ACS Applied Materials & Interfaces
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2018
·
IF 8.097
Weixuan Zeng,Yuan Bian,Sheng Cao,Yongjin Ma,Yi Liu,Anquan Zhu,Pengfei Tan,Jun Pan
Tantalum oxynitride-based materials, which possess narrow band gaps and sufficient band energy potentials, have been of immense interest for water splitting. However, the efficiency of photocatalytic reactions is still low because of the fast electron–hole recombination. Here, a Sr2Ta2O7–xNx/SrTaO2N heterostructured photocatalyst with a well-matched band structure was in situ constructed by the nitridation of hydrothermal-prepared Sr2Ta2O7 nanosheets. Compared to Sr2Ta2O7–xNx and pure SrTaO2N, the Sr2Ta2O7–xNx/SrTaO2N heterostructured photocatalyst exhibited the highest rate of hydrogen evolution, which is ca. 2.0 and 76.4 times of Sr2Ta2O7–xNx and pure SrTaO2N, respectively, under the similar reaction condition. The enhanced performance arises from the formation of suitable band-matched heterojunction-accelerated charge separation. This work provides a promising strategy for the construction of tantalum oxynitride-based heterojunction photocatalysts.
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APPLIED SURFACE SCIENCE
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2018
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IF 4.439
Xiaojie Zhang,Jipeng Yang,Tiancong Cai,Guoqiang Zuo,Changqing Tang
Boron carbide (B 4 C) nanoparticles-decorated anatase titanium dioxide (TiO 2 ) nanosheets photocatalysts were synthesized by a hydrothermal method in the presence of hydrofluoric acid and characterized by field emission scanning electron microscope, high-resolution transmission electron microscope, UV–vis diffuse reflectance spectra, photoluminescence spectra, etc. With metallic Pt nanoparticles as a co-catalyst, the as-synthesized B 4 C/TiO 2 composites were evaluated using photocatalytic CO 2 or H 2 O reduction to solar fuels such as methane and hydrogen. Under either simulated sunlight or visible light irradiation, coupling p-type B 4 C with n-type anatase TiO 2 significantly improved the photocatalytic performance. Both photoluminescence and transient photocurrent measurements indicated that the interfacial coupling effect between B 4 C and anatase TiO 2 could significantly promote photo-excited charges separations. On the basis of measurements and literatures, a possible mechanism of excited charges transfer at the B 4 C-anatase TiO 2 heterojunction interface during irradiation was deduced.
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PHYSICAL CHEMISTRY CHEMICAL PHYSICS
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2018
·Vol. 20
·期 18
·12808-12816
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IF 3.906
Zhiyong Li,Xiaoqing Yuan,Ying Feng,Yongkui Chen,Yuling Zhao,Huiyong Wang,Qingli Xu,Jianji Wang
Photo-induced conductivity modulation of stimuli-responsive materials is of great importance from the viewpoint of fundamental research and technology. In this work, 5 new kinds of azobenzene-based photo-responsive ionic liquids were synthesized and characterized, and UV/vis light modulation of their conductivity was investigated in an aqueous solution. The factors affecting the conductivity modulation of the photo-responsive fluids, such as photo-isomerization efficiency, photo-regulation aggregation, concentration and chemical structure of the ionic liquids, were examined systematically. It was found that the conductivity of the ionic liquids in water exhibited a significant increase upon UV light irradiation and the ionic liquids with a shorter alkyl spacer in the cation showed a more remarkable photo-induced conductivity enhancement with a maximum increase of 150%. In addition, the solution conductivity was restored (or very close) to the initial value upon an alternative irradiation with visible light. Thus, the solution conductivity can be modulated using alternative irradiation with UV and visible light. Although the reversible photo-isomerization of the azobenzene group under UV/vis irradiation is the origin of the conductivity modulation, the photo-regulated aggregation of the ionic liquid in water is indispensable for the maximum degree of conductivity modulation because UV irradiation can weaken, even break the aggregated cis-isomers of the ionic liquids in an aqueous solution.
