Scanning Electrode Microscopy Research Articles

Morphological Analysis of Fabricated 5.0 μM Interdigitated Electrode (IDE)

The aim of this research is to study the morphological analysis of fabricated Interdigitated Electrode (IDE). This device electrode was physically characterized using 3D nano profiler, scanning electrode microscope (SEM), Energy-dispersive X-ray spectroscopy (EDX) and Atomic Force Microscope (AFM). Based on this analysis, IDE pattern was analyzed thoroughly based on the IDE pattern specifications with 5 μM finger gap and this research significantly will stand as a platform quantify the biomolecules in further analysis.

Development of Absorbent Using Amylose-Graphite Composite Electrode for Removal of Heavy Metals.

Amylose of Phragmites Australis captures heavy metals in a box consisting of sugar chains. However, its absorption rate is low in the period of the month scale. Therefore, the electrochemical driving force was used to promote the absorption rate in this research. Amylose was doped with TiO2 porous graphite electrode. The composted absorbent was characterized using XRD(X-ray diffraction), SEM (Scanning Electrode Microscopy), Raman spectroscopy, and electrochemical methods. The affinity and maximum absorption amount were calculated using the isotherm method. In this study, Pb2+, Cu2+, Cd2+, and Cr6+ were chosen to demonstrate because these heavy metals are significant pollutants in Japan’s surface water. It was found that the maximum absorption was Cu2+ (56.82-mg/L) > Pb2+ (55.89-mg/L) > Cr6+ (53.97-mg/L) > Cd2+ (52.83.68-mg/L) at −0.5 V vs. Ag/AgCl. This is approximately the same order as the hydration radius of heavy metals. In other words, the absorption amounts were determined by the size of heavy metal ions. Subsequently, the mixed heavy metal standard solution was tested; the maximum absorption amount was 21.46 ± 10.03 mg/L. It was inferred that the electrochemical driving force could be shown as the ion size effect in the mixed solution. Despite there being no support for this hypothesis at this time, this study succeeded in showing that the electrochemical driving force can improve the ability of the absorbent.

Increased Disorder at Graphite Particle Edges Revealed by Multi-length Scale Characterization of Anodes from Fast-Charged Lithium-Ion Cells

Fast charging of lithium-ion cells increases voltage polarization of the electrodes and creates conditions that are favorable for Li-deposition at the graphite anode. Repeated fast charging induces changes in the capacity-voltage profiles and increases the probability of lithium-plating on the electrode. This higher probability results from structural, morphological and chemical modifications that are revealed by multi-length scale characterization of graphite anodes extracted from discharged lithium-ion cells, previously charged at rates up to 6 C. The distinct differences between anodes with lithium-plating and as-prepared electrodes are clearly seen in analytical electron microscopy data. Scanning electrode microscopy (SEM) images show that the fast-charged anode is significantly thicker, apparently because of the electrolyte reduction/hydrolysis products that accumulate in electrode pores. High resolution electron microscopy (HREM) images reveal wavy graphite fringes near the particle edges. Analysis of scanning electron nanodiffraction (SEND) data reveal higher d-spacings and greater lattice rotations, indicating disorder in the graphite near the particle edges that extend about 20 nm into the bulk. The extent of this disorder is greater near larger internal pores, highlighting nanoscale heterogeneities within particles. As graphite lithiation occurs primarily through edge planes, this permanent disorder would hinder Li+ intercalation kinetics and favor Li0 plating during repeated cycling.

Effect of Silver and Tin on the Corrosion Behaviour of Zinc Alloy in Alkaline Medium

The electrochemical and corrosion behaviour of Zn-20Sn and Zn-0.50Ag alloys in dishwasher detergent solution was investigated by Tafel plot and characterized X-ray diffraction (XRD) and Scanning Electrode Microscope (SEM). The measurements were conducted using different composition of elements addition (Ag: 0.03%, 0.27% and 0.50%. Sn: 1%, 8%, and 15%) under the same experimental conditions. The results showed that the addition of Ag led to decreased corrosion rate compared to Sn addition. The corrosion potential for Zn alloy with Ag addition are shifted towards more noble values compared to Zn alloys with Sn addition . By adding Ag, the current density is decreased and thus reducing the hydrogen evolution rate. The corrosion layer formed on Zinc sample in dishwasher detergent was investigated. The corrosion layer formed on Zn-20Sn-0.5Ag appeared more compact than other alloys. Zinc oxide (ZnO) and Zinc hydroxide (Zn(OH)2) were formed on Zinc alloy surface. Probable mechanisms of Zinc corrosion products formation are presented.

