Facile Chemical Solution Method Research Articles

Controllable Connection of Fe2Se3 Double Chains and Fe(dien)2 Complexes for Organic-Inorganic Hybrid Ferrimagnet with a Large Coercivity.

Organic-inorganic hybrid materials built by inorganic and organic building units have attracted intensive interest in the past decades due to unique chemical and physical properties. However, rare organic-inorganic hybrid materials show excellent permanent magnetic properties. Here, we develop a facile chemical solution method to bottom-up synthesize a new hybrid (Fe2Se3)2[Fe(dien)2]0.9. This hybrid phase with the space group P21/c (14) possesses a rodlike shape with a diameter of 100-2000 nm and a length of 5-50 µm. The hybrid rods are ferrimagnetic with a Curie temperature (TC) of 11 K. They show a high coercivity (HC) of 4.67 kOe and a saturation magnetization (MS) of 13.5 emu/g at 2 K. Compared with orthorhombic (FeSe2)2Fe(dien)2, the excellent magnetic performance of the hybrid rods is ascribed to the monoclinic hybrid structure built by Fe(dien)2 complexes and Fe2Se3 double chains. Our study provides guidance for connecting inorganic fragments of FeSe2 single chains, Fe2Se3 double chains or β-Fe3Se4 layers with Fe(dien)2 complexes for organic-inorganic hybrid phases with varied crystal structures and magnetic properties.

Tuning the intermediate reaction barriers by a CuPd catalyst to improve the selectivity of CO2 electroreduction to C2 products

Electrochemical CO2 reduction is a promising strategy for the utilization of CO2 and intermittent excess electricity. Cu is the only single metal catalyst that can electrochemically convert CO2 into multicarbon products. However, Cu exhibits an unfavorable activity and selectivity for the generation of C2 products because of the insufficient amount of CO* provided for the C-C coupling. Based on the strong CO2 adsorption and ultrafast reaction kinetics of CO* formation on Pd, an intimate CuPd(100) interface was designed to lower the intermediate reaction barriers and improve the efficiency of C2 product formation. Density functional theory (DFT) calculations showed that the CuPd(100) interface enhanced the CO2 adsorption and decreased the CO2* hydrogenation energy barrier, which was beneficial for the C-C coupling. The potential-determining step (PDS) barrier of CO2 to C2 products on the CuPd(100) interface was 0.61 eV, which was lower than that on Cu(100) (0.72 eV). Encouraged by the DFT calculation results, the CuPd(100) interface catalyst was prepared by a facile chemical solution method and characterized by transmission electron microscopy. CO2 temperature-programmed desorption and gas sensor experiments further confirmed the enhancement of the CO2 adsorption and CO2* hydrogenation ability of the CuPd(100) interface catalyst. Specifically, the obtained CuPd(100) interface catalyst exhibited a C2 Faradaic efficiency of 50.3% ± 1.2% at −1.4 VRHE in 0.1 M KHCO3, which was 2.1 times higher than that of the Cu catalyst (23.6% ± 1.5%). This study provides the basis for the rational design of Cu-based electrocatalysts for the generation of multicarbon products by fine-tuning the intermediate reaction barriers.

Electrochemical performance of nanosheet-like- and nanoparticle-structured cobalt oxyhydroxide grown on stainless steel mesh substrate

Hierarchical cobalt oxyhydroxide (CoOOH) nanostructures were directly grown on flexible stainless steel (SS) mesh substrates via a cost-effective, facile chemical solution method. The nanostructures were grown at 90 °C with different time intervals, and their morphological evolution and electrochemical performance were investigated. Initially, the nanowires and nanoparticles were randomly distributed on the surface of the SS mesh substrate. With increasing growth times, the nanowire-like structures were assembled as nanosheet-like structures having widths of ~20 nm. The small nanoparticles between the nanosheet-like structures agglomerated into large nanoparticles with a diameter of ~130 nm. The mixed nanosheet-like- and nanoparticle-structured CoOOH grown on the SS mesh substrate exhibited mass specific capacitances of ~383 F/g at 2 mV/s and ~176 F/g at 100 mV/s with excellent cycling stability (~96%, 3000 cycles).

