Journal of Physical Chemistry C
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2019
·
IF 4.309
Min Lu,Jie Guo,Po Lu,Liu Zhang,Ying Zhang,Qilin Dai,Yue Hu,Vicki L. Colvin,William W. Yu
Lead halide perovskite nanocrystals (NCs) as a promising material have been widely applied in optoelectronic devices, but the massive defects reduce their optical properties and consequently limit the device performance. In this work, we developed a method to reduce the surface defects caused by unbonded lead on the surface of NCs by introducing ammonium thiocyanate in the synthesis of CsPbI3 NCs. Thiocyanate ions can link to the unbonded lead on the surface of perovskite NCs, resulting in a prolonged lifetime and enhanced photoluminescence quantum yield. At the same time, the whole energy level of passivated CsPbI3 NC films goes down compared to the pristine CsPbI3 NC films, which contributes to better electron injection. As a result, the passivated NCs based light-emitting diodes (LEDs) realized 10.3% external quantum efficiency and 823 cd m–2 luminance, higher than the LEDs made from the non-passivated NCs.
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Nano Energy
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2018
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IF 13.12
Ping Chen,Yan Meng,Mahshid Ahmadi,Qiming Peng,Chunhong Gao,Long Xu,Ming Shao,Zuhong Xiong,Bin Hu
“Ruddlesden-Popper” perovskites with multiple quantum wells (MQWs) layered structure are extremely attractive for light-emitting diodes (LEDs) due to their effective energy confinement and high device stability properties. Two important processes of energy transfer (ET) and charge transfer (CT) are responsible for the effective energy confinement in MQWs. At present stage, the ET mechanism has been widely accepted as the main origin of high efficiency in MQWs. However, the high dielectric constant (ε) of hybrid perovskites should significantly limit the ET process, because the ET rate is inversely proportional to the ε. Therefore, the detailed contribution of CT mechanism, especially under electrical excitation, should be carefully considered. Herein, we report a high quality quasi-2D perovskite film of PA 2 (CsPbBr 3 ) n-1 PbBr 4 MQWs through a simple solution process, with highly-dense and smooth morphology, and a high photoluminescence (PL) quantum efficiency. Then, the PL and transient PL spectra were measured under electrical injection in a hole-only and electron-only devices, respectively, to verify the CT mechanism. Furthermore, the photo-excitation intensity dependent PL spectra reveal that the CT mechanism is more important than ET mechanism for the electroluminescence of PA 2 (CsPbBr 3 ) n-1 PbBr 4 perovskite LEDs (PeLEDs), resulting in a pure cyan emission at ~ 505 nm and maximal external quantum efficiency up to 3.6%, representing one of the best results in reported blue PeLEDs.
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ADVANCED FUNCTIONAL MATERIALS
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2018
·Vol. 28
·期 22
·1801193
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IF 13.325
Yuequn Shang,Gang Li,Weimin Liu,Zhijun Ning
Metal halide perovskites are rising as a competitive material for next-generation light-emitting diodes (LEDs). However, the development of perovskite LEDs is impeded by their fast carriers diffusion and poor stability in bias condition. Herein, quasi-2D CsPbBr 3 quantum wells homogeneously surrounded by inorganic crystalline Cs 4 PbBr 6 of large bandgap are grown. The centralization of carriers in nanoregion facilitates radiative recombination and brings much enhanced luminescence quantum yield. The external quantum efficiency and luminescence intensity of the LEDs based on this nanocomposite are one order of magnitude higher than the conventional low-dimensional perovskite. Meanwhile, the use of inorganic nanocomposite materials brings much improved device operation lifetime under constant electrical field.
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Optical Materials Express
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2019
·Vol. 9
·期 2
·423-434
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IF 2.673
Xinying Ding,Zhan Wei,Ying Chen,Pengcheng Lin,Qi Yan,Yufeng Fan,Xiaodan Chen,Zhengdong Cheng
Understanding the dispersion state of 2D black phosphorus (BP) nanosheets is of great significance for the application of BP based materials. However, the dispersion state of BP colloids cannot be analyzed by the conventional methods based on the optical signal detecting due to the intensive light absorption of BP in the ultraviolet-visible region and the high turbidity caused by the aggregation of pristine BP nanosheets. In this work, 3D light scattering has been proven to be an effective technique to characterize the dispersion characteristics of nanocolloids with intensive light absorption and limited dispersity by suppressing multiple scattering. The effect of the concentration, the temperature and the solvent on the dispersion stability of BP nanosheets has been systematically studied by modulated 3D cross-correlation. It has been shown that measurements at smaller angles can obtain better autocorrelation functions. The BP colloids exhibit excellent colloidal stability when the concentration is below 250 μgmL−1, above which aggregation tends to form. Increasing the temperature has shown to result in the formation of aggregation in the colloids. BP nanosheets possess better dispersion state in polar solvents than in nonpolar solvents, and the aggregation process in nonpolar solvents can be monitored by the slow relaxation mode of 3D light scattering. This study indicates that 3D light scattering paves way to analyze the dispersion dynamics of various 2D nanoparticle colloids with intensive light absorption and poor dispensability.
