Lower Charge Transfer Resistance Research Articles

Strain-Induced Photocatalytic H2 Production over BiVO4 in Pure Water without Any Cocatalyst.

In this study, BiVO4 nanosheets (BiVO4-NS) were prepared by a facile hydrothermal method. It is found that sonication-induced strain can effectively promote the H2 production over BiVO4-NS in the presence of pure water without any cocatalysts. With the assistance of the sonication, the H2 production over BiVO4-NS is 1.344 mmol·g-1 after 3 h simulated sunlight irradiation, which is 24.8 times higher than that of BiVO4-NS without sonication (0.054 mmol·g-1). In addition, the products of water oxidation are determined to be hydroxyl radicals and hydrogen peroxide. Moreover, BiVO4-NS also shows obviously enhanced photoactivity than that of the commercially available BiVO4 nanoparticles (BiVO4-C). The improved photoactivity of BiVO4-NS is attributed to the effective charge separation and low charge transfer resistance. The underlying mechanism of sonication-promoted water splitting is investigated by a variety of controlled experiments. The results show that ultrasonic waves can produce obvious strain inside the sample, which results in lattice distortion of BiVO4. Therefore, the conduction band of BiVO4 is obviously negative shifted, which is beneficial for H2 production. In addition, the strain in BiVO4 also produces local polarization of the sample, which effectively promotes the charge transfer and separation process. It is hoped that our study could provide a new strategy for achieving efficient photocatalytic water splitting.

Efficient degradation of organics via sodium p-styrene sulfonate modified PbO2 electrode: The role of boosting electrocatalytic performance

In this work, Sodium p-styrene sulfonate (SSS)/PbO2 electrode was successfully prepared and further applied for the electrocatalytic degradation of methyl blue (MB). 95.8 % of methylene blue degradation via PbO2 electrodes was observed at the optimized conditions (100 mg/L-1 of MB solution, current density of 30 mA·cm−2, pH=5, 180 min). When compared with PbO2 electrodes, SSS/PbO2 electrode was found to possess most effective electrocatalytic activity due to its higher oxygen evolution potential, lower charge transfer resistance, and longer service lifetime. When the concentration of SSS increases to 2vt%, the grain size of PbO2 decreases from 21.79 nm to 19.42 nm, and the degradation rate of MB was enhanced for 5 %. Besides, the degradation rate of SSS/PbO2 electrode remained 86 % after 10 cycles, indicating that the stability and catalytic activity of the electrode were improved when the PbO2 was decorated by SSS. Moreover, the law of degradation of MB catalyzed by SSS/PbO2 electrode follows the first order kinetics. Furthermore, the energy consumption and mineralization efficiency of the SSS/PbO2 electrode were 68.73 kWh· L-1 and 4.39 %, respectively. Finally, a possible mechanism was proposed, which was further uncovered by DFT calculations.

An efficient and green strategy for the synthesis of graphene with aqueous polyphenol extracts of orchid flower (Dendrobium Anosmum) for charge storage

This study introduces the use of orchid flower extract as a green reducing agent for the first time to produce reduced graphene oxide (ORGO). Raman, XRD and FTIR confirmed the reduction process whereas TGA analysis provides the thermal stability of the prepared samples. SEM imaging validates the improved morphology of ORGO as compared to the crumpled and folded region of graphene oxide (GO). Electrochemical tests reveal ORGO’s superior specific capacitance (489.8F/g) value at scan rate of 20 mV/s, low charge transfer resistance (2.1 Ω) and high specific capacity retention (96.63 %) after 10,000 cycles, highlighting its potential application for charge storage devices.

