Printex 6L Carbon Research Articles

Degradation of diethyl phthalate by photolysis of hydrogen peroxide electrogenerated using a Printex L6 carbon modified with Benzophenone cathode in an improved tangential flow cell

In this work, a gas diffusion electrode (GDE) made of Printex L6 carbon modified with 2.0% w/w of benzophenone-3,3′,4,4′-tetracarboxylic dianhydride (PL6C/BTDA 2%) was employed as cathode in a new 3D printed electrochemical cell with tangential flow. With this configuration, the performance of the technology was evaluated for hydrogen peroxide (H2O2) electrogeneration and remediation of aqueous wastes contaminated with diethyl phthalate (DEP) using different H2O2-based advanced oxidation processes (AOPs). The electrogeneration study was carried out varying the current density applied to the system, and it was found that 50 mA cm-2 was the best performing value, resulting in remarkable Faradaic efficiencies of nearly 100%. This led to the production of higher amounts of H2O2 (442.5 mg L-1) in 90 minutes at an acceptable energy consumption (8.5 kWh kg-1) compared to values reported in the literature. Based on these findings, H2O2-based AOPs were employed to investigate the removal of DEP in cathodic compartment, including mediated electrochemical degradation with electrogenerated H2O2 (e-H2O2) and the integration of this technology with ultraviolet-C (UVC) photolysis (e-H2O2/UVC). The integrated e-H2O2/UVC obtained the best performance compared to single photolysis and e-H2O2, leading to the total elimination of DEP (90 μmol L-1) within only 30 min of treatment, reaching the highest kinetic rate constant (0.3 min-1). Fifteen by-products, generated through oxidation processes studied, were successfully identified by LC-MS/MS, enabling the proposal of the degradation mechanism of DEP.

Electrocatalytic hydrogen peroxide generation using WO3 nanoparticle-decorated sodium niobate microcubes

The current work studies the electrocatalytic performance of NaNbO3 microcubes decorated with WO3 nanoparticles on Printex L6 at varying concentrations (1%, 3%, 5%, and 10% by weight) for H2O2 electrogeneration aiming for future use in electrochemical advanced oxidation processes for organic pollutant degradation·H2O2 electrogeneration was studied using oxygen reduction reaction (ORR) with the rotating ring-disk electrode (RRDE) technique. Electrochemical results revealed an improvement in H2O2 electrogeneration for the NaNbO3@WO3/C materials compared to that achieved with Printex L6 carbon. Notably, the 5% NaNbO3@WO3/C electrocatalyst exhibited a higher ring current for oxygen reduction reaction and promoted a 2.1-electron transfer, facilitating a higher rate of H2O2 electrogeneration through the 2-electron mechanism. Also, enhancing oxygen-containing functional groups has shown the capability to thoroughly adjust characteristics and enhance active sites, increasing H2O2 electrogeneration. These findings suggest that 5% NaNbO3@WO3/C electrocatalysts hold promise for in situ hydrogen peroxide electrogeneration.

Using ZrNb and ZrMo oxide nanoparticles as catalytic activity boosters supported on Printex L6 carbon for H2O2 production

Oxygen reduction reaction (ORR) is an important reaction which is widely applied in advanced oxidative processes (AOP) through the in-situ electrogeneration of hydrogen peroxide. Oxygen gas can either be reduced to hydrogen peroxide via two-electron pathway or be converted to water in a competitive way via four-electron pathway. In this study, we report the effective enhancement of H2O2 generation in K2SO4 0.1 mol/L (pH 2) through the application of Printex L6 carbon (PL6C) modified with zirconium/niobium (ZrNb) and zirconium/molybdenum (ZrMo) oxides compared to unmodified PL6C. The proposed catalysts were prepared by the polymeric precursors synthesis method (on carbon). The catalysts were analyzed by X-ray fluorescence (FRX), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS), and were electrochemically characterised by cyclic voltammetry (CV) and hydrodynamic linear sweep voltammetry (LSV). The electroactivity of ZrNb/PL6C and ZrMo/PL6C oxides was analyzed in the ratio of 50/50 w/w. The results obtained from the electrochemical characterisations of the electrodes showed that the application of 5% ZrNb/PL6C and 1% ZrMo/PL6C yielded H2O2 selectivity of 84.3 and 77%, respectively, compared to 84.3% recorded for the unmodified PL6C. Also, based on the application of a determined current density, 5% ZrNb/PL6C and 1% ZrMo/PL6C recorded a potential shift of 200 and 400 mV to less negative potentials, respectively, compared to the unmodified PL6C, which implies in less energy consumption. The results obtained from the morphological and surface characterisations of the materials pointed to a practically homogeneous distribution of ZrO2, Nb2O5, and MoO3 with particle size of ca. 5 nm on the PL6C surface compared to the unmodified PL6C which exhibited particle size of ca. 30–50 nm.

