Showing papers by "Huijun Ren published in 2017"
TL;DR: In this paper, the structure, morphology, surface composition and chemical state of mpg-C3N4/BiPO4 hybrid photocatalysts were characterized by XRD, TEM, FTIR and XPS, respectively.
Abstract: Highly efficient mpg-C3N4/BiPO4 heterostructured photocatalysts were successfully synthesized via a facile ultrasonic chemical method. The structure, morphology, surface composition and chemical state of mpg-C3N4/BiPO4 hybrid photocatalysts were characterized by XRD, TEM, FTIR and XPS, respectively. Their photocatalytic activity was evaluated under visible light, UV light and solar light irradiation against the photodegradation of rhodamine B (RhB). BiPO4 nanorod was anchored on the surface of mpg-C3N4 nanosheets and the strong electrostatic interaction between mpg-C3N4 and BiPO4 facilitated the formation of mpg-C3N4/BiPO4 heterostructure. Under visible light irradiation, O2− and h+ were the two primary active species. BiPO4 served as an electron trap to efficiently promote the separation of photogenerated electron-hole pairs. The electrons in the CB of both BiPO4 and mpg-C3N4 could react with O2 adsorbed onto the surface of BiPO4/mpg-C3N4 and reduce it to form O2−, the holes left behind in the VB of mpg-C3N4 could not directly oxidize OH− or H2O to form OH. The 9.5CN/0.5BPO could degrade 92.3% of RhB in 30 min, which was about 1.3 times as high as that of mpg-C3N4. The TOC removal rate of 9.5CN/0.5BPO was 1.23 times higher than that of mpg-C3N4. Under UV light irradiation, O2−, h+ and OH were the primary active species, the inhibition degree followed the order BQ > EDTA-2Na > TBA. The electrons in the CB of both BiPO4 and mpg-C3N4 could react with O2 to generate O2−, the holes in the VB of BiPO4 could react with OH− or H2O to produce OH. The 9.5CN/0.5BPO could degrade 94.3% of RhB in 6 min, which was approximately 4.2 times higher than that of BiPO4 and 1.5 times larger than that of mpg-C3N4. The TOC removal rate of 9.5CN/0.5BPO was 6.98 times higher than that of P25. HPLC analysis proved that the destruction of the conjugated structure of RhB would be the major process. Based on the experimental results, a possible charge transfer mechanism for the enhanced visible and UV light photocatalytic activity was proposed.
113 citations
TL;DR: In this paper, the Nd/Er co-doped tetragonal BiVO4 photocatalysts are synthesized by a microwave hydrothermal method, and the crystal structures, morphologies and optical properties are characterized.
Abstract: The Nd/Er co-doped tetragonal BiVO4 photocatalysts are synthesized by a microwave hydrothermal method, and the crystal structures, morphologies and optical properties are characterized. The substitution of Nd3+ and Er3+ for Bi3+ sites leads to distortion of the [VO4] tetrahedron chains and induces the monoclinic structure transforming into the tetragonal structure, with the morphology evolving from nano particle agglomerations to disorganized regular rods agglomerations. The impurity energy levels induced by Nd3+ and Er3+ in the energy band of BiVO4 act as electron traps and have further energy transfer in the up-conversion processes to facilitate the photocarriers’ separation. The more positive VB positions in the co-doped BiVO4 band structures can also effectively enhance oxidation capacity. Based on the above synergetic effect, the degradation rate the degradation rate of co-doped tetragonal BiVO4 photocatalyst can reach the highest 96% within 150 min under simulated sunlight and 20 min under the NIR irradiation.
93 citations
TL;DR: The asymmetric character of leakage current density curves and resistive switching effects have been explored and the ion substitution impacts on the resistive Switching effects may be due to the existence of local fields.
Abstract: Bilayer Bi085-xPr015RExFe097Mn003O3/CuFe2O4 (BPRExFMO/CuFO, RE = Sr, Dy) thin films were prepared on FTO/glass substrates by the chemical solution deposition method The structure transition does not appear after ion doping, which is confirmed by XRD and its refined results The samples remain in the trigonal R3c:H structure in the BFO phase and in the tetragonal I41/amd structure in the CuFO phase The asymmetric character of leakage current density curves and resistive switching effects have been explored And the ion substitution impacts on the resistive switching effects may be due to the existence of local fields Under the applied electric field, carries are accumulated and arranged directionally at the interface between the BFO and CuFO layers to form the local electric field Such local field is affected by ion dopants, and the field compensates or weakens the applied electrical field The reinforced or weakened resistive behavior is dependent on the direction of the local field and the inject
14 citations
TL;DR: In this paper, the structure, surface morphologies, and electric properties of the thin films were investigated, and the results showed that the structure of BHSrghazi x�� FMO thin films transformed from rhombohedral R3c:H to rhombohedric R3m:R when doped with the Sr2+ ions.
Abstract: The Bi0.92−x
Ho0.08Sr
x
Fe0.97Mn0.03O3(BHSr
x
FMO) thin films were deposited on FTO/glass substrates by the sol–gel method. The structure, surface morphologies, and electric properties of the thin films were investigated. The results show that the structure of BHSr
x
FMO thin films transformed from rhombohedral R3c:H to rhombohedral R3m:R when doped with the Sr2+ ions. When the ferroelectric domain structure of the BHSr
x
FMO(x = 0.00–0.04) thin films is converted from ferroelectric phase and antiferroelectric phase to ferroelectric phase, the coercive field (E
c) increased. This change occurs when the defect dipole of $$ ({\text{Sr}}_{{_{{\text{Bi}}} }}^{{\prime }} - {\text{V}}_{{\text{O}}}^{ \cdot \cdot } )^{ \cdot } $$
of BHSr
x
FMO thin films increased, which clamps the domain wall motion and changes the directions of spontaneous polarization. In an electric field of 536 kV/cm, the 2P
r and 2E
c of BHSr3FMO thin film are 81.9 μC/cm2 and 524 kV/cm, respectively. In the magnetic field of 8000 Oe, the magnetization of the BHSr3FMO thin film is 8.34 emu/cm3. The BHSr3FMO thin film shows the great multiferroic properties, which are mainly connected with the rhombohedral structure of R3c:H (51%)/R3m:R(49%) space groups at morphotropic phase boundary.
