RSC Advances
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2017
·Vol. 7
·期 17
·10494-10502
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IF 3.108
Yanming Zhao,Futai Lu,Jie Zhang,Yuze Dong,Bao Zhang,Yaqing Feng
How to graft co-sensitizers with different binding strengths onto TiO2 surfaces for enhancing the performance of dye-sensitized solar cells (DSSCs) has not been discussed very much. Herein a ruthenium-based sensitizer (N719) and a porphyrin molecule (LP-2) with complementary absorption spectra (300–750 nm) have been chosen to investigate how the dye loading procedure would influence the photovoltaic performance of co-sensitized solar cells. Interestingly, it is found that 54.7% of the loading amounts of pre-adsorbed LP-2 are replaced by the post-adsorption of N719. The replacement adsorption is not observed when the two molecules are loaded in reverse order, which is attributed to their different adsorption configurations and binding energies. The competitive adsorption between co-sensitizers is thus systematically investigated by UV-visible absorption spectroscopy, energy dispersive spectrometry (EDS) and electron probe microanalysis (EPMA). Upon optimization, the device sequentially sensitized with LP-2 and N719 exhibits efficiency (7.72%) enhancement of 38.6% and 18.0% compared with those fabricated with single LP-2 and N719, respectively. The results provide a new vision on the stepwise sensitization of TiO2 films using co-sensitizers with a difference in adsorption properties, suggesting that complementary spectral absorption of co-sensitizers can lead to excellent cell performance by choosing an appropriate dye loading procedure.
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CRYSTENGCOMM
·
2016
·Vol. 19
·期 2
·325-334
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IF 3.849
Javid Khan,Jiuwang Gu,Yuying Meng,Zhisheng Chai,Shiman He,Qili Wu,Shengfu Tong,Gulzar Ahmed,Wenjie Mai,Mingmei Wu
In this paper, we successfully synthesized anatase TiO2 hierarchical microspheres (S0), anatase TiO2 sub-micro hollow mesospheres (S50), anatase TiO2 single crystal hollow nanoparticles (S100), nanoparticles (S250) and (S500) by using different amounts of hydrofluoric acid (HF) versus titanium n-tetrabutoxide (TBT) and acetic acid (AcOH). The structure and morphology of the as-prepared materials were confirmed by X-ray diffraction analysis (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The DSSCs (dye-sensitized solar cells) based on anatase single crystal hollow TiO2 nanoparticles (S100) as a photoanode showed an efficient power conversion efficiency of 8.94% along with a current density of 17.39 mA cm−2 and an open circuit voltage of 778 mV, which is higher than the DSSCs based on S0 (8.10%), S50 (8.57%), S250 (7.25%) and S500 (6.12%). The high performance of S100 as a DSSC is attributed to their hollow structure which might help to harvest more light, higher light scattering and trapping abilities and comparatively higher surface area. Therefore, we can expect that our materials are promising for assembling superior photoelectrodes for future preparation of highly-efficient DSSCs and may lead to applications for energy storage, water splitting, catalysis, and gas sensing.
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JOURNAL OF POWER SOURCES
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2016
·
IF 6.333
Hong Yuan,Qingze Jiao,Shenli Zhang,Yun Zhao,Qin Wu,Hansheng Li
The composites of hollow CoFe 2 O 4 and carbon nanotubes (h-CoFe 2 O 4 @CNTs) are successfully prepared by using a simple hydrothermal process coupling with the in-situ chemical vapor deposition (CVD) as electrocatalytic materials for counter electrode of dye-sensitized solar cells. The CNTs are uniformly grown on the surface of hollow CoFe 2 O 4 particles verified by X-ray powder diffraction (XRD), scanning electron microscope (SEM), transmission electron microscopy (TEM) and energy dispersive X-ray spectroscopy (EDX) measurements. The electrochemical performances of hollow CoFe 2 O 4 @CNTs composites are evaluated by the EIS, Tafel polarization and CV measurements, and exhibiting high electrocatalytic performance for the reduction of triiodide. The presence of conductive polypyrrole nanoparticles could further improve the conductivity and catalytic performance of the resultant composites. Controlling the thickness of composites film , the optimum photovoltaic conversion efficiency of 6.55% is obtained, which is comparable to that of the cells fabricated with Pt counter electrode (6.61%). In addition, the composites exhibit a good long-term electrochemical stability in I 3 − /I − electrolyte.