Super capacitive electrode performance analysis of facile synthesized α-Fe2O3 aerogel and its nanocomposite with in-situ formed polyaniline (α-Fe2O3/PANI)

This paper presents the synthesis of an α-Fe2O3-assisted polyaniline (α-Fe2O3/PANI) nanocomposite using a straightforward two-step process. Initially, α-Fe2O3 aerogels with cratered nanohexagon structures are synthesized through a solution combustion method assisted by noni (Morinda citrifolia) fruit extract. In the second step, these nanohexagons facilitate the preparation of α-Fe2O3/PANI via in-situ chemical oxidative polymerization of anilinium chloride. The structural, optical, and morphological properties were characterized using X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), and scanning electron microscopy with energy-dispersive X-ray analysis (SEM-EDAX). Electrical conductivity, wettability, and electrochemical properties of the prepared materials were assessed. The results indicate that the 2D cratered α-Fe2O3 aerogel is effectively embedded within PANI, forming a modified nano α-Fe2O3/PANI composite. The composite exhibited altered DC conductivity and electrolyte wettability. After 200 cycles of cyclic voltammetry (CV), the specific capacitance of the nano α-Fe2O3/PANI was determined to be 153 Fg⁻¹ at a scan rate of 10 mVs⁻¹, retaining approximately 90% of its cycle stability. Electrochemical impedance spectroscopy (EIS) revealed significantly lower charge transfer and equivalent series resistance values for the nano α-Fe2O3/PANI electrode compared to the pure α-Fe2O3-based electrode. Galvanostatic charge-discharge (GCD) tests further demonstrated the superior electrochemical performance of the α-Fe2O3/PANI nanocomposite electrode. Therefore, this α-Fe2O3/PANI is an advanced conducting polymeric electrode for electrochemical applications.

Efficient and stability electrochemical degradation of Bisphenol A on Ti/TiO2-NTA/PbO2-Nd anode: Mechanistic analysis

The Ti/TiO2-NTA/PbO2-Nd electrodes were fabricated using anodic oxidation and electrodeposition techniques for the electrocatalytic treatment of bisphenol A (BPA) pollutants in coking wastewater. Characterization revealed well-organized TiO2 nanotube arrays (TiO2-NTA) with a hollow structure, featuring a wall thickness of 36 nm and an inner diameter of approximately 83 nm. The TiO2-NTA interlayer restricted PbO2 growth, leading to a compact crystal structure and increased electrode surface area. Electrochemical tests showed that the Ti/TiO2-NTA/PbO2-Nd electrode outperformed Ti/TiO2-NTA/PbO2 and Ti/PbO2 electrodes, exhibiting the highest oxygen evolution potential, lowest charge transfer resistance, optimal hydroxyl radical generation, and longest service lifetime. The removal efficiencies for BPA were 95.4 % for Ti/TiO2-NTA/PbO2-Nd, 90.8 % for Ti/TiO2-NTA/PbO2, and 80.6 % for Ti/PbO2. The Ti/TiO2-NTA/PbO2-Nd electrode also achieved the lowest energy consumption at 0.157 kWh/(g·COD), a 40 % reduction compared to Ti/PbO2. The introduction of TiO2-NTA enhanced electrode stability, electron transfer, and surface area, while neodymium (Nd) doping improved oxygen evolution potential and hydroxyl radical production. Under optimized conditions, the Ti/TiO2-NTA/PbO2-Nd electrode achieved BPA removal efficiencies of 99.24 %, COD removal efficiencies of 82.77 %, and TOC removal efficiencies of 78.92 %. UV–Vis spectrophotometry, three-dimensional excitation-emission matrix fluorescence spectra (3D EEM), and gas chromatography–mass spectrometry (GC–MS) analyses revealed potential BPA degradation pathways.

Activating peroxymonosulfate with MOF-derived NiO-NiCo2O4/titanium membrane for water treatment: A non-radical dominated oxidation mechanism

