Wet chemical synthesis of Gd+3 doped vanadium Oxide/MXene based mesoporous hierarchical architectures as advanced supercapacitor material

In this paper, Gd³⁺ doped V₂O₅/Ti₃C₂T_x MXene (GVO/MX) hierarchical architectures have been synthesized by wet chemical approach. As prepared GVO/MX composite, along undoped VO and unsupported GVO were well characterized by XRD, FESEM, EDX, FT-IR and BET techniques. Electrochemical performance of VO, GVO and GVO/MX was evaluated by CV, GCD and EIS measurements. Among the three electrodes, GVO/MX composite exhibited highest electrochemical activity with the optimum specific capacitance of 1024 Fg^-1 at 10 mVs^?1. The specific capacitance of GVO/MX was ～1.7 and ～3 times higher than unsupported GVO (585 Fg^-1) and VO (326 Fg^-1), respectively. The cyclic life of GVO/MX with capacitance retention 96.12% was observed at 60 mVs^?1. EIS measurements showed reduction in electrochemical impedance for GVO/MX as compared to GVO and VO. The corresponding impedance values of Rct and Resr for GVO/MX were calculated as 18 Ω and 1.8 Ω, respectively. The superior capacitive ability of GVO/MX can be ascribed to its unique morphology, short diffusion path and high surface area of fabricated composite. Considering it, the present work provides a feasible strategy to fabricate highly effective electrode materials for next generation energy storage devices.     

Facile Fabrication of Binder-Free CoZn LDH/CFP Electrode with Enhanced Capacitive Properties for Asymmetric Supercapacitor

CoZn layered double hydroxide (LDH) or Co(OH)₂ pseudocapacitive material has been prepared on the current collector of carbon fiber paper (CFP) using an eco-friendly one-step electrodeposition. Benefiting from its unique structural feature, the binder-free CoZn LDH/CFP electrode material realizes high specific capacitance of 1156 Fg^?1 at a current density of 1 Ag^?1 and excellent rate capability of 80% retention with 16 fold current density increment, which is much better than that of Co(OH)₂ (617 Fg^?1, 65%). Notably, the CoZn LDH/CFP can retain an outstanding electrochemical stability with a capacitance degradation of only 6% after 6000 charge–discharge cycles at 32 Ag^?1. Moreover, an asymmetric supercapacitor (ASC) using CoZn LDH/CFP as a positive electrode and AC/CFP as a negative electrode has been assembled. The ASC exhibits a superior energy density of 30.0 Whkg^?1 at a power density of 800 Wkg^?1 with a specific capacitance up to 84.4 Fg^?1 and a potential window wide to 1.6 V. These encouraging results indicate that CoZn LDH/CFP composite material has a great potential for next-generation energy conversion/storage devices.

     

Synthesis of rGO/nanoclay/PVK nanocomposites,electrochemical performances of supercapacitors

ABSTRACT

In this study, graphene oxide (GO) was chemically reacted with sodium borohydride (NaBH₄) to form reduced graphene oxide (rGO). rGO, Montmorillonite nanoclay, and polyvinylcarbazole (PVK) were used to form a ternary nanocomposite via chemical reaction. These nanocomposite qualities were described via scanning electron microscopy (SEM), energy-dispersive X-ray analysis (EDX), Fourier transform infrared spectroscopy-attenuated transmission reflectance (FTIR-ATR). In addition, these materials were used in supercapacitor device as an active material to test electrochemical performances via cyclic voltammetry (CV), galvanostatic charge–discharge (GCD), and electrochemical impedance spectroscopy (EIS). The rGO/nanoclay/PVK nanocomposite shows significantly improved specific capacitance (C_sp = 168.64 Fg^?1) compared to that of rGO (C_sp = 63.26 Fg^?1) at the scan rate of 10 mVs^?1 by CV method. The enhanced capacitance results in high power density (P = 5522.6 Wkg^?1) and energy density (E = 28.84 Whkg^?1) capabilities of the rGO/nanoclay/PVK nanocomposite material. The addition of nanoclay and PVK increased the specific capacitance of rGO material due to a dopant effect for supercapacitor studies. Ragone plots were drawn to observe energy and power density of supercapacitor devices. The C_sp of rGO/nanoclay/PVK nanocomposite has only 86.4% of initial capacitance for charge/discharge performances obtained by CV method for 5000 cycles.     

