Guorong Duan

A novel yet simple strategy to fabricate visible light responsive C,N-TiO2/g-C3N4 heterostructures with significantly enhanced photocatalytic hydrogen generation

In this report, we first successfully designed and fabricated novel C,N co-doped titanium dioxide nanoparticles/graphite-like carbon nitrogen ultrathin nanosheets (C,N-TiO2 NPs/g-C3N4) heterostructures, wherein the C,N-TiO2 NPs were in situ grown on the porous g-C3N4 ultrathin nanosheets (NSs) by a simple one-pot solvothermal route with the assistance of concentrated nitric acid. The resulting C,N-TiO2 NPs/g-C3N4 nanocomposite photocatalysts were systematically characterized by powder X-ray diffraction (PXRD), Fourier transform infrared spectroscopy (FT-IR), diffuse reflectance spectroscopy (DRS), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), photoluminescence (PL) spectroscopy, transient photocurrent–time (I–t) curves and electrochemical impedance spectroscopy (EIS) Nyquist plots. The photocatalytic ability was evaluated by photocatalytic water splitting for hydrogen evolution. These studies indicate that C,N-TiO2 NPs/g-C3N4 composites exhibit superior ability for hydrogen generation compared to single C,N-TiO2 NPs and pure g-C3N4 NSs under visible light illumination. The optimal composites with 3 wt% C,N-TiO2 NPs/g-C3N4 showed the highest hydrogen evolution rate of 39.18 μmol g−1 h−1, which is about 10.9 and 21.3 times higher than those of C,N-TiO2 NPs and pure g-C3N4 NSs, respectively. The improved photocatalytic H2 evolution can be attributed to improved optical absorption and the lengthening lifetime of charge carrier pairs as a result of the C,N elemental codoping and the construction of intimate heterogeneous interfaces. This simple and feasible method for the fabrication of highly-efficient visible light responsive catalysts provides a great applied potential in energy generation.

One-pot hydrothermal route to synthesize the ZnIn2S4/g-C3N4 composites with enhanced photocatalytic activity

Heterogeneous ZnIn2S4/g-C3N4 hybrid composites, as highly efficient visible-light-driven photocatalysts, were designed and fabricated by a simple one-step hydrothermal route for the first time, wherein the cubic ZnIn2S4 nanoparticles were in situ immobilized on the surface of porous g-C3N4 nanosheets (NSs). The resultant composites exhibit efficient photocatalytic activities, excellent photo-stability, and versatile photocatalytic abilities towards organic dye degradation, Cr(VI) reduction, and water splitting for H2 evolution. The significant enhancement of photocatalytic activity is attributed to the effective separation of photo-generated charge carrier pairs based on the construction of close heterogeneous interface and well-matched band structure, which can obviously lengthen the life span of holes and electrons pairs. Besides, the effective charge transfer from cubic ZnIn2S4 to ultrathin g-C3N4 NSs was confirmed by photoluminescence spectra, transient photocurrent–time (I–t) curves and electrochemical impedance spectroscopy Nyquist plots. This research provides a new sight in designing the highly efficient visible light responsive photocatalysts for environmental remediation and energy production.

Synthesis of homogeneous one-dimensional NixCd1−xS nanorods with enhanced visible-light response by ethanediamine-assisted decomposition of complex precursors

Abstract A route to fabricate the homogeneous one-dimensional (1D) NixCd1−xS nanorods (NRs) photocatalysts is designed with ethanediamine-assisted decomposition of NixCd1−x (DDTC)2 complex precursors. This route developed NixCd1−x (DDTC)2 complex precursors by co-precipitation method at room temperature condition. The effects of Ni2+ doped into CdS lattice on the length and photocatalytic performance of the NixCd1−xS NRs have been investigated in detail. It is found that doping of Ni2+ significantly affects the aspect ratio of 1D NixCd1−xS NRs. With the increasing doping concentration of Ni2+, the length of as-obtained NixCd1−xS NRs becomes shorter. In addition, their photocatalytic activity was evaluated by the degradation of Rhodamine B dye as a probe reaction under visible-light irradiation. The results show that the optimal Ni2+ addition shows efficient photocatalytic performance and excellent photo stability, which may result from Ni2+ lattice doping. A tentative photocatalytic mechanism of 1D NixCd1−xS NRs is proposed for further explanation of photocatalytic performance.

Deposition-precipitation preparation of Ag/Ag3PO4/WO3 nanocomposites for efficient Visible-light degradation of rhodamine B under strongly acidic/alkaline conditions

A series of novel visible-light-driven Ag/Ag3PO4/WO3 (AAPW) Z-scheme heterostructures were fabricated using a facile deposition-precipitation method followed by photo-reduction without adding any surfactant. To explore more deeply about the photocatalytic activity of AAPW nanocomposites under neutral and strongly acidic/alkaline conditions, we investigated their photocatalytic rhodamine B (RhB) efficiency at different pH value that was controlled by adding HNO3 or NaOH aqueous solution. It was found that as-prepared AAPW photocatalysts showed enhanced photocatalytic RhB efficiency under neutral and even strongly acidic/alkaline environment. The process of charge carrier separation and transfer in the AAPW nanocomposites and Z-scheme mechanism for RhB degradation were described in sufficient detail based on systematical characterizations and measurements. The silver particles introduced to build AAPW Z-scheme structure should contribute to more efficient charge separation, resulting in enhanced photocurrent response and photocatalytic activity. We expect thatthis work will provide systematic study concerning Z-scheme Ag/Ag3PO4/WO3 structure, and fulfill the research about photodegrade activity of catalyst under strongly acidic/alkaline conditions.

