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Evaluation of solution processable polymer reduced graphene oxide transparent films as counter electrodes for dye-sensitized solar cells
摘要： This paper reports the synthesis of reduced oxide (RGO) coated polyaniline (PANi) nanocomposites via in-situ emulsion polymerization and its application as counter electrode for dye sensitized solar cells (DSSCs). The synthesized nanocomposites were systematically characterized through Scanning electron microscope (SEM), X-ray diffraction (XRD), Fourier transform resonance infra-red (FTIR) and Raman spectroscopy indicating the uniform intercalation of polyaniline with reduced graphene oxide. The synergy between RGO and PANi chains owing to the co-doped SDS and H2SO4 leads to the enhanced solubility and improved electrocatalytic activity, that was further confirmed through electrochemical measurements to satisfy the criteria for application as cost effective counter electrode material for scalable DSSC. The fabricated CE was highly transparent and reached the conversion efficiency which is comparable to that of Platinum with a current density of (12.58 mA. cm-2) and (13.11 mA. cm-2) respectively under an illumination of AM 1.5 G (100 mW. cm-2) simulated solar light with an overall photo conversion efficiency of 3.9 %. Thus PANi/RGO based nanocomposites could therefore serve as efficient alternative material to Pt. free CE in DSSC.
关键词： In-situ emulsion polymerization,PANi,DSSC,counter electrode,reduced graphene oxide
更新于2025-09-23 15:19:57
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Nickel sulphide-reduced graphene oxide composites as counter electrode for dye-sensitized solar cells: Influence of nickel chloride concentration
摘要： Nickel sulphide-reduced graphene oxide (NiS-rGO) composite ?lms have been prepared via modi?ed Hummers’s method assisted with spin coating technique. The NiS-rGO samples were then employed as counter electrode in a dye-sensitized solar cell (DSSC). The main aim of this work is to investigate the relationship between the concentrations of NiCl2 with the properties of NiS-rGO and performance parameters of the device. The dominant rGO and minor NiS phase exist in the composite. The morphology of the composite is white strips rGO and NiS agglomerate particle. The element of C, O, Ni and S present in the composite. The highest g of 1.04% and Jsc of 7.39 mA cm(cid:1)2 were obtained from the device with 0.06 M NiCl2 resulted from the longest carrier lifetime. The photovoltaic parameters results reveal that NiS-rGO composite has potential to become as a free platinum counter electrode of DSSC.
关键词： Reduced graphene oxide,Dye-sensitized solar cells,Nickel sulphide,Counter electrode
更新于2025-09-23 15:19:57
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Sensitive Detection of Dengue Virus Type 2 E-Proteins Signals Using Self-Assembled Monolayers/Reduced Graphene Oxide-PAMAM Dendrimer Thin Film-SPR Optical Sensor
摘要： In this work, sensitive detection of dengue virus type 2 E-proteins (DENV-2 E-proteins) was performed in the range of 0.08 pM to 0.5 pM. The successful DENV detection at very low concentration is a matter of concern for targeting the early detection after the onset of dengue symptoms. Here, we developed a SPR sensor based on self-assembled monolayer/reduced graphene oxide-polyamidoamine dendrimer (SAM/NH2rGO/PAMAM) thin film to detect DENV-2 E-proteins. Surface characterizations involving X-ray diffraction (XRD) and Fourier-transform infrared spectroscopy (FTIR) confirms the incorporation of NH2rGO-PAMAM nanoparticles in the prepared sensor films. The specificity, sensitivity, binding affinity, and selectivity of the SPR sensor were then evaluated. Results indicated that the variation of the sensing layer due to different spin speed, time incubation, and concentration provided a better interaction between the analyte and sensing layer. The linear dependence of the SPR sensor showed good linearity (R2 = 0.92) with the lowest detection of 0.08 pM DENV-2 E-proteins. By using the Langmuir model, the equilibrium association constant was obtained at very high value of 6.6844 TM?1 (R2 = 0.99). High selectivity of the SPR sensor towards DENV-2 E-proteins was achieved in the presence of other competitors.
关键词： optical sensor,E-proteins,SPR sensor,PAMAM dendrimer,reduced graphene oxide,dengue virus,self-assembled monolayer
更新于2025-09-23 15:19:57
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Improved photovoltaic performance of graphene-based solar cells on textured silicon substrate
摘要： Graphene has attracted much interest as an active layer in heterojunction solar cells due to its outstanding properties such as flexibility, transparency, mechanical strength and elevated carrier mobility. In this research, a new technique was presented in order to enhance the efficiency of graphene–based heterojunction solar cells by employing a textured silicon (Si) substrate. Here, two sets of devices were fabricated based on flat and pyramidal structure of Si and the photovoltaic properties of graphene/Si heterojunction solar cells were compared. Selective chemical dissolution of Si wafers was carried out in order to produce pyramidal skeleton. Reduced graphene oxide (rGO) was then transferred on pyramidal Si through electrophoretic deposition (EPD) technique. The evidence of graphene layers on Si substrates was studied using Raman spectroscopy, X–ray diffractometry (XRD) and atomic force microscopy (AFM) analysis. The morphology of samples indicated an enhancement in rGO/Si interface area when the pyramidal structure is applied. Moreover, the enhanced surface area of this sample which is due to elevated roughness of pyramidal structure and wrinkles of graphene layers promotes its antireflective behavior which was proven using reflectance spectroscopy. The average reflectance of the graphene layer on the textured Si was ~14% in the wavelength range of 400–800 nm which is lower than that of rGO on flat Si. The improved optical properties of graphene on pyramidal silicon can broaden its potential applications in optoelectrical devices such as high-efficiency solar cells. In order to study the photovoltaic properties of rGO/Si samples, a passive layer was formed on Si substrate and a square frame of Ag was coated on it which was acted as a top contact. The current–voltage characteristics showed that the efficiency of rGO/Si heterojunction solar cells was improved when textured silicon was applied.