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RSC Advances
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2017
·Vol. 7
·期 72
·45280-45286
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IF 3.108
Bo Tang,Guojian Ji,Zhengwei Wang,Haiqun Chen,Xufei Li,Haogang Yu,Sen Li,Hong Liu
Graphene assisted dye-sensitized solar cells (DSSCs) have drawn increasing attention because of their high performances. However, two bottlenecks (the high defect density and the discontinuous structure) of the widely adopted reduced graphene oxide (RGO) nanosheets bring about that the practical photovoltaic properties are far inferior to the theoretical prediction values. Therefore, three-dimensional graphene networks (3DGNs) of high quality have been employed to modify DSSCs to avoid the above mentioned problems. However, a close contact between the graphene basal plane and TiO2 particles in the resulting photoanode is difficult to achieve due to the absence of surface functional groups of the 3DNG. In this study, the RGO nanosheets and 3DGNs co-modified DSSCs are prepared, and the advantages from these two modifiers can give full play to their synergy. The added RGO nanosheets enhance the electron transport ability at the interfaces between graphene, TiO2 and conductive substrate. After optimizing the reduction degree and mass fraction of the RGO nanosheets, the power conversion efficiency of the resulting DSSC reaches 7.68%, which is much higher than those cases of using the 3DGNs (or RGO nanosheets) as modifier alone.
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ELECTROCHIMICA ACTA
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2017
·
IF 4.798
Panpan Sun,Taian Huang,Ziyu Chen,Liangyu Tian,Huihui Huang,Niu Huang,Sha Zhou,Min Long,Yihua Sun,Xiaohua Sun
The design and facile fabrication of highly efficient, cost-effective and earth abundant counter electrode material on an electrode surface is highly desirable for the application of dye-sensitized solar cells (DSSCs). Herein, using a N,N-dimethylformamide based solution process, transition metal chalcogenide Ni x S y films have been obtained by spin-coating a NiCl 2 -thiourea (Ni-Tu) solution combining mild thermal treatment. XRD, SEM and TEM characterizations reveal that the current procedure allows for phase composition (Ni 3 S 2 , NiS and NiS-NiS 2 ), crystallinity , morphology (film uniformity and compactness) control of the films through simple adjusting Ni/S ratio in the precursor solution. Electrochemical analysis indicates that the FTO supported Ni 3 S 2 and NiS films exhibit excellent electrocatalytic activity toward the reduction of triiodide, resulting in higher photo-electric conversion efficiencies of 6.86% and 6.95% when used as counter electrode in DSSCs, versus 6.66% for Pt. In particular, even without the support of conductive FTO layer, Hall effect measurements and electrocatalytic analysis reveal that pristine Ni x S y films exhibit good electrical conductivity and electrocatalytic activity, yielding a highest photo-electric conversion efficiency of 4.41% when used as counter electrode in DSSCs. Our study thus provides a facile procedure which allows for composition, morphology optimization and high performance for low-cost, large-scale DSSC application.
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JOURNAL OF SOLID STATE ELECTROCHEMISTRY
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2016
·Vol. 20
·期 10
·2643-2650
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IF 2.327
Lan Zhang,Wu Wanxia,Zhang Sheng,Que Lanfang,Wu Jihuai
High-performance dye-sensitized photoelectrodes using ordered TiO 2 nanotube arrays (TNTs) and TiO 2 quantum dot blocking layers are fabricated. The free-standing TNT membranes with perfect ordered morphology are prepared by three times of anodic oxidation on Ti foils. These TNT membranes can be easily transported to conductive glasses to fabricate front-side illuminated photoelectrodes. By changing anodic oxidation duration, the thickness of TNT membranes can be controlled, which shows significant influence on the UV-Vis reflectance and absorption abilities of TNT-based photoelectrodes and further influence photovoltaic performance of dye-sensitized solar cells (DSSCs). The highest power conversion efficiency ( PCE ) of DSSCs about 6.21 % can be obtained by using TNT membranes prepared with anodic oxidation of 3 h. For further improving photovoltaic performance of DSSCs, TiO 2 quantum dot (QDs) blocking layers are inserted between conductive glasses and TNT membranes in the photoelectrodes, which show remarkable effects. The highest PCE of DSSCs with this kind of blocking layers can increase to 8.43 %, producing 35.75 % enhancement compared with that of the counterparts without TiO 2 QD blocking layers.