Poly(acridine orange)-modified glassy carbon electrodes: electrosynthesis,characterisation and sensor application with uric acid

Poly(acridine orange) was electropolymerised on glassy carbon electrodes by potential cycling in phosphate buffer solution at pH 5.5, 6.0, 7.0 and 8.0. Electrochemical behaviour of the modified electrodes was studied by cyclic voltammetry in phosphate buffer solution at various pHs and found that the best polymer film formation was obtained at pH 5.5. Quantitative determination of uric acid was achieved by cyclic voltammetry, differential pulse voltammetry (DPV) and fixed-potential amperometry in phosphate buffer solution at pH 5.5. Anodic peak currents were linearly proportional to concentration of uric acid in the range 1–75 µM for cyclic voltammetry, 0.4–75 µM for DPV and 0.04–5.3 µM for amperometry. Detection limits were 3.7 × 10^?1, 9.7 × 10^?2 and 9.5 × 10^?3 µM for cyclic voltammetry, DPV and amperometry, respectively. The modified electrodes exhibited good sensitivity, wide linear range and good stability. There is no interference from substances commonly present in natural samples.     

Synthesis of In2O3/GNPs nanocomposites with integrated approaches to tune overall performance of electrochemical devices

The electroactive material with a porous structure, good electrical conductivity, hybrid composition, and a higher surface is considered more suitable for applications as an electrode in the energy storage device. Herein, we report the preparation of In₂O₃ nanoparticles via a simple chemical route and their nanocomposites with 10% (IOG-10), 30% (IOG-30), 50% (IOG-50), 70% (IOG-70), and 100% G-100 graphene nanoplatelets (GNPs) via ultra-sonication. The presence of GNPs in the nanocomposite samples was verified by powder X-ray diffraction (PXRD), Raman, and scanning electron microscopy (SEM) results. The prepared samples were loaded onto the porous 3D nickel foam (NF) substrate to manufacture the working electrode for electrochemical testing. The cyclic voltammetry (CV), as well as galvanostatic charge/discharge (GCD), results proposed the IOG-30@NF as a suitable electrode for electrochemical applications. More precisely, the IOG-30@NF electrode shows a specific capacitance of 1768 Fg^-1 at 1 Ag^-1, which is considerably higher than that of either G-100@NF or In₂O₃@NF electrodes. Besides, the IOG-30@NF electrode shows good cyclic stability of 92.2% after 4000 GCD tests completed at 12 Ag^-1. When increasing the current density value from 1 to 4, the IOG-30@NF electrode maintains a specific capability of 81%, ensuring its exceptional rate capability. The higher specific capacity, higher rate-performance, and better cyclic activity of the IOG-30@NF electrode can be ascribed to its hybrid-composition, nanoarchitecture In₂O₃, 3D but porous nickel foam substrate, appropriate graphene content, and interaction between In₂O₃ nanoparticles and GNPs nanosheets.     

A facile synthesis of CuO nanowires and nanorods,and their catalytic activity in the oxidative degradation of Rhodamine B with hydrogen peroxide

In this study, a new and facile solution-phase route to prepare CuO nanowires and nanorods with the assistance of salicylic acid was reported. Compared with the commercial CuO nanoparticles, both the CuO nanowires and nanorods exhibited significantly improved catalytic activity in the degradation of Rhodamine B with H₂O₂, which may result from their special one dimensional nanostructures. The apparent activation energy of Rhodamine B oxidation with H₂O₂ in the presence of the CuO nanowires and nanorods was 30.95 kJ·mol^− 1 and 32.07 kJ·mol^− 1, respectively, which was much lower than that in the absence of catalysts.     

Electrochemical remediation of BPA in a soil matrix by Pd/Ti and RuO2/Ti electrodes