Rational Solution-assisted Synthesis of Copper Sulfide Nanoparticles for Ultrahigh-rate Electrochemical Energy Storage

The aim of this research work is to explore and compare electrochemical activity of the cupric sulfide (CuS) and cuprous sulfide (Cu2S) nanoparticles. For this purpose, CuS and Cu2S were synthesized by a facile chemical solution method. The morphology, structure, and surface area of the synthesized CuS and Cu2S nanoparticles were characterized by transmission electron microscope, X-ray diffraction, and Brunauer–Emmett–Teller analysis, respectively. The electrochemical activities of the prepared materials were studied by performing cyclic voltammetry and electrochemical impedance spectroscopy analysis in 1 M LiClO4 using a three-electrode system. It was observed that specific capacitance of the CuS (435 Fg−1) is higher than that of Cu2S (273 Fg−1) at the same current density (5 Ag−1). Furthermore, CuS retained 86% while Cu2S retained 75% of their initial capacitance after 6,000 charge–discharge cycles. Therefore, CuS owing to its higher electrochemical activity and cyclic stability is a superior electrode material than Cu2S for supercapacitor applications.

Elemental Cu doped Co3O4 thin film for highly sensitive non-enzymatic glucose detection

We report on the non-enzymatic glucose sensing ability of elemental Cu doped Co3O4 thin film deposited on FTO in this study. A facile chemical solution method was used to substitute elemental Cu into the Co3O4 host lattice. The morphology of the electrode was characterized by XRD, SEM, HRTEM, SAED and EELS. The as prepared thin film exhibited very high sensitivity of 1850 μAcm-2 mM−1, and linear range up to 7.6 mM. The sensor showed a limit of detection of 153 nM at a signal to noise ratio of 3. The developed sensor was used successfully to measure glucose level in human serum and spiked saliva samples.

Self-Assembling VO2 Nanonet with High Switching Performance at Wafer-Scale

Technologically controlling nanostructures is essential to tailoring the functionalities and properties of nanomaterials. Various methods free from lithography-based techniques have been employed to fabricate 2D nanostructures; however it is still hard to achieve a well interconnected 2D regular nanostructure. Here, we demonstrate a facile chemical solution method to self-assemble a regular and interconnected VO2 nanonet on the wafer scale. The nanonet shows a well-defined 2D truss network constructed by VO2 nanorods with twinning relationships. The growth direction and crystallographic orientation of nanorods are synchronously controlled, leading to horizontally epitaxial growth of nanorods along three symmetric directions of the (001) single-crystal sapphire substrate. The unique nanonets enable the acquisition of excellent resistance switching properties and dramatic fatigue endurance. A large resistance change of near 5 orders with a 1.7 °C width of the hysteresis loop is characterized comparably to t...

Synthesis of amorphous ZnSnO3 double-shell hollow microcubes as advanced anode materials for lithium ion batteries

Amorphous ZnSnO3 double-shell and yolk-shell hollow microcubes were synthesized by calcination of their corresponding ZnSn(OH)6 precursors pre-prepared through a facile chemical solution method in argon. The as-prepared amorphous ZnSnO3 double-shell hollow microcubes have an average edge length of 1.6μm. When used as the anode materials, amorphous ZnSnO3 double-shell hollow microcubes (D-ZnSnO3) reveal better electrochemical properties than ZnSnO3 yolk-shell counterparts (Y-ZnSnO3). D-ZnSnO3 anodes can retain a high reversible capacity of 741mA h g−1 after 50 cycles with a coulombic efficiency of 99% at 100mA g−1. The amorphous feature and unique box-in-box hollow architecture of D-ZnSnO3 play a key role in their excellent electrochemical properties.

Facile synthesis of porous Fe2O3 nanorods and their photocatalytic properties

Porous Fe2O3 nanorods were obtained using a facile chemical solution method with subsequent calcination. The structures and morphological evolution were characterized by X-ray diffraction, field emission scanning electron microscopy, thermogravimetric-differential thermal analysis, and Brunauer–Emmett–Teller (BET) N2 adsorption–desorption analyses. The calculated BET surface area of the porous Fe2O3 nanorods was 18.8m2g−1. The porous Fe2O3 nanorods were used as a catalyst to photodegrade Rhodamine B, methylene blue, methyl orange, p-nitrophenol, and eosin B. Compared to the commercial Fe2O3 powder, the as-prepared porous Fe2O3 nanorods exhibited higher catalytic activities owing to their large surface areas and porous nanostructures. The photocatalytic reaction rate constant of the porous Fe2O3 nanorods in the photocatalytic decomposition of Rhodamine B under simulated solar light was calculated to be 0.0131min−1. Moreover, the catalyst was found to have superior stability and reusability.

Facile synthesis of porous ZnO microbelts and analysis of their gas-sensing property

Porous ZnO microbelts were achieved using a facile chemical solution method combined with subsequent calcination. The micro-nanostructures were characterized through X-ray diffraction, field emission scanning electron microscopy, thermogravimetric-differential thermal analysis, and Brunauer–Emmett–Teller N2 adsorption-desorption analyses, among others. The BET surface area of the porous ZnO microbelts was calculated at 23.0 m² g−1. Furthermore, the gas sensing properties of the as-prepared porous ZnO microbelts were investigated using volatile organic compounds. Compared with ZnO microflowers, the porous ZnO microbelts exhibited higher response with certain organic vapors, such as formaldehyde, acetone, and ethanol. The responses to 100 ppm formaldehyde, acetone, and ethanol were 45.7, 40.6, and 38.4, respectively, at a working temperature of 300 °C. The results showed that the porous ZnO microbelts are highly promising candidates for gas sensing applications.