Traditional peroxymonosulfate (PMS) catalytic membranes dominated by radical pathways often face interference from complex components in water bodies. Herein, we employed a controlled electro-deposition technique to coat a Ni-Co metal–organic framework (MOF) precursor onto titanium hollow fiber membrane (THFM), followed by high-temperature calcination to synthesize a MOF-derived NiO-NiCo2O4/THFM (M−NNCO−THFM) PMS catalytic membrane. Then, the M−NNCO−THFM filtration integrated with PMS activation (MFPA process) for water treatment. Experimental results demonstrated that the M−NNCO−THFM MFPA process successfully achieved complete phenol (PE) removal via a non-radical-dominated degradation pathway, involving singlet oxygen (1O2) and electron transfer, while exhibiting wide pH adaptability and exceptional stability in complex water matrices. Mechanism analysis revealed that the electron transfer process was significantly enhanced by the MOF-derived heterojunction structure, which increased the flat-band potential from 0.39 eV to 0.56 eV, thereby facilitating efficient electron transfer for PE removal. The non-radical 1O2 pathway was primarily due to the cycling of metal valence states (Ni2+/Co3+), leading to the reduction of Co2+ and its reaction with PMS, resulting in the generation of reactive species. Furthermore, electrochemical measurements indicated that the M−NNCO−THFM exhibited lower charge transfer resistance and enhanced charge transfer efficiency compared to non-MOF-derived NNCO-THFM, corresponding to the superior catalytic performance and electrochemically active surface area of M−NNCO−THFM.

Enhanced efficiency and stability of dye-sensitized solar cells utilizing FeCo2S4 nanowires as Pt-free counter electrodes

Replacing traditional Pt-based counter electrodes with low-cost and highly stable materials is crucial for the development of commercially viable dye-sensitized solar cells (DSSCs). In this study, we synthesized a ternary Pt-free FeCo2S4 nanowire (NW)-based sulfide electrocatalyst by a three-step solvothermal method. This material was then used as a counter electrode in DSSCs to facilitate the reduction of triiodide species. The formation of FeCo2S4 NW was confirmed by various characterization techniques such as X-ray diffraction, energy dispersive X-ray spectroscopy and X-ray photoelectron spectroscopy. Scanning electron microscopy analysis revealed the structure of the nanowires. Electrochemical studies, which included cyclic voltammetry, electrochemical impedance spectroscopy and Tafel polarization methods, revealed the excellent stability, superior electrocatalytic activity and remarkable kinetics of FeCo2S4 NW in the reduction of triiodide to iodide. Photovoltaic measurements of the fabricated DSSCs yielded a power conversion efficiency (PCE) of 7.88 % for the FeCo2S4-based devices, outperforming the control device made of Pt (PCE=7.45 %). This improvement was primarily due to the increase in short-circuit current density (JSC), thanks to the lower charge transfer resistance (RCT) of FeCo2S4 NW (JSC=15.23 mA/cm2; RCT=5.54 Ω cm2) compared to Pt (JSC=14.12 mA/cm2; RCT=7.07 Ω cm2). In addition, the FeCo2S4 NW-based solar cells exhibited excellent stability and maintained their high PCE value even after 10 days of aging under ambient conditions, while Pt-based DSSCs showed a 3 % decrease from their initial PCE value. This FeCo2S4 NW counter electrode proves to be an excellent alternative to Pt, and the presented results provide valuable insights for the development of cost-effective and highly stable DSSCs.

3D porous reduced graphene oxide-coated zinc anodes for highly-stable aqueous zinc-ion capacitors via electrostatic spray deposition

Zinc-ion energy storage devices are inexpensive and safe, benefitting from the abundance of Zn metal and high chemical stability. However, their electrochemical performance is poor, owing to the unstable Zn stripping/plating process of the Zn metal anode and the occurrence of side reactions. In this study, 3D porous reduced graphene oxide-coated Zn (rGO@Zn) was prepared via electrostatic spray deposition (ESD) and used as an anode for aqueous hybrid Zn-ion capacitors (ZICs). ESD is a cost-effective one-step technique that affords excellent control over the deposition morphology. Coating 3D porous rGO with a large surface area on Zn foil, resulted in a low charge transfer resistance and small voltage hysteresis (44.5 mV) with a long cycle life of over 3000 h. Moreover, the energy density improved at high rates (25 Wh kg−1 at 10,882 W kg−1) in aqueous hybrid ZICs. In-situ synchrotron transmission X-ray microscopy and optical microscopy analyses revealed that the formation of dendrites was inhibited in the as-fabricated ZICs. Furthermore, the conductive rGO on the surface of the Zn anode stabilized the electric field during the Zn stripping/plating process, and the functional groups guided the Zn2+ deposition sites, resulting in uniform Zn deposition during cycling and improved electrochemical performance.