This study aimed to investigate the bisphenol A (BPA) degradation performance of an electrokinetic process coupled with Pd/Ti (PT) and RuO₂/Ti (RT) binary metallic oxidation electrodes under a potential gradient of 2 Vcm^?1 for 5 days. Fifteen experiments conducted with five processing fluids, namely deionized water (DW), Na₂SO₄, citric acid (CA), NaOH and NaCl, and two binary metallic oxidation electrodes, Pd/Ti and RT, were investigated in this study. Electroosmosis permeability of 3.2 × 10^?6–4.7 × 10^?6, 4.0 × 10^?6–4.9 × 10^?6, and 3.7 × 10^?6–6.8 × 10^?6 cm² V^?1 s^?1 were observed in the electrokinetic system with Ti, PT, and RT electrodes, respectively. A significant detachment of the coated metals was observed in BMOEEK–PT system with Na₂SO₄, CA, and NaOH processing fluids. A higher BPA treatment efficiency of 52.2–67.3 % was found in the BMOEEK–RT system, which was 1.4–1.8 times greater than in the EK–Ti system with DW as the processing fluid. The best treatment efficiency was found in the system with NaCl as the processing fluid, which may mostly result from less detachment of the coated metal from electrode and increased hypochlorite (OCl^?) generation in the anode reservoir. The primary treatment mechanism in the BMOEEK system with NaCl procession fluid was degradation by anodic oxidation. It was concluded that both the binary metallic electrode and processing fluid played key roles in enhancing the electrochemical degradation of BPA. The electrode characteristics (progressive cyclic voltammogram and SEM micrograph with EDAX), electrokinetic behavior (specimen pH and current density), and treatment mechanism were also discussed in this study.     

Construction and Performance Characteristics of Modified Screen Printed and Modified Carbon Paste Sensors for Selective Determination of Cu(II) Ion in Different Polluted Water Samples

Four new ion-selective electrodes (ISEs), based on N,N′-bis(salicylaldehyde)-p-phenylene diamine (SPD) as ionophore, are constructed for the determination of copper(II) ion. The modified carbon paste (MCPEs; electrodes I and II) and modified screen-printed sensors (MSPEs; electrodes III and IV) exhibit good potentiometric response for Cu(II) over a wide concentration range of 1.0 × 10^?6 – 1.0 × 10^?2 mol L^?1 for electrodes (I and II) and 4.8 × 10^?7–1.0 × 10^?2 mol L^?1 for electrodes (III and IV) with a detection limit of 1.0 × 10^?6 mol L^?1 for electrodes (I and II) and 4.8 × 10^?7 mol L^?1 for electrodes (III and IV), respectively. The slopes of the calibration graphs are 29.62 ± 0.9 and 30.12 ± 0.7 mV decade^?1 for electrode (I) (tricresylphosphate (TCP) plasticizer) and electrode (II) (o-nitrophenyloctylether o-NPOE plasticizer), respectively. Also, the MSPEs showed good potentiometric slopes of 29.91 ± 0.5 and 30.70 ± 0.3 mV decade^?1 for electrode (III) (TCP plasticizer) and electrode (IV) (o-NPOE plasticizer), respectively. The electrodes showed stable and reproducible potentials over a period of 60, 88, 120, and 145 days at the pH range from 3 to 7 for electrodes (II), (III), and (IV) and pH range from 3 to 6 for electrode (I). This method was successfully applied for potentiometric determination of Cu(II) in tap water, river, and formation water samples in addition to pharmaceutical preparation. The results obtained agree with those obtained with the atomic absorption spectrometry (AAS).     

Effect of electrolyte on the supercapacitive behaviour of copper oxide/reduced graphene oxide nanocomposite

Cupric oxide/reduced graphene oxide (CuO/rGO) nanocomposites were synthesized through a chemical reduction method using hydrazine hydrate as the reducing agent. The morphology, elemental composition, and bonding network of the CuO/rGOnanocomposites were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy respectively. The XRD results reveal lattice spacing and lattice strain from 3.371 to 3.428 Å and 1.05 × 10⁻³to 5.44 × 10⁻³ respectively, with the increasing ratio of rGO: CuO from 1:1 to 1:5. The cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS)and galvanostatic charge-discharge (GCD) studyofCuO/rGOas the electrode material showed excellent super-capacitive behavior in H₂SO₄ over Na₂SO₄ electrolytes. Moreover CuO/rGO nanocomposites exhibited better capacitance retention in H₂SO₄(75.69%) compared to Na₂SO₄(12.06%).     