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CARBON
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2017
·
IF 6.337
Yan-Jun Wan,Peng-Li Zhu,Shu-Hui Yu,Rong Sun,Ching-Ping Wong,Wei-Hsin Liao
Large-sized graphene sheets (LG) and doping strategy were employed to fabricate lightweight and flexible graphene paper with exceptional electromagnetic interference (EMI) shielding performance. Compared with the smaller sized ones, LG with fewer defects and more conjugated carbon domain size as well as better alignment result in higher electrical conductivity and strength of graphene paper. The iodine doping further improves the carrier density of LG by formation of triiodide ( I 3 − ) and pentaiodide ( I 5 − ) through charge transfer process without deteriorating the mechanical property, thus leading to superior EMI shielding effectiveness (SE). The EMI SE of iodine doped LG film with thickness of 12.5 μm is up to ∼52.2 dB at 8.2 GHz, which is much higher than that of undoped LG with the same thickness (∼47.0 dB). More important, the improvements in EMI SE is contributed to the SE absorption, while the SE reflection is almost unchanged. The mechanisms of improved EMI shielding performance as well as mechanical property were investigated and discussed. The present study provides a facile way to fully develop graphene in lightweight and flexible EMI shielding materials and devices.
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JOURNAL OF NON-CRYSTALLINE SOLIDS
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2017
·
IF 2.124
Quan Guo,Yantao Xu,Haitao Guo,Xusheng Xiao,Changgui Lin,Xiaoxia Cui,Pengfei Wang,Fei Gao,Min Lu,Bo Peng
A serial (100 − x)Ge 25 Sb 10 S 65 -xI (x = 0, 5, 10, 15, 20, 25 and 30 wt%) chalcohalide glasses and ones doped with 0.1 wt% Dy 3 + rare-earth ions were synthesized and their structural, thermal and optical properties were systematically studied. It indicates that addition of I 2 into Ge 25 Sb 10 S 65 glass significantly decreases the connectivity of glass network and average bond energy, and modifies the associated properties. The glass transition temperature and refractive index decrease monotonically, and the density increases almost linearly with the increasing of iodine content in glass. The thermal stability is improved, which has a maximum of ΔT max = 174 °C. While the optical bandgap has a peak value at x = 10 wt%. The absorption spectra and mid-infrared fluorescence spectra of Dy 3 + rare-earth ions doped glasses were investigated together with the Judd-Ofelt analysis. GeS 2 nano-crystals were found in the sample with x ≥ 15 wt%, which is supposed to induce enhancements of mid-infrared fluorescence at 2.95 and 4.32 μm.
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ELECTROCHIMICA ACTA
·
2017
·
IF 4.798
Yuanyuan Meng,Yue Zhang,Weiyin Sun,Min Wang,Benlin He,Haiyan Chen,Qunwei Tang
A great challenge for state-of-the-art photovoltaic devices is to realize electric power generation in all weathers. We constructively demonstrate here the conversion from biomass to carbon quantum dots for all-weather carbon quantum dot solar cells that can generate electricity in the daytime and in the dark. The combination of green-emitting long persistence phosphors with mesoscopic titanium dioxide realizes optical storage by composite photoanode under illumination and excitation to monochromatic green light in the dark. The optimized all-weather solar cell yields maximized dark power conversion efficiency as high as 7.97% along with persistent electricity output for several hours. This work begins a photovoltaic revolution to forward all-weather solar cells as future energy solutions.
