Self-Templated Synthesis of Ultrathin Nanosheets Constructed TiO2 Hollow Spheres with High Electrochemical Properties.
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ABSTRACT:
SUBMITTER: Xie H
PROVIDER: S-EPMC5102664 | biostudies-literature |
REPOSITORIES: biostudies-literature
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Project description:To achieve the rational design of nanostructures for superior gas sensors, the ultrasmall nanoparticles (NPs) loaded on ternary metal oxide (TMO) hollow spheres (HS) were synthesized by using the polystyrene (PS) sphere template and bimetallic metal-organic framework (BM-MOFs) mold. The zinc and cobalt based zeolite imidazole frameworks (BM-ZIFs) encapsulating ultrasmall Pd NPs (2-3 nm) were assembled on PS spheres at room temperature. After calcination at 450 °C, these nanoscale Pd particles were effectively infiltrated on the surface of ZnO/ZnCo2O4 HSs. In addition, the heterojunctions of Pd-ZnO, Pd-ZnCo2O4, and ZnO-ZnCo2O4 were formed on each phase. The synthesized Pd-ZnO/ZnCo2O4 HSs exhibited extremely high selectivity toward acetone gas with notable sensitivity (S = 69% to 5 ppm at 250 °C). The results demonstrate that MOF driven ultrasmall catalyst loaded TMO HSs were highly effective platform for high performance chemical gas sensors.
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Project description:SnO2 is a promising anode material for lithium-ion batteries due to its high theoretical specific capacity and low operation voltage. However, its poor cycling performance hinders its commercial application. In order to improve the cycling stability of SnO2 electrodes, novel flower-like SnO2/TiO2 hollow spheres were prepared by facile hydrothermal method using carbon spheres as templates. Their flower-like shell and mesoporous structure highlighted a large specific surface area and excellent ion migration performance. Their TiO2 hollow sphere matrix and 2D SnO2 nano-flakes ensured good cycle stability. The electrochemical measurements indicated that novel flower-like SnO2/TiO2 hollow spheres delivered a high specific capacity, low irreversible capacity loss and superior rate performance. After 1,000 cycles at current densities of 200 mA g-1, the capacity of the flower-like SnO2/TiO2 hollow spheres was still maintained at 720 mAh g-1. Their rate capacity reached 486 mAh g-1 when the current densities gradually increase to 2,000 mA g-1.
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Project description:Hollow-structured mesoporous silica has wide applications in catalysis and drug delivery due to its high surface area, large hollow space, and short diffusion mesochannels. However, the synthesis of hollow structures usually requires sacrificial templates, leading to increased production costs and environmental problems. Here, for the first time, amino-functionalized mesoporous silica hollow spheres were synthesized by using CO2 gaseous bubbles as templates. The assembly of anionic surfactants, co-structure directing agents, and inorganic silica precursors around CO2 bubbles formed the mesoporous silica shells. The hollow silica spheres, 200-400 nm in size with 20-30 nm spherical shell thickness, had abundant amine groups on the surface of the mesopores, indicating excellent applications for CO2 capture, Knoevenagel condensation reaction, and the controlled release of Drugs.
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Project description:As the most commonly used antipyretic and analgesic drug, paracetamol (PA) coexists with neurotransmitter dopamine (DA) in real biological samples. Their simultaneous determination is extremely important for human health, but they also interfere with each other. In order to improve the conductivity, adsorption affinity, sensitivity, and selectivity of TiO2-based electrochemical sensor, N-doped carbon@TiO2 double-shelled hollow sphere (H-C/N@TiO2) is designed and synthesized by simple alcoholic and hydrothermal method, using polystyrene sphere (PS) as a template. Meanwhile, TiO2 hollow spheres (H-TiO2) or N-doped carbon hollow spheres (H-C/N) are also prepared by the same method. H-C/N@TiO2 has good conductivity, charge separation, and the highly enhanced and stable current responses for the detection of PA and DA. The detection limit and linear range are 50.0 nmol/L and 0.3-50 μmol/L for PA, 40.0 nmol/L and 0.3-50 μmol/L for DA, respectively, which are better than those of carbon-based sensors. Moreover, this electrochemical sensor, with high selectivity, strong anti-interference, high reliability, and long time durability, can be used for the simultaneous detection of PA and DA in human blood serum and saliva. The high electrochemical performance of H-C/N@TiO2 is attributed to the multi-functional combination of different layers, because of good conductivity, absorption and electrons transfer ability from in-situ N-doped carbon and electrocatalytic activity from TiO2.
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Project description:ObjectiveAlthough photoelectrochemical (PEC) water splitting heralds the emergence of the hydrogen economy, the need for external bias and low efficiency stymies the widespread application of this technology. By coupling water splitting (in a PEC cell) to a microbial fuel cell (MFC) using Escherichia coli as the biocatalyst, this work aims to successfully demonstrate a sustainable hybrid PEC-MFC platform functioning solely by biocatalysis and solar energy, at zero bias. Through further chemical modification of the photo-anode (in the PEC cell) and biofilm (in the MFC), the performance of the hybrid system is expected to improve in terms of the photocurrent generated and hydrogen evolved.MethodsThe hybrid system constitutes the interconnected PEC cell with the MFC. Both PEC cell and MFC are typical two-chambered systems housing the anode and cathode. Au-TiO2 hollow spheres and conjugated oligoelectrolytes were synthesised chemically and introduced to the PEC cell and MFC, respectively. Hydrogen evolution measurements were performed in triplicates.ResultsThe hybrid PEC-MFC platform generated a photocurrent density of 0.35?mA/cm2 (~70× enhancement) as compared with the stand-alone P25 standard PEC cell (0.005?mA/cm2) under one-sun illumination (100?mW/cm2) at zero bias (0?V vs. Pt). This increase in photocurrent density was accompanied by continuous H2 production. No H2 was observed in the P25 standard PEC cell whereas H2 evolution rate was ~3.4??mol/h in the hybrid system. The remarkable performance is attributed to the chemical modification of E. coli through the incorporation of novel conjugated oligoelectrolytes in the MFC as well as the lower recombination rate and higher photoabsorption capabilities in the Au-TiO2 hollow spheres electrode.ConclusionsThe combined strategy of photo-anode modification in PEC cells and chemically modified MFCs shows great promise for future exploitation of such synergistic effects between MFCs and semiconductor-based PEC water splitting.
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