Algae-derived hard carbon anodes for Na-ion batteries

In this work, the production of low cost and environment friendly anodes for sodium ion batteries is investigated. Algae are selected as bio-source of non-graphitic Hard Carbon (HC) with open structure acting as intercalation active material for Na ions storage. Chlorella vulgaris algae were pyrolyzed at temperatures comprised between 800 and 1100 °C. The decomposition products have been characterized with Scanning Electrode Microscope (SEM) and X-Ray Diffraction (XRD) analyses and their structure compared to one of the synthetic commercial HC. Thermogravimetric analysis (TGA) allowed to assess the decomposition process throughout the selected temperature scan. The obtained algae-derived HC is tested as anodic material for Na-ion battery, investigating the effect of pyrolysis temperature on the electrochemical behaviour. Their performances are compared with respect to a commercial synthetic HC active material. The results allow to consider algae as an environmentally benign and sustainable high added-value material for the production of HC anodes for Na-ion batteries.Graphic abstract

Application of a Thiadiazole‐derivative in a Tyrosinase‐based Amperometric Biosensor for Epinephrine Detection

AbstractEnzyme‐based amperometric biosensors are proving to be important analytical tools in several fields such as food, environmental and, in recent years, the biomedical one. This work describes the use of 4,7‐bis(5‐(pyridin‐2‐yl)thiophen‐2‐yl)benzo[c][1,2,5]thiadiazole (TBT) in the development of a tyrosinase‐based biosensor for epinephrine detection. The modifying agent was obtained as a film by electrochemical oxidation of TBT on a gold disk electrode. Electrochemical characterization and scanning electrode microscopy (SEM) images suggest the formation of a conducting film on the electrode surface. Tyrosinase from mushroom was then immobilized by a mixed technique of adsorption and cross‐linking. Glutaraldehyde was used as a coupling agent. The obtained device shows a very good linear response (0.1–50 μM) with a LoD value of 0.06 μM and a LoQ of 0.09 μM. Moreover, good selectivity towards some typical interferents (namely, ascorbic acid, tryptophan, uric acid and L‐cysteine) and satisfactory recoveries have been observed.

Low-platinum catalyst based on sulfur doped graphene for methanol oxidation in alkaline media

A novel two-step, low-temperature method was employed for the synthesis of a catalyst with small platinum content (2 wt%) based on sulfur doped reduced graphene oxide (S-RGO-Pt). Morphology and chemical composition of the hybrid material were investigated by several methods: X-ray powder diffraction (XRD), transmission and scanning electrode microscopy (TEM, SEM), elemental analysis, X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy. The electrocatalytic performance of the prepared hybrid material was investigated in 1M CH3OH/1M NaOH using a modified glassy carbon electrode (GC_S-RGO-Pt). The results showed excellent electrocatalytic activity and stability toward methanol oxidation in alkaline media (50.4% activity retained after 500 cycles and 8.4% after 1000 cycles) compared to commercial platinum 10 wt% on carbon (Pt/C) material (8.09% activity retained after 500 cycles). The catalyst tolerance to CO poisoning intermediates was evaluated using CO stripping voltammetry and the ratio of forward and backward peak current density (If/Ib). The If/Ib ratio calculated for S-RGO-Pt is 15, while for Pt/C is 9.6, which clearly demonstrates that the prepared hybrid material is significantly more efficient than commercial Pt/C, even if the platinum content is only 2 wt%. The rotating disk electrode (RDE) technique was employed to study the kinetic aspects of methanol oxidation reaction in alkaline media. To follow the transformations occurred at the electrodes' surfaces after the electrochemical treatment, the Raman spectroscopy and Machine Learning (ML) algorithms were used; the results also indicated a greater stability of the S-RGO-Pt composite for Methanol oxidation reaction (MOR) in alkaline media.

