Nickel Foam Cathode Research Articles

In-situ catalytic degradation of sulfamethoxazole with efficient CuCo–O@CNTs/NF cathode in a neutral electro-Fenton-like system

In this paper, a CuCo–O@CNTs/NF electrode was successfully prepared and used for in-situ degradation of sulfamethoxazole (SMX) in an electro-Fenton-like system. Carbon nanotubes (CNTs) and coral-like copper-cobalt oxides were successively loaded on nickel foam (NF). CNTs contributed to improving the dispersibility and stability of copper-cobalt oxides, and the coral-like copper-cobalt oxide catalyst was anchored on CNTs without any adhesive. In the electro-Fenton-like system, dissolved oxygen can be reduced to superoxide anions in a one-electron step, which could be further transformed into hydrogen peroxide and then reacted with the active components on the electrode to generate reactive oxygen species (ROS) to participate in the degradation of SMX. Almost 100% SMX removal was obtained within 60 min in a wide near-neutral pH range (5.6–9.0), and the electrode could still achieve a 90.4% removal rate after ten recycle runs. Radical-quenching results showed that superoxide anions were the main species in the degradation of SMX. In addition, a possible degradation pathway of SMX was proposed. According to the result of toxicological simulations, the toxicity of the pollutant solution during the degradation process exhibited a decreasing trend. This study provides new insights for in-situ catalysis of electrodes with bimetallic active components to generate ROS for high-efficiency degradation of refractory organic pollutants.

Separation and Characterization of Cellulose Fibers from Cannabis Bast Using Foamed Nickel by Cathodic Electro-Fenton Oxidation Strategy.

Degumming is the most important link in the textile industry. The main purpose of degumming is to effectively remove non-cellulose substances in plant bast fibers. In this research, we propose an electro-Fenton (EF) system with a nickel-foam (Ni-F) cathode in weak acid pH (EF/Ni-F) to degum cannabis fiber in EF while reducing the content of pollutants in degumming wastewater. FT-IR, XPS, XRD, SEM, and TG were employed to thoroughly understand the reaction characteristics to characterize chemical components, element qualities, the crystallinity, and the morphologies of degummed fibers. Additionally, physical and mechanical properties such as breaking strength, elongation at breaking, residual glue rate, whiteness, and diameter of degummed fibers were measured. Through testing, it was found that the fiber degummed by the EF method had higher breaking strength, lower residual tackiness, and higher whiteness than other methods. The antibacterial test was used to detect the effect of fiber on Staphylococcus aureus before and after degumming. EF could remove more colloidal components from cannabis than other methods, and the mechanical properties were also enhanced. The characteristics of the degummed fiber further confirmed the effectiveness of the new degumming method. Moreover, the antibacterial experiment found that the antibacterial property of the degummed fiber was enhanced. The colloidal components in the degumming wastewater were flocculated and precipitated. The upper liquid of the solution had low chromaticity, low COD value, and weak acid pH value, which can meet the discharge requirements. The above test proves that EF is an effective degumming method that is environmentally friendly, takes less time, and enhances antibacterial performance.

Electrochemical production of hydrogen in molten salt

Clean and economical production of hydrogen is a key step for the decarbonization of energy systems. Current water electrolysis technologies developed for the green hydrogen production require high voltage values of around 2.0 V, making them uneconomical for large-scale applications. The voltage required for the production of hydrogen can be substantially reduced to around 1.0 V by performing the electrolysis at high temperatures. This article concerns the low-cost and green electrolytic production of hydrogen operating at such a low voltage performed by the dissolution of steam in high temperature molten salt electrolytes, and the subsequent electrochemical reduction of the dissolved hydrogen ions. The electro-generation of hydrogen is confirmed by performing cyclic voltammetry using molten lithium chloride as the electrolyte at 660 °C under a flow of moisturized argon. Furthermore, hydrogen is generated by the electrolysis of molten salt containing hydrogen ions using a nickel foam cathode at the constant cell voltage of 1.5 V with a high Faradaic efficiency of 83.2%. The results obtained provide crucial insights for further development of molten salt technologies for clean and efficient hydrogen production.

