We developed two-step solution-phase reactions to form hybrid materials of Mn3O4 nanoparticles on reduced graphene oxide (RGO) sheets for lithium ion battery applications. Mn3O4 nanoparticles grown selectively on RGO sheets over free particle growth in solution allowed for the electrically insulating Mn3O4 nanoparticles wired up to a current collector through the underlying conducting graphene network. The Mn3O4 nanoparticles formed on RGO show a high specific capacity up to ~900mAh/g near its theoretical capacity with good rate capability and cycling stability, owing to the intimate interactions between the graphene substrates and the Mn3O4 nanoparticles grown atop. The Mn3O4/RGO hybrid could be a promising candidate material for high-capacity, low-cost, and environmentally friendly anode for lithium ion batteries. Our growth-on-graphene approach should offer a new technique for design and synthesis of battery electrodes based on highly insulating materials.

Mn3O4-Graphene Hybrid as a High Capacity Anode Material for Lithium Ion Batteries

The development of gas sensor that is capable of detecting ppb-level detection of acetone and possesses high response toward low-concentration acetone remains a great challenge. Herein, we present the construction of the W18O49/Ti3C2Tx composites based on the in situ grown of the 1D W18O49 nanorods (NRs) on the surfaces of the 2D Ti3C2Tx Mxene sheets via a facile solvothermal process. The W18O49/Ti3C2Tx composites exhibit high response to low concentration acetone (11.6 to 20 ppm acetone), ideal selectivity, long-term stability, very low limit of detection of 170 ppb acetone, and fast response and recover rates (5.6/6 s to 170 ppb acetone). Compared to the W18O49 NRs and Ti3C2Tx sheets, the W18O49/Ti3C2Tx composites show significant improvement on the acetone-sensing performance, which can be ascribed to the homogeneous distribution of the W18O49 NRs on the Ti3C2Tx surface, the removal of the fluorine-containing groups from the Ti3C2Tx after the solvothermal process, and the synergistic interfacial interactions between the W18O49 NRs and the Ti3C2Tx sheets. The synthesis of the 1D/2D W18O49/Ti3C2Tx Mxene composites provides a new avenue to develop other promising hybrids for acetone sensing.

W18O49/Ti3C2Tx Mxene nanocomposites for highly sensitive acetone gas sensor with low detection limit

The introduction of oxygen vacancies into metal oxide semiconductors is an effective way to enhance their gas sensing performance. In this review paper, firstly, the roles of oxygen vacancies on band structure, electrical conductivity, optical absorption and gas adsorption are presented. The presence of highly concentrated oxygen vacancies narrows the bandgap width of semiconductors, thus reducing the energy required for electron transition. It also increases the active sites on the material surface and enhances the chemisorption, thus improving the adsorption performance of the material. In addition, it also improves the electrical conductivity and light absorption ability of the material. Then, this review paper briefly introduced the state of the art of metal oxide semiconductors with highly concentrated oxygen vacancies fabricated by various processes, which are mainly divided into direct and indirect methods. At last, the application of metal oxide semiconductors with highly concentrated oxygen vacancies in the field of gas sensors is reviewed.

Metal oxide semiconductors with highly concentrated oxygen vacancies for gas sensing materials: a review

In this study, porous ZnO ultrathin nanosheets with abundant surface oxygen vacancies were prepared by a hydrothermal technique followed by an annealing method using graphene oxide (GO) as a templa...

Porous ZnO Ultrathin Nanosheets with High Specific Surface Areas and Abundant Oxygen Vacancies for Acetylacetone Gas Sensing