Investigation of Frequent Failure of Francis Hydraulic Turbine Guide-Vane Shear Pin of Shiroro Hydro-Electric Power Station

Francis Hydraulic Turbine Guide-vane shear pin is a mechanical sacrificial component designed to break when the mechanical overload arises to prevent severe damage of guide-vane, which is an expensive component in the turbine assembly of hydro-power station. The pin is expected to serve for a minimum period of 10 years under normal working condition before failure occurs as obtained in most hydro-electric power stations globally. The shear pins in Shiroro hydro-electric power generation station located in Niger state of Nigeria were found to be frequently failing within a year of operation before reaching its predetermined load. This research investigated the possible causes of the frequent failure of the shear pins with a view to proffer solution. Analyses of the existing shear pin with respect to material specifications, micro-structural analysis using spectrophotometer where both visual and scanning electrode microscopy (SEM) was done in addition to mechanical tests to ascertain conformity with standards. The results showed that the shear pin material conforms to the ASTM 420, which is the standard for production of the shear pin. The SEM results shows that the failure of the shear pins was due to low cyclic fatigue growth attributed to the effect of intermittent and unsteady operations of the turbine. The visual examination revealed no defect on the phases of the material indicating that the fractured failure was not due to any form of inconsistency resulting from segregation or related effects. The mechanical test revealed yield strength of 600 N/mm2, ultimate tensile strength of 750 N/mm2 and hardness of 29 HRC which agreed with standard specifications for the shear pin. The results indicated that the frequent failure of shear pins could be as a result of other sources other than material specifications.

Interaction between Amorphous Zirconia Nanoparticles and Graphite: Electrochemical Applications for Gallic Acid Sensing Using Carbon Paste Electrodes in Wine.

Amorphous zirconium oxide nanoparticles (ZrO2) have been used for the first time, to modify carbon paste electrode (CPE) and used as a sensor for the electrochemical determination of gallic acid (GA). The voltammetric results of the ZrO2 nanoparticles-modified CPE showed efficient electrochemical oxidation of gallic acid, with a significantly enhanced peak current from 261 µA ± 3 to about 451 µA ± 1. The modified surface of the electrode and the synthesised zirconia nanoparticles were characterised by scanning electrode microscopy (SEM), Energy-dispersive x-ray spectroscopy (EDXA), X-ray powdered diffraction (XRD) and Fourier-transform infrared spectroscopy (FTIR). Meanwhile, the electrochemical behaviour of GA on the surface of the modified electrode was studied using differential pulse voltammetry (DPV), showing a sensitivity of the electrode for GA determination, within a concentration range of 1 × 10−6 mol L−1 to 1 × 10−3 mol L−1 with a correlation coefficient of R2 of 0.9945 and a limit of detection of 1.24 × 10−7 mol L−1 (S/N = 3). The proposed ZrO2 nanoparticles modified CPE was successfully used for the determination of GA in red and white wine, with concentrations of 0.103 mmol L−1 and 0.049 mmol L−1 respectively.

Carbon Nanofiber Composites As Anode Materials in Li+ and Na+ Batteries

Carbon nanofibers (CNFs) are well known by their one-dimensional (1D) nanostructure, high conductivity and large surface area, which can provide direct and short pathways for ion transport. These unique properties have facilitated their application as anode materials in both lithium-ion batteries (LIBs) and sodium-ion batteries (SIBs). Electrospinning, as a versatile and controllable method of CNFs manufacturing, has been widely investigated in the battery field. Electrospun CNFs still have limited capacity and rate capability. To further improve their performance, additives such as nickel metal nanoparticles and macromolecular Pluronic were added in this work. Pure CNFs derived from polyacrylonitrile (PAN) and two composite systems: CNFs/Ni and CNFs/Pluronic were synthesized. Morphology of the electrospun fibers and their electrochemical performance in both LIBs and SIBs were studied. Metallic nickel plays the role of an electronic conducting agent, while Pluronic serves as a template to generate micropores, which is favorable for sodium ion transport. Nanofibers with diameters around 200 nm were successfully prepared. Nanoparticles of nickel were observed on the surface of these CNFs by scanning electrode microscope (SEM). A high capacity of 460 mA h g-1 of pure CNFs when cycled at 100 mA g-1 in LIBs has been achieved with an outstanding stability. After 300 cycles, the capacity stays above 400 mA h g-1. With the addition of nickel particles, an even higher capacity of around 800 mA h g-1 was obtained. CNFs/Pluronic showed the best capacity retention among all composites with a steady capacity at around 600 mA h g-1. The influence of porosity and carbonization temperature on overall electrochemistry performance in LIBs and NIBs are being investigated. In summary, introduction of additives of Ni and micropores can effectively improve capacity of CNFs as anode materials. Charge/discharge profiles did not vary a lot which can prove that the additives are electrochemically inert. Electrospinning is a flexible method to develop 1D nanostructured electrode materials for both LIBs and SIBs. The outstanding electrochemical properties of such electrospun anodes will further stimulate their applications in LIBs and SIBs.