Using a novel gas diffusion electrode based on PL6 carbon modified with benzophenone for efficient H2O2 electrogeneration and degradation of ciprofloxacin

The present study reports the development and application of a gas diffusion electrode (GDE) based on Printex L6 carbon modified with 2.0% benzophenone-3,3′,4,4′-tetracarboxylic dianhydride (PL6C/2.0%BTDA) for the efficient electrogeneration of hydrogen peroxide (H2O2) and degradation of ciprofloxacin (CIP) using different advanced oxidation processes (AOPs). The modified GDE was studied under different current densities and 25 mA cm−2 was found to be the most efficient current density, since the application of the modified GDE at this current density yielded higher amounts of H2O2, greater kinetic constant and lower energy consumption compared to unmodified GDE. Based on these results, the modified GDE was used for the degradation of CIP in alkaline solutions using different AOPs, including anodic oxidation (AO), UVC photolysis, and processes based on H2O2 electrogeneration (AO/e-H2O2/UVC and AO/e-H2O2). The AO/e-H2O2/UVC technique was found to be the most efficient among the AOPs investigated; the application of this technique led to the complete removal of CIP (75 µmol L–1) in 20 min of treatment, apart from yielding the highest kinetic constant rate and lower electrical energy per order (2.1 kWh m−3 order–1). The oxidation by-products generated during CIP degradation via AO/e-H2O2/UVC were successfully identified and a pathway for CIP degradation was proposed.

Using Au NPs anchored on ZrO2/carbon black toward more efficient H2O2 electrogeneration in flow-by reactor for carbaryl removal in real wastewater

In the present study, we designed a highly efficient catalyst for H2O2 production using gold nanoparticles (Au NPs) anchored on hybrid substrate composed of ZrO2 and Printex L6 carbon (Au-ZrO2/PL6C). The higher selectivity of Au-ZrO2/PL6C (97%) toward H2O2 electrogeneration and its improved activity in terms of ORR onset potential (140 mV for more positive values) compared to Au/PL6C (80%) were attributed to the synergism between Au NPs anchored on ZrO2/PL6C hybrid support. The results obtained from the application of the catalysts for H2O2 generation on gas diffusion electrode (GDE) after 120 min of electrolysis reflected the following order of efficiency: PL6C (∼140 mg L−1) < ZrO2/PL6C (∼235 mg L−1) < Au/PL6C (∼374 mg L−1) < Au-ZrO2/PL6C (∼600 mg L−1). Given that Au-ZrO2/PL6C exhibited the highest catalytic efficiency, this catalyst was employed for the removal of carbaryl (CBR) using different electrochemical advanced oxidation processes. The CBR degradation tests exhibited pseudo first-order kinetics, with the electro-Fenton (EF) and photoelectro-Fenton (PEF) processes recording the fastest removal kinetics (3.5 × 10−2 s−1 and 4.1 × 10−2 s−1, respectively). The PEF process exhibited the highest efficiency in terms of organic by-products mineralization; this was attributed to the additional photodecarboxylation of the Fe(III)-RCOOH complexes by UVC light. The aromatic by-products, short chain carboxylic acids, and ionic nitrogen species produced during the mineralization process contributed to the successful degradation of CBR. Apart from the analysis with synthetic water, the study also analyzed the treatment of urban wastewater spiked with CBR using a pre-pilot flow plant.

