Counter Electrode Research Articles

Electrochemical activation and characterization of carbon cloth

Here, carbon cloth (CC), which is a disposable, inexpensive, conductive substrate, was electrochemically activated for the formation of function al groups on the electrode surface. The electrochemical activation of commercial CC was achieved in various acidic solutions such as 0.1 M H2SO4, 0.1 M HCl and 0.1 M HNO3 to create functional groups on the surface of the gas diffusion layer by applying a constant 100 mA current (galvanostatic) for 10 s, 20 s, and 30 s, respectively. The electrochemical measurements were conducted using a 3-electrode system, including disposable carbon cloth as a working electrode, saturated Ag/AgCl as a reference electrode and Pt wire as a counter electrode. The modified CCs were tested via cyclic voltammetry using 5 mM Fe(CN)63−/Fe(CN)64− redox probe. Electrochemical experiment results showed that acid treatment of CC resulted in a significant increase in peak current compared to bare CC, indicating formation of functional groups on the electrode surface and improved electrical conductivity.

Boosting BOD/COD biodegradability of automobile service stations wastewater by electrocoagulation

ABSTRACT This study investigates the application of electrocoagulation for enhancing the biodegradability of organic matter in automobile service station wastewater, notorious for its contamination with polyaromatic hydrocarbons, heavy metals, and surfactants. Optimization of key variables such as electrode material, current density, and electrical consumption is conducted, with correlation analysis assessing their impact on water quality. Experimental setups utilize a vertical configuration comprising eight monopolar steel electrode plates as cathodes and eight counter electrodes (either iron or aluminum) connected in parallel. Results indicate that employing iron as the sacrificial electrode significantly increases the biochemical oxygen demand/chemical oxygen demand (BOD/COD) ratio, highlighting the efficacy of heightened power levels in enhancing organic matter degradation. Optimal removal efficiencies, including 87.5 for COD, 96.01 for BOD, and 92.2% for total solids, are achieved at a current density of 42 A/m2 and energy consumption of 360 kWh/m3, while maintaining pH levels between 6 and 9. The findings underscore the potential of electrocoagulation with Fe, Al as anodes, and stainless-steel cathodes as an efficient wastewater treatment approach, particularly for COD, BOD, and solid particle removal, thus contributing significantly to environmental sustainability.

Sputtered Zero‐Excess Electrodes with Metallic Seed Layers for Solid‐State Sodium Batteries

Zero‐excess sodium metal solid‐state batteries offer improved safety, lower cost, higher energy density, and reduced resource dependency compared to today’s lithium‐ion technology. This study demonstrates the fabrication of zero‐excess electrodes with unprecedented stability during plating/stripping cycles. The fabrication process involves the sputter deposition of 20 nm metallic seed layers – zinc, silver, indium, or tin – onto NASICON (Na3.4Zr2Si2.4P0.6O12) ceramic separators, followed by the sputter deposition of a 30 µm copper current collector. The favorable influence of these seed layers on the in‐situ formation of the sodium|NASICON interface is examined through nucleation and cycling experiments, with a sodium metal reservoir serving as the non‐limiting counter electrode. Due to alloy formation the seed layers – particularly tin – stabilize sodium nucleation and cycling substantially and reduce dendrite formation compared to reference cells with bare copper current collectors. Sodium loss during cycling is primarily attributed to local cracking of the current collector and its partial delamination from the NASICON. Compared to polished NASICON, a roughened surface reduces the resistance e.g. of the counter electrode 200‐fold to approx. 1 Ωcm² at 3 MPa and suppresses delamination further.