Preparation of porous flower-like CuO/ZnO nanostructures and analysis of their gas-sensing property

Abstract Porous flower-like CuO/ZnO nanostructures were obtained using a facile chemical solution method combined with subsequent calcination. The calcination of the precursors produced flower-like CuO/ZnO nanostructures, which is comprised of interconnected highly porous CuO/ZnO nanosheets that resulted from the thermal decomposition of the as-prepared precursors, i.e., flower-like zinc copper hydroxide carbonate. Moreover, the nanostructures were characterized through X-ray diffraction, field emission scanning electron microscopy, thermogravimetric–differential thermal analysis, and Brunauer–Emmett–Teller N2 adsorption–desorption analyses, among others. The BET surface area of the hierarchically porous CuO/ZnO nanostructures was calculated at 17.1 m2 g−1. Furthermore, the gas sensing properties of the as-prepared porous flower-like CuO/ZnO nanostructures were investigated using volatile organic compounds. Compared with the porous flower-like ZnO nanostructures, the porous flower-like CuO/ZnO nanostructures exhibited a higher response and lower working temperature with certain organic vapors, such as ethanol, acetone, and formaldehyde. The responses to 100 ppm ethanol and formaldehyde were 25.5 and 28.9, respectively, at a working temperature of 220 °C. These results showed that the porous flower-like CuO/ZnO nanostructures are highly promising candidates gas sensing applications.

Excellent electrical conductivity of the exfoliated and fluorinated hexagonal boron nitride nanosheets

The insulator characteristic of hexagonal boron nitride limits its applications in microelectronics. In this paper, the fluorinated hexagonal boron nitride nanosheets were prepared by doping fluorine into the boron nitride nanosheets exfoliated from the bulk boron nitride in isopropanol via a facile chemical solution method with fluoboric acid; interestingly, these boron nitride nanosheets demonstrate a typical semiconductor characteristic which were studied on a new scanning tunneling microscope-transmission electron microscope holder. Since this property changes from an insulator to a semiconductor of the boron nitride, these nanosheets will be able to extend their applications in designing and fabricating electronic nanodevices.

CoO nanocrystals as a highly active catalyst for the generation of hydrogen from hydrolysis of sodium borohydride

We report the excellent catalytic performance of CoO nanocrystals on the catalytic hydrolysis of alkaline NaBH4 solutions. CoO nanocrystals with octahedral and near-spherical shapes are synthesized using a facile chemical solution method that employed cobalt acetate tetrahydrate as metal precursor in the presence of oleylamine. The octahedral CoO nanocrystals typically have a size of 40–50 nm, while the near-spherical nanocrystals have a size varying from 8 to 13 nm. Both of them have a face centered cubic (fcc) crystalline phase. Catalytic tests show that the as-synthesized CoO nanocrystals exhibit very high activities for the H2 generation from the hydrolysis of alkaline NaBH4 solutions. The maximum hydrogen generation rate of the as-synthesized CoO nanocrystals exceeds most reported values of transition metal or noble metal contained catalysts performed in alkaline NaBH4 solutions. The influences of shape on the catalytic behaviors of as-synthesized CoO nanocrystals are also compared and analyzed. The results presented in this study indicate that CoO nanocrystals are a promising candidate to replace noble metal catalysts in the H2 generation from the hydrolysis of borohydrides.

CdS/CdSe Double-Sensitized ZnO Nanocable Arrays Synthesized by Chemical Solution Method and Their Photovoltaic Applications

A facile chemical solution method was reported for the first time to synthesize CdS/CdSe double-sensitized ZnO nanocable arrays. In this method, CdS was prepared by chemical bath deposition method, and CdSe was formed on the surface of CdS via ion exchange reaction thereafter. Comprehensive characterization techniques were carried out to study the composition, microstructure, and crystallinity of the sensitization layers. The CdS/CdSe ratio was revealed to be controllable by varying the temperature of ion exchange reaction. It was further demonstrated that sensitization of ZnO nanorods with CdS and CdSe exhibited enhanced light-harvesting ability. The photovoltaic performance of the double-sensitized ZnO nanocables in photoelectrochemical solar cells was evaluated. An increase in short-circuit current and an improvement of power conversion efficiency to 3.23% were achieved. In addition, the formation mechanism of the double-sensitizing layer is discussed in the Article.