Extended surface area in addition to higher conductivity and abundant free electrons/holes generation has been key players for any efficient sensor design. Therefore, contribution from graphene as highest conductive material and plasmonics from gold (Au) were expected to facilitate efficient zinc oxides (ZnO) nanostructures-based Hydrogen gas detection. We have presented herewith a facile route to synthesize ZnO nanosheets from elongated nanoblocks of the same in presence of reduced graphene oxide (rGO) under laser ablation environment. Au decorated such rGO/ZnO heterostructured nanosheets were found to be highly selective and sensitive to H2 detection under ultraviolet radiation at room temperature (RT). A detailed investigation was carried out to confirm topographic evolution through high resolution scanning electron microscopy. Optical band gap and infrared absorption of as-synthesized specimens at different stages were investigated further in addition to structural confirmation using X-ray diffraction analysis. Raman spectroscopy, a complementary technique was utilized to investigate the specimens at different stages too. SEM-aided elemental analysis inferred that gold nanoparticles were homogeneously distributed over the rGO/ZnO heterostructure. A custom-made setup designed at our disposal were utilized to understand the selectivity and sensitivity of as-fabricated heterostructure for H2 detection. The H2 gas sensing properties of Au nanoparticles decorated rGO/ZnO heterostructure were investigated at RT under UV irradiation and compared with those observed using pristine ZnO nanostructure at high working temperature. A plausible mechanism was illustrated with reference to well-known ‘spell-over’ scenario usually observed in plasmonic sensors.

UV-activated gold decorated rGO/ZnO heterostructured nanocomposite sensor for efficient room temperature H2 detection

Acetone sensor based on WO3 nanocrystallines with oxygen defects for low concentration detection

rGO/CoTiO3 nanocomposite with enhanced gas sensing performance at low working temperature

Enhanced cyclic performance of Cu 2 V 2 O 7 / reduced Graphene Oxide mesoporous microspheres assembled by nanoparticles as anode for Li-ion battery

The invention relates to a method for preparing a flower-like Cu2V2O7 material by a homogeneous hydrothermal method and the prepared Cu2V2O7 material. The method comprises the steps: dispersing cuprous oxide into deionized water, carrying out uniform dispersing, and then, adding ammonium metavanadate into the dispersion, so as to obtain a reaction precursor solution; subjecting the reaction precursor solution to a hydrothermal reaction for 5 to 48 hours at the temperature of 100 DEG C to 200 DEG C, then, cooling the reaction solution to room temperature, carrying out centrifuging, washing precipitates, and drying the precipitates, so as to obtain powder; and sintering the powder, thereby obtaining the flower-like Cu2V2O7 material. According to the method for preparing the flower-like Cu2V2O7 material by the homogeneous hydrothermal method and the prepared Cu2V2O7 material, a hard template-in-situ topology reaction method is adopted, and the Cu2V2O7 material for negative poles of lithium-ion batteries is prepared specifically through mixing Cu2O and NH4VO3 to prepare the reaction precursor solution, then, carrying out the hydrothermal reaction, and finally, carrying out sintering to remove crystalline water; and the method is simple in process and does not need complicated equipment, the required material can be prepared at normal temperature and normal pressure, the reaction time is short, the purity of the product is high, the reaction conditions are easily controlled, and thus large-scale industrial production can be achieved.

Method for preparing flower-like Cu2V2O7 material by homogeneous hydrothermal method and prepared Cu2V2O7 material

A preparation method of copper vanadate for lithium-ion battery cathode material includes: dispersing cuprous oxide in ethanol solution, and stirring to obtain suspension A; adding vanadium pentoxide powder into hydrogen peroxide solution, and stirring to obtain solution B; dropwise adding the solution B into the suspension A, continuing to stir until the color of obtained solution turns from dark red to olive green, filtering, washing and drying to obtain powder; holding the powder at 200-400 DEG C for 0.1-2 h to obtain the copper vanadate for lithium-ion battery cathode material. Copper vanadate is material is generated directly based on cuprous oxide through in-situ topological reactions by using insoluble cuprous oxide as a template. The method is simple, has no need for complex equipment, enables preparation of a required material under normal temperature and normal pressure, and since the cuprous copper is used as a hard template, it is possible to control the shape of a product. In addition, the reaction time is short, product purity is high, the whole process flow is simple, and it is easy to implement industrialization.

Jia Na

Papers

Acetone sensor based on WO3 nanocrystallines with oxygen defects for low concentration detection

rGO/CoTiO3 nanocomposite with enhanced gas sensing performance at low working temperature

Enhanced cyclic performance of Cu 2 V 2 O 7 / reduced Graphene Oxide mesoporous microspheres assembled by nanoparticles as anode for Li-ion battery

Method for preparing flower-like Cu2V2O7 material by homogeneous hydrothermal method and prepared Cu2V2O7 material

Preparation method of copper vanadate for lithium-ion battery cathode material