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高影响因子
POLYMER
·
2017
·
IF 3.684
Zhongying Wu,Yiyao Tang,Dewen Sun,Shujiang Zhang,Yixuan Xu,Hua Wei,Chenliang Gong
Organic-inorganic hybrid polymers based on poly(arylene ether sulfone) (PAES) containing multi-sulfonated polyhedral oligosilsesquioxane (POSS) pendants (PAES-sPOSS-x) were synthesized to improve the inorganic fillers' distribution in polymer matrix and to enhance the ion conductivity and swelling resistance of aromatic polymer electrolyte membrane. The synthesis of the graft hybrid polymers in this study involves the grafting of mono-functional 3-Iodopropylheptaphenyl POSS with an -OH functionalized polymer main-chain and postsulfonation of the POSS grafted PAES. Notably, nearly all of the benzene rings on the POSS side chains were sulfonated successfully without any sulfonation of main chains. The structure with hydrophobic aromatic backbone and hydrophilic hybrid side chains made an improvement of the nano-phase hydrophilic/hydrophobic separation, thereby facilitating the formation of continuous proton exchange channels. The transmission electron microscopy (TEM) images of the comb-shaped polymer membranes showed homogeneous sulfonated POSS (sPOSS) dispersion, significant phase separation and well-defined interconnected hydrophilic networks. This morphological structure leaded to dramatically enhanced comprehensive properties as proton conductive membranes.
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CARBON
·
2017
·
IF 6.337
Hong Yuan,Qingze Jiao,Jia Liu,Xiufeng Liu,Yongjian Li,Daxin Shi,Qin Wu,Yun Zhao,Hansheng Li
A novel nanocomposite of Co 0.85 Se nanotubes with reduced graphene oxide (Co 0.85 Se/RGO) is prepared by a facile hydrothermal approach coupled with in situ selenization, which is applied as counter electrode in dye-sensitized solar cells. Electrochemical analysis shows that the Co 0.85 Se/RGO composite displays a higher electrocatalytic activity for the reduction of triiodide respect to its single components due to the unique hollow structure of Co 0.85 Se as well as the synergistic effects of high catalytically active Co 0.85 Se and conductive RGO. As a consequence, the dye-sensitized solar cell (DSSC) fabricated with the Co 0.85 Se/RGO electrode presents a high photovoltaic conversion efficiency of 7.81%, exceeding the cell based on a Pt electrode (7.55%). Moreover, a considerable electrochemical stability is also achieved when the material was used as a counter electrode in a I − /I 3 − electrolyte. Therefore, the Co 0.85 Se/RGO exhibits a huge potential as efficient and low-cost Pt-free counter electrode material to replace Pt allowing for large-scale fabrication of DSSCs.
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CRYSTAL GROWTH & DESIGN
·
2016
·
IF 4.425
Ting He,Huiqiong Wu,Xiaojuan Wang,Qiguang Zang,Peng Xue,Rujuan Shen,Li Dang,Yi Zhang,Juan Xiang
A facile strategy was developed to fabricate structure controllable microcrystals of ferrocene-based metal–organic (Fc-Ala-BCB) materials through evaporation-induced self-assembly. Two distinctive microcrystals, microrods and microtubes had been achieved by tuning the solvents during the self-assemblies. X-ray diffraction analysis was conducted on single crystals to investigate the packing mode of Fc-Ala-BCB molecules, which indicated the two crystals with the hexagonal system. Inheriting the aromaticity and chirality of ferrocenyl and l-Ala, this organic molecule self-assembled into a single-helix structure through intermolecule hydrogen bonds and π–π stacking. Theoretical analysis and stimulated computations were carried out to compare the surface energies of certain planes. Among those microcrystals, the microrods exhibited a higher chemical activity in catalyzing the decomposition of H2O2, due to the high-density atomic steps and kinks on the high energy surfaces. However, the hollow hexagonal tubes displayed appropriate catalytic activity and novel maneuverability toward catalyzing H2O2. The O2 bubbles accumulated at the inner walls of the microtube were periodically released as individual bubbles, suggesting their potential application as a new kind of microengine (e.g., the microrotor).
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