Confira nossas publicações recentes

2022

Visible Light Photoelectrochemical Sensor for Dopamine: Determination Using Iron Vanadate Modified Electrode

Luan Pereira Camargo, Marcelo Rodrigues da Silva Pelissari, Paulo Rogério Catarini da Silva, Augusto Batagin-Neto, Roberta Antigo Medeiros, Marcos Antônio Dias, Luiz Henrique Dall’Antonia 

Abstract

 This study reports a facile approach for constructing low-cost and remarkable electroactivity iron vanadate (Fe-V-O) semiconductor material to be used as a photoelectrochemical sensor for dopamine detection. The structure and morphology of the iron vanadate obtained by the Successive Ionic Adsorption and Reaction process were critically characterized, and the photoelectrochemical characterization showed a high photoelectroactivity of the photoanode in visible light irradiation. Under best conditions, dopamine was detected by chronoamperometry at +0.35 V vs. Ag/AgCl, achieving two linear response ranges (between 1.21 and 30.32 μmol L⁻¹, and between 30.32 and 72.77 μmol L⁻¹). The limits of detection and quantification were 0.34 and 1.12 μmol L⁻¹, respectively. Besides, the accuracy of the proposed electrode was assessed by determining dopamine in artificial cerebrospinal fluid, obtaining recovery values ranging from 98.7 to 102.4%. The selectivity was also evaluated by dopamine detection against several interferent species, demonstrating good precision and promising application for the proposed method. Furthermore, DFT-based electronic structure calculations were also conducted to help the interpretation. The dominant dopamine species were determined according to the experimental conditions, and their interaction with the iron vanadate photoanode was proposed. The improved light-induced DOP detection was likewise evaluated regarding the charge transfer process.

Molecules 2022, 27(19), 6410

DOI = 10.3390/molecules27196410

Reactive sputtering deposition of Co₃O₄ films and an evaluation of its use as an electrochemical sensor for ascorbic acid

Nilton Francelosi Azevedo Neto, João C. Angelico, Marcelo R. da Silva Pelissari, Luan Pereira Camargo, Rafael Plana Simões, Luiz Henrique Dall’Antonia, José Humberto Dias da Silva

Abstract

Co₃O₄ films have been deposited using reactive DC magnetron sputtering onto fluorine-doped tin oxide (FTO) and fused silica (SiO₂). X-ray diffraction measurements confirmed the spinel Co3O4 phase. The surface roughness of the films were 4 nm and 20 nm for SiO₂ and FTO substrates, respectively, as measured by atomic force microscopy. Optical transmission spectra of Co₃O₄ films show strong absorption in the near-infrared and visible regions. The photoconductivity response of SiO2/Co₃O₄, using 405 nm excitation, measured at room temperature is much smaller than the observed at 10 K. The electrochemical activity of the FTO/Co₃O₄ for the oxidation reaction of the ascorbic acid (AA) was investigated by differential pulse voltammetry and chronoamperometric. A model for the oxidation, based on density functional theory calculations for the electronic structure of the AA, is proposed. The set of results show that the assembled FTO/Co₃O₄ electrode can be used as an alternative and remarkable-performance non-enzymatic device to ascorbic acid electrooxidation.

J. Mater. Sci. Mater., Volume 33, pages19678–19692 (2022)

DOI = 10.1007/s10854-022-08804-7

Over 21.0% faradaic efficiency of ambient ammonia production: Photoelectrocatalytic activity of MOF-235

Luan Pereira Camargo, Paulo Rogério Catarini da Silva, Augusto Batagin-Neto, Vanessa Klobukoski, Marcio Vidotti, Luiz Henrique Dall'Antonia