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Journal of Materials Chemistry A
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2018
·Vol. 6
·期 21
·9874-9881
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IF 9.931
Yuchao Wang,Canzhu Wang,Xiangju Song,Minghua Huang,Suresh Kumar Megarajan,Saleem Farooq Shaukat,Heqing Jiang
Solar-driven evaporation based on photothermal membrane has been proved to be promising in the field of fresh water generation, and it is considered as an emerging strategy both in laboratory and in industrial scales. However, further research efforts have to be made on light harvesting and thermal management to improve water evaporation. In this study, an extensive research was carried out to develop a bio-inspired 3D photothermal cone for high-efficiency solar-driven evaporation with minimum light reflection and heat loss to bulk water. The artificial photothermal cone with a polypyrrole (PPy) coating layer was facilely fabricated via chemical vapor deposition polymerization (CVDP). The present 3D cone with a rationally designed conical structure exhibited satisfactory absorbance around 99.2% in the entire solar spectrum, which is comparable with the performances of super-black materials. Additionally, the heat loss has been minimized by elevating the photothermal cone to narrow the contact area between water and the PPy-based cone with good wettability, thus achieving a highly efficient interface heating. The solar conversion efficiency up to 93.8% for evaporation was achieved for the photothermal cone under one sun illumination, which is about 1.7 times as high as the result obtained for a plane film. Based on our results, controlling the 3D morphology can be considered as an important strategy for designing a novel high-efficiency photothermal membrane and also, it provides new opportunities in practical application.
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JOURNAL OF MATERIALS SCIENCE-MATERIALS IN ELECTRONICS
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2018
·Vol. 29
·期 12
·10453-10460
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IF 2.324
Yuan Rongrong,Liu Jianming,Xiang Weidong,Liang Xiaojuan
Various luminescent carbon materials are artificially synthesized and as admirable fluorescent materials because of the increased research of carbon nanodots (CDs). Herein, a novel solvent-dependent red CDs (rCDs) is introduced through solvothermal method. The as-prepared rCDs remain benzene structure and possess abundant surface function groups that endow them well solubility in various solvents. Furthermore, multicolor luminescence are observed when rCDs are dissolved in different solvents, and the emission wavelength of these materials can be well-tuned from 475 to 624 nm, which presents intensity solvent-dependent properties. Red luminescence carbon phosphors are successfully synthesized by mix rCDs with silica powder. Finally, warm white light emitting diodes (WLEDs) are constructed using rCDs powder with Ce 3+ : YAG single crystal and blue GaN chips. The results demonstrate that the rCDs can act as red component to modify the correlated color temperature (CCT) and the color rendering index (CRI) of WLEDs .
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APPLIED CATALYSIS B-ENVIRONMENTAL
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2018
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IF 11.698
Ruyi Zhong,Zisheng Zhang,Huqiang Yi,Lei Zeng,Chao Tang,Limin Huang,Meng Gu
Visible-light photocatalytic hydrogen evolution is a key step towards utilizing solar energy. Here we constructed covalently bonded oxidized graphitic C 3 N 4 /TiO 2 (O-g-C 3 N 4 /TiO 2 ) heterostructure with high surface area via an in-situ solvothermal synthetic strategy. The edge-anchoring of two-dimensional (2D) TiO 2 on 2D O-g-C 3 N 4 was evidenced by the HAADF-STEM EDS mapping, EELS and XPS analysis. Density functional theory computations suggest strong affinity between TiO 2 and O-g-C 3 N 4 2D structures through N O Ti covalent bonding, which drastically enhances the synergetic effect of the light absorption of O-g-C 3 N 4 and high surface area of TiO 2 . The as-formed heterojunction can remarkably boost the visible-light photocatalytic activity for H 2 evolution by 6.1 times compared to physical mixture of TiO 2 nanosheets (NS) and O-g-C 3 N 4 .
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DALTON TRANSACTIONS
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2018
·Vol. 47
·期 33
·11705-11712
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IF 4.099
Cong-Cong Shen,Ya-Nan Liu,Xin Wang,Xiao-Xiang Fang,Zhi-Wei Zhao,Nan Jiang,Liu-Bo Ma,Xiao Zhou,Tuck-Yun Cheang,An-Wu Xu
Metal–organic framework (MOF)-based materials possess numerous attractive characteristics; however, the application of MOF-based photocatalysts in the area of visible-light photocatalytic H2 evolution is still in its infancy. Herein, we develop a series of novel UiO-66-NH2-based composites with embedded NiO nanoparticles via solvothermal treatment and subsequent calcination. Their characterizations demonstrate intimate lattice-level contacts between UiO-66-NH2 photocatalysts and NiO nanoparticles. By optimizing each component, even without noble metal loading, the U6N-NiO-2 sample (the weight ratio of NiO to U6N-NiO-2 is theoretically calculated to be ca. 10 wt%) with 15 mg eosin Y as a sensitizer causes an enhanced H2 generation rate of 2561.32 μmol h−1 g−1 under visible-light irradiation using TEOA as a sacrificial reagent; furthermore, its corresponding quantum efficiency is as high as 6.4% at 420 nm. The H2 evolution activity of U6N-NiO-2 is about 5 times higher than that of the UiO-66-NH2 photocatalyst (denoted as U6N) and 23 times higher than that of U6N-NiO-2 without sensitizer. It is demonstrated that the high efficiency originates from the visible-light generated electrons of eosin Y and UiO-66-NH2, the efficient separation of carriers by the cascaded band structure and more negative CB of NiO as well as the good dispersion of NiO nanoparticles on the octahedral skeleton. This study provides new insights for the design of MOF-based materials without noble metal loading for visible-light photocatalytic H2 evolution.