Influence of the Electron Transport Layer on the Performance of Perovskite Solar Cells under Low Illuminance Conditions.

Owing to the tunable band gap of metal-halide perovskite compounds, perovskite solar cells (PSCs) are promising energy-harvesting devices for indoor applications. Since the electron transport layer (ETL) plays a critical role in the performance of PSCs, selecting a suitable ETL is important for improving the performance of PSCs. Here, we compared the characteristics of PSCs employing TiO2 and SnO2, which are widely used as ETLs in PSCs, under low illuminance conditions. Electrochemical impedance spectroscopy revealed that PSCs employing SnO2 as the ETL exhibited lower charge transfer resistance than those employing TiO2 in low light intensity environments. Consequently, SnO2-based PSCs showed a higher power conversion efficiency of 27.7% than that of TiO2-based PSCs (22.5%) under 1000 lx white LED illumination. Space-charge-limited current measurements have shown that the defect density of ETLs strongly affects the performance of PSCs, especially under low illuminance conditions. We believe that this report provides an effective strategy for selecting appropriate ETLs for indoor applications of PSCs.

Elucidating the local structure and electronic properties of a highly active overall alkaline water splitting NixCo1-xO/hollow carbon sphere catalyst

A NixCo1-xO/HCS catalyst with superior water-splitting is presented. High water-splitting reaction kinetics and enhanced durability were observed. The structure-function relationship was investigated with XPS, which demonstrated the presence of dominant Ni2+ and Co2+ species and a functionalized HCS support where nucleation of small metal oxide nanoparticles occurred. The PDF showed broadened Nickel/Cobalt-oxide bonds and expansion of the metal-metal pair distances. The alteration of the Metal-Oxide and Metal-Metal-Oxide bonds favored better HER and OER electrocatalysis, also as supported by DFT. EXAFS showed the existence of the bimetallic oxide catalyst and the stretching of the Ni–O bonds due to the coordination of the Ni–O with the Co. The composite exhibited higher activity and enhanced electrocatalytic mechanism towards water splitting through higher exchange current densities (0.615 and 0.886 mA cm−2) and low charge transfer resistance (14 and 10 Ω) respectively. Chronoamperometry proved the catalyst's stability during prolonged electrolysis.

In-situ synthesis of Fe3O4@Fe3C nanoparticles with heterostructures embedded in the N-doped porous carbon for high-performance lithium ion batteries

Metal oxides (Fe3O4) have attracted immense attention as high-capacity anode materials for high-performance electrochemical energy storage systems. However, the large structural change and sluggish reaction kinetics in the lithiation and delithiation reactions critically limit their practical development. Here, we design a novel composite consisting of Fe3O4@Fe3C nanoparticles embedded in N-doped porous carbon (Fe3O4@Fe3C-NPC) for lithium ion batteries. Benefiting from the synergistic effect of heterostructures, the Fe3O4@Fe3C-NPC delivers high reversible capacities (911.9 mAh g−1 at 0.2 A g−1, 319.6 mAh g−1 at 5.0 A g−1). The formed heterointerfaces can build an internal electric field, which help to improve reaction kinetics with fast ion diffusion kinetics and low charge transfer resistance. Furthermore, the Fe3O4@Fe3C-NPC//LiFePO4 full cell also displays great performance. The structural design concept and efficient synthesis method in the work can be extended to construct metal oxide/carbide heterostructures for anode materials.

