are investigated by XRD, FESEM, TEM, FTIR, Raman, and XPS analysis. This electrode exhibits an overpotential of 296 mV (at 25 mA cm−2 current density), a Tafel slope of 82 mV dec−1, and excellent electrochemical stability for 15 h. This approach combines the features of a green synthesis with an adapted hydrothermal route to offer the advantages of a controllable reaction process, with good reproducibility, ally to uniform particle size distribution, short reaction time, and, mainly, respect for the environment. This demonstrates great potential in reproducing effective OER electrocatalysts for future applications.

Gas sensing selectivity of SnO2-xNiO sensors for homogeneous gases and its selectivity mechanism: Experimental and theoretical studies

Although the MOS gas sensors are widely employed to detect gas owing to the excellent sensing performance in fast response and recovery time and high sensitivity. However, the poor selectivity is among the most severe challenge to determine the homogeneous gases, especially when CO and H2 coexist. The sensors have the same gas sensing response to homogeneous gases, which attribute to the cross-sensitivity. Herein, a facile sol-gel method has been used to prepare SnO2-xNiO composites and the sensing performances of sensors are further investigated using XRD, TEM, XPS. The experimental results indicate that the selectivity of SnO2-based gas sensor to CO and H2 can be improved by modulating electron and hole concentration in the p-n composites. Interestingly, the gas sensing results show that SnO2-3.58NiO sensor annealed at 550 °C worked at 350 °C presents opposite sensing response to homogeneous gases CO and H2, that is, p-type response to CO but n-type to H2. Insight into the interactions between CO and H2 target gas molecules with SnO2 and NiO surfaces in addition to the target gas-dependent modulation of SnO2 and NiO conductivity are investigated through density functional theory calculations supporting the experimental results. The opposite gas sensing behavior of the SnO2-3.58NiO composites to both gases suggests that the SnO2-3.58NiO composite can distinguish between CO and H2. This paper provides an approach to effectively enhance this type gas sensor selectivity.

Enhanced Activation of Peroxymonosulfate via Sulfate Radicals and Singlet Oxygen by SrCoxMn1−xO3 Perovskites for the Degradation of Rhodamine B

Perovskite is of burgeoning interest in catalysis, principally due to such material having high thermal stability, modifiable variability, ferromagnetism, and excellent catalytic performance in peroxomonosulfate (PMS) activation. In this study, the SrCoxMn1−xO3 perovskites with different Mn doping were synthesized by a facile sol-gel method for peroxymonosulfate (PMS) activation to degrade Rhodamine B. The obtained SrCo0.5Mn0.5O3 perovskite exhibited the best catalytic efficiency, as Rhodamine B (40 mg/L) was removed completely within 30 min. In the system of SrCo0.5Mn0.5O3–PMS, several reactive species were produced, among which sulfate radicals and the singlet oxygen mainly contributed to Rhodamine B degradation. The relatively high catalytic performance could be attributed to the coupled redox cycle between Mn and Co, and the abundant oxygen vacancies. Moreover, the SrCo0.5Mn0.5O3 catalyst showed excellent stability and reusability, maintaining a high catalytic activity after several cycling tests. This study demonstrated that the Mn doping of SrCoO3 could not only enhance the B-site activation in SrCo0.5Mn0.5O3 but also enrich the oxygen vacancies, thus improving the efficiency of PMS activation.

Understanding the role of oxygen vacancy on corrosion resistance of coating containing cerium oxide nanoparticles doped with cobalt as highly effective corrosion inhibitors