High-performance gas-diffusion electrodes for H2O2 electrosynthesis

The application of gas diffusion electrodes (GDE) modified with carbon black materials at high overpotentials leads to the substantial production of H2O2 via oxygen reduction reaction. The greatest challenge in this process lies in the reduction of the high overpotentials without affecting H2O2 selectivity. One way of circumventing this problem is through the modification of GDEs with coordination compounds. The present work investigates the modification of Printex L6 carbon (CPL6) with different amounts of porphyrin complexes containing the following metallic centers: Mn, Co, Ni, Cu and Zn. The application of 5.0 wt % Co-Porphyrin/CPL6 modifier yielded the best results, with high selectivity for H2O2 generation (90.2%) and marked improvement in catalytic activity (72.6%) compared to CPL6; these positive effects are attributed to the enhancement of both the interaction energy between Co and HOO* reaction intermediate and the effect of the conjugated π-electrons of the CPL6. The application of the modified GDE led to the electrogeneration of 340 mg L−1 of H2O2 with energy consumption of 86.6 kWh kg−1 and 92.1% improvement in efficiency compared to the unmodified GDE. Thus, the findings show that the 5.0 wt % Co-Porphyrin/CPL6 modifier is an excellent cathode for application in H2O2 generation and in electrochemical advanced oxidation processes.

Electrochemical production of extremely high concentrations of hydrogen peroxide in discontinuous processes

This work reports the development and application of a gas diffusion electrode based on Printex L6 carbon for the production of high concentrations of hydrogen peroxide (H2O2) using a flow-by electrochemical reactor in discontinuous operation mode. With the application of current densities ranging between 75 and 200 mA cm−2, the use of Printex L6 carbon-based GDE generated H2O2 concentrations in the range of 4,000–5,000 mg/L, despite the formation of scavengers. The proposed technique also promoted the production of ozone and persulfate species though at low concentrations. The application of the Printex L6 carbon-based GDE led to a roughly 3.4–3.9-fold increase in H2O2 concentrations ​​compared to Vulcan XC-72R carbon-based GDE which was used for comparison purposes (Vulcan XC-72R carbon is currently-one of the most widely employed carbon materials in electrochemical processes). In addition, the Printex L6 carbon-based GDE exhibited high stability with a lifetime of 36 Ah (7,5 days) of uninterrupted use at 200 mA cm−2. The improvements observed in the Printex L6 carbon-based GDE can be attributed to the presence of higher amounts of carboxyl oxygenated functional groups in the material and its greater electrochemically active surface area compared to the Vulcan XC-72R-based GDE.

Application of a Screen-Printed Carbon Electrode Modified with Printex 6L and Deep Eutectic Solvent for Detection and Quantification of 17β-estradiol

This work proposes the development of a screen-printed electrode (SPE) modified with a mixture of Printex 6L carbon and deep eutectic solvent (DES) (SPE-P6LCDES), used for detection of 17β-estradiol (E2) in mineral water, synthetic urine, and artificial saliva. The characterization of SPE was evaluated by Scanning Electron Microscopy, Fourier Transform Infrared and Electrochemical Impedance Spectroscopy. Electrochemical studies for E2 detection were performed in 0.1 mol L−1 phosphate buffer solution at pH 7.0. The linear range of E2 concentration was 0.00732–0.417 μmol L−1 to unmodified SPE and 0.00090–0.21 μmol L−1 to SPE-P6LCDES, with LOD of 0.177 μmol L−1 and 0.0065 μmol L−1, respectively. The use of DES + Printex 6L carbon as a modifier allowed strong intramolecular interactions between DES and the E2 molecule, increasing the intensity of the current response, since it showed high sensibility, sensitivity and reproducibility. The results obtained to E2 recovery on samples were between 92.15% and 102.10%. The validation study (UV–vis spectroscopy) demonstrated recovery of +99.16% (+1.4%) and +100.16% (+1.9%) to 10 and 60 μmol L−1 E2, respectively.

One-step preparation of Co2V2O7: synthesis and application as a Fenton-like catalyst in a gas diffusion electrode.