Oxalate and adipate mediated fabrication of CuO nanocrystallites for their electrochemical and supercapacitance studies

Cupric oxide (CuO) has been comprehensively studied in the field of electrochemistry due to its high Tc-Superconducting property. The present work focus on two different CuO materials i.e. CuO-1 and CuO-2 nanocrystallites which are successfully synthesized from their oxalate and adipate precursors respectively. The calcination temperature for the synthesis of CuO from their precursors is ascertained by TGA analysis of the dicarboxylates. Both the CuO materials are thoroughly characterized by SEM–EDS, XRD, IR and XPS spectroscopic techniques. As a candidate for supercapacitor electrode material, CuO-1/C and CuO-2/C showed a specific capacitance of 4.15 F/g and 22.24 F/g using cyclic voltammetry, 10.4 F/g and 46.6 F/g using GCD curves respectively at a current density of 1 A/g. Also, the CuO-1/C and CuO-2/C showed a specific energy density (Es) 1.59 Wh kg−1 and 0.36 Wh kg−1 at a specific power density (Ps) of 0.02 kW kg−1 and 0.025 kW kg−1 respectively. Moreover, the CuO-2/C exhibits ≈ 96.1% coulombic efficiency following 1000 cycles, whereas, CuO-1/C lags in coulombic efficiency with only 51.8%. As a better candidate, CuO-2/C exhibited excellent rate capability with an outstanding cycling stability of 93.7% retention after 1,000 cycles. The factors contributing to the significant specific capacitance of CuO-2/C along with better stability and reproducibility are its low electrolyte resistance Rs (2.47Ω) and charge transfer resistance Rct (1.01 Ω).

Facile construction of porous carbon fibers from coal pitch for Li-S batteries

Coal pitch, an important by-product in the coal coking industry with a high output, is a low-cost and high-carbon yield precursor for the manufacturing of high-value carbon materials. Herein, N/O co-doped carbon fiber (CFCP), fabricated by electrospinning using pre-oxidized coal pitch as the precursor, was employed as the sulfur host for Li-S batteries. The presence of more pyrrolic N and graphic N in CFCP than carbon fiber made from polyacrylonitrile benefits the adsorption of lithium polysulfide and the battery’s life. Sulphur-CFCP cathode (S@CFCP) exhibited excellent specific capacity and cyclability, with a specific capacity of 701.1 mAh/g and a low capacity decay rate of 0.088% per cycle over 200 cycles at 2.0 C, respectively. The high ion diffusion rate, low charge transfer resistance, and effective conversion of lithium polysulfides enable the high electrochemical performance of S@CFCP.

In Situ Growth of Hierarchical Silver Sub‐Nanosheets on Zinc Nanosheets‐Based Hollow Fiber Gas‐Diffusion Electrodes for Electrochemical CO2 Reduction to CO

Electrochemical reduction of CO2 (CO2RR) is an effective strategy to mitigate carbon emission effects and store renewable electricity in value‐added feedstocks, but it still suffers low production rate and current density. A nanostructured catalyst offers opportunities to enhance CO2RR activity by contributing numerous active sites and promoting charge transfer. Herein, a Cu hollow fiber gas diffusion electrode (HFGDE) with silver sub‐nanosheets on a zinc nanosheet structure to produce CO is reported. Compared to the HFGDE only possessed zinc nanosheet structure, the as‐prepared HFGDE with hierarchical sub‐nano AgZn bimetal nanosheets exhibits a twice‐partial current density of CO and a CO production rate at the applied potential −1.3 V (versus reversible hydrogen electrode). The unique Ag sub‐nanosheets interconnected Zn nanosheets provide multiple charge transfer channels, and the synergistic effect between Ag and Zn improves the adsorption binding energy of COOH* intermediate, resulting in a lower charge transfer resistance and fast CO2RR kinetics to produce CO. This research demonstrates the high potential of nanoengineering electrocatalysts for HFGDE to achieve highly efficient CO2 reduction.