Highly Electrocatalytic Conversion and Separation of Organometallic Ions to Vapor on an Au-Modified Nickel Foam Cathode: A Classic Application for Mercury Speciation Analysis at the μg/L Level

A simple, accurate, and sustainable electrocatalytic conversion strategy has been used for the speciation analysis of trace mercury. An Au- or Ag-modified nickel foam electrode (Au/NFE or Ag/NFE) prepared by cyclic voltammetry was used first as a cathode for the gaseous conversion of organomercury. The mechanism of improving the electrochemical inertness of methylmercury is considered to be the migration of charge centers and the weakening of C–Hg bonds caused by the formation of Au–Hg amalgam. A large specific surface area, high catalytic activity, and low transport resistance allow an effective conversion of 0.1 μg L–1 level organomercury on the Au/NFE surface. The difference of gaseous conversion behavior under current control also provides a green way for the analysis of mercury speciation. A lower limit of detection (4.9 pg g –1 for Hg2+ and 5.5 pg g –1 for CH3Hg+), stronger anti-interference ability, more than 180 sample analysis capacities, and less than 8% signal fluctuation, importantly, confirmed that the electrocatalytic conversion technology based on the gold/silver-modified NFE is very suitable for the analysis of ultratrace methylmercury in complex matrix samples, such as animal and plant samples.

Degradation of triclosan by anodic oxidation/in-situ peroxone process: Kinetics, pathway and reaction mechanism

Triclosan (TCS) is an emerging contaminant that threatens the environment and human health. This study was conducted to investigate TCS abatement by a novel electro-oxidation (EO) process, which used a Ti-based nickel and antimony doped tin oxide (NATO/Ti) anode and a carbon nanotubes (CNTs) doped carbon/PTFE (CNTs-C/PTFE) gas diffusion electrode (GDE) for oxygen reduction reaction (ORR). A comparative study was also performed for TCS degradation by using a traditional EO with a nickel foam cathode, termed as HER-EO. The optimal initial TCS concentration, current density and solution pH for TCS degradation during the ORR-EO and HER-EO were investigated. Results showed that ORR-EO removed more than 98% of TCS in 10–60 min under the concentration of 5–50 mg/L. The TCS degradation followed pseudo-first-order kinetics and its main intermediates were observed during the ORR-EO and HER-EO using liquid chromatography combined mass (LC-MS). The results of FED analysis and toxicity prediction by ECOSAR software showed that less intermediates accumulated during the ORR-EO and the residues were less harmful. The ORR-EO degradation mechanism for TCS was attacking on the ether bond and the benzene ring by •OH. This novel ORR-EO process exhibits a great merit in the field of emerging contaminants abatement.

Electro-Fenton Degradation of High Concentration Rhodamine B on Nickel Foam Cathode Catalyzed by Cucumber Bio-Templated Fe3O4@PTFE

Electro-Fenton Degradation of High Concentration Rhodamine B on Nickel Foam Cathode Catalyzed by Cucumber Bio-Templated Fe3O4@PTFE

Dye wastewater treatment and hydrogen production in microbial electrolysis cells using MoS2-graphene oxide cathode: Effects of dye concentration, co-substrate and buffer solution