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JOURNAL OF ALLOYS AND COMPOUNDS
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2018
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IF 3.779
Xiaoya Gao,Wen Peng,Guangbei Tang,Qian Guo,Yongming Luo
Visible-light-driven BiOCl microspheres were directly synthesized via a facile one-pot ethylene glycol mediated solvothermal method. The crystallinity, surface, optical and electronic properties of BiOCl samples were highly depended on the precursor concentration. Benefiting from the exposed (110) facet and oxygen vacancy , BiOCl-10 (synthesized from 0.02 mol of Bi(NO 3 ) 3 ·5H 2 O) displayed a maximum CBZ degradation efficiency of 70% after 180 min under visible light illumination. The reaction kinetics rate constant ( k ) of CBZ degradation in BiOCl-10 (0.0935 min −1 ) was 52 times higher than ordinary BiOCl-1 (0.0018 min −1 ). The improved photocatalytic activities of BiOCl-10 were attributed to the combination of enhanced CBZ adsorption, increased visible light absorption and efficient separation of photogenerated e − - h + pairs. Radicals and holes trapping experiments showed that •O 2 − and h + were predominant active species in the photocatalytic process. Most importantly, BiOCl-10 was also efficient in natural water without any additive. Our findings indicate that the BiOCl-10 photocatalysis can be used as an efficient and cost-effective technology for removal of recalcitrant pharmaceutical contaminants.
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NEW JOURNAL OF CHEMISTRY
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2018
·Vol. 42
·期 14
·12205-12211
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IF 3.201
Qin Wang,Jianling Zhang,Yuyan Yu,Yi Dan,Long Jiang
Aiming to develop a visible-light-driven polymeric photocatalyst that can be fabricated by an easy-to-scale-up polymerization method, a porous polyimide (PPI) with a specific surface area (SBET) of 79.3 m2 g−1 was synthesized by a facile polycondensation of 3,3′,4,4′-benzophenonetetracarboxylic dianhydride (BTDA) with 4,4′,4′′-triaminotriphenylamine (TPA). UV-vis diffused reflection spectroscopy (DRS), electrochemical analysis, valence band X-ray photoelectron spectroscopy (XPS), and density functional theory (DFT) calculation results reveal that the prepared PPI possesses a narrow band gap (2.04 eV) with the valence band (VB) located at 1.26 V (vs. NHE) and the conduction band (CB) edge at −0.78 V (vs. NHE), clearly indicating the visible light activity of PPI. The photocatalytic performance for the degradation of methylene blue (MB) in water was studied, and the results demonstrate that PPI possesses excellent photocatalytic activity under visible light irradiation. Electron paramagnetic resonance (EPR) and photo-current analyses were used to study the photocatalytic mechanism, which show that PPI has a lot of single electron trapped oxygen and more light-generated electrons. This work may provide a cost-effective, potentially scalable strategy to design and develop a polymeric photocatalyst with continuously tunable photoelectrical properties.
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INTERNATIONAL JOURNAL OF HYDROGEN ENERGY
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2018
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IF 4.229
Meng Yuan,Wen-Hui Zhou,Dong-Xing Kou,Zheng-Ji Zhou,Yue-Na Meng,Si-Xin Wu
Design and preparation of high performance photocatalysts are always the keys for photocatalytic hydrogen production by using green and unlimited solar energy. In this work, we present the synthesis of Cu 2 ZnSnS 4 (CZTS) decorated CdS nanorods and their use for visible-light-driven photocatalytic hydrogen production. The as-synthesized CZTS decorated CdS nanorods exhibit much higher visible-light-driven photocatalytic hydrogen production performance than that of individual CdS nanorods and individual CZTS nanoparticles . Specifically, the hydrogen production rate of representative CZTS decorated CdS nanorods was 48-times and 165-times higher than that of individual CdS nanorods and individual CZTS nanoparticles. The enhanced photocatalytic hydrogen production performance may be contributed by the p-n heterojunction as well as the synergistic effect between CdS nanorods and CZTS particles. The present work not only reported new low-cost and highly efficient photocatalysts for visible-light-driven photocatalytic hydrogen production, but also provided new method for the design and preparation of high performance visible-light-driven heterostructured photocatalysts for photocatalytic hydrogen production.
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JOURNAL OF MATERIALS RESEARCH
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2018
·Vol. 33
·期 21
·3549-3558
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IF 1.495
Mengdie Chen,Haiming Xu,Xiaofang Zhang,Dongya Li,Dongsheng Xia
Activation of persulfate (PS) by ultraviolet light or transition metal catalysts has been extensively studied. However, little is known about the activation of PS by iron oxychloride (FeOCl) in the presence of visible light irradiation. Herein, the catalytic activity of FeOCl was developed for oxidative degradation of rhodamine B (RhB) with the FeOCl/PS/Vis process. The characterization of FeOCl for reaction kinetics, degradation mechanism, and catalyst stability was investigated. It is found that the redox cycle of iron species and photoinduced electrons formed on the FeOCl catalyst surface can effectively activate PS, to generate radicals. Based on quenching experiments and electron paramagnetic resonance, the photogenerated holes (h+) and sulfate radicals (SO4−•) are the predominant reactive oxidants for RhB decolorization, while superoxide radicals (•O2−) and hydroxyl radicals (•OH) are also involved. Moreover, FeOCl shows good catalytic performance in a wide range of pH values (pH = 3–10) and excellent reusability and stability, as well.