Bimetallic oxides and MOFs have been used as catalysts for the ORR via two-electron and Fenton-based processes. This work reports the development of a new green one-step route for obtaining Co2V2O7. The Co2V2O7 oxide was immobilized on Printex-L6 carbon and used as a catalyst for the oxygen reduction reaction (ORR) and in heterogeneous Fenton-based processes. The PL6C/2.5% Co2V2O7 sample exhibited the best performance in the ORR via a two-electron pathway, increasing the selectivity for H2O2 generation. Electrochemical impedance spectroscopy analysis showed a decrease in charge transfer resistance in the Co2V2O7/PL6C matrix. The application of a gas diffusion electrode (GDE) modified with 2.5% Co2V2O7 resulted in a 30% increase in H2O2 production compared to the unmodified GDE. The unmodified GDE promoted methyl-paraben (MeP) removal of ∼80% after 90 min treatment, whereas the modified GDE promoted ∼90% of MeP removal in 30 min. The results obtained point to the potential of Co2V2O7 in improving the efficiency of GDE when applied for the treatment of organic pollutants.

Application of a Screen-Printed Carbon Electrode Modified with Printex 6L and Deep Eutectic Solvent for Detection and Quantification of 17β-Estradiol

This work proposes the development of a screen-printed electrode (SPE) based on graphite ink as carbonaceous material and modified with a mixture of Printex 6L carbon and deep eutectic solvent (DES) (SPE-P6LCDES), used for detection and quantification of 17β-estradiol (E2) in mineral water, synthetic urine, and artificial saliva samples. The characterization of all electrodes was evaluated by Scanning Electron Microscopy (SEM), Fourier transform infrared (FTIR) and Electrochemical Impedance Spectroscopy (EIS). Electrochemical measurements were performed in a system composed of a single compartment cell (100.0 mL), containing a reference electrode (Ag/AgCl/KClsat), Pt wire as a counter electrode and SPE as a working electrode. Electrochemical studies of E2 were performed in 0.1 mol L-1 phosphate buffer solution (PBS) at pH 7.0 by cyclic voltammetry (CV) and differential pulse voltammetry (DPV). These studies evaluate the electroactivity of SPE-P6LCDES for E2, showing oxidative signals close to +0.98 V. The linear ranges of E2 concentrations studied were 0.00732 – 0.417 μmol L -1 for unmodified SPE and 0.00090 – 0.21 μmol L-1 for the SPE-P6LCDES, presenting limit of detection (LOD) of 0.177 μmol L-1 and 0.0065 μmol L -1, respectively. The use of DES + Printex 6L carbon as a modifier in the unmodified SPE allowed for strong intramolecular interactions between DES and the E2 molecule, which increased the intensity of the current responses because it is a sensor with greater sensibility, sensitivity, and reproducibility. The results obtained from the E2 recovery study on real samples were between 92.15% and 102.10%. By the method validation study (UV-Vis spectroscopy), the studied E2 concentrations of 10 and 60 μmol L-1 demonstrated recovery of +99.16% (+ 1.4%) and +100.16% (+1.9%), respectively.

Using black carbon modified with NbMo and NbPd oxide nanoparticles for the improvement of H2O2 electrosynthesis