Activated carbon‐polyethylenedioxythiophene composite electrodes for symmetrical supercapacitors

A symmetrical (p/p) supercapacitor has been fabricated by making use of activated carbon (AC)‐polyethylenedioxythiophene (PEDOT)‐composite electrodes for the first time. The composite electrodes have been prepared via electrochemical deposition of β‐napthalenesulphonate doped PEDOT onto AC electrodes. The characteristics of the electrodes and the fabricated supercapacitor have been investigated using cyclic voltammetry (CV) and AC impedance spectroscopy. The electrodes show a maximum specific capacitance of 158 Fg^?1 at a scan rate of 10 mV s^?1. This indicates that the in situ electro‐polymerization of ethylenedioxythiophene (EDOT) onto AC could improve the performance of carbon electrodes for use in supercapacitors. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2008     

Morphology tailoring and enhanced electrochemical properties of Cd–Zn co-doped NiO nanorods for high performance supercapacitor

A systematic approach has been introduced to synthesize Cd–Zn co-doped NiO nanostructures with different ratios such as Cd_0.07Zn_0.03NiO, Cd_0.05Zn_0.05NiO, Cd_0.03Zn_0.07NiO and Cd_0.01Zn_0.09NiO for supercapacitor applications. The XRD studies has confirmed the phase purity with average crystallite size of 40 nm. The SEM characterization has shown that the morphology of nanostructures was tuned from particles to nano-rods structure with increasing the at. % concentration of Zn doping. Optical properties revealed that band gap and recombination rate have strong co-relation with specific capacitance. The CV results have confirmed the pseudocapacitive nature of the as prepared nanostructures and maximum specific capacitance (1485.19 Fg^-1) was measured for Cd_0.03Zn_0.07NiO which is superior than numerous reported values of NiO. The GCD results of Cd_0.03Zn_0.07NiO performed at 1 A/g scan rate, exhibited excellent charging-discharging ability with high cyclic retention of 82.8%. High capacitance and superior stability of Cd_0.03Zn_0.07NiO material indicate it as a potential candidate for supercapacitor applications.     

Evaluation of sorption behavior of polymethylene-bis(2-hydroxybenzaldehyde) for Cu(II), Ni(II), Fe(III), Co(II) and Cd(II) ions

Poly[5,5??-methylene-bis(2-hydroxybenzaldehyde)1,2-phenylenediimine] resin was prepared and characterized by employing elemental, thermal analysis, FTIR, and UV?Cvisible spectroscopy. The metal uptake behavior of synthesized polymer towards Cu(II), Co(II), Ni(II), Fe(III) and Cd(II) ions was investigated and optimized with respect to pH, shaking speed, and equilibration time. The sorption data of all these metal ions followed Langmuir, Freundlich, and Dubinin?CRadushkevich isotherms. The Freundlich parameters were computed 1/n?=?0.31?±?0.02, 0.3091?±?0.02, 0.3201?±?0.05, 0.368?±?0.04, and 0.23?±?0.01, A?=?3.4?±?0.03, 4.31?±?0.02, 4.683?±?0.01, 5.43?±?0.03, and 2.8?±?0.05?mmol?g^?1 for Cu(II), Co(II), Ni(II), Fe(III), and Cd(II) ions, respectively. The variation of sorption with temperature gives thermodynamic quantity (??H) in the range of 36.72?C53.21?kJ/mol. Using kinetic equations (Morris?CWeber and Lagergren equations), values of intraparticle transport and the first-order rate constant was computed for all the five metals ions. The sorption procedure is utilized to preconcentrate these ions prior to their determination by atomic absorption spectrometer. It was found that the adsorption capacity values for metal-ion intake followed the following order: Cd(II)?>?Co(II)?>?Fe(III)?>?Ni(II)?>?Cu(II).     

Biosorption of Heavy Metals by Anoxybacillus gonensis Immobilized on Diaion HP-2MG

Abstract

The determination of trace metal ions usually requires previous separation and preconcentration stages in order to cope with low levels and to remove the interfering components. Nowadays emphasis is given to the utilization of microorganisms because of their great ability to absorb metal ions from aqueous solution. In this paper, for this, Zn²⁺, Fe³⁺, Cu²⁺, Cd²⁺, Ni²⁺, Co²⁺, and Pb²⁺ ions at trace levels have been separated and preconcentrated on a column containing a bacterium, Anoxybacillus gonensis immobilized on Diaion HP-2MG as a new biosorption system prior to their atomic absorption spectrometric determinations. The effects of some analytical parameters were investigated. Optimum pH values were found to be 6 for Zn, Fe, Cu and Pb, 8 for Cd, Ni, and Co. Recoveries of Zn²⁺, Fe³⁺, Cu²⁺, Cd²⁺, Ni²⁺, Co²⁺, and Pb²⁺ were 95 ± 3, 98 ± 6, 96 ± 2, 98 ± 2, 97 ± 2, 95 ± 4 and 95 ± 3 at 95% confidence level, respectively. No significant matrix interferences on the quantitative recoveries of the analyte ions were observed. Preconcentration factors of the anlayte ions were calculated as 50 for Zn, Cd and Pb, and 75 for Fe, Cu, Ni, and Co. The limits of detection for the analyte ions were in the range 0.2–1.3 µg L^?1. The procedure was validated by spike addition and analysis of standard reference materials.     