A single-chamber microbial electrolysis cell (MEC) constructed with MoS2-GO nickel foam (NF) cathode was established for alizarin yellow R (AYR) decolorization and hydrogen production, and influences of AYR initial concentration, co-substrate and buffer on MECs performances were determined. The cathode was obtained by in-situ growing MoS2-GO on NF. Physico-chemical and electrochemical characterizations showed that MoS2-GO NF cathode exhibited superior performance towards catalytic hydrogen evolution. The decolorization efficiency of ∼ 90 % within 10 h was achieved with AYR initial concentrations ranging from 30 to 150 mg/L (PBS + NaAc medium), indicating that MECs performances were not severely inhibited as the mutual impact between electrochemically active bacteria (EAB) and azo dye decolorization. Improved hydrogen production (0.183 m3/d/m3) and COD removal (92.44 %) were obtained with NaAc + glucose co-substrate and PBS buffer, owing to lower cathodic potential, desired solution conductivity for charge transfer, and better growth of microbial communities under neutral condition. Besides, better MECs performances were obtained when using NaHCO3 as buffer, compared to Na2CO3, as milder environment could be provided for microbial growth by NaHCO3. Findings in this study could promote application potential of MECs for synchronous dye removal and clean energy production with proper operations.

Influence of Nickel molybdate nanocatalyst for enhancing biohydrogen production in microbial electrolysis cell utilizing sugar industrial effluent

Biohydrogen production in Microbial Electrolysis Cell (MEC) had inspired the researchers to overcome the challenges associated towards sustainability. Despite microbial community and various substrates, economical cathode catalyst development is most significant factor for enhancing hydrogen production in the MEC. Hence, in this study, the performance of MEC was investigated with a sugar industry effluent (COD 4200 ± 20 mg/L) with graphite anode and modified Nickel foam (NF) cathode. Nickel molybdate (NiMoO4) coated NF achieved a higher hydrogen production rate 0.12 ± 0.01 L.L−1D−1 as compared to control under favorable conditions. Electrochemical characterizations demonstrated that the improved catalytic activity of novel nanocatalyst with lower impedance favoring faster hydrogen evolution kinetics. The MEC with the novel catalyst performed with 58.2% coloumbic efficiency, 20.36% cathodic hydrogen recovery, 11.96% overall hydrogen recovery and 54.38% COD removal efficiency for a 250 mL substrate during 5 days’ batch cycle. Hence, the potentiality of modified cathode was established with the real time industrial effluent highlighting the waste to wealth bio-electrochemical technology.

A ClO[rad]-mediated photoelectrochemical filtration system for highly-efficient and complete ammonia conversion

The ability to convert excess ammonia in water into harmless N2 is highly desirable for environmental remediation. We present a chlorine-oxygen radical (ClO)-mediated photoelectrochemical filtration system for highly efficient and complete ammonia removal from water. The customized photochemical device comprised a Ag-functionalized TiO2nanotube array mesh photoanode and a Pd-Cu co-modified nickel foam (Pd-Cu/NF) cathode. Under illumination, holes generated at the anode catalyzed the conversion of H2O and Cl− to HOand Cl, respectively. In turn, these radicals then reacted further, yielding ClO, which selectively decomposed ammonia. The cathode enabled further reduction of anodic byproducts such as NO3− to N2. The complete oxidation of all dissolved ammonia was achieved within 15 min reaction under neutral conditions, where N2 was the dominant product. The impact of key parameters was assessed, which enabled the discovery of optimal reaction conditions and the proposal of the underlying working mechanism. The flow-through configuration demonstrated a 5-fold increase of ammonia oxidation rate compared to the conventional batch reactor. The role of ClO in the oxidation of ammonia was verified with electron paramagnetic resonance and scavenger studies. This study provided greater mechanistic insights into photoelectrochemical filtration technology and demonstrated the potential of future nanotechnology for removing ammonia.

Preparation of NiAl coated Nickel foam cathode for Alkaline Water Electrolysis using Atmospheric Plasma Spraying

Preparation of NiAl coated Nickel foam cathode for Alkaline Water Electrolysis using Atmospheric Plasma Spraying

Simple deposition of mixed α, β-nickel hydroxide thin film onto nickel foam as high-performance supercapacitor electrode material

Here, uniform thin nanosheets’ film of mixed α- and β-Ni(OH)2 phases was cathodically electrodeposited onto nickel foam support and the fabricated electrode was utilized as binder-free electrode