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Journal of Materials Chemistry C
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2018
·Vol. 6
·期 22
·6033-6037
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IF 5.976
Yu Peng,Yunpeng Yao,Lina Li,Zhenyue Wu,Sasa Wang,Junhua Luo
Recently, white-light emissions arising from self-trapped excitons in a distorted lattice have attracted significant attention in organic–inorganic hybrid perovskites. Although exciton self-trapping is reported to be easier in lower dimensional structures, one-dimensional organic–inorganic perovskites with white-light emission are rare. Herein, we report a single-component white-light emissive hybrid perovskite, C5H14N2PbCl4·H2O (1), which adopts a distinct quantum-wire structure formed by edge-shared highly distorted lead chloride octahedra. Notably, 1 shows a color rendering index as high as 93.9, which almost falls around the highest value for hybrid perovskite white-light emissive materials. In addition, 1 is nonlinear and has circularly polarized optical activity induced by the incorporation of pure enantiomeric organic cations. The combination of white-light emission and chirality may pave the way for the design of new white-light emission organic–inorganic perovskites for multifunctional applications.
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ACS Catalysis
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2018
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IF 11.384
Hai-Peng Liang,Qi Chen,Bao-Hang Han
Photoredox catalysis has aroused great interest from chemists, as it offers a powerful tool for organic synthesis. Cationic polycarbazole networks (CPOP-28 and CPOP-29) were prepared via simple oxidative coupling reaction and applied as heterogeneous photocatalysts for a wide range of oxidative organic transformations, including oxidation of sulfides, hydroxylation of arylboronic acids, and cross-dehydrogenative coupling reactions, in the presence of visible light and air. Remarkably, photocatalytic activities are enhanced by ingenious introduction of trifluoromethyl groups to the polymeric network CPOP-29. The effects of the trifluoromethyl group on photocatalytic activities were elucidated in terms of photophysical and electrochemical properties. The appealing photocatalytic performance of the trifluoromethylated polymer is ascribed to superior light-absorption ability, longer fluorescence lifetime, and stronger oxidative capability. In addition, the photocatalysts showed good recyclability and could be reused after a simple separation workup.
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Photonics Research
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2018
·Vol. 6
·期 12
·1107-1115
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IF 5.242
Jia-Sheng Li,Yong Tang,Zong-Tao Li,Long-Shi Rao,Xin-Rui Ding,Bin-Hai Yu
Quantum dots (QDs) can achieve high quantum yields close to unity in liquid solutions, whereas they exhibit a decreased conversion efficiency after being integrated into solid-state polymer matrices for light-emitting diode (LED) devices, which is called the host matrix effect. In this study, we propose a solid–liquid hybrid-state QD-LED to solve this issue. The ethylene-terminated polydimethylsiloxane (ethylene-PDMS) is used to establish a solid-state cross-linked network, whereas the methyl-terminated PDMS (methyl-PDMS) is used in its liquid state. From a macroscopic level, the cured solid–liquid hybrid-state PDMS (SLHP) composites reach a solid state, which is stable and flexible enough to be used in LED devices. Compared with LEDs using conventional QD/solid PDMS composites at equal color conversion efficiency ranging from 40% to 60%, the luminous flux of LEDs with QD/SLHP composites is increased by 13.0% using an optimized methyl-PDMS concentration of 85 wt. %. As a result, high efficiency QD-LEDs using QDs as the only color convertor with luminous efficacy of 89.6 lm/W (0.19 A) were achieved, which show a working stability comparable with that using conventional solid-state structures at a harsh condition. Consequently, the novel approach shows great potential for achieving high efficiency and high stability QD-LEDs, which is also compatible with current structures used in illumination and display applications.
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APPLIED THERMAL ENGINEERING
·
2018
·
IF 3.771
Rong Chen,Ming Xia,Xun Zhu,Qiang Liao,Dingding Ye,Liang An,Youxu Yu,Long Jiao,Wei Zhang
A micro photocatalytic fuel cell with a visible-light responsive photoanode and the lateral arrangement of the electrodes at the same plane was developed to enable simultaneous organics degradation and electricity generation . The developed micro photocatalytic fuel cell was assessed by using methanol as a representative organic compound in the alkaline environment . It is shown that good visible-light response was achieved. The effects of the light intensity, methanol concentration , KOH concentration and liquid flow rate were also explored. Experimental results showed that when the light intensity was increased, the cell performance was improved due to more photo-excited electron-hole pairs. Upgrading the KOH concentration led to the increased performance due to more efficient capture of the holes and enhanced cathodic reaction and ion transport. The increase of the methanol concentration in the testing range led to the improved performance as a result of the enhanced mass transport. The discharging performance was firstly increased and then decreased with increasing the liquid flow rate due to the competition of enhanced mass transfer and decreased residence time and increased methanol crossover .
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