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Journal of Materials Chemistry A
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2018
·Vol. 6
·期 42
·20760-20768
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IF 9.931
Xiaoqin Sun,Fangfang Wu,Gang Liu,Xiaoxiang Xu
The perovskite oxynitride SrTaO2N is a promising compound for solar energy conversion because it has strong visible light absorption at wavelengths as long as 650 nm. However, its photocatalytic activity is generally very poor, primarily because of the high defect concentration induced during its synthetic procedures as well as photocatalytic self-decomposition events. In this work, we introduce Sr into the B site of SrTaO2N to form a complex perovskite oxynitride, Sr3(Sr1/3Ta2/3)3O9−xNy (i.e. Sr4Ta2O9−xNy). The new compound has a much lower defect concentration compared to SrTaO2N and much higher stability against photocatalytic self-decomposition. More importantly, Sr4Ta2O9−xNy demonstrates significantly improved photocatalytic activity for water oxidation and reduction reactions under visible light irradiation (λ ≥ 400 nm) than SrTaO2N, approaching an apparent quantum efficiency as high as 3.4% at 420 ± 20 nm.
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CHEMICAL ENGINEERING JOURNAL
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2018
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IF 6.735
Liang Wang,Zhiqiang Wang,Lili Zhang,Chun Hu
An iodine intercalated Bi 2 WO 6 was fabricated by a facile hydrothermal method (160 °C, 2 h) and characterized by field emission scanning electron microscope, high resolution transmission electron microscopy, nitrogen adsorption/desorption isotherms, X-ray diffraction and X-ray photoelectron spectroscopy, Fourier-transform infrared and UV-Vis diffuse reflectance spectra. The I 0.30 -Bi 2 WO 6 with an I/W molar ratio of 0.30 was highly effective for the degradation and mineralization of 2-chlorophenol, rhodamine B, bisphenol A, phenol, ciprofloxacin and sulfamethoxazole in water under visible light. Furthermore, the visible-light-driven photocatalytic activity of Bi 2 WO 6 was enhanced 3.1 times by the introduction of I − . The characterized results indicated that I − mainly inserted into the interlayer of Bi 2 WO 6 , expanding the layer spacing, favoring the efficient charge separation and transfer and prohibiting the recombination of the photogenerated electrons and holes. Specially, the XPS analysis indicated the I − ions substitued the absorbed oxygen to chemically bond in the layered Bi 2 WO 6 , resulting in the change of the electric charge distribution of Bi 2 WO 6 . Moreover, the BET surface area was increased from 25.2 m 2 g −1 for Bi 2 WO 6 to 66.7 m 2 g −1 for I 0.30 -Bi 2 WO 6 for more surface active sites. In addition, the band gap was narrowed for expanded optical absorption in the visible light region. ESR and radicals trapping experiments verified holes were the main active species for the degradation of organic pollutants. Simultaneously, the more positive potential of valence band in iodine intercalated Bi 2 WO 6 could enhance the oxidative power of the photogenerated holes, resulting in the efficient removal of refractory organic pollutants in water.
