Nanoscale
·
2018
·Vol. 10
·期 19
·9353-9359
·
IF 7.233
Huhui Fu,Pengfei Peng,Renfu Li,Caiping Liu,Yongsheng Liu,Feilong Jiang,Maochun Hong,Xueyuan Chen
A local structure around lanthanide (Ln3+) emitters in Ln3+-doped upconversion nanocrystals (UCNCs) is of fundamental importance in tailoring their upconversion luminescence (UCL) features. However, a general strategy responsible for the local-structure-dependent UCL in Ln3+-doped UCNCs has not been conclusively established to date. Herein, we report a new class of alkaline zirconium fluoride-based Yb3+/Er3+ co-doped UCNCs featuring a diversity of crystallographic structures for Ln3+ ion doping, which thereby allow us to thoroughly understand the origin underlying the local-structure-dependent UCL of the Er3+ ion for the first time. We reveal that the high-symmetry crystal lattice of Yb3+/Er3+ co-doped UCNCs may incur the large UCL red-to-green intensity ratio of Er3+ regardless of their identical elemental compositions. In combination with the first-principles calculations, we show that such local-structure-dependent UCL of Er3+ is primarily due to the varied electronic band structures induced by the Yb3+/Er3+ doping in different crystallographic structures of alkaline zirconium fluorides. These findings may open up a new avenue for constructing high-quality UCNCs with a tailored UCL profile and lifetime for diverse applications.
研究领域:
材料科学
·
光学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
JOURNAL OF CATALYSIS
·
2020
·
IF 7.888
Yaping Pan,Fawei Zheng,Xixi Wang,Hongye Qin,Enzuo Liu,Junwei Sha,Naiqin Zhao,Ping Zhang,Liying Ma
Hydrogen evolution reaction (HER) activities of WS 2 can be improved by doping exotic atom to increase active sites on base plane and narrow the bandgap. However, most of these catalysts of exotic atom doped WS 2 are composed of semiconductor and the electronegativity between atoms is similar, which do harm to tuning bandgap with a wide range and decreasing the value of free Gibbs energy (Δ G H ) for hydrogen adsorption. Given that Te can tune bandgap with a wide range and the electronegativity between S and Te differ greatly, a vertically arranged WS 2 nanoelectrode is prepared by doping Te on WS 2 . According to experimental studies and the density functional theory calculations (DFT), the bandgap of WS 2 nanosheets is successfully narrowed after doping Te. This lowers the Schottky barrier which benefits the transfer of charges and improves electrocatalytic performance in turn. Meanwhile, the presence of Te atoms with much lower electronegativity than S increases the electron density of the adjacent region, thereby the S edges of basal plane around Te atoms and hollow sites of WS 2 nanosheet become active to drive HER, which has been verified by the reduced Δ G H of S edges of basal plane from 2.27 to 2.08 eV and hollow sites from 2.28 to 1.85 eV after the doping in DFT. Te-doped WS 2 nanosheets used as excellent HER catalysts with an overpotential of 213 mV to drive a current density of 10 mA/cm 2 , a small Tafel slope of 94 mV/dec, along with a superior stability in acid media.
研究领域:
材料科学
·
电化学
✓ 已验证
产品关联
DOI
高影响因子
CHEMICAL ENGINEERING JOURNAL
·
2023
·
IF 15.1
Yunning Chen,Zhengkai Wu,Renquan Guan,Xueying Cheng,Qingkun Shang,Yingnan Sun
Improving the efficiency of photogenerated charge separation and transport is the primary goal of designing and constructing efficient composite photocatalysts. The matching of energy bands and the formation of chemical bond between the two components are very conducive to the separation and transmission of photogenerated charges. Herein, three perylene diimide derivatives (PDIs) are synthesized by introducing sulfonic acid group (PDI-SA) and benzenesulfonic acid (PDI-BSA) respectively into the amide bond and further chlorine bay-substituting (Cl-PDI-BSA). The good water solubility of Cl-PDI-BSA ensures its forms a stable chemical bond with TiO 2 through the sulfonic acid group in the single molecular state, coupled with the matching of energy band structure, TiO 2 @Cl-PDI-BSA exhibited excellent performance upon visible light photocatalytic degradation to phenol and trenbolone acetate (TBA). It can remove 100% of phenol in 15 min and 100% trenbolone acetate (TBA) in 30 min, which is 14.3 times that of TiO 2 . Combining to DFT calculation, Kelvin probe force microscope and EPR analysis prove that bay chlorine substitution has a greater impact on the energy band structure and electron cloud distribution of PDIs than N-sulfonation, thereby seriously affecting the transport of photogenerated carriers with TiO 2 .