Abstract

In recent years, the Haber-Bosh process's ammonia synthesis has shown a lot of energy consumption and significant CO₂ emissions. In this sense, the photoelectrochemical production of NH₃ via dinitrogen fixation has been showing a promising strategy. Thus, in this work, ammonia production under photoelectrocatalytic condition was carried out using the metal-organic iron terephthalate structure (MOF-235), obtained by a simple and low-cost process (solvothermal). The results indicated greater activity for the nitrogen reduction reaction (NRR) compared to the hydrogen reduction reaction (HRR), in addition to a high yield of NH3 0.716 µg h⁻¹ cm⁻² and Faradaic efficiency greater than 21.0% at - 0.2 V vs reversible hydrogen electrode in 0.1 mol L⁻¹ Na₂SO₄ electrolyte. It is believed that the good results of MOF-235 during NRR are related to a high specific area of MOF, making available active sites of trinuclear-oxocentered iron in abundance. The material homogeneity in the electrode and the excellent light absorption were also decisive factors for the supply of high energy electrons necessary for ammonia production.

Appl. Mater. Today, Volume 28, August 2022, 101540

DOI = 10.1016/j.apmt.2022.101540

Efficient removal of glyphosate from aqueous solutions by adsorption on Mg–Al-layered double oxides: thermodynamic, kinetic, and mechanistic investigation

Emanoel Hottes, Clarissa Oliveira da Silva, Glauco Favilla Bauerfeldt, Rosane Nora Castro, Jackson Henrique Cardoso de Lima, Luan Pereira Camargo, Luiz Henrique Dall’Antonia, Marcelo Hawrylak Herbst

Abstract

 Up to 90% of glyphosate was removed in 40 min by a 2:1 Mg₂Al-layered double oxide (LDO) at pH 10, and the adsorption kinetics fitted a pseudo-second-order law. The adsorption isotherms were type L, and the Langmuir model best fitted the experimental data, with qmax of 158.22 μg/mg at 25 °C. The intraparticle diffusion model suggested that the adsorption process is dependent on the thickness and formation of the film at the solution/solid interface. The XRD results excluded the intercalation of glyphosate anions, and FTIR along with solid-state 13C and 31P MAS NMR confirmed that the glyphosate anions interact through the carboxylate and/or phosphonate moieties, both in end-on and side-on modes to the LDO surface. Glyphosate removal was also investigated in the presence of different anionic species, and simultaneous adsorption showed that carbonate and phosphate ions strongly influence glyphosate removal.

Environ Sci Pollut Res (2022).

DOI = 10.1007/s11356-022-21703-y

Fe₂V₄O₁₃ photoanode material: an interesting approach to non-enzymatic glucose oxidation  

Marcelo Rodrigues da Silva Pelissari, Luan Pereira Camargo, Paulo Rogério Catarini da Silva, Luiz Henrique Dall’Antonia

Abstract

The use of non-enzymatic material for the electrooxidation reaction of glucose is still a challenge to be overcome since these materials must have high sensitivity to glucose, high chemical stability and, if possible, be obtained quickly and with a low-cost process. In this context, iron vanadate (Fe₂V₄O₁₃) was successfully synthesized using the easy and low-cost Successive Ionic Layer Adsorption and Reaction process and used as an interesting non-enzymatic photoanode material approach for the photoelectrochemical oxidation reaction of glucose. From the X-ray diffraction and Raman measurements, it was possible to observe that the monoclinic crystalline phase Fe₂V₄O₁₃ was formed at 500 °C, without any secondary phases. The electrochemical characterization, performed by linear sweep voltammetry (LSV), chronoamperometry and electrochemical impedance spectroscopy techniques, under light condition, showed the remarkable photoelectrochemical activity of the FTO/Fe₂V₄O₁₃ electrode, such as a high photocurrent density at + 0.6 V vs. Ag/AgCl (0.2 mA cm⁻²); good reproducibility under transient light condition; low charge transfer resistance; and flat band potential consistent with the LSV and typical value of this material (+ 0.45 V). The performance of the electrode as non-enzymatic glucose interaction, carried out by chronoamperometry technique, showed a remarkable performance in the photoelectrooxidation reaction of glucose, with linear behavior (R2 = 0.9975) of the analytical curve (glucose concentration from 0 to 10 mmol L⁻¹), excellent reproducibility, a slight loss in photoelectrochemical signal after five successive reading cycles, good sensitivity (0.370 μA mM⁻¹ cm⁻²) and limit of detection (52 µmol L^–1). Besides, the analysis of interference species showed good electrode selectivity.