Influence of Sensitization on Mechanical Properties of AISI 304 Stainless Steel under High-Temperature.

This study investigated influence of sensitization on the mechanical properties of AISI 304 stainless steel. The small and tensile specimens were isothermally aged at 650 °C for up to 1000 hours. Microstructure and precipitates of these specimens were characterized by scanning electrode microscope with energy dispersive X-ray spectroscopy. The degree of sensitization of aged specimens was measured by double loop electrochemical potentiodynamic reactivation method. The tensile test was conducted to evaluate mechanical properties of these specimens. With the progress of aging, the degree of sensitization value drastically increased to more than 50% as Cr-rich carbides were precipitated in the austenite grain boundaries. Also, the mechanical properties were degraded, and fracture mode drastically changed from ductile to brittle. As a result, the surface damage and degradation of mechanical properties were correlated with the degree of sensitization value.

Electro-Stimulation of Thermotoga Neapolitana Metabolism

Thermotoga neapolitana (DSM 4359, ATCC 49049), more than others Thermotogales is able to accumulate biohydrogen from waste organic matter, in a selective environment (>80ºC). Thanks to the high temperature, this bacterium is able to use a peculiar anaplerotic biochemical pathway named Capnophilic Lactic Fermentation (CLF) that accomplishes chain elongation of acetate with direct reduction of CO2, producing lactic acid (Pradhan et al. 2015). This is a carbon fixation mechanism which, differently from autotrophism, leads to direct elimination of fixed carbon into excreted metabolites, such as lactic acid, instead of converting and accumulating it into biomass. T. neapolitana is therefore a promising microorganism for recovering added-value chemicals from organic wastes (Fontana, EP14711847.5). In this work, the possibility of bioelectrostimulate the production of lactic acid by Thermotoga Neapolitana supplying additional electric energy in polarized and unpolarized bioreactors is investigated. For this, an alternating polarization up to ±1.2V was imposed between two identical electrodes of carbon cloth, immersed in the electrochemical bioreactors. Bioreactor without electrodes were also tested, as control. Glass reactors of 250 mL were operated at temperature of 85°C with a culture media of T. neapolitana containing 5 g/L (~30mM) of glucose, in triplicates. Three successive cycles of chemical measurements was carried out every 24 hours for three measurement cycles, to estimate the glucose consume and the acetic/lactic acid production, as well the hydrogen yieldin each tested bioreactor. The solution Optical density (OD) and micrographs produced by scanning electrode microscopy (SEM) showed a strong affinity of bacteria to form biofilm on the polarized and unpolarized electrodes. Evidence of the lactate/acetate ratio modification with respect the control bioreactors was achieved, especially under higher polarized condition, but also in the bioreactors with unpolarized electrodes. Glucose fermentation was strongly inhibited in electrochemical bioreactors in the first 24-48 hours test and during the whole three days test in some cases. Only in the control bioreactor glucose was oxidized to acetic acid in the molar rate similar to dark fermentation (glucose:acetic 1:2) and only the first day. Lactic acid in a relative high ratio versus the glucose consume, although at lower concentration with respect acetate, was found especially in some polarized bioereactors. These results globally confirm the affinity of Thermotoga neapolitana to carbon cloth electrodes and the possibility of electrostimultate their metabolism, opening future perspectives on electro-fermentation with this hyperthermophilic strain. Pradhan N., Dipasquale L., et al. 2015, Int. J. Mol. Sci. 16, 12578-12600 Fontana EP EP14711847.5. EU patent application: EP14711847.5; Priority IT20130109 24/01/2013 d’Ippolito G, Dipasquale L, Vella FM, Romano I, Gambacorta A, Cutignano A, Fontana A. Int J Hydrogen Energy 2010;35:2290–5. doi:10.1016/j.ijhydene.2009.12.044.

Reduced graphene oxide on the performance of solid-state dye-sensitized solar cell

Dye-sensitized solar cell (DSSC) is a third generation solar cell which provides a good research platform for future photovoltaic technologies. DSSC can be categorized into two types based on the nature of its electrolyte, namely liquid and solid-state. In general, DSSC with liquid-based electrolyte has risk of electrolyte leakage. Therefore, the utilization of solid-state hole transport materials instead of liquid electrolytes can overcome the leakage issue of liquid-based DSSC. Despite of this advantage, the performance of solid-state dye-sensitized solar cell (SS-DSSC) is low compared to the cell that uses liquid electrolyte. To remedy this, doping with foreign materials is used to enhance the performance of the solar cell. Hence, this work focuses on the effect of reduced graphene oxide (RGO) on the performance of SS-DSSC utilizing TiO2 nanoparticles. The electrode samples were characterized with scanning electrode microscopy, energy dispersive spectroscopy, UV-Visible spectroscopy, IV test, and electrochemical impedance spectroscopy (EIS). By introducing RGO into SS-DSSC, the efficiency and fill factor was improved by at least 15%. Moreover, the presence of RGO increased the electron lifetime with higher recombination resistance as observed from EIS result.