Enhanced Photovoltaic Performance of Poly(3,4-Ethylenedioxythiophene)Poly(N-Alkylcarbazole) Copolymer-Based Counter Electrode in Dye-Sensitized Solar Cells

Conducting polymers are emerging as promising alternatives to rare and expensive platinum for counter electrodes in dye-sensitized solar cells; due to their ease of synthesis, they can be chemically tuned and are suitable for roll-to-roll production. Among these, poly (3,4-ethylenedioxythiophene) (PEDOT)-based counter electrodes have shown leading photovoltaic performance. However, certain conductivity issues remain that affect the effectiveness of these counter electrodes. In this study, we present an electropolymerized PEDOT and poly(N-alkylated-carbazole) copolymer as an efficient electrocatalyst for the reduction in I3− in dye-sensitized solar cells. Copolymerization with N-alkylated carbazoles significantly increases the conductivity of the polymer film and facilitates rapid charge transport at the interface between the polymer electrode and the electrolyte. The length of the alkyl substituents also plays a crucial role in this improvement. Electrochemical analysis showed a reduction in charge transport resistance from 3.31 Ω·cm2 for PEDOT to 2.26 Ω·cm2 for the PEDOT:poly(N-octylcarbazole) copolymer, which is almost half the resistance of a platinum-based counter electrode (4.12 Ω·cm2). Photovoltaic measurements showed that the solar cell with the PEDOT:poly(N-octylcarbazole) counter electrode achieved an efficiency of 8.88%, outperforming both PEDOT (7.90%) and platinum-based devices (7.57%).

Hydrothermal synthesis of novel CeO2/g-C3N4 nanocomposite: dual function of highly efficient supercapacitor electrode and Pt-free counter electrode for dye synthesized solar cell applications

Hydrothermal synthesis of novel CeO2/g-C3N4 nanocomposite: dual function of highly efficient supercapacitor electrode and Pt-free counter electrode for dye synthesized solar cell applications

Exploring the potential of SnSe/PANi composite counter electrodes for improved efficiency in dye-sensitized solar cells

This paper investigates the synthesis and characterization of novel counter electrodes (CEs) for dye-sensitized solar cells (DSSCs), focusing on composite polyaniline (PANi) nanofibers integrated with tin selenide (SnSe). Three CEs, namely SnSe, PANi, and their composite, were prepared via facile hydrothermal and cyclic voltammetry methods and compared with a standard platinum (Pt) CE. The efficiencies obtained were 4.20 %, 5.63 %, 8.39 %, and 7.72 % for SnSe, PANi, SnSe/PANi, and Pt CEs, respectively. The improved efficiencies, particularly in the case of the SnSe/PANi composite, were attributed to increased short-circuit density of the composite sample. The materials and devices prepared in this study are characterized using various methods including FESEM, TEM, XRD, Raman and FTIR spectroscopies, EIS, Tafel, OCVD, IPCE and etc to support our proposed CE structure. Our findings demonstrate the promising potential of SnSe/PANi composite CEs in enhancing the performance and affordability of DSSCs.

Improved transparency and charge matching of electrochromic devices with Ce-doped NiO counter electrode

The quest for cost-effective and efficient electrochromic electrodes, featuring high color contrast and rapid response times, has sparked increasing interest in research of metal oxides for electrochromic applications. In this study, nickel oxide thin films with various cerium dopant concentrations are synthesized, with the optimized doping concentration identified as 1 at%. X-ray diffraction analysis confirmed that the dopant successfully reduces crystal size and alters the preferred orientation to (111). The 1 % Ce:NiO thin film exhibits enhanced electrochromic performance, with a transmittance modulation increase of 27.4 % at 633 nm, a 27.1 % rise in coloration efficiency and faster response time (tb=9.64 s and tc=6.76 s) compare to the undoped NiO. Importantly, the charge density of 1 % Ce:NiO thin film increases from 4.86 to 8.14 mC cm−2, representing a 67.5 % improvement, which becomes a better charge matching with WO3 in electrochromic devices. The incorporation of Ce into the NiO thin films not only leads to increased transmittance in the bleached state and optical modulation in the electrochromic devices but also contributes to a rise in the optical band gap of the NiO thin films and improved charge balance matching. These results underscore the positive impact of cerium doping on microstructure and electrochromic performance, indicating a promising future for electrochromic devices.