研究领域:
材料科学
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环境科学
·
化学
✓ 已验证
产品关联
DOI
高影响因子
APPLIED SURFACE SCIENCE
·
2021
·
IF 6.707
Tianyu Wang,Yong Yang,Qinghua Deng,Xiaoyue Zhang,Lijun Xiong,Zheng Tang,Panjie Li,Nan Yin,Aiwu Sun,Dan Chen,Jinyou Shen
Developing of a photocatalyst for multiple antibiotics degradation and revealing their different mechanism are of great importance for wastewater remediation. Herein, a 3D marigold-like CoAl-LDH/Ti 3 C 2 hybrid is developed via in situ growth of CoAl-LDH on Ti 3 C 2 nanosheets and on-spot self-assembly during the hydrothermal process. The existence of optimized Ti 3 C 2 steers the morphology evolution from 2D lotus leaf-like nanoplate to 3D marigold-like hierarchical architecture, which greatly boosts the adsorption capacity and photon capture of the catalyst by the increased specific surface area and the scattering cross section. Meanwhile, the well-defined 2D/2D interface between the components effectively promotes the electron transfer from CoAl-LDH to Ti 3 C 2 , and the photoinduced electron-hole pairs on CoAl-LDH can be greatly separated. The density functional theory (DFT) calculations further demonstrate the change of electronic structure for the composite photocatalyst. As a result, CoAl-LDH/Ti 3 C 2 hybrid presents 85%, 56% and 70% degradation efficiency towards tetracycline hydrochloride, chloramphenicol and terramycin, which are 3.1, 3 and 2.1 times of the pristine CoAl-LDH. Furthermore, the degradation path for chloramphenicol is explored and the reason for its different degradation efficiency is revealed. The design of 3D hierarchical scaffold cooperating with 2D/2D heterogeneous interface provides a new avenue to develop ideal catalysts for wastewater remediation.
研究领域:
环境科学
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材料科学
✓ 已验证
DOI
高影响因子
RSC Advances
·
2021
·Vol. 11
·期 45
·28410-28419
·
IF 3.361
Shu Zhou
We report the rapid separation and purification of lead halide perovskite quantum dots (QDs) in a nonpolar solvent by using a convenient and efficient differential separation method. Size-selective precipitation effectively separates the perovskite QDs from larger aggregates and provides direct evidence for strong quantum confinement in the photoluminescence (PL). Significantly, the size-selected perovskite QDs are readily well-dispersed in a nonpolar solvent and remain stable in ambient air (humidity > 60%) for >20 days. These enable measurement of the electronic band structure of versatile perovskite QDs as a function of size for the first time. Despite a clear blue-shift of the optical bandgap, the lowest unoccupied molecular orbital (LUMO) readily moves towards the vacuum level while the highest occupied molecular orbital (HOMO) changes slightly, in good agreement with that observed in the quantum size effect tuning of quasi-2D perovskites and colloidal semiconductor QDs. The results demonstrate the possibility of utilizing differential centrifugation as a novel method to attain size-dependent tunability for property-specific perovskite-QD based optoelectronic applications.
研究领域:
材料科学
·
光电子学
✓ 已验证
DOI
PubMed
高影响因子
JOURNAL OF CATALYSIS
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2020
·
IF 7.888
Xiaorong Gan,Huimin Zhao,Dangyuan Lei,Peifang Wang
Liquid phase exfoliation (LPE) is a promising method for synthesizing two-dimensional (2D) 2H-MoS 2 due to the balance obtained in the resulting yield and quality. Improvements in the electrocatalytic activity of 2D 2H-MoS 2 are typically attributed to an increased number of active sites at the plane edges. However, the conclusion need be carefully redefined in the case of LPE, because the covalent surface modification and solvent intercalation between layers can affect the electrocatalytic activity as well. In this study, bulk 2H-MoS 2 was exfoliated in three typical solvents, including N, N-dimethyl formamide (DMF), formamide, and 1-methyl-2-pyrrolidinone (NMP), to synthesize 2H-MoS 2 nanosheets . X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and Raman spectrum were used to confirm the possibility of surface and interface functionalization of the 2H-MoS 2 nanosheets. Further, the effects on the electrocatalytic activity of 2H-MoS 2 nanosheets were investigated mainly by density functional theory periodic calculations based on the analysis of electronic energy band structures. The results have demonstrated that 2H-MoS 2 nanosheets prepared in formamide exhibit smaller average size and thickness, and higher electrocatalytic activity. The surface functionalization of the 2H-MoS 2 nanosheets is indeed generated by Mo-N covalent bonds due to the presence of S vacancies. Such covalent functionalization leads to a slight decrease of energy band gap with 0.03 eV in a (3 × 3 × 1) 2H-MoS 2 supercell. In contrast, the interface functionalization formed by the intercalation of solvent molecules (e.g., formamide) between layers can cause a remarkable decrease in the band gap of (1 × 1 × 2) 2H-MoS 2 , the phase transition from semiconductor to semimetal , higher carrier mobility, and smaller effective mass ( m e = 0.052 m 0 ).