Mesoporous transition metal oxides quasi-nanospheres with enhanced electrochemical properties for supercapacitor applications.

In this report, we obtain mesoporous transition metal oxides quasi-nanospheres (includes MnO2, NiO, and Co3O4) by utilizing mesoporous silica nanospheres as a template for high-performance supercapacitor electrodes. All samples have a large specific surface area of approximately 254-325m(2)g(-1) and a relatively narrow pore size distribution in the region of 7nm. Utilization of a nanosized template resulted in a product with a relative uniform morphology and a small particle diameter in the region of 50-100nm. As supercapacitor electrodes, MnO2, NiO, and Co3O4 exhibit an outstanding capacity as high as 838-1185Fg(-1) at 0.5Ag(-1) and a superior long-term stability with minimal loss of 3-7% after 6000 cycles at 1Ag(-1). Their excellent electrochemical performances are attributed to favorable morphologies with a large surface area and a uniform architecture with abundant pores. The associated enhancement of electrolyte ion circulation within the electrode facilitates a significant increase in availability of Faradic reaction electroactive sites.

Facile fabrication of Ag 3 VO 4 /attapulgite composites for highly efficient visible light-driven photodegradation towards organic dyes and tetracycline hydrochloride

An efficient one-dimensional attapulgite (ATP)-based photocatalyst, Ag3VO4/ATP nanocomposite, was fabricated by a facile deposition precipitation method with well-dispersed Ag3VO4 nanoparticles anchored on the surface of natural ATP fibers. X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS), and UV-visible diffused reflectance spectroscopy (UV-vis DRS) were employed to investigate the morphologies, structure, and optical property of the prepared photocatalysts. The photocatalytic experiments indicated that the Ag3VO4/ATP nanocomposites exhibited enhanced visible light-driven photocatalytic activity towards the degradation of rhodamine B (RhB), methyl orange (MO), and tetracycline hydrochloride (TCH), of which the 20 wt% Ag3VO4/ATP sample showed superb photocatalytic performance. As demonstrated by N2 adsorption-desorption, photocurrent measurements, electrochemical impedance spectroscopy (EIS), and photoluminescence (PL) spectra analyses, the improved photocatalytic activity arose from the enlarged surface area, the facilitated charge transfer, and the suppressed recombination of photogenerated charge carriers in Ag3VO4/ATP system. Furthermore, radical scavengers trapping experiments and recycling tests were also conducted. This work gives a new insight into fabrication of highly efficient, stable, and cost-effective visible light-driven photocatalyst for practical application in wastewater treatment and environmental remediation.

Super Molecular-polarization Phenomenon of Poly (ethylene glycol) in Deionized Water

A new discovery describing nonionic surfactant poly(ethylene glycol) being added into deionized water, electrical conductivity of the water would show a remarkable increase phenomenon. The mechanism study indicated that the electrical conductivity increase of the water doped some PEG was formed by super-polarization of a PEG molecule on the water molecule. A PEG molecule can form a super polarization body in the water, which will generate a strong polarization effect on the water molecule, thereby increasing water ionization degree and makes the electrical conductivity of water greater.

Study on a novel oil-in-water-type microemulsion system of water/Triton X-100/Tween80/n-hexyl alcohol/n-octane

A novel oil-in-water-type microemulsion system (water/Triton X-100/Tween80/n-hexyl alcohol/n-octane) has been studied. The results of investigations of the mechanism of formation of this system have indicated that the mixture of Triton X-100, Tween80 and n-hexyl alcohol acts as a surface layer. Further studies have shown that by controlling the n-octane content of this system, it is possible to change its cloud point. Furthermore, variation of the environmental temperature has been shown to affect the maximum n-octane content of this system, the maximum n-octane content increases with increasing environmental temperature.

Super Molecular Polarization of Polyoxyethylene-Water Binary Systems

When polyoxyethylene-based non-ionic surfactants were added to deionized water, the electrical conductivity of the water increased. The increase was proportional to the surfactant concentration until a maximum value was reached at concentrations between 20∼25%. As long as the macromolecules contained a polyoxyethylene structure (-C-C-O-) there was noticeable molecular polarization in aqueous solution. The highest polarization capacity was observed at surfactant concentrations of 20∼25%.

Influences of ionic environment on self-assembly behaviour of hyperbranched polymers

Detection of electrical conductivity is carried out to study the characteristics of adsorptive action between several ions such as Ca2+, Cl−, Na+, and hyperbranched comb-like polymers. The results show that the strength of their adsorptions is in the descending order as follows: Ca2+ >   > Cl− (Na+). CaCl2 solution will significantly reduce the electrical conductivity of hyperbranched comb-like polymers, whereas NaCl solution will increase it obviously. Due to association and dispersion of ions in hyperbranched comb-like polymers; all salt ionic solutions can enlarge the critical micelle concentration of hyperbranched comb-like polymers.