Dispersion phenomena in EIS and DIS spectra of porous materials and their representation as transmission line bases ‘diffusion’ elements—part I: a case study of lead-acid systems

A number techniques exist to assess the porosity of materials, however a large number of them cannot be used to monitor the behaviour of such in ‘live’ systems. This problem can be overcome by the usage of Electrochemical Impedance Spectroscopy (EIS). However, porous systems and their qualities, can not be easily described using regular equivalent circuit and basic elements. An approximation of such has to be made using transmission lines, which can, in turn, be equated to specific diffusion elements. The parameters of these elements can be related to porous material qualities. And in turn, the changes of these parameters can then be related to various processes—such as ageing or degeneration. In this part of the material a case study was performed on a number of lead-acid systems—a VRLA battery, a maintenance-free one and system consisting of a lead electrode and a platinum mesh counter electrode. This was done in order to test the validity of using the Warburg impedance element in equivalent circuits. During the course of the tests it was found that not only a Gerischer element is a better choice, but the changes in its parameters can be related to different ageing-related processes.

Rational Design of Facile and Low‐Cost Construction of Carbon‐Based Dye‐Sensitized Solar Cells using Garcinia Mangostana L. as a Photosensitizer

Research on solar cell devices is not only always related to how to obtain high power conversion efficiency (PCE), but also other factors need to be fully considered, such as the cost and their ecofriendliness. In this present research, a low‐cost and ecofriendly dye‐sensitized solar cell (DSSC) is being developed using a graphite‐based nanocomposite and an unusual plant extract (Garcinia mangostana L.) as the dye photosensitizer. A rational design on how to use graphite as a photoanode and counter electrode (CE) in DSSC is carried out by combining the graphite with ZnO and multiwalled carbon nanotube (MWCNT), respectively. It is observed that graphite acts as a matrix for ZnO and MWCNT to make these nanocomposites have very appropriate optoelectronics and catalytic properties compared to the control sample. Therefore, they could serve as an excellent photoanode and CE, respectively. It is also expected that the anthocyanin absorption in Garcinia mangostana L. dye which is found in the visible light range can efficiently absorb photons, thus supporting the enhancement of photovoltaic performance of the DSSC. The generated voltage (V) and current (I) from light irradiation using commercial lamps are higher compared to halogen lamps, indicating that the obtained DSSC has potential as indoor powered devices. It is believed that our study can shed light on the development of DSSC using low‐cost material graphite as the main component for the realization of low‐cost DSSC devices.

AgBiS2/g-C3N4 hybrid composites: synthesis, characterization and counter electrode performance in photovoltaic device

AgBiS2/g-C3N4 hybrid composites: synthesis, characterization and counter electrode performance in photovoltaic device

Development of binary transition metallic selenide (NiSe/Co3Se4) hybrid counter electrode for highly efficient Pt-free dye-sensitized solar cells

Development of binary transition metallic selenide (NiSe/Co3Se4) hybrid counter electrode for highly efficient Pt-free dye-sensitized solar cells

Flower-like SnS2/rGO composites with efficient iodide-triiodide redox performance for counter electrodes in Pt-free dye-sensitized solar cells

The work function (WF) of the counter electrode (CE) predominantly determines the device performance of dye sensitized solar cells (DSSCs) as it controls the electron transfer rate for dye regeneration. Hence in this work, tin disulphide/reduced graphene oxide (SnS2/rGO) composites were synthesized with different wt.% of rGO (3, 5, 7, 10 %) and investigated their performance in DSSCs applications. At the outset, the formation of pristine SnS2 and SnS2/rGO composites were confirmed through X-ray diffraction and Raman spectral analysis. The morphological imaging revealed the micro flower-like structure of SnS2 with cross-sectional width of 5 ± 0.2 μm, and petal thickness ranges from 30.7 nm to 46.4 nm. The binding energy spectra confirms the 4+ oxidation state of Sn in both SnS2 and 7 wt% SnS2/rGO, suggesting that the rGO does not alter the chemical states of SnS2. Further, the peak-to-peak separation values obtained from Cylic-Voltammetry analysis were found to be 0.37 and 0.57 V for S7 and Pt CE respectively, indicating the rapid electrolyte reduction of 7 wt% SnS2/rGO. Finally, a photo conversion efficiency (PCE) of 7.3 % has been achieved with 7 wt% SnS2/rGO CE which is greater than that of the PCE with Pt CE (6.5 %) and also higher than that of pristine SnS2 with 4.7 %. The improved PCE is attributed to the reduced WF of the 7 wt% SnS2/rGO composite as measured from the Kelvin probe force microscopy analysis, enabling the rapid redox reaction towards triiodide reduction.