研究领域:
材料科学
·
电化学
✓ 已验证
DOI
高影响因子
CHEMICAL ENGINEERING JOURNAL
·
2025
·
IF 13.2
Wenping Shi,Jing Zhou,Yuli Xiong,Wen Chen
Two-dimensional covalent organic frameworks (2D-COFs) based on imine linkages have been shown to offer intriguing optical and electrochromic (EC) performance, attracting extensive attention in the field of advanced photo-electrochemistry. However, few studies have explored how the orientation of imine linkages in 2D-COFs regulates electron transfer behavior and subsequently affects EC performance. In this work, we report an isomeric pair (Py-C-TP-COF and Py-N-TP-COF), differing only in the orientations of the imine linkages. Experimental and theoretical results demonstrate that significant differences in the electronic orbital contributions and bandgaps of 2D-COFs with distinct imine linkage orientations. Furthermore, the different orientations of imine linkages play a crucial role in the distribution of the highest occupied and the lowest unoccupied molecular orbital (HOMO and LUMO), thus significantly influencing electron separation and charge transfer. This approach of altering imine linkage orientations allows for the fine control of the charge transport and band structure of the 2D-COFs. As a result, the Py-C-TP-COF film exhibits excellent EC performance with high coloration efficiency (η CE ,1316 cm 2 ·C -1 ), fast switching time (2.0/0.4 s) and outstanding cycling stability (99.5 % retention of EC cyclic stability after 150 cycles). This study provides new insights for further rational design and optimization of functional COFs as EC materials with atomically regulated charge transfer.
研究领域:
材料科学
·
光电化学
✓ 已验证
产品关联
DOI
高影响因子
APPLIED SURFACE SCIENCE
·
2014
·
IF 2.538
Weimin Du,Lixin Liu,Keke Zhou,Xiaodan Ma,Yaming Hao,Xuefeng Qian
Black lead molybdate (PbMoO 4 ) nanoparticles were first synthesized by the glycol–solvothermal method. Phase, morphology, crystal lattice, and specific surface of products were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, and Brunauer–Emmett–Teller nitrogen adsorption–desorption, respectively. Results revealed that the as-synthesized PbMoO 4 nanoparticles are the scheelite-type tetragonal structure with 30–50 nm in size. Also, glycol played a dual function in present synthetic system: solvent and surface modification agent. Optical properties reveal glycol-modification on the surface of PbMoO 4 nanoparticles can generate new energy level between the original conduction band and valence band, leading to better absorption of visible light and the black appearance. Photocatalytic experimental results demonstrate that black PbMoO 4 nanoparticles synthesized in glycol medium have pretty visible-light-responsive photocatalytic degradation performance on methylene blue and phenol solution. Reaction mechanism investigations show that the excellent photocatalytic activities of black PbMoO 4 nanoparticles derive from the novel energy band structure, smaller size, and larger specific surface area. Hence one can see that black PbMoO 4 nanoparticles are a type of visible-light-responsive photocatalysts with excellent photocatalytic activities and potentially applied prospects in dye wastewater treatment and environmental protection. Meanwhile, the present work provides an innovative strategy for adjusting the energy band structure of wide band-gap semiconductors.
研究领域:
材料科学
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环境科学
✓ 已验证
产品关联
DOI
高影响因子
Small
·
2023
·
IF 13.3
Zhengzheng Xie,Qiang Gao,Sajjad Hussain,Jianjun Yang,Qiuye Li
Porous graphitic carbon nitride microsphere with large specific surface area and controllable energy band structure is synthesized via a simple method with the supermolecule polymer of melamine-cyanuric acid (MCA) as the intermediates. The energy band structure and morphology of carbon nitride are closely correlative to the calcination time. And the CN-20 catalyst fabricated by calcination for 20 h exhibit superior photocatalytic activity of hydrogen evolution reaction (HER) under visible-light (λ ≥ 420 nm) irradiation. The photocatalytic and photoelectrochemical test results indicate that Pt is the optimum cocatalyst candidate compared with Pd, Ru, and Ag. Meanwhile, the time-dependent process of the intermediate pyrolysis to carbon nitride and the internal mechanism of photogenerated charge transfer between semiconductors and cocatalyst is investigated and supplemented by theoretical calculations. This work provides a novel and energy band structure controllable manufacture strategy for porous carbon nitride semiconductor with satisfying visible-light photocatalytic reduction performance.