Cerium salts have received significant attention for their potential in constructing protective materials on metallic substrates. However, there are few studies on the use of cerium oxide nanoparticles (CeO2 NPs) as corrosion inhibitors, and even fewer on the mechanisms by which they protect steel. In this work, we discuss the effect of oxygen vacancy on the corrosion resistance of an epoxy coating containing cobalt-doped CeO2 NPs in detail. To evaluate the effect of oxygen vacancy on corrosion resistance, we obtained CeO2 and Ce7CoO16 NPs, as well as KH560-Ce7CoO16 NPs, through a controlled facile sol-gel method. The results indicated that KH560-Ce7CoO16 NPs had a higher percentage of Ce3+ and oxygen vacancy (Ov) compared to CeO2 and Ce7CoO16 NPs. Specifically, KH560-Ce7CoO16 NPs were found to have 32.12% Ce3+ and 46.65% Ov, whereas CeO2 and Ce7CoO16 nanoparticles had lower Ce3+ and Ov ratios, with values of 23.46% and 27.30%, and 29.79% and 45.60%, respectively. The micromorphology of CeO2, Ce7CoO16, and KH560-Ce7CoO16 in the epoxy matrix indicated that the addition of 2% KH560-Ce7CoO16 NPs achieved a homogeneous dispersion. Compared to the CeO2 and Ce7CoO16 NPs, KH560-Ce7CoO16 NPs at an appropriate concentration exhibited excellent corrosion resistance performance for the substrate, as evaluated by electrochemical and salt spray tests. We propose that two mechanisms synergistically contribute to the corrosion protection. Firstly, due to oxygen reduction, insoluble cerium hydroxide is formed at the cathodic sites. Secondly, Ov acts as a charge capture center, facilitating the transfer of electrons lost by the anode to the oxygen vacancies and blocking the OH– generated by the cathodic reaction, as well as the new substances generated by the Fe2+ produced by the anodic reaction, which ultimately slows down the corrosion chemical reaction process. This work provides a novel understanding of cerium oxide nanoparticles as corrosion inhibitors, and presents an effective strategy for achieving excellent corrosion resistance performance in a corrosive environment.

Reduced graphene oxide and carbon nanotube anchored NASICON-type NaTi2(PO4)3 nanocomposite anodes for high-rate performance sodium-ion batteries

NASICON-structured NaTi2(PO4)3 (NTP) anode consist of an open 3D framework is received as a zero-stress anode for Na-ion batteries. Herein, we have reported a novel NTP/GO/CNT nanocomposite anodes, in which NTP particles are engineered with reduce graphene oxide (rGO) and carbon nano tube (CNT) and wrapped using a low-cost facile sol-gel method. NTP-rGO10-CNT10 has been chosen as the optimum electrode after studying the effects of rGO/CNT ratio on the electrochemical performance of NTP. The combine effect of structural integrity, high electronic conductivity and high ionic diffusivity in NTP-rGO10-CNT10 leads to excellent electrochemical performance with regards to specific capacity (124 mA h g−1 at 100 mA g−1), remarkable high-rate cycleability (62.5% capacity retention after 400 cycles at 10 C), and excellent rate capability (87 mA h g−1 at 25C). Using cyclic voltammetry investigation, we have estimated the capacitive and faradaic contributions to the total capacities of the composite electrode at various rate. Besides, carbon incorporated NVOPF obtained by carbo-thermal reduction delivers a specific discharge capacity of 106 mA h g−1 as cathode against sodium. Finally, a Na-ion full-cell with the structure of NTP-rGO10-CNT10│1 M NaClO4 in PC│NVOPF@C has been fabricated. This newly designed full-cell can deliver good electrochemical performance in terms of cycleability and power.

Polymorphism in LiDy(WO4)2: Phase tunable synthesis, neutron diffraction, and symmetry-driven upconversion red emission

Tunable polymorphic structures to achieve novel properties are of great concern for energy-related applications. Herein, we demonstrate temperature-driven irreversible structural phase transition in LiDy(WO4)2 (β-LiDyW and α-LiDyW). A facile sol-gel method has been employed to achieve phase pure crystalline polymorphs at relatively lower temperatures and time. LiDy(WO4)2 crystallizes in a monoclinic wolframite-type structure (space group, P21/n, No = 14) at ambient temperature and a Scheelite-like tetragonal structure (space group, I41/a, No = 88) upon heating at high temperature. Crystal structure analysis shows that Li+ and Dy3+ occupy the distinct site, and W forms a distorted WO6 octahedron in the β-LiDyW phase. In contrast, Li+ and Dy3+ are statistically distributed on a dodecahedral S4 site sharing a similar crystallographic lattice site, and W forms a WO4 tetrahedron in the α-LiDyW phase. The Wolframite to Scheelite (β → α) transformation is due to the increase in the crystal symmetry on the heating function where distorted WO6 transformed to free WO4 going from β → α phase and coordination of W+6 is lowered. Density functional theory calculations at 0 K revealed that the β-LiDyW is energetically more favorable than α-LiDyW by 337.3 meV per formula unit. The co-substitution of the Yb3+−Er3+ pair in LiDy(WO4)2 lattice displays a concentration-dependent upconversion red emission when excited with 980 nm. The monoclinic phase of LiDy0.7Yb0.2Er0.1(WO4)2 shows an intense red emission at 656 nm due to inherent lower crystal symmetry. Distorted WO6 and chemically induced lattice distortions in β-LiDy0.7Yb0.2Er0.1(WO4)2 would have strongly influenced the coordination environment of the Er3+ to achieve red emission. This study presents the structural relationship among the tunable crystallographic phases of LiDy(WO4)2 with the observed red emission induced by Yb3+−Er3 upon 980 nm irradiation.