Revolutionizing dye-sensitized solar cells: Chassalia curviflora fruit extract as photosensitizer and charge recombination inhibitor

The utilization of natural dyes from Chassalia curviflora (CCE), which were successfully extracted to provide bioactive chemicals for the development of dye-sensitized solar cells (DSSCs), is the main focus of this work. These CCEs efficiently absorb light and stop charge recombination in solar cells after being extracted using ethanol. The absorption properties of these natural dyes are discovered to be greatly influenced by the kind and concentration of CCE, with an absorption peak observed at 350 nm. The dyes’ improved adsorption properties on TiO2 are indicated by the presence of functional groups, bond stretching, and bending features, as confirmed by FTIR and UV–Visible spectroscopic investigations. In the DSSC design, these dyes have been effectively combined with an FTO substrate covered with TiO2, serving as a photoanode. The resultant solar cells, which comprise a graphite-based counter electrode, I−/I3− electrolyte, and photoanode, have a power conversion efficiency (PCE) of 0.49 %. The measurements for fill factor, Voc, and Jsc are 0.4761, 1.652 mA/cm2, and 0.52 V, in that order. The phytochemical components of the dye are shown to be crucial in trapping electrons and holes, hence reducing charge recombination and promoting enhanced charge transport towards the titanium dioxide transmission group finding is noteworthy. Furthermore, a dipping time analysis reveals that a 15-minute duration is optimal for achieving a 0.146 % photoelectric conversion efficiency in DSSCs utilizing CCE.

Poly(aniline)-multiwall carbon nanotube (PANI@MWCNT) composite as high-cost Pt free counter electrode for dye-sensitized solar cells

In this study, we synthesized a poly (aniline)-multiwall carbon nanotube (PANI@MWCNT) composite for use as a counter electrode (CE) in dye-sensitized solar cells. Moreover, FE-SEM and HR-TEM images of PANI@MWCNT revealed carbon nanotube/ropes embedded in the polymer matrix. An X-ray diffraction pattern confirmed the amorphous nature of the composite. Further, Electrochemical impedance spectroscopy studies indicated a charge transport resistance value (Rct) of 4.36 KΩ for PANI@MWCNT. CV studies demonstrated improved electrocatalytic performance and faster redox behavior in the PANI@MWCNT composite. BET analysis measured the pore size of the as-prepared composite to be 15–50 nm. Subsequently, the as-synthesized PANI, PANT@MWNCT, pristine MWCNT, and platinum were evaluated as CEs in DSSCs using a polyethylene oxide polymer-based liquid electrolyte and a TiO2 nanocrystalline photoanode. Among these CEs, the PANI@MWCNT CE exhibited an efficiency of 8.07 %, and the stability test indicated that the as-prepared composite CE retained 7.81 % efficiency after 15 days.