关键词： Schottky junction solar cell,Heterojunctions,Thin films,Reduced graphene oxide,Silicon pyramids,Electrophoretic deposition
更新于2025-09-23 15:19:57
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Plasma-processed CoSn/RGO nanocomposite: A low-cost and sustainable counter electrode for dye-sensitized solar cells
摘要： The high cost of state-of-the-art Pt counter electrodes (CEs) hinders the large-scale applications of dye-sensitized solar cells (DSCs). The development of Pt-free catalysts while maintaining state-of-the-art catalytic activity for CE materials is one mean to reduce costs. Here, CoxSn1-x/reduced graphene oxide (RGO) (0 ≤ x ≤ 1) nanohybrids were synthesized and employed as inexpensive, stable, and earth-abundant CEs in DSCs. The synthesis was performed through the plasma-assisted reduction of the oxygen functional groups of the graphene oxide along with the immobilization of bimetallic nanoparticles (NPs) on the surface of RGO. The optimization of the composition of the alloy NPs for the highest e?ciency of DSC yields the Co0.9Sn0.1/RGO nanocomposite. The highest device performance correlates well with the experimentally obtained lowest charge transfer resistance in conjunction with the highest electrocatalytic activity of the Co0.9Sn0.1/RGO CE. The DSC employed the synthesized CE showed good stability over long term operation. Both the developed CoSn/RGO nanohybrids and the strategy used for their synthesis are cost-e?ective. Our results provide economically implementable and green nanotechnology for e?cient and stable DSCs required for commercialization.
关键词： Plasma reduction,Bimetalic alloy CoxSn1-x,Nanohybrids,Reduced graphene oxide,Counter electrode,Dye-sensitized solar cells
更新于2025-09-23 15:19:57
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Modification of reduced graphene oxide layers by electron-withdrawing/donating units on molecular dopants: Facile metal-free counter electrode electrocatalysts for dye-sensitized solar cells
摘要： Small molecules of aniline (AN) and nitrobenzene (NB) doped on reduced graphene oxide nanosheets (rGO) represent the attractive Pt-free and earth abundant counter electrodes (CEs) in dye-sensitized solar cells (DSSCs). Scanning electron microscope and transmission electron microscope confirm a very thin layer structure with wrinkled and folded nanosheets. The binding between AN or NB and rGO is confirmed by Fourier-transform infrared spectroscopy (FTIR), Raman spectroscopy, and X-ray photoelectron spectroscopy (XPS). In this work, two different redox electrolytes are investigated: I?/I3? and [Co(bpy)3]3+/2+. Compared to rGO electrode-based DSSCs, the AN-rGO (1:10) and NB-rGO (1:10) electrode-based DSSCs applying I?/I3? and [Co(bpy)3]3+/2+ electrolytes show 40–50% and 30–35% increase in power conversion efficiency, respectively. Furthermore, both AN-rGO (1:10) and NB-rGO (1:10) perform stably upon electrochemical continuous test. Such excellent photoelectric performance correlates with the induced charge transfer between reduced graphene oxide and the molecules which effectively promotes the reduction and regeneration of I?/I3? and [Co(bpy)3]3+/2+ ions.
关键词： Electrocatalyst,Dye-sensitized solar cell,Molecular dopant,Reduced graphene oxide,Counter electrode
更新于2025-09-23 15:19:57
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Photoactivity improvement of TiO2 electrodes by thin hole transport layers of reduced graphene oxide
摘要： Nanostructured TiO2 and graphene-based materials constitute components of actual interest in devices related to solar energy conversion and storage. In this work, we show that a thin layer of electrochemically reduced graphene oxide (ECrGO), covering nanostructured TiO2 photoelectrodes, can significantly improve the photoactivity. In order to understand the working principle, ECrGO/TiO2 photoelectrodes with different ECrGO thicknesses were prepared and studied by a set of photoelectrochemical measurements. Methanol in alkaline conditions was employed as effective hole acceptor probe to elucidate the electronic phenomena in the electrode layers and interfaces. These studies underline the hole accepting properties of ECrGO and reveal the formation of a p-n junction at the interface between ECrGO and TiO2. It is shown for the first time that the resulting space charge region of about 10 nm defines the operational functionality of the ECrGO layer. Films thinner than the space charge region act as hole transport layer (HTL), which efficiently transfers holes to the liquid interface thus leading to enhanced photoactivity. Thicker films however act as hole blocking layer (HBL), resulting in a systematic decrease of the photoactivity. The finding of a thickness dependent threshold value for the operation of ECrGO as HTL and HBL is of general interest for the fabrication of optoelectronic devices with improved performance.