Journal of Materials Science, 57, 7173-7190 (2022) 

DOI = 10.1007/s10853-022-07093-z

Zn_1-xCo_xO vs Ag-ZnO photoanodes design via combustion: Characterization and application in photoelectrocatalysis  

Adriana Campano Lucilha, Luan Pereira Camargo, Vanessa Rocha Liberatti, Eduardo Cesar Melo Barbosa, Luiz Henrique Dall’Antonia

Abstract

In this work, different synthetic conditions were analyzed to prepare modified ZnO photoelectrodes, in order to prevent the recombination of their photogenerated charge carriers and thus allow the continuous formation of electrons and holes on photoelectrocatalytic reactions. Thus, an investigation was carried out by the chemical modification using cobalt and surface modification using silver, as well as the final heat treatment temperature, to monitor its effects onto the properties of this semiconductor oxide. In this context, Zn_1−xCo_xO and Ag-ZnO photoelectrodes were produced from combustion synthesis and prepared simply and efficiently, directly on the indium tin oxide (ITO) surface. These material modifications were efficient to improve the properties of pure ZnO, and the presence of silver on the ZnO surface provided significantly superior photoelectrochemical and photoelectrocatalytic responses for methylene blue discoloration. Zn_1−xCo_xO presented a current density of 132 μA cm−2 and kinetic discoloration constant of 9.05 × 10⁻³ min⁻¹, and Ag-ZnO displayed a current density of 162 μA cm⁻² and kinetic discoloration constant of 15.0 × 10⁻³ min⁻¹. Among the ZnO modification conditions, the addition of 2.0% (mol L⁻¹) of a metal nitrate precursor (either Co or Ag) and thermal treatment at 600 °C provided the best responses to the photoelectrodes.

Colloids and Surfaces A: Physicochemical and Engineering Aspects, 638 (2022)

DOI = 10.1016/j.colsurfa.2022.128261

 2021

The Role of PEG 6000 and PVP as Stabilizing and Surfactant Agents in the Photoelectrochemical Properties of BiVO₄ Monoclinic Structure 

Marcelo Rodrigues da Silva Pelissari, Luis Vicente A. Scalvi, Luiz Henrique Dall’Antonia

Abstract

Nanocrystalline BiVO₄ on monoclinic phase was obtained by a modified-solution combustion synthesis (SCS) using poly(ethylene glycol) (PEG 6000) and polyvinylpyrrolidone (PVP) as stabilizing and surfactant agents, respectively. An active photoanode was built using a simple procedure by dip-coating deposition process on fluorine-doped tin dioxide (FTO). The structure, morphology and optical properties of FTO/BiVO₄ photoanode were evaluated by means of X-ray diffraction (XRD), Raman spectroscopy, scanning electron microscopy (SEM) and diffuse reflectance UV-Vis spectroscopy. The photoelectrochemical performance measurements were carried out by linear sweep voltammetry (LSV), chronoamperometry and electrochemical impedance spectroscopy (EIS) under InGaN blue light emitting diode (LED) illumination condition (about 450 nm). In Na2SO₄ electrolyte solution, the electrode has presented better photoelectroactivity than in NaNO₃ solution, as evidenced by photoelectrochemical parameters such as: the highest photocurrent density (j_s) value, cathodic shifts of the onset potential (OP) and lower charge-transfer resistence (R_ct). In the methyl orange (MO) degradation reaction the FTO/BiVO₄ electrode has presented high photoelectroactivity, where the estimated kinetic constant rate (k_obs) is 4.74 × 10⁻³ and 7.54 × 10⁻³ min⁻¹ in NaNO₃ and Na₂SO₄ solutions, respectively. This remarkable performance of the as-prepared electrode is due to the morphological BiVO₄ structure, with elongated-shape nano-sized domain particles, besides the considerable porosity and roughness levels on electrode surface.