Boosting visible-light photoelectrochemical water splitting response of WO3–MoS2 nanocomposites by transition metal doping: Experimental and first-principles studies

The current study employs both theoretical and experimental methods to investigate the effect of Ti and Co doping on the WO3 nanocomposite with MoS2 photoanode's photoelectrochemical (PEC) water-splitting reaction. A simple hydrothermal and sol-gel method was adopted for the preparation of samples. The Ti-doped WO3–MoS2 (1.96 at %) sample showed the maximum optical absorption with a photocurrent density of 1.15 mA/cm2 at 1.6 V vs Ag/AgCl. The improvement in photocurrent density may be ascribed to the upward shifting of the conduction band edge towards the H+/H2 redox potential as well as the presence of a large number of active sites in MoS2. A high value of flat band potential of −0.3 V vs Ag/AgCl was achieved in Ti-doped WO3–MoS2, which was confirmed by Mott-Schottky measurements with the corresponding lowest charge transfer resistance at the semiconducting electrode/electrolyte interface. Furthermore, density functional theory calculations have also indicated that on doping WO3 with Ti and Co, there is a slight upward shift in the conduction band minimum, without any significant change in the valence band maximum, with respect to the Fermi level. This study provides new insight into the impact of transition metal doping and nanocomposite of chalcogenide materials for WO3-based PEC electrodes.

Effect of Bi2MoO6 Morphology on Adsorption and Visible-Light-Driven Degradation of 2,4-Dichlorophenoxyacetic Acid.

The development of highly efficient and stable visible-light-driven photocatalysts for the removal of herbicide 2,4-dichlorophenoxyacetic acid (2,4-D) from water is still a challenge. In this work, Bi2MoO6 (BMO) materials with different morphology were successfully prepared via a simple hydrothermal method by altering the solvent. The morphology of the BMO material is mainly influenced by the solvent used in the synthesis (H2O, ethanol, and ethylene glycol or their mixtures) and to a lesser extent by subsequent thermal annealing. BMO with aggregated spheres and nanoplate-like structures hydrothermally synthesized in ethylene glycol (EG) and subsequently calcined at 400 °C (BMO-400 (EG)) showed the highest adsorption capacity and photocatalytic activity compared to other synthesized morphologies. Complete degradation of 2,4-D on BMO upon irradiation with a blue light-emitting diode (LED, λmax = 467 nm) was reached within 150 min, resulting in 2,4-dichlorophenol (2,4-DCP) as the main degradation product. Holes (h+) and superoxide radicals (⋅O2-) are assumed to be the reactive species observed for the rapid conversion of 2,4-D to 2,4-DCP. The addition of H2O2 to the reaction mixture not only accelerates the degradation of 2,4-DCP but also significantly reduces the total organic carbon (TOC) content, indicating that hydroxyl radicals are crucial for the rapid mineralization of 2,4-D. Under optimal conditions, the TOC value was reduced by 84.5% within 180 min using BMO-400 (EG) and H2O2. The improved degradation performance of BMO-400 (EG) can be attributed to its particular morphology leading to lower charge transfer resistance, higher electron-hole separation, and larger specific surface area.

Platinum Cluster Decoration on Hollow Carbon Spheres for High-Efficiency Hydrogen Evolution Reaction.

Currently, platinum (Pt)/carbon support composite materials have tremendous application prospects in the hydrogen evolution reaction (HER). However, one of the primary challenges for boosting their performance is designing a substrate with the desired microstructure. Herein, the intact hollow carbon spheres (HCSs) were prepared via template method. Based on the morphology variation of the as-prepared HCSs-x, we conjectured that the polydopamine (PDA) core was generated first and then slowly grew into a complete overburden (SiO2@PDA). Afterward, Pt atomic clusters were anchored on the outer shells of HCSs-4 to construct composite electrocatalysts (Pty/HCSs-4) by a chemical reduction method. Due to the low charge-transfer resistance, the HCSs have a large electrochemical surface area and provide a continuous electron transport pathway, boosting the atom utilization efficiency during hydrogen production and release. The synthesized Pt2.5/HCSs-4 electrocatalysts exhibit excellent HER activity in acidic media, which can be ascribed to the compositional modulation and delicate structural design. Specifically, when the overpotential is 10 A g-1, the overpotential can achieve 92 mV. This work opens a new route to fabricate Pt-based electrocatalysts and brings a new understanding of the formation mechanism of HCSs.