Comparison of the performance of copper oxide and yttrium oxide nanoparticle based hydroxylethyl cellulose electrolytes for supercapacitors

Biodegradable solid polymer electrolyte (SPE) systems composed of hydroxylethyl cellulose blended with copper(II) oxide (CuO) and yttrium(III) oxide (Y₂O₃) nanoparticles as fillers, magnesium trifluoromethane sulfonate salt, and 1‐ethyl‐3‐methylimidazolium trifluoromethane sulfonate ionic liquid were prepared, and the effects of the incorporation of CuO and Y₂O₃ nanoparticles on the performance of the SPEs for electric double‐layer capacitors (EDLCs) were compared. The X‐ray diffraction results reveal that the crystallinity of the SPE complex decreased upon inclusion of the Y₂O₃ nanoparticles compared to CuO nanoparticles; this led to a higher ionic conductivity of the Y₂O₃‐based SPE [(3.08 ± 0.01) × 10^?4 S/cm] as compared to CuO [(2.03 ± 0.01) × 10^?4 S/cm]. The EDLC performances demonstrated that the cell based on CuO nanoparticles had superior performance in terms of the specific capacitance, energy, and power density compared to the Y₂O₃‐nanoparticle‐based cell. However, Y₂O₃‐nanoparticle‐based cell displayed a high cyclic retention (91.32%) compared to the CuO‐nanoparticle‐based cell (80.46%) after 3000 charge–discharge cycles. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134 , 44636.     

Mesoporous Fe-doped In2O3 nanorods derived from metal organic frameworks for enhanced nitrogen dioxide detection at low temperature

Mesoporous Fe-doped In₂O₃ nanorods derived from metal-organic frameworks (In/Fe-MIL-68s) were synthesized for NO₂ detection. The morphologies, structures and NO₂ gas-sensing performances of the Fe–In₂O₃ nanorods were systematically investigated. Texture characterizations demonstrate that the as-prepared Fe–In₂O₃ nanorods show rich porous structures, high specific surface areas and reduced grain sizes. Gas-sensing measurements display that the Fe–In₂O₃ nanorods derived from In/Fe-MIL-68s with the Fe(Ⅲ) content of 5 mol.% (Fe(5)-In₂O₃) exhibit high response (82) and short response/recovery time (70/65 s) towards 2 ppm NO₂ at 80 °C compared with their counterparts. Besides, superior selectivity and good stability are observed. The sensing mechanism studies reveal that the improved gas-sensing performances are attributed to the decrease in the gran size, the formation of rich oxygen vacancies and band gaps narrowing caused by Fe(Ⅲ) doping. Therefore, this work indicates that the Fe–In₂O₃ nanorods derived from metal-organic frameworks precursors can be a promising candidate for NO₂ detection.     

Development of a lead‐free copper co‐fired BNT‐based piezoceramic sintered at low temperature

Compatibility of Bi‐based piezoelectric ceramic and copper electrodes is demonstrated by co‐firing 0.88Bi_1/2Na_1/2TiO₃–0.08Bi_1/2K_1/2TiO₃–0.04BaTiO₃ (BNKBT88) with copper. A combination of Bi₂O₃, CuO, ZnO, Li₂CO₃, and B₂O₃ are used as additives to reduce firing temperature to 900°C with minimal effect on the electromechanical properties compared to sintering at 1150°C without additives. Co‐firing with copper electrodes requires controlled oxygen sintering at low temperature. The atmosphere is controlled using carbon dioxide and hydrogen gas to maintain an oxygen partial pressure of 6.1 × 10^?8 atm, which is necessary for the coexistence of Cu metal and Bi₂O₃. The thermodynamic activity of bismuth oxide in BNKBT88 is calculated to be 0.38. BNKBT88 ceramics were successfully co‐fired with internal as well as surface Cu metal electrodes. The copper co‐fired ceramics were successfully polarized and the dielectric and piezoelectric properties are evaluated.     