J. Braz. Chem. Soc., 32,  (2021)

DOI = 10.21577/0103-5053.20210076

Visible Light Photoelectrochemical Sensor for Acetaminophen Determination using a Glassy Carbon Electrode Modified with BiVO₄ Nanoparticles 

Mayara da Silva Araújo, Túlio Rolim Barretto, Juliana Costa Rolim Galvão, César Ricardo Teixeira Tarley, Luiz Henrrique Dall'Antônia, Roberto de Matos, Roberta Antigo Medeiros

Abstract

A new and simple photoelectrochemical (PEC) sensor using a glassy carbon electrode (GCE) modified with bismuth vanadate (BiVO₄) nanoparticles and dihexadecyl phosphate (DHP) film was useful for acetaminophen (AC) determination. In 0.2 mol L⁻¹ phosphate buffer (pH=9), the GCE without modification exhibited the smaller photocurrent (0.86 μA) when compared with GCE modified with 1.0 mg mL⁻¹ or 2.0 mg mL⁻¹ BiVO4 nanoparticles suspension (5.9 and 34 μA, respectively). Based on the photocurrent signal generated through the interaction between GCE, BiVO₄ and the energy of visible light a chronoamperometric method for AC determination was developed. The AC linear range concentration from 0.099 to 0.99 μmol L⁻¹ and limits of detection and quantification of 0.027 and 0.091 μmol L⁻¹, respectively, was obtained. The proposed method was applied to the AC determination in commercial drugs and tap water with satisfactory accuracy and precision. Moreover, the PEC construction was easy and had a short response time, which might confer higher sample throughput for the method.

Electroanalysis, 33, 663 – 671 (2021)

DOI = 10.1002/elan.202060031

Synthesis of novel poly(methacrylic acid)/β-cyclodextrin dual grafted MWCNT-based nanocomposite and its use as electrochemical sensing platform for highly selective determination of cocaine 

Tainara Boareto Capelari, Jhessica de Cássia Mendonça, Luana Rianne da Rocha, Maiyara Carolyne Prete, Pedro Nunes Angelis, Luan Pereira Camargo, Luiz Henrique Dall'Antonia, César Ricardo Teixeira Tarley

Abstract

The assessment of a novel electrochemical sensing platform based on poly(methacrylic acid) (poly(MAA)) and β-cyclodextrin (β-CD) grafted onto multi-walled carbon nanotubes (MWCNT) for highly sensitive and selective cocaine (COC) determination in seized samples is reported. Nanocomposite characterization was performed by FT-IR, Raman Spectroscopy, X-ray diffraction, TGA, SEM, TEM, nitrogen adsorption/desorption and static contact angle. The poly(MAA)/MWCNT/β-CD at 3.0 mg mL⁻¹ concentration in DMF containing 0.7% of Nafion^® was cast on the surface of glassy carbon electrode (GCE) by the drop-casting method. The nanocomposite modified electrode showed substantial improvement in terms of selectivity and sensitivity in the COC determination as a result of the synergic effect of MWCNT, poly(MAA), and β-CD. By using differential pulse voltammetry (DPV) under optimized conditions (scan rate of 28.0 mV s⁻¹, pulse amplitude of 164.0 mV and modulation time of 7.0 ms) and at pH 7.0 in 0.1 mol L⁻¹ Britton-Robinson (BR) buffer, a linear response range from 12.2 to 200.0 μmol L⁻¹ with a limit of detection (LOD) of 3.6 μmol L⁻¹ was obtained. The modified electrode showed outstanding selectivity towards COC determination even in the presence of adulterants usually found in seized COC sample, including caffeine, lidocaine, phenacetin, benzocaine, paracetamol, procaine, and levamisole. The proposed method was applied to COC determination in street seized sample and the accuracy was attested by HPLD-DAD.