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MATERIALS CHEMISTRY AND PHYSICS
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2018
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IF 2.21
Meng Li,Zipeng Xing,Jiaojiao Jiang,Zhenzi Li,Junyan Kuang,Junwei Yin,Ning Wan,Qi Zhu,Wei Zhou
In-situ Ti 3+ /S doped high thermostable anatase TiO 2 nanorods using ethanediamine-modified TiOSO 4 as precursor are synthesized under 700 °C calcination , then combined with controllable in-situ solid-phase reaction method, calcined at 350 °C in argon. The outcomes declare that the obtained photocatalyst with a high crystallinity is effectively doped with S element and Ti 3+ species, and synchronously possesses one-dimensional (1D) anatase nanorods structure with length of ∼ 2–5 μm and width of ∼0.5–1 μm. The S and Ti 3+ co-doped 1D nanorod with a narrowed bandgap (2.56 eV) stretches the optical response range to visible-light. The visible-light-driven photocatalytic degradation efficiency of methyl orange and H 2 production rate for Ti 3+ /S-TiO 2 nanorods are as high as 96% and 166 μmol h −1 g −1 , showing about 6 times greater than 600-TR (TiO 2 nanorods). This is be ascribed to the synergistic reaction of S and Ti 3+ species co-doping narrows the bandgap and promotes the separation efficiency of photoexcited carriers, and the one-dimensional structure favors the transportation of photogenerated charge carriers. Hence, the prepared photocatalyst will have a great latent application prospect in fields of energy and environment.
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ACS Catalysis
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2018
·
IF 11.384
Chunwei Dong,Siyu Lu,Shiyu Yao,Rui Ge,Zidong Wang,Ze Wang,Pengfei An,Yi Liu,Bai Yang,Hao Zhang
Recently, ultrathin 2D photocatalysts have attracted people’s attention due to their performances in the area of solar energy conversion. However, the synthesis of ultrathin 2D photocatalysts with a nonlayered crystal structure is still full of challenges. Herein, ultrathin 2D BiVO4 nanosheets (NSs) with monoclinic crystal structure are synthesized through a convenient colloidal two-phase method. The as-prepared BiVO4 NSs possess a thickness of less than 3 nm but a diameter larger than 1.2 μm. Furthermore, the presence of HNO3 facilitates the growth of BiVO4 NSs with nearly naked surfaces, largely exposed {010} planes, and widely distributed oxygen vacancies (VO) inside the crystalline structure, which are of great benefit to their photocatalytic activity under visible light irradiation. As a result, our ultrathin 2D BiVO4 NSs exhibit an impressive photocatalytic performance for water oxidation. The O2 evolution rate is 107.4 μmol h–1, and the apparent quantum yield (AQY) is as high as 26.1% (420 nm). Furthermore, by employing our ultrathin 2D BiVO4 NSs as the O2-evolving photocatalyst, Ru-SrTiO3:Rh and Fe3+/Fe2+ as the H2-evolving photocatalyst, and the redox mediator, respectively, a Z-scheme overall water splitting system is successfully constructed. Under visible light irradiation, our Z-scheme photocatalytic system presents high H2 and O2 evolution rates (16.7 and 8.0 μmol h–1) with an AQY of 1.88% (420 nm) and good photocatalytic stability.
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JOURNAL OF ALLOYS AND COMPOUNDS
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2018
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IF 3.779
Pengyuan Wang,Changsheng Guo,Song Hou,Xin Zhao,Linlin Wu,Yingying Pei,Yuan Zhang,Jianfeng Gao,Jian Xu
A novel photocatalytic material that is phosphorus-doped and graphite-like (carbon nitride (g-C 3 N 4 )) was successfully prepared through direct thermal co-poly-condensation using ammonium dihydrogen orthophosphate as the phosphorus source and melamine as the g-C 3 N 4 precursor. The catalyst was characterized by analyses from multiple tools: X-ray powder diffraction, Fourier transform infrared spectroscopy , scanning electron microscopy, transmission electron microscopy , BET surface area, ultraviolet–visible diffuse reflection spectroscopy , and X-ray photoelectron spectroscopy. The unique bubble-like structure provided the phosphorus-doped g-C 3 N 4 (P-C 3 N 4 ) with a unique property for spatial electron transfer and a large specific surface area (40.89 m 2 g -1 ). The photocatalytic performance of P-C 3 N 4 was determined by assessing rhodamine B (RhB) degradation under visible-light irradiation. The results showed that P-C 3 N 4 exhibited superior photocatalytic performance that is 18 and 4 times higher than pristine bulk g-C 3 N 4 (B-C 3 N 4 ) and modified multi-aperture g-C 3 N 4 (M-C 3 N 4 ), respectively. The enhancement of photocatalytic activity was attributed to the improved light harvesting capacity and the narrowing energy band structure of the copolymer that result from the substitution of phosphorus atoms by carbon atoms in the g-C 3 N 4 framework. The photoelectron emission measurements confirmed that P-C 3 N 4 promoted the separation efficiency of the charge carriers. The bubble-like structured P-C 3 N 4 also possessed superior durability and stability. The radical quenching tests indicated that superoxide radicals ( O 2 − ) and holes (h + ) were the dominant active species for RhB degradation.
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