Synthesis of an Efficient Counter Electrode Material for Dye-Sensitized Solar Cells by Pyrolysis of Melamine and Graphene Oxide.

An efficient counter electrode material for dye sensitized solar cells (DSSCs) was synthesized by pyrolysis of melamine and graphene oxide. The synthesized samples were characterized by X-ray diffraction, X-ray photoelectron spectroscopy, Raman spectroscopy and scanning electrode microscopy, which show that nitrogen doped reduced graphene oxide (NRGO) was obtained by this synthesis method. In the synthesized NRGO, graphitic structure was kept and the nitrogen was existence as pyrrolic, pyridinic, graphitic, and oxidized nitrogen species in the samples. After deposited as counter electrode films for DSSCs, it shows lower charge-transfer resistance at the electrode/electrolyte interface and higher electrocatalytic activity towards reduction of triiodide (I-₃) than that of reduced graphene oxide (RGO) prepared also by this method without adding melamine. Consequently, the DSSCs based on NRGO counter electrodes achieve an energy conversion efficiency of 4.60%, which is higher than that of RGO counter electrode (2.35%). Although the photovoltaic performance of NRGO counter electrode was lower than that of Pt counter electrode (5.70%), it is still a promising counter electrode to replace noble metal Pt due to its low cost and simple synthesis process.

Electrochemical monitoring of Acidithiobacillus thiooxidans biofilm formation on graphite surface with elemental sulfur

Inorganic wastewaters and sediments from the mining industry and mineral bioleaching processes have not been fully explored in bioelectrochemical systems (BES). Knowledge of interfacial changes due to biofilm evolution under acidic conditions may improve applications in electrochemical processes, specifically those related to sulfur compounds. Biofilm evolution of Acidithiobacillus thiooxidans on a graphite plate was monitored by electrochemical techniques, using the graphite plate as biofilm support and elemental sulfur as the only energy source. Even though the elemental sulfur was in suspension, S0 particles adhered to the graphite surface favoring biofilm development. The biofilms grown at different incubation times (without electric perturbation) were characterized in a classical three electrode electrochemical cell (sulfur and bacteria free culture medium) by non-invasive electrochemical impedance spectroscopy (EIS) and cyclic voltammetry. The biofilm structure was confirmed by Environmental Scanning Electrode Microscopy, while the relative fractions of exopolysaccharides and extracellular hydrophobic compounds at different incubation times were evaluated by Confocal Laser Scanning Microscopy. The experimental conditions chosen in this work allowed the EIS monitoring of the biofilm growth as well as the modification of Extracellular Polymeric Substances (EPS) composition (hydrophobic/ exopolysaccharides EPS ratio). This strategy could be useful to control biofilms for BES operation under acidic conditions.

Exploration of the Microscopic Pore Structure of Unconventional Energy Resource using Electrodeposition

The microscopic pore structure of unconventional petroleum reservoirs, such as shale gas、 tight oil、tight gas, and so on, namely the size, geometry, distribution, and interconnected relations of the pores and throats of a shale rock, directly affects their porosity, storage, and permeability. Studies related to the microscopic pore structure of shale are considered to be attractive to evaluate the shale resource and to elucidate their distribution law; additionally, studies aim to improve the productivity and recovery ratio of both oil and gas. Therefore, methods that can be used to accurately characterize the microscopic pore structure of shale have received considerable attention. In this study, we combine electrochemical deposition and scanning electrode microscopy to characterize the microscopic pore structure of shale. Therefore, we could directly observe the three-dimensional microstructure of shale that are smaller than 50 nm with a large observing area. Additionally, the surface areas of the connected pores and throats of the shale are calculated.

Investigation of a novel pyrolusite particle electrode effects in the chlorine-containing wastewater.