Journal of Electroanalytical Chemistry, volume 880, 114791 (2021)

DOI = 10.1016/j.jelechem.2020.114791

Characterization and Photo-Induced Electrocatalytic Evaluation for BiVO₄ Films Obtained by the SILAR Process 

Marcelo Rodrigues da Silva Pelissari, Nilton Francelosi Azevedo Neto, Luan Pereira Camargo & Luiz Henrique Dall’Antonia

Abstract

BiVO₄ is an important semiconductor material that can be applied as a photoanode in several electrochemical systems, using the visible region of the electromagnetic spectrum as an excitation source to charge carrier generation. However, due to the unfavorable charge carrier recombination process, which is an intrinsic property of semiconductor materials, alternative conditions of synthesis and different electrode architecture are fundamental to improving their photoelectrocatalytic activity. In this paper, the construction of a photoanode using BiVO4 films with the monoclinic crystalline structure was successfully obtained by a quick and low-cost process: the Successive Ionic Layer Adsorption and Reaction (SILAR). The characterization of electrodes (5, 10, and 15 SILAR-deposited layers), which was carried out by x-ray diffraction (XRD), Raman spectroscopy, scanning electron microscope (SEM), and UV-Vis spectroscopy diffuse reflectance techniques, showed the efficiency of the SILAR process in the construction and architecture of the FTO/BiVO4 electrode. The FTO/BiVO4 photoanodes constructed have exhibited interesting photoelectrochemical responses, such as high photocurrent density (j_ph), low resistance to charge transfer (R_ct), and high charge carrier density (ND). The photocurrent value obtained for a 5-layer film was 1.95 mA cm⁻², twice as large than a 10-layer film (0.97 mA cm⁻²) and three times greater than a 15-layer film (0.61 mA cm⁻²). The resistance-to-charge transfer values are in good agreement with the photocurrent density values, where the 5-layer film presented the Rct value of 0.15 kΩ, lower than the other obtained electrodes. Regarding the rhodamine b (RhB) photoelectrodegradation reaction, all electrodes showed good photoelectrocatalytic activity as evidenced by pseudo-first order kinetics constant (k_obs) values.

Electrocatalysis, volume 12, pages 211–224 (2021)

DOI = 10.1007/s12678-021-00641-2

 2020

Evaluation of the heterostructure ITO/BiVO₄ under blue monochromatic light irradiation for photoelectrochemical application

 M. R. da Silva Pelissari, L. V. A. Scalvi, V. S. L. Neto, L. H. Dall’Antonia

Abstract

In this paper, the semiconductor material BiVO₄ was obtained by an adapted process of solution combustion synthesis, using poly(ethylene glycol) (PEG 6000) as an additional stabilizing agent, and deposited on indium-doped tin oxide (ITO) substrate, by the dip-coating deposition process, to build an ITO/BiVO₄ thin film heterostructure, which can be used as photoanode in photoelectrochemical (PEC) cell. The ITO/BiVO4 photoanode has its performance evaluated by linear sweep voltammetry (LSV), chronoamperometry, and electrochemical impedance spectroscopy (EIS) techniques, under blue monochromatic light, provided by an InGaN LED source. The LSV curve shows that the photoactivity of the photoanode presents a drastic jump in the current density under illumination and negligible dark current density. Reproducibility of the electrode photoactivity is observed under light-chopped illumination. The decay profile of photocurrent suggests that despite of charge carriers recombination process occurring in the ITO/BiVO4 electrode, it still presents good photoelectrocatalytic efficiency. Additionally, the long-term current stability indicates that the current density stays stable, without considerable decay, for at least one hour. The steady-state photocurrent density obtained is equal 91 µA cm^− 2. EIS results showed that under illumination, the charge transfer resistance (Rct) is considerably lower than the dark condition. The PEC performance evaluated for discoloration reaction in rhodamine B (RhB) and methylene blue (MB) shows that the photoelectrochemical system is quite efficient.