Oxygen reduction reaction (ORR) is an important reaction with applications in advanced oxidative processes through in situ hydrogen peroxide electrogeneration. Oxygen can be reduced either to hydrogen peroxide via two-electron pathway or in a competitive way to water via four-electron pathway. This study shows the application of Printex L6 carbon modified with niobium/molybdenum or niobium/palladium oxides for H 2 O 2 generation in K 2 SO 4 0.1 mol L −1 (pH 2), where the modified carbon contributed to an increase in electroconductivity compared to unmodified carbon. The catalysts were prepared by the polymeric precursor method and were analyzed by x-ray absorption near edge structure (XANES), x-ray diffraction (XRD), and x-ray photoelectron spectroscopy (XPS) which showed the presence of orthorhombic Nb 2 O 5 and MoO 3 and tetragonal PdO independent phases. Also, the data obtained from x-ray fluorescence (FRX) and transmission electron microscopy (TEM) showed particle size of about 5 nm for the modified Printex L6 carbon compared to 25–30 nm for the unmodified Printex L6 carbon in an almost homogeneous distribution on the carbon surface. Based on the electrochemical analyses, the values obtained for H 2 O 2 selectivity were 77, 77 and 88% for 5% Nb 50 Mo 50 /C, 5% Nb 90 Pd 10 /C, and 5% Nb 95 Pd 05 /C, respectively, compared to 89% for unmodified Printex L6 carbon. The materials investigated presented potential shifts of 110, 420 and 340 mV for 5% Nb 50 Mo 50 /C, 5% Nb 90 Pd 10 /C and 5% Nb 95 Pd 05 /C, respectively, compared to Printex L6 carbon at a determined current density. • H 2 O 2 selectivity of 77 and 88% with 420 and 340 mV potential shifts were obtained for 5% Nb 90 Pd/C and 5% Nb 95 Pd/C. • Structural analysis by XANES showed the formation of Nb 2 O 5 , MoO 3 and PdO oxides. • Morphological analysis showed interaction between Nb 2 O 5 /PdO (5 nm) and Printex L6 carbon (25–30 nm).

Low Pd loadings onto Printex L6: Synthesis, characterization and performance towards H2O2 generation for electrochemical water treatment technologies

In order to enhance hydrogen peroxide (H2O2) electrogeneration, a catalyst based on less than 1 wt% of Pd nanoparticles dispersed onto commercially available Printex L6 carbon black (PCL6) is proposed and synthetized. The material was characterized by physico-chemical and electroanalytical methods, demonstrating high activity with a 320 mV lower onset potential compared to pristine PCL6 and high stability after 5000 potential cycles. Its performance places it among the most efficient bi- and monometallic electrocatalysts for H2O2 production. When testing the accumulation of H2O2, a 1.69-fold molar increase was observed for Pd1%/PCL6 compared to PCL6. Different electrochemical advanced oxidation processes based on H2O2 generation have been performed to oxidize and remove pollutants as exemplarily shown on methyl paraben in Na2SO4 solution as model pollutant. A boron-doped diamond electrode was used as anode while Pd1%/PCL6 was tested in a rotating ring disk electrode (RRDE) and gas diffusion setup. Pollutant degradation followed a pseudo-first-order reaction kinetic in the following order: anodic oxidation along with H2O2 generation (AO-H2O2) < AO-H2O2/UVC < electro-Fenton (EF) < photoelectro-Fenton (PEF). The best mineralization performance was found for PEF due to the photodecarboxylation of Fe (III) complexes with UVC light, while the process with lowest energy consumption per order was EF with 0.488 kWh m−3 order−1. At the end of the work a route for pollutant mineralization was suggested.

Tailoring the ORR selectivity for H2O2 electrogeneration by modification of Printex L6 carbon with 1,4-naphthoquinone: a theoretical, experimental and environmental application study

Printex L6 carbon exhibited an increase in H2O2 selectivity by modification with 1.0% (w/w) 1,4-naphthoquinone (NQE).

Oxygen reduction reaction: Semi-empirical quantum mechanical and electrochemical study of Printex L6 carbon black

Amorphous carbon black (CB) is a highly reactive material for O2 reduction and widely employed in H2O2 generation. Most studies published have confined their investigation to few electrochemical properties of CB and its morphological and structural characterization. However, an in-depth understanding of CB properties and their effects on oxygen reduction reaction appears to be the key to making significant progress in this field. This paper describes the use of quantum mechanical semi-empirical calculations to obtain structural information and electrochemical impedance spectroscopy to access the electrochemical information of Printex L6 CB (PCL6). It is the first report of its kind in the literature. The semi-empirical results show that PCL6 electrode presents an increase in the number of hotspots due to the presence of large amount of sp2 carbon and functional groups in its composition, which favors O2 adsorption at lower potentials. The equilibrium distance on PCL6 electrode is closer to the distance of a double bond (CO), reinforcing O2 bridge-like adsorption model. Furthermore, PCL6 had proved to be thermodynamically more favourable to O2 adsorption and requires relatively lower energy and potential (shift of 150 mV). PLC6 is found to undergo an activation process, probably associated with O2 adsorption, prior to the beginning of reaction.