Thermophysical properties of laboratory-prepared corn/wheat dried distillers grains and dried distillers solubles dehydrated with superheated steam and hot air

The objective of this study was to dry–wet distillers grains and centrifuged solubles and to examine the effect of two different drying media, superheated steam and hot air, at different drying temperatures (110, 130, and 160°C), moisture contents (5–30% wb), and percentages of solubles’ presence (0 or 100%) on some thermophysical properties of laboratory-prepared corn/wheat dried distillers co-products, including geometric mean diameter (d_g), particle density (ρ_p), bulk density (ρ_b), bulk porosity (?_b), specific heat (C), effective thermal diffusivity (α_eff), and bulk thermal conductivity (λ_b). The values of d_g of corn/wheat dried distillers co-products ranged from 0.358 ± 0.001 to 0.449 ± 0.001 mm. Experimental values of ρ_p, ρ_b, and ?_b varied from 1171 ± 6 to 1269 ± 3 kg m^?3, from 359 ± 7 to 605 ± 5 kg m^?3, and from 0.54 ± 0.01 to 0.71 ± 0.01 kg m^?3, respectively. The values of α_eff were between 0.58 × 10^?7 and 0.93 × 10^?7 m² s^?1. The calculated values of C ranged from 1887 ± 11 to 2599 ± 19 J kg^?1 K^?1, and the values of λ_b of corn/wheat dried distillers co-products ranged from 0.06 ± 0.01 to 0.09 ± 0.01 W m^?1 K^?1. Multiple linear regression prediction models were developed to predict the changes in d_g, ρ_p, ρ_b, ?_b, C, α_eff, and λ_b of laboratory-prepared corn/wheat dried distillers co-products with different operational factors.     

Structural and electrochemical properties of mixed calcium-zinc spinel ferrites nanoparticles

In the current work, we provide the electrochemical (EC) characteristics and considerable size of Ca-doped ZnFe₂O₄ nanoparticles. Mixed transition metal oxides are widely used as excellent electrode materials in superior supercapacitors because of their superior capacitance, low cost, and environmental friendliness. The prepared nanoparticles were characterized by X-ray diffraction (XRD), Field-emission scanning electron microscope (FE-SEM), energy-dispersive X-ray (EDX) spectroscopy, X-ray photoelectron spectroscopy (XPS), and EC methods. The results exhibited that the as-synthesized nanoparticles had a cubic spinel crystal structure and efficient EC properties. The EC properties of the prepared electrodes were explored by cyclic voltammetry (CV), galvanostatic charge/discharge (GCD), and electrochemical impedance spectroscopy (EIS) studies. The Ca_0.1Zn_0.9Fe₂O₄ electrode demonstrated a specific capacitance (SC) ～208 Fg^-1 at a 2 mV/s scan rate due to significant morphological behavior. Therefore may be the prepared materials are the finest electrodes for supercapacitor applications.     

Photoelectrochemical properties of iron (III)-doped TiO2 nanorods

Fe (iron)-doped TiO₂ nanorods were grown on fluorine doped tin oxide (FTO) substrates with various Fe doping concentrations using modified chemical bath deposition (M-CBD). We investigated the effects of Fe doping concentration on the morphological, structural, optical, and photoelectrochemical (PEC) properties of the TiO₂ nanorods. From this study, it was found that the PEC properties were mainly dependent on the morphological and optical properties of the Fe-doped TiO₂ nanorods. At low Fe doping concentration, the PEC properties were highly affected by the optical properties. On the other hand, the PEC properties were significantly affected by the morphological properties at high doping concentration. We observed a maximum photocurrent density of 0.48 mA/cm² at a Fe doping concentration of 2 at% from this study. In addition, the donor density and flat-band potential of the Fe doping concentration from the Mott–Schottky plot were analyzed.     

Oxygen overvoltage on SnO2-based anodes in NafAlF3Al2O3 melts. Electrocatalytic effects of doping agents

Oxygen overvoltage on sintered anodes made of SnO₂ + 2 wt% Sb₂O₃ + 2 wt% CuO was measured in 2.7 NaFAlF₃Al₂O₃ (sat) melts at 1000°C. Prior to use the sintered electrodes were dipped into solutions containing doping agents. Doping with Ru, Fe and Cr showed a marked electrocatalytic effect. Ru was the most effective, and compared with undoped material the coefficients for the initial Tafel line decreased from a = 0.11 to 0.070 V and from b = 0.065 to 0.035 V dec^?1. Steeper slopes appeared at high cds, being 0.14 V dec^?1 for Ru, but the overvoltage was as low as 0.15 V even at 4 A cm^?2.