Journal of Materials Science: Materials in Electronics, volume 31, pages 2833–2844 (2020)

Copper pyrovanadate electrodes prepared by combustion synthesis: evaluation of photoelectroactivity

 Luan Pereira Camargo, Adriana Campano Lucilha, Guilherme Augusto Barros Gomes, Vanessa Rocha Liberatti, Avacir Casanova Andrello, Paulo Rogério Catarini da Silva & Luiz Henrique Dall’Antonia

Abstract

Photoelectrodegradation of dyes using semiconductors under visible light is currently a major research topic. In this work, copper pyrovanadate (Cu₂V₂O₇) was obtained by combustion synthesis, and the influence of different fuels such as citric acid, glycine, and urea on the properties of this semiconductor was evaluated. Using X-ray diffraction analysis, it was observed that the β-Cu₂V₂O₇ phase was formed in greater proportions for the three samples, especially with the use of urea. On the other hand, the formation of the α-Cu₂V₂O₇ phase was not verified when glycine was used, which can be associated with the occurrence of a higher flame temperature during the combustion step (1507 °C). Among the photoelectrodes obtained, the ITO/Cu₂V₂O₇-Urea presented the best photoelectrocatalytic performance, with a greater discoloration rate constant of methylene blue dye (k_obs = 28.61 × 10⁻³ min⁻¹) and less charge transfer resistance (42.75 Ω), while in the other photoelectrodes, the proportion of the β-Cu₂V₂O₇ phase was lower, as well as the discoloration rate constant. Thus, this work has contributed to demonstrate how the choice of fuel can influence the formation of the α- and β-phases of Cu₂V₂O₇ and, therefore, may promote the development of materials with greater stability and photoelectrocatalytic efficiency.

Journal of Solid State Electrochemistry, volume 24, pages 1935–1950 (2020)

DOI = 10.1007/s10008-020-04721-z

Fabrication of rGO/α-Fe₂O₃ electrodes: characterization and use in photoelectrocatalysis

Vanildo Souza Leão-Neto, Aruã Clayton da Silva, Luan Pereira Camargo, Marcelo Rodrigues Da Silva Pelissari, Paulo Rogério Catarini da Silva, Paulo Sergio Parreira, Mariana Gava Segatelli & Luiz Henrique Dall′Antonia

Abstract

In the current study, the synthesis of hematite (α-Fe₂O₃) at different temperatures (750 and 900 °C), and reduced graphene oxide (rGO), obtained from an adaptation to the Hummers’s method, was evaluated. These materials were characterized by X-ray diffraction, Raman spectroscopy, Fourier-transform infrared spectroscopy, scanning electron microscopy, thermogravimetric analysis, among others. The deposition of samples on the conductive surface of tin-doped indium oxide coated glass substrate, was performed by the Layer-by-Layer technique. The films were prepared with 1- and 4-bilayers α-Fe₂O₃, using a cationic polyelectrolyte diallyldimethylammonium chloride (PDDA) or rGO. It was observed that the rGO/α-Fe₂O₃ films presented higher photocurrent and less resistivity when compared to the PDDA/α-Fe₂O₃ films. The largest photocurrent was obtained with the 4-bilayers rGO/α-Fe₂O₃ at 900 °C film, with 2.15 µA cm⁻². In addition, a kinetic study for photoelectrocatalytic decolorization of the methylene blue dye under visible light was performed. The electrode that showed the greatest photoelectroactivity was the 4-bilayers rGO/α-Fe₂O₃ at 900 °C film, resulting in k_obs = 11.90 × 10⁻³ min⁻¹ and about 78% decolorization after 120 min.