9 citations
TL;DR: In this article, the chemical solution deposition route was employed to prepare Bi 0.85-x Pr 0.15 Dy 3+ ions and Fe 0.97 Mn 0.03 O 3 thin films.
7 citations
TL;DR: In this paper, a multion doped BiFeO3/NiFe2O4 bilayered thin films were successfully prepared on fluorine-doped SnO2/glass (SnO2:F) substrates by sol-gel method.
Abstract: Multi-ion doped BiFeO3/NiFe2O4 bilayered thin films were successfully prepared on fluorine-doped SnO2/glass (SnO2:F) substrates by sol-gel method. The crystalline structure, leakage current, interfacial characteristics, and multiferroic properties were investigated in detail. The results of Rietveld refinement showed that the structure of BSrSFMC layer is transformed from rhombohedral to tetragonal structure by the means of ion-doping. The difference of leakage current density of the BSrSFMC/NiFe2O4 (NFO) bilayered films of the −40 V to 40 V and 40 V to −40 V are 0.32 × 10−5 and 1.13 × 10−5 A/cm2, respectively. It was observed that there are obvious interface effects between BSrSFMC and NFO layers, which will cause the accumulation of space charges and the establishment of built-in internal electric field (EI) at the interface. Therefore, different EI directions will affect the dipoles reversal and migration of carriers in the BSrSFMC layer, which will result in different values of transient current with ...
6 citations
TL;DR: In this paper, a two-phase coexistence of rhombohedral-R3c:H (BiFeO3) to two phase R3m:R (BExFO) was investigated and the results indicated that the abundant Fe2+ is observed in BExFO, which induces larger leakage current.
Abstract: Bi1−xErxFeO3 (BExFO, x = 0.07–0.12) films have been deposited on fluorine-doped SnO2 (FTO) substrates by a chemical solution deposition method (CSD). The structure and multiferroic properties were investigated. The results indicate that there is a structural transition from the typical rhombohedral-R3c:H (BiFeO3) to two-phase coexistence of rhombohedral-R3c:H and rhombohedral-R3m:R (BExFO). The abundant Fe2+ are observed in BExFO, which induces the larger leakage current. The BE0.09FO shows the ferroelectric switching current of 1.42 × 10−2 A and the enhanced magnetization (saturation magnetization Ms ~ 2.60 emu/cm3). From the investigation, the BExFO films will be expected to show the great multiferroic properties after reducing the leakage current.
4 citations
Patent•
07 Jul 2017
TL;DR: In this paper, the authors provided a titanium oxide/ bismuth vanadate heterojunction film having visible light response characteristic as well as a preparation method and application thereof.
Abstract: The invention provides a titanium oxide/ bismuth vanadate heterojunction film having visible light response characteristic as well as a preparation method and application thereof The preparation method comprises the steps of preparing a BiVO4 precursor solution and a TiO2 precursor solution, then putting a substrate into the BiVO4 precursor solution to prepare an amorphous BiVO4 film having certain thickness by using a reverse layer-by-layer self-assembly technology of an electrostatic adsorption effect of a hydroxyl layer, irradiating the amorphous BiVO4 film in ultraviolet light to form a hydroxyl layer, putting the amorphous BiVO4 film into the TiO2 precursor solution, performing second reverse layer-by-layer self-assembly to form a BiVO4-TiO2 amorphous film, and finally performing heat preservation crystallization at 500 DEG C to obtain the titanium oxide/ bismuth vanadate heterojunction film having visible light response characteristic The process is simple and easy to control, the requirement for the experimental condition is relatively low, and the prepared TiO2/ BiVO4 heterojunction film has a broad application prospect in the field of photo-catalysis
1 citations
Patent•
07 Jul 2017
TL;DR: In this paper, a spherical titanium oxide/tin dioxide photo-electrode as well as a preparation method and application of thereof is described, which comprises the steps of preparing a TiO2 precursor solution, then irradiating a SnO2/glass substrate in ultraviolet light to form a hydroxyl monomolecular layer on the surface of the substrate, performing layer-by-layer self assembly and inverse induction on small molecular [Ti(OH)6] by using inverse polymerization reaction between the hydroxy monomolescular layer and the [Ti[
Abstract: The invention provides a spherical titanium oxide/ tin dioxide photo-electrode as well as a preparation method and application thereof. The preparation method comprises the steps of preparing a TiO2 precursor solution, then irradiating a SnO2/glass substrate in ultraviolet light to form a hydroxyl monomolecular layer on the surface of the SnO2/glass substrate, performing layer-by-layer self assembly and inverse induction on small molecular [Ti(OH)6] by using inverse polymerization reaction between the hydroxyl monomolecular layer and the [Ti(OH)6] in the TiO2 precursor solution to prepare an amorphous glass/SnO2-O-TiO2 composite film, and finally performing heat preservation crystallization at 500 DEG C, thus obtaining the spherical titanium oxide/tin dioxide photo-electrode. The process is simple and easy to control, the experimental condition requirement is relatively low, and the prepared TiO2/SnO2 photo-electrode is high in utilization rate of light and high in current density, is suitable for degrading organic pollutants in water or air via photo-catalysis and has a wide application prospect in the field of photo-catalysis.