Multispectral compatible anti-reconnaissance strategy: Implementing a modulation system integrating visible light-hyperspectral-radar wave

To tackle the challenges of multi-spectral reconnaissance technology, a pioneering anti-reconnaissance device that integrates visible-light, hyperspectral, and microwave radar functionalities has been developed for the first time. By oxidative polymerization method to create a core–shell Fe3O4@polyaniline composite material for the counter electrode. This design optimized impedance matching, achieving wideband radar wave absorption up to 10.5 GHz (reflection loss < -10 dB). The core–shell structure enhanced specific surface area, improving charge exchange and electrochemical performance to meet stringent counter electrode requirements. And, constructed a frequency-selective metal electrode based on metamaterial principles, complementing the radar wave absorption capabilities of the counter electrode material. Additionally, synthesized an asymmetric viologen molecule as the working electrode, mimicking vegetation color transitions from green to yellow while preserving hyperspectral characteristics and radar wave absorption properties. To enhance hyperspectral compatibility without compromising radar wave absorption or color dynamics, we developed a cross-linked polyvinyl alcohol/hydroxyethyl cellulose film based on biomimetic principles. The device can switch between yellow and green under voltages of 0 or −1.2 V, with both states exhibiting a spectral similarity to foliage exceeding 0.95 and an effective bandwidth reaching 13.44 GHz. The integration of these three functionalities allows the device to operate independently without interference.

An Antiferroelectric‐Coated Metal Foam Infiltrated with Liquid Metal as a Dielectric Capacitor

Nickel metal foams serve as both a substrate and bottom electrode for a dielectric capacitor using atomic‐layer deposition (ALD) and a eutectic gallium–indium (EGaIn) liquid metal (LQM) counter electrode. The conformal dielectric has a composition of 6.25% Al–HfO2 in the antiferroelectric phase, confirmed with polarization versus electric field measurements. Liquid EGaIn is pressure‐infiltrated within the coated foams to form the dielectric capacitor. Capacitances up to 4 μF are realized. Calorimetry of the infiltrated capacitor shows a 60 J g−1 latent heat upon melting a frozen EGaIn electrode, suggesting that the phase change can alleviate thermal deviations from pulsed power capacitor operation. Infiltrated capacitors are also shown to survive bending and freeze–thaw cycles. The metal foam–ALD dielectric–LQM capacitor shows a combined set of thermal and electrical properties not available in other classes of capacitors.

Exploring the Impact of In Situ-Formed Solid-Electrolyte Interphase on the Cycling Performance of Aluminum Metal Anodes.

Unwanted processes in metal anode batteries, e.g., non-uniform metal electrodeposition, electrolyte decomposition, and/or short-circuiting, are not fully captured by the electrolyte bulk solvation structure but rather defined by the electrode-electrolyte interface and its changes induced by cycling conditions. Specifically, for aluminum-ion batteries (AIBs), the role of the solid-electrolyte interphase (SEI) on the Al0 electrodeposition mechanism and associated changes during resting or cycling remain unclear. Here, we investigated the current-dependent changes at the electrified aluminum anode/ionic liquid electrolyte interface to reveal the conditions of the SEI formation leading to irreversible cycling in the AIBs. We identified that the mechanism of anode failure depends on the nature of the counter electrode, where the areal capacity and cycling current for Al0 electrodeposition dictates the number of successful cycles. Notwithstanding the differences behind unstable aluminum anode cycling in symmetrical cells and AIBs, the uniform removal of electrochemically inactive SEI components, e.g., oxide-rich or solvent-derived organic-rich interphases, leads to more efficient cycling behavior. These understandings raise the importance of using specific conditioning protocols for efficient cycling of the aluminum anode in conjugation with different cathode materials.

Honeycomb shaped carbon dopped 1T-2H-MoS2 heterojunction counter electrode with high short current for dye sensitized solar cells

Recent years have witnessed energy crises in various regions and the utilization of new energy is crucial. Dye-sensitized solar cells (DSSCs) are the third generation of photovoltaic cells that are expected to be more cost-effective than other types of solar cells. In this work, we report the synthesis of 1T-2H-MoS2/honeycomb shaped carbon (HSC) heterojunction composite counter electrodes for DSSCs via adding porous carbon in the facile hydrothermal method. The effects of HSC on the morphology, structure, electrochemical and photoelectric conversion properties of the 1T-2H-MoS2/HSC composites were investigated systematically. Both the results of electrochemical and photoelectric measurement suggest the excellent performance of the reduction of I3- and the regeneration of dye. The whole cell assembled with the MoS2/HSC-5.0 counter electrode achieved a short current density 22.24 mA∙cm−2 and a power conversion efficiency (PCE) of 8.42 %, which is significantly higher than that of the pure MoS2 electrode (5.89 %) and Platinum electrode (6.76 %), implying the MoS2/HSC-5.0 composite is a promising candidate for counter electrodes catalyst of DSSCs.