A new electrochemical platform based on low cost nanomaterials for sensitive detection of the amoxicillin antibiotic in different matrices

A new electrochemical device based on a combination of nanomaterials such as Printex 6L Carbon and cadmium telluride quantum dots within a poly(3,4-ethylenedioxythiophene) polystyrene sulfonate film was developed for sensitive determination of amoxicillin. The morphological, structural and electrochemical characteristics of the nanostructured material were evaluated using X-ray diffraction, confocal microscopy, transmission electron microscopy and voltammetric techniques. The synergy between these materials increased the electrochemical activity, the electron transfer rate and the electrode surface area, leading to a high magnitude of the anodic peak current for the determination of amoxicillin. The electrochemical determination of the antibiotic was carried out using square-wave voltammetry. Under the optimised experimental conditions, the proposed sensor showed high sensitivity, repeatability and stability to amoxicillin determination, with an analytical curve in the amoxicillin concentration range from 0.90 to 69 μmol L−1, and a low detection limit of 50 nmol L−1. No significant interference in the electrochemical signal of amoxicillin was observed from potential biological interferences and drugs widely used, such as uric acid, paracetamol, urea, ascorbic acid and caffeine. It was demonstrated that without any sample pre-treatment and using a simple measurement device, the sensor could be an alternative method for not only the analysis of pharmaceutical products (commercial tablets) and clinical samples (urine), but also to examine food quality (milk samples).

Voltammetric determination of 17β-estradiol in different matrices using a screen-printed sensor modified with CuPc, Printex 6L carbon and Nafion film

A screen-printed disposable electrode made of carbon ink modified with CuPc, P6LC and Nafion film is proposed as a low-cost and simple analytical method for sensitive determination of 17β-estradiol in different matrices. The electrochemical behaviour of 17β-estradiol was evaluated by cyclic voltammetry in the potential range from 0 to 0.55 V at a scan rate of 0.05 V s−1 using 0.1 mol L−1 phosphate buffer (pH 5.0) as supporting electrolyte. One oxidation peak was observed during anodic potential scanning, at a potential of 0.39 V. Under optimized experimental conditions, using the differential pulse voltammetry (DPV) technique, the proposed sensor showed a linear concentration range for 17β-estradiol between 8.0 × 10−8 to 7.3 × 10−6 mol L−1, and detection limit of 5.0 × 10−9 mol L−1.The CuPc-P6LC-Nafion/SPEF sensor showed good selectivity, sensitivity, stability, reproducibility, and repeatability; it is a low-cost disposable device and shows no interference in DPV experiments. The proposed sensor was successful when applied to environmental and synthetic urine samples, with recoveries close to 100%.

Carbon black nanospheres modified with Cu (II)-phthalocyanine for electrochemical determination of Trimethoprim antibiotic

This work investigates the electrochemical sensing properties of glassy carbon (GC) electrodes modified with Printex L6 carbon black (PC) and copper (II) phthalocyanine (CuPh) films. Successful incorporation of the CuPh into carbon black was confirmed by FEG-SEM, EDS and TEM analysis. The transition from nanocrystalline graphite to amorphous carbon material could be evidenced for Printex L6 carbon black using Raman analysis. The modified material (CuPh/PC/GC) demonstrated electrocatalytic effect towards TMP detection according to cyclic voltammetric studies. CuPh modification resulted in strong adsorption to carbon black and TMP due to π-π interactions. Scan rate studies proved reactions across the electrode/electrolyte interface progressively change from adsorption to diffusion. The developed method presented linear relationship in the ranges of 0.4–1.1 µmol L−1 and 1.5–6.0 µmol L−1 with limit of detection of 0.6 µmol L−1 under optimized experimental conditions. The proposed CuPh/PC/GC electrode was effectively employed towards the detection of TMP in natural water samples.