Preparation and sodium storage performance of 2D bilayered V2O5⋅nH2O nanomaterial with Zn2+ intercalation

Two-dimensional (2D) bilayered vanadium pentoxide (V2O5⋅nH2O) nanomaterial with Zn2+ intercalation is prepared by a facile sol–gel method combined with the vacuum freeze-drying technique. The microstructure and surface morphology of the sample are analyzed by XRD, EDS, XPS, and SEM measurements. The sodium storage performance of the sample is characterized by discharge–charge, CV, and EIS tests. The results demonstrate that the Zn2+ intercalation leads to more low valance state V4+ in V2O5⋅nH2O and induces the formation of a layer-by-layer stacked sheet-like morphology. Compared to pure V2O5⋅nH2O sample (without Zn2+ intercalation), the V2O5⋅nH2O sample with Zn2+ intercalation exhibits improved rate capability, better cycling stability, enhanced Na+ diffusivity, and lower electrochemical reaction resistance. At 1.0 A g−1, the V2O5⋅nH2O sample with Zn2+ intercalation delivers a reversible specific capacity of 71.2 mAh g−1, much higher than the corresponding value (12.1 mAh g−1) of the pure V2O5⋅nH2O sample was only. After 100 cycles at 0.1 Ag−1, the specific capacity of the V2O5⋅nH2O sample with Zn2+ intercalation maintains at 98.9 mAh g−1, obviously higher than that (72.7 mAh g−1) of the pure-V2O5⋅nH2O sample.

Green and Efficient Al-Doped LaFexAl1–xO3 Perovskite Oxide for Enhanced Phosphate Adsorption with Creation of Oxygen Vacancies

La-based metal oxide materials are environmentally friendly and show promise for phosphate adsorption. A series of Al-doped perovskite oxides, such as LaFexAl1-xO3, were prepared using a facile citric acid-assisted sol-gel method. The characterization results demonstrated that with optimized Al doping, there was a significant increase in the specific surface area and increased defect content of perovskite oxide LaFexAl1-xO3. Adsorption experiments showed that the performance of phosphate removal by LaFexAl1-xO3 was largely enhanced due to the improved adsorption capacity, which is maximum eight times higher compared with control perovskites prepared under neutral conditions. The mass transfer rate for adsorption was considerably boosted with phosphate removal within the initial 15 min. Spectroscopy analysis and density functional theory calculation results showed that the process of phosphate removal by the Al-doped perovskite oxides LaFexAl1-xO3 involved electrostatic interactions, an inner-sphere complex, and surface oxygen vacancies, among which the creation of oxygen vacancies caused by the Al doping was the predominant mechanism for reducing the bonding barrier during adsorption and generating adsorption sites. The results enable the development of a green and efficient perovskite adsorbent with a La-based perovskite material for phosphorus removal.

Characterization of Mg–Pb–O systems, and MgPbO–thermoplastic blend: Nanocomposites for photonic and microelectronic devices

The synthesis of nanoparticles (NP)-reinforced polymers became an attractive approach to developing multifunctional materials used for optoelectronic and energy storage devices. In this report, two different systems of composition, Mg0.75Pb0.25O NP (Mg75), and Mg0.25Pb0.75O NP (Pb75) were prepared by a facile sol-gel method and characterized. Following that, the solution casting method was used to create Mg75/Poly(vinyl chloride)/Poly(vinyl acetate) PV(C/Ac) and Pb75/PV(C/Ac) nanocomposites. The HR-TEM, energy-dispersive spectroscopy (EDS), XRD, and FTIR analyses revealed the high purity of both Mg75 and Pb75 NP and their crystallite sizes were found to be 16 and 20 nm, respectively. Besides the cubic MgO, several phases of lead oxide (β-PbO, α-PbO, Pb3O4) were detected. The Pb, Mg, and O elements were uniformly distributed in Mg75 and Pb75, but the Pb dominated the Mg in the two systems (the atom% ratio of [Mg]:[Pb] in the two systems was 2.71:1 and 1:2.1, respectively). The width and intensity of the XRD and FTIR peaks as well as the surface morphology of the blend were influenced by the Mg75 and Pb75 NP contents. The films displayed high transmittance (70–90%), and the optical band gap (Eg) was reduced from 4.1 eV (pure blend) to 3.6 eV (4.0% Mg75/blend) and 3.7 eV (4.0% Pb75/blend). The corresponding values of the refractive index were 1.86, 3.18, and 2.50, respectively. In addition, the optical conductivity increased significantly after doping. According to the results of the thermo-gravimetric analysis and differential scanning calorimetry, the films were stable in the temperature range of 30–250 °C, which is suitable for various practical and space applications without damage. The dielectric constant (ϵ′), loss (ϵ′'), and ac conductivity (σac) were determined in the temperature range (30–100 °C) and frequency range of 102–106 Hz. The ϵ′ values were increased after doping and influenced by the temperature, whereas the values of ϵ′' were small and stable. The improved optical and dielectric properties of the nanocomposites make these materials the best candidates for highly efficient photonic and microelectronic devices.