 Journal of Materials Science: Materials in Electronics, volume 31, pages 16882–16897 (2020)

DOI = 10.1007/s10854-020-04244-3

Conducting polymers and composites nanowires for energy devices: A brief review

Larissa Bach-Toledo, Bruna M. Hryniewicz, Luís F. Marchesi, Luiz H. Dall'Antonia, Marcio Vidotti, Franciele Wolfart

Abstract

Supercapacitors and batteries have been widely used in portable electronic devices and electric vehicles requiring safety and reliable devices. The improvement in the supercapacitors and battery performance can be achieved by the tuning of the electroactive material architecture used in the construction of such devices. A broad range of different kind of material has been investigated such as conducting polymers, transition metals oxides, graphene and carbon nanotubes, all of them presented in a different morphology, as nanosheets, nanorods, nanowires, nanotubes, nanoflowers, nanofibers, etc. This short review brings out the main approaches about the conducting polymers and composites nanowires for energy devices application. Methods of synthesis, combination of materials and applications are discussed in terms of supercapacitors and Lithium-ion batteries.

Materials Science for Energy Technologies, volume 3, pages 78-90 (2020)

DOI = 10.1016/j.mset.2019.09.006

2019

Ascorbic acid electrocatalytic activity in different electrolyte solutions using electrodeposited Co(OH)₂ 

Marcelo Rodrigues da Silva Pelissari, Edson Archela, Cesar Ricardo Teixeira Tarley & Luiz Henrique Dall’Antonia

Abstract

The present paper describes the use of electrodeposited Co(OH)₂ on transparent conducting fluorine-doped tin oxide electrode (FTO) as functional material for ascorbic acid electrooxidation in different electrolyte solutions. The structure, composition, and morphology of film were investigated through Fourier transform infrared spectroscopy (FTIR), energy-dispersive X-ray spectrum (EDS), and scanning electron microscope (SEM). The electrochemical characterization in different electrolyte solutions was carried out by cyclic voltammetry (CV) and chronoamperometry. The voltammetric profile showed the presence of two possible reactions involving almost reversible redox processes during sweeping potential in KOH solution and a single redox process in KCl solution. The Co(OH)₂ film presented electrocatalytic activity in ascorbic acid electrooxidation, being the sensitivity values found were 182.3 mA L mol⁻¹ cm⁻² and 119.4 mA L mol⁻¹ cm⁻² in KOH and KCl solutions, respectively. The results showed that the electrolytic solution strongly influenced the sensitivity of the FTO/Co(OH)₂ film in ascorbic acid electrooxidation reaction. Kinetic studies showed that the electrode process was controlled by mass diffusion. In addition, chronoamperometric technique was carried out to verify the stability of the electrode. The obtained results reveal a good stability of electrode in the KCl solution; once in current density terms, the results are quite similar.

Ionics, volume 25, pages 1911–1920 (2019)

DOI = 10.1007/s11581-019-02845-5

ZnO/p-Cu₂O Heterojunction Electrode: Characterization and Evaluation of Their Photoelectrochemical Properties 

Edson Archela, Luan Pereira Camargo, Marcelo Rodrigues da Silva Pelissari, Luiz Henrique Dall’Antonia

Abstract

In this work an easy way to prepared heterojunction electrodes based on ZnO and Cu2O were developed. The electrodes were synthetized by a simple electrodeposition method. The photoelectrodes obtained were not submitted to a high temperature treatment. The electrodeposited films prevent the recombination of photogenerated charge carriers and thus allow the continuous formation of electrons and holes on photoelectrocatalytic reactions. Moreover, the films electrodeposited were characterized by X-ray diffraction, Raman spectroscopy, scanning electronic microscopy and UV-Vis. The photoelectrochemical activity was evaluated under visible light irradiation. The Cu2O addition at the photoelectrodes were efficient to improve the properties of pure ZnO and also promote superior photoelectrochemical and photoelectrocatalytic responses for methylene blue discoloration.

Int. J. Electrochem. Sci., 14, 3581 – 3594 (2019)

DOI = 10.20964/2019.04.04