Elevating Oxygen Evolution using Iron Phthalocyanine Infused Vanillic acid Electrocatalyst.

Oxygen evolution reaction (OER) is the bottle neck step in water splitting reaction towards the realization of hydrogen based clean energy production and storage. Transition metal based N4 organics are explored extensively as oxygen electrocatalysts i.e.,(OER) and oxygen reduction reaction (ORR) catalysts because of their ease of synthesis, tuneable properties, low cost and high performance with long term stability. Here, vanillic acid functionalized iron phthalocyanine (FeVAPc) was synthesised and characterised. The novel FeVAPc exhibited good thermal stability and was coated on Ni foam for OER studies. The scanning electron microscopy images showed net-work like surface morphology and the X-ray photoelectron spectroscopy indicated the presence of Fe in +3 oxidation state. The Ni/FeVAPc demonstrated excellent electrocatalytic activity for OER with overpotential of 312 mV at 10 mA.cm-2 current density in 1.0 M KOH . The designed catalyst exhibited lesser Tafel slope value which is nearer to the benchmark catalyst, IrO2. The proposed catalyst exhibited good stability as phthalocyanines are highly stable and do not undergo decomposition even in strong acidic and basic corrosive media. Integration of FeVAPc onto Ni foam resulted in higher mass activity, lower charge transfer resistance, high active surface area leading to enhanced conductivity and activity.

Hierarchical CaZrO3@rGO nanostructure as an electrode material for high-performance supercapacitor devices

The primary focus of energy-storage system development is to find cost-effective solutions that improve performance, efficiency and stability. The electrode composed of CaZrO3 nanoparticles supported by reduced graphene oxide demonstrates higher capacitance and long-term cyclic stability. In this work, CaZrO3@rGO nanocomposite synthesized through a hydrothermal approach exhibited a specific capacitance of 1564 F/g @ 1 A/g with lower charge transfer resistance of 0.2 Ω which showed cyclic stability after 10,000th cycles. Due to the increased surface area and enrichment of active zones, the capacitive properties of the electrode are greatly improved when metal oxides are combined with rGO. Based on these results, it seems that CaZrO3@rGO nanocomposite may be used for future energy-saving equipment.

Electrodeposited polyaniline modified CNT fiber as efficient counter electrode in flexible dye-sensitized solar cells

Carbon-based electrodes played a significant role toward the development of wearable and flexible photovoltaic energy devices in an efficient and affordable manners. Here, all-carbon-based electrodes composed of carbon nanotubes fiber (CNTF) have been used to fabricate a flexible wire shaped dye-sensitized solar cell (DSSC). A facile electrodeposited approach has been adopted to modify a CNTF with polyaniline (PANI) under acidic conditions. Both photoanode (TiO2@CNTs) and counter electrode (PANI@CNTs) twisted around each other, acted as electrons and hole collectors in the presence of redox couple (iodide/triiodide) as electrolyte. Scanning electron microscopy (SEM) images demonstrated the successful growth of TiO2 nanoparticles and conducting polyaniline (PANI) over the surface of CNTs fibers, as photoanode and counter electrode, respectively. Cyclic voltammetric (CV) measurements and electrochemical impedance spectroscopy (EIS), examined the reduction of triiodide and resistance of charge transfer. While the current-voltage measurements were carried out to check the performance of fabricated device when illuminated under simulated light source. With APNI modified counter electrode, device exhibited higher photoelectric conversion efficiency (3.57 %) under optimal conditions as compared to pristine CNTs fiber-based device with lower efficiency (2.26 %). The improved performance of modified counter electrode further confirmed by the lower peak separation (ΔEp= 0.42 V) and charge transfer resistance (RCE =19.28 Ω) in cyclic voltammetry and impedance spectroscopy, respectively. These fabricated electrodes could be promising alternate for metal-based electrodes in dye-sensitized solar cells due to its facile fabrication process, low cost, and higher chemical stability.