Facile preparation of porous SiO2 antireflection film with high transmittance and hardness via self-templating method for perovskite solar cells

An antireflection (AR) film on the surface of the photovoltaic glass can significantly improve the photoelectric conversion efficiency of solar cells. However, AR films prepared by a facile and low-cost sol-gel method usually exhibit poor mechanical properties, which limits their applications. Herein, hexamethoxy methyl melamine resin (CYMEL 303LF) was employed as a pore-forming agent in the sol and sacrificial template to prepare porous SiO2 film on glass by a facile sol-gel method and subsequent heat treatment. The obtained SiO2 film showed a high solar transmittance increase of 3.24% in the wavelength range of 380–1100 nm and a good hardness of H when the dosage of CYMEL 303LF is 10 wt%, the short circuit current density and photoelectric conversion efficiency of the solar cell are increased respectively by 1.44 mA/cm2 and 1.08%, compared with the substrate, which is better than most SiO2 films in the previous works. With increasing the dosage of CYMEL 303LF from 0% to 12%, the solar transmittance gain was increased at first and then decreased, while the film hardness was decreased straightly. This was probably because that the introduction of CYMEL 303LF can facilitate the formation of more pores in the SiO2 film, leading to a decrease in the refractive index and film adhesion. Therefore, this work can provide a facile method to prepare high-performance SiO2 as AR film for solar cells.

Enhanced photocatalytic degradation of organic dye by CeO2/CNT/GO hybrid nanocomposites under UV light for wastewater treatment.

Development of nanocomposites as efficient photocatalysts for the removal of hazardous organic pollutants is always in dire demand due to increase in water pollution. In this article, a facile sol-gel method has been used to synthesize cerium oxide (CeO2) nanoparticles followed by their decoration over multi-walled carbon nanotubes (CNTs) and graphene oxide (GO) to construct binary as well ternary hybrid nanocomposites using ultrasonic treatment. The oxygen vacancy defects have been depicted using X-ray photoelectron spectroscopy (XPS) that may result into improved photocatalytic efficiency. The ternary hybrid nanocomposites (CeO2/CNT/GO) showed excellent photocatalytic efficiency towards degradation of rose bengal (RB) dye up to 96.9% in 50 min. CNTs and GO provide the interfacial charge transfer which inhibits the electron-hole pair recombination. The results obtained here indicate that these composites can be effectively utilized as promising materials for the degradation of harmful organic pollutants for wastewater treatment.

Robust superhydrophilic antifogging coatings by a facile sol–gel method

Robust superhydrophilic antifogging coatings by a facile sol–gel method

Stable CuFeO/Kaolin-based catalytic particle electrode in 3D heterogeneous electro-Fenton system for orange G removal: Synthesis, performance and mechanism

Orange G is a kind of widely applied but environment-unfriendly dye. Three-dimensional heterogeneous electro-Fenton (3D/HEF), as a combination of three-dimensional electrochemical (3D/E) and heterogeneous electron-Fenton (HEF), having attracted more attentions. However, it is still insufficient in the investigation of coupling mechanism and preparation of highly stable catalytic particle electrodes. Herein, stable copper iron oxide/Kaolin catalytic particle electrodes were synthesized via a facile sol-gel method and applied in 3D/HEF for OG removal. A 40 %-CuFeO/Kaolin (450 °C, 2 h) catalytic particle electrode was optimized and a stable Fe-O-Al bond was found to form between CuFeO and Kaolin. Under optimal conditions, the removal of OG and TOC could reach 99.48 % and 58.13 % respectively within 60 min in neutral environment. From well-designed comparative experiments, various effects such as anodic oxidation, three-dimensional electrochemical oxidation were distinguished, indicating that an excellent synergism between 3D/E attributed to Kaolin and HEF due to CuFeO was the significant cause for the superiority of CuFeO/Kaolin-based 3D/HEF. Radical scavenging experiments verified both hydroxyl radical (•OH) and superoxide radical were generated with •OH dominated, which could efficiently degrade OG through such steps as desulfonation, decolorization, naphthalene opening, benzene opening. Besides, the CuFeO/Kaolin catalysts represented high stability with OG removal still maintaining 92.18 % after 8 cycles, low ion leaching and wide applicability to other dyes, manifesting a kind of fine catalytic particle electrode applied in 3D/HEF have been designed for dye removal and furthermore, providing a new idea for preparing composite catalytic particle electrode in 3D/HEF hybrid system.