Research on three-dimensional electrode system mainly focuses on the material of plate electrode and catalytic activity, and minimal attention is provided to particle electrode. Pyrolusite was prepared as a novel particle electrode with high active chlorine (ACl) yield. The particle electrode was characterised by scanning electrode microscopy (SEM), X-ray diffraction (XRD), X-ray fluorescence (XRF) and electrochemical properties. Results show that the intended pyrolusite particle electrode was prepared successfully. These pyrolusite particle electrodes were applied to degrade sulphonated phenolic resin in chlorine-containing wastewater and displayed an excellent catalytic activity. A total of 68.76 mg/L ACl was produced, and the CODCr removal rate was 49.55%. These results indicated that pyrolusite particle electrode is much more effective than the reference material, that is, granular activated carbon. Furthermore, the product of electrolytic process was characterised by gas chromatography-mass spectrometry (GC-MS) and ultraviolet visible spectrometry (UV-vis). The enhanced mechanism was proposed that the high degradation efficiency could be ascribed to the increase of ACl.

Nano Size Magnetite Particles Layered with the Blend of Conductive Polymer and Superadsorbent Hydrogel: A Core–Shell Based Nanocomposite for Trivalent Arsenide Uptake form Aqueous Solution

The polymer polypyrrole (PPy)/polyvinyl alcohol (PVA) polymer blend incorporated with Fe3O4 nanoparticle is synthesized successfully using solution blending technique. The study is focused on developing core shell nanocomposite using magnetite nanoparticles as core layered with the shell of a blend of conducting PPy and PVA prepared via in-situ polymerization in the presence of magnetite precursor. The surface area, pore size and pore volume for the blend improved upon reinforcement of magnetite nano filler. The surface morphology show the single phase for the blend indicating the uniform dispersion the two polymers with the smooth surface. The internal structure shows the magnetite nanoparticles were uniformly reinforced into the bulk of the blend and were of formed in the size range of 50 nm and above. The structural morphologies was evaluated using scanning electrode microscope. Thermogravimetric analysis show that thermal stability of polymer blend has improved with the addition of iron oxide improved almost by 200 °C. X-ray diffraction analysis for the crystallinity. The nanocomposite was applied to remove As(III) trivalent arsenide from aqueous solution using adsorption technology and kinetics models and isotherms model were applied to study the course of adsorption. The bionanocomposite show adsorbent efficiency of 1.21 mg/g.

The Comparison of the AST 908, AST 915 and AST 928 of Micro-Hardness of Tungsten Based Alloy Films on AISI 1050 Steel by HVOF Coating Method

In this study, the commercial powder tungsten based alloys was sprayed by using high velocity oxygen fuel (HVOF) method on AISI 1050 steel substrate. These films of powder tungsten based alloys of AST 908, AST 915 and AST 928 were included. The powder was mainly composed of tungsten (W), Chromium (Cr), Nickel (Ni) and Cobalt (Co) with an average particle size in the range of 10-45 μm. The microstructure and compositional analysis was used by the scanning electrode microscopy (SEM) and energy dispersive spectroscopy (EDS) respectively. The micro-hardness of coating films was investigated by Vickers micro- hardness tester. The SEM results exhibited good deposition between the coating films with the specimens (AISI 1050 steel). Accordingly, the coating films showed a very homogeneous microstructure. In addition, the micro-hardness of substrate was 81.30% lower than the AST 908 particles. Finally, the AST 908, AST 915 and AST 928 coating improved the micro- hardness of 1559.3 HV, 1468.4 HV and 1306.2 HV respectively

Facile synthesis of nitrogen-doped reduced graphene oxide as an efficient counter electrode for dye-sensitized solar cells

A nitrogen-doped reduced graphene oxide (N-RGO) nanosheet was synthesized by a simple hydrothermal method and characterized by X-ray diffraction, Raman spectroscopy, X-ray photoelectron spectroscopy, and scanning electrode microscopy. After being deposited as counter electrode film for dye-sensitized solar cells (DSSCs), it is found that the synthesized N-RGO nanosheet has smaller charge-transfer resistance and better electrocatalytic activity towards reduction of triiodide than the reduced graphene oxide (RGO) nanosheet. Consequently, the DSSCs based on the N-RGO counter electrode achieve an energy conversion efficiency of 4.26%, which is higher than that of the RGO counter electrode (2.85%) prepared under the same conditions, and comparable to the value (5.21%) obtained with the Pt counter electrode as a reference. This N-RGO counter electrode offers the advantages of not only saving the cost of Pt itself but also simplifying the process of counter electrode preparation. Therefore, an inexpensive N-RGO nanosheet is a promising counter electrode material to replace noble metal Pt.