Nanorod-based smart windows with solid-gel electrolyte: An integrated electrochromic and pseudocapacitive technology for energy-saving and conversion

We fabricated two emerging nanorod-based smart windows with WO3 and NiO nanorods grown on the ITO/glass and ITO/muscovite mica (MM) substrates, respectively. The WO3/ITO/glass and WO3/ITO/MM substrates are excellent working electrodes, while the NiO/ITO/glass and NiO/ITO/MM substrates are exceptional counter electrodes. The nanorod-based WO3/Li+(s)/NiO@glass smart window consists of a WO3/ITO/glass working electrode, a NiO/ITO/glass counter electrode, and a solid-gel LiClO4 electrolyte (labeled as Li+(s)), respectively. The other nanorod-based WO3/Li+(s)/NiO@MM is comprised of a WO3/ITO/MM working electrode, a NiO/ITO/MM counter electrode, and a solid-gel LiClO4 electrolyte, respectively. Both the nanorod-based WO3/Li+(s)/NiO@glass and WO3/Li+(s)/NiO@MM smart windows have brilliant dual-band (red and near-infrared lights) electrochromic behaviors, such as large transmittance differences (ΔT), fast response times (bleaching time, tb, and coloration time, tc) at red (680nm) and near infrared (1000nm) lights and great electrochromic retention (4,000 cycles), and outstanding pseudocapacitive performances like good specific capacitances of ~18.4F/g and ~7.6F/g, intensive power densities of ~1779W/kg and ~2100W/kg with corresponding energy densities of ~5.4Wh/kg and ~2.2Wh/kg, enormous pseudocapacitive retention (10,000 cycles), and so on. Therefore, the brilliant dual-band electrochromic behaviors and outstanding pseudocapacitive performances make the nanorod-based WO3/Li+(s)/NiO@glass and WO3/Li+(s)/NiO@MM smart windows tremendous for use in multifunctional energy-saving-conversion devices.

Density functional theory study of cobalt sulfide as a counter electrode material for dye-sensitized solar cells

Abstract Dye-sensitized solar cells (DSSCs) are viewed as potential substitutes for traditional silicon-based solar cells due to their affordability, impressive performance in low-light conditions, eco-friendly energy production, and adaptability in solar product integration. The use of noble metals such as platinum as counter electrodes in DSSCs was initially limited by their high cost; however, cobalt sulfide has been recognized as a viable alternative due to its abundance, non-toxic properties, and cost-effectiveness. In this work, the crystal structure, electronic, optical characteristics and electrocatalytic activity of the tetragonal phases of cobalt sulfide are investigated through density functional theory with a quantum espresso package. The results obtained for the lattice parameter are a = b = 3.53 Å and c = 4.80 Å. The generalized gradient approximation and hybrid exchange correlation function yield bandgaps of 1.63 and 1.69 eV, respectively, which are consistent with the reported experimental values. An analysis of the density of states and the projected density was carried out to validate the accuracy of the calculated band gaps. Additionally, significant information was obtained from the optical properties through the calculation of the dielectric function. The findings reveal real and imaginary static dielectric constants of 11.85 and 0.13, respectively. Furthermore, the measured absorption and conductivity spectra exhibit promising attributes in the UV–visible range and good electrical conductivity. Moreover, the electrocatalytic activity was studied to analyze the adsorption energy of CoS and the electrolyte. Generally, the calculated electronic and optical properties of CoS crystals indicate their potential application as counter electrodes in dye-sensitized solar cells.