关键词： reduced graphene oxide,photoelectrodes,titanium dioxide,photoelectrochemistry,hole-transport layer
更新于2025-09-23 15:19:57
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A ternary nanocomposites of graphene / TiO <sub/>2</sub> / polypyrrole for energy storage applications
摘要： Designing a new electrode active materials including graphene and nanomaterials such as Titanium dioxide (TiO2) with polypyrrole have important for supercapacitor devices. In this work, we present a new ternary nanocomposite for using reduced graphene oxide (rGO), TiO2 and polypyrrole (rGO/TiO2/PPy) for supercapacitors. rGO/TiO2/PPy nanocomposites were characterized by the analysis of Fourier transform infrared-attenuated transmission reflectance (FTIR-ATR), Raman spectroscopy, and scanning electron microscopy-energy dispersion X-ray analysis (SEM-EDX). Electrochemical tests were taken by galvanostatic charge/discharge (GCD), cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) studies. We have obtained the highest specific capacitance of Csp D 431.23 F/g for [rGO]o/[Py]o D 1/1 at 10 mV/s. A ternary rGO/TiO2/PPy nanocomposite has higher Csp values than Csp D 122.12 F/g at 10 mV/s for rGO/PPy, Csp D 93.17 F/g at 4 mV/s for rGO and Csp D 45.16 F/g at 4 mV/s for GO. A high energy density was obtained as E D 2.03 Wh/kg and power density of P D 18.3 kW/kg for rGO/TiO2/PPy nanocomposite at 1000 mV/s. rGO/TiO2/PPy nanocomposite had a relatively high Coulombic efficiency, as well as a retention of ?100% of its original capacitance for [rGO]o/[Py]o D 1/1 after 1000 cycles. A novel synthesized rGO/TiO2/PPy nanocomposite may be used for supercapacitor devices due to its good electrochemical performances.
关键词： energy density,reduced graphene oxide,circuit model,TiO2,supercapacitor,polypyrrole
更新于2025-09-23 15:19:57
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Facile and <i>in-situ</i> spray deposition of SnO <sub/>2</sub> – reduced graphene oxide heterostructure sensor devices
摘要： A facile and economic solution based technique is developed for the deposition of SnO2 – Reduced Graphene Oxide (RGO) heterostructure thin films. The single step deposition process leads to uniformly coated films of SnO2 nanocrystallites on well exfoliated RGO sheets as confirmed by xray diffraction, Raman spectroscopy and transmission electron microscopy investigations. The response to NO2 gas at room temperature (25 oC) is studied. The interface between n-type SnO2 and p-type RGO flakes forms a hetrostrcuture barrier, which enhances the native sensitivity of pristine RGO towards toxic gases like NO2. The technique allows controlling the density of SnO2 nanoparticles (~3 nm in size) attached to the RGO flakes and thereby enhancing the response of the heterostructure sensor device. The highest SnO2 loading shows a 14 fold increase in response to 200 ppm of NO2 and a response time as low as 5 sec compared to that of ~200 sec for bare RGO films.
关键词： tin oxide,thin films,Reduced graphene Oxide,heterostructure,NO2 sensing
更新于2025-09-19 17:15:36
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Metal-ion bridged high conductive RGO-M-MoS2 (M = Fe3+, Co2+, Ni2+, Cu2+ and Zn2+) composite electrocatalysts for photo-assisted hydrogen evolution
摘要： Efficient photo-electrocatalysts for hydrogen evolution reaction (HER) are synthesized using a facile one-step hydrothermal method. With metal-ion bridges, highly dispersed molybdenum disulfide (MoS2) nanolayers are vertically grown on the reduced graphene oxide (RGO) to form RGO-M-MoS2 photocatalysts for HER, where M = Fe3+, Co2+, Ni2+, Cu2+ and Zn2+. The results show that the cross-bridging ions can modulate the MoS2 growth priority and act as efficient charge transfer channels between RGO and MoS2, and combine the advantages of the high conductivity of graphene with the photo-electrochemical activity of MoS2. The metal-ion bridged MoS2-M-RGO heterostructures demonstrate superior catalytic activity toward hydrogen evolution reaction (HER) in acid medium, evidenced by the remarkable higher catalytic current density at low overpotential compared with that of MoS2-RGO without metal-ion bridge. This study provides a novel and facile route for establishing efficient composite photo-electrocatalysts for water splitting to generate hydrogen.
关键词： hydrogen evolution reaction,MoS2 nanosheets,reduced graphene oxide,metal-ion bridge
更新于2025-09-19 17:15:36