研究领域:
材料科学
·
化学工程
✓ 已验证
产品关联
DOI
PubMed
高影响因子
MATERIALS LETTERS
·
2014
·
IF 2.269
Jianxiu Liu,Dafeng Zhang,Xipeng Pu,Daoyou Dong,Peiqing Cai,Hyo Jin Seo
Magnetically separable Zn 1− x Cd x S/γ-Fe 2 O 3 ( x =0–1) photocatalysts were synthesized by a one-step combustion method. The structures, morphologies, absorbance, optical and photocatalytic properties of the samples were studied by X-ray powder diffraction, scanning electron microscopy, transmission electron microscopy , ultraviolet–visible spectrophotometry and photoluminescence . The experimental results show that the formation of hexagonal Zn 1− x Cd x S and γ-Fe 2 O 3 and the combination of them were one-pot achieved. The Cd 2+ content has a significant influence on the absorbance of visible light and fluorescence properties. The magnetic properties of samples ensure the magnetic separation by using a magnet. CdS/γ-Fe 2 O 3 shows the best photocatalytic performance compared with other samples, ascribed to its small energy band gap and matching energy band structure between CdS and γ-Fe 2 O 3 . Moreover, no obvious deterioration was observed in the stability tests.
研究领域:
材料化学
·
光催化
·
纳米材料
·
环境功能材料
·
无机合成
✓ 已验证
DOI
高影响因子
INTERNATIONAL JOURNAL OF HYDROGEN ENERGY
·
2013
·
IF 3.548
Zhenlong Zhang,Guangsheng Liu,Yanli Mao
To investigate the mechanisms of the improvement on separation efficiency of photogenerated carriers , a Fe 2 O 3 /SrTiO 3 heterojunction semiconductor with an improved separation efficiency was successfully prepared. The heterojunction semiconductor was characterized with X-ray diffraction (XRD), UV–vis absorption spectrum , scanning electron microscope (SEM) and surface photovoltage (SPV) spectroscopy. The energy band diagrams of Fe 2 O 3 and SrTiO 3 were determined with X-ray photoelectron spectroscopy (XPS), based on which the conduction band offset (CBO) between Fe 2 O 3 and SrTiO 3 was quantified to be 1.26 ± 0.03 eV. The recombination of photogenerated carriers was investigated with photoluminescence (PL) spectrum, which indicates that the formation of Fe 2 O 3 /SrTiO 3 decreases the recombination. Thus the improved separation efficiency is mainly due to the energy difference between the conduction band edges of Fe 2 O 3 and SrTiO 3 , and the decreased electron-hole recombination for Fe 2 O 3 /SrTiO 3 .
研究领域:
材料科学
·
光电化学
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF ALLOYS AND COMPOUNDS
·
2024
·
IF 5.8
Zhenyu Bai,Jing Tian,Yuanhang Cheng,Li Liu,Yang Zhou,Feng Qian,Jiarun Li
The degree of band matching is crucial for the photoelectric conversion performance of heterojunctions. In this work, TiO 2 /Zn x In 2 S 3+x (TO/ZIS-X, X=1, 2, 3, 4) heterostructures and their electrochemical and photoelectrochemical tests were studied. According to the energy band analysis of a series of TO/ZIS-X, it is found that I-type heterojunction can be formed between TO and ZIS-1, while Z-type heterojunction would be formed between TO and ZIS-2, ZIS-3 and ZIS-4. The photoinduced potential drop associated with current density of TO/ZIS-2 in 3.5 wt% NaCl are 505.82 mV and 18.61 μA·cm −2 , respectively. This result is much higher than those of homogeneous TO and single-phase ZIS-X. The desirable photoelectrochemical cathodic protection performance of the photoelectrode is owing to the loading of Zn x In 2 S 3+x , which broadens the light absorption threshold and improves the electrochemical activity area. Besides, the construction of Z-type heterojunction retains the photogenerated electrons/holes with strong reduction/oxidation ability, which greatly promotes the photoelectrochemical cathodic protection capability on 316 L stainless steel.
研究领域:
材料科学
·
电化学
·
表面工程
✓ 已验证
产品关联
DOI
高影响因子
危险品化学品经营许可证（带存储）