Facile preparation of regular truncated octahedral LiMn2O4 cathode with high rate cyclability and stability for Li-ion batteries

Spinel LiMn2O4, as a mainstream commercial cathode material for lithium-ion batteries, is still suffered from severe capacity fading caused by Mn dissolution and Jahn-Teller distortion during the cycle process, which can be solved by developing selectively exposed crystal planes. Herein, a perfect monocrystal LiMn2O4 with regular truncated octahedral structure has been synthesized via a facile and low-cost carbon template sol-gel method. The phase composition and morphology of LiMn2O4 can be regulated by carbon template content, ranging from irregular micro-aggregates to nanoporous network structure composed of truncated nano-octahedrons with high crystallinity. The high crystallinity suppresses Jahn-Teller distortion and the large presence of {111} surfaces inhibit Mn dissolution can both improve its cycle stability, the unique nanoporous network structure facilitates shortening the Li+ diffusion path and the truncated {100} and {110} surfaces promote Li+ diffusion can increase the discharge capacity and rate capability. Accordingly, the as-obtained LMO-0.5 sample achieves remarkable discharge specific capacity (135.8 mA h/g at 0.1 C), excellent rate capability (91.2 mA h/g even at 20 C) and prominent cycle stability (a capacity retention of 91.7 % after 2000 cycles at 20 C), which will be an ideal cathode material for developing long-lifespan lithium-ion batteries.

Effect of Bismuth on the Structure, Magnetic and Photocatalytic Characteristics of GdFeO3

In this paper, a series of Gd1-xBixFeO3 (x = 0, 0.1, 0.3, 0.5, 0.7, 0.9, 1) nanoparticles have been readily synthesized by a green and facile sol–gel method. It gradually changed from the orthorhombic structure (space group Pbnm) to the rhombohedral perovskite structure (space group R3c). Weak ferromagnetic behavior was effectively induced by Bi3+, with reduced magnetization. It was closely related with the lattice distortion of the perovskite structure and modified interactions between Fe-O-Fe. Boosted photocatalytic activities of Gd1-xBixFeO3 were observed for the removal of methylene blue (MB) under the visible light irradiation. In particular, Gd0.5Bi0.5FeO3 showed the optimum photocatalytic efficiency, in which the degradation efficiency reached 82.1% after 180 min of visible light illumination, with good stability and repeatability. The improved performance was mainly ascribed to enhanced visible light absorption, decreased optical band gap from 2.21 to 1.8eV and stronger charge transfer efficiency. A possible photocatalytic mechanism is also proposed according to the band structure. The results indicate that this system will be a promising candidate for the degradation of organic pollutant as a novel magnetically recoverable photocatalyst.

Cubic CuFe2O4 Spinel with Octahedral Fe Active Sites for Electrochemical Dechlorination of 1,2-Dichloroethane.

CuFe2O4 spinel has been considered as a promising catalyst for the electrochemical reaction, while the nature of the crystal phase on its intrinsic activity and the kind of active site need to be further explored. Herein, the crystal phase-dependent catalytic behavior and the main active sites of CuFe2O4 spinel for electrochemical dechlorination of 1,2-dichloroethane are carefully studied based on the combination of experiments and theoretical calculations. Cubic and tetragonal CuFe2O4 are successfully prepared by a facile sol-gel method combined with high temperature calcination. Impressively, CuFe2O4 with the cubic phase shows a higher activity and ethylene selectivity compared to CuFe2O4 with the tetragonal phase, suggesting a significant facilitation of electrocatalytic performance by the cubic crystal structure. Moreover, the octahedral Fe atom on the surface of cubic CuFe2O4(311) is the active site responsible to produce ethylene with the energy barrier of 0.40 eV. This work demonstrates the significance of crystal phase engineering for the optimization of electrocatalytic performance and offers an efficient strategy for the development of advanced electrocatalysts.