Printex 6L Carbon Nanoballs used in Electrochemical Sensors for Simultaneous Detection of Emerging Pollutants Hydroquinone and Paracetamol

We report the use of Printex 6L Carbon nanoballs (CNB) as electrode material for electrochemical detection of hydroquinone (HQ) and paracetamol (PARA). Nanoballs with diameters between 20 and 25nm are amorphous, impurity-free according to energy-dispersive X-ray spectroscopy, and formed homogeneous films on glassy carbon (GC) electrodes. Their conductive behavior was confirmed with cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS), which could be exploited in differential pulse voltammetry (DPV) to detect HQ and PARA at low overpotential (67 and 341mV vs. Ag/AgCl for HQ and PARA, respectively) between 8.0×10−8 and 2.3×10−4molL−1. The limit of detection for these GC/CNB sensors was 13.0 and 8.0×10−9molL−1 for HQ and PARA, respectively, being competitive with other devices made with carbonaceous materials. In spite of their simplicity, the sensors were also stable, reproducible and robust against typical interferents in biological fluids such as nitrite, sulfite, the antibiotic amoxicillin, sodium dodecyl sulfate (SDS) and humic substances. Experiments with natural waters from a creek indicated that electrochemical sensing of HQ and PARA with GC/CNB is as efficient as standard chromatography. Because CNB are much simpler and cheaper to produce than other carbon materials, e.g. graphene and nanotubes, their use may be advantageous in other electroanalytical applications.

Synergy between Printex nano-carbons and silver nanoparticles for sensitive estimation of antioxidant activity

We report on the synthesis, characterization and applications of a Printex L6 carbon-silver hybrid nanomaterial (PC-Ag), which was obtained using a polyol method. In addition, we also highlight the use of Printex L6 nano-carbon as a much cheaper alternative to the use of carbon nanotubes and graphene. The silver nanoparticles (AgNP) were prepared directly on the surface of the Printex 6L carbon “nanocarbon” material using ethylene glycol as the reducing agent. The hybrid nanomaterial was characterized by High-angle annular dark-field transmission electron microscopy (HAADF-TEM), energy–dispersive X-ray spectroscopy (EDX), selected area electron diffraction (SAED), Raman spectroscopy and cyclic voltammetry. Optimized electrocatalytic activity on glassy carbon electrode was reached for the architecture GC/PC-Ag, the silver nanoparticles with size ranging between 1 and 2 nm were well–distributed throughout the hybrid material. The synergy between PC nano-carbons and AgNPs was verified by detection of gallic acid (GA) at a low applied potential (0.091 V vs. Ag/AgCl). GA detection was performed in a concentration range between 5.0 × 10−7 and 8.5 × 10−6 mol L−1, with a detection limit of 6.63 × 10−8 mol L−1 (66.3 nmol L−1), which is considerably lower than similar devices. The approach for fabricating the reproducible GC/PC-Ag electrodes is entirely generic and may be explored for other types of (bio)sensors and devices.

Nb2O5 nanoparticles supported on reduced graphene oxide sheets as electrocatalyst for the H2O2 electrogeneration

The use of electrogenerated H2O2 in wastewater treatment is a promising method to degrade the potentially hazardous organic contaminants. Hydrothermally prepared nanocomposites of Nb2O5 nanoparticles on reduced graphene oxide (rGO) were tested toward the oxygen reduction reaction (ORR), via the production of H2O2. The Nb2O5-rGO composite shifts the onset potential to less negatives values when compared to unmodified rGO and Printex 6L carbon. Moreover, an increase in H2O2 production in acidic media from 73.7% to 85.3% was observed for rGO and Nb2O5-rGO, respectively. Nonetheless, the activity of both catalysts in alkaline medium is not significantly different. When compared to carbon Printex, the standard for this type of reaction, the Nb2O5-rGO electrode gives higher yields of H2O2 in either acidic (70.5% vs. 85.3%) or alkaline media (63.4% vs. 74.9%). The selectivity of Nb2O5-rGO composite toward H2O2 formation is attributed to the synergistic effect between the Nb2O5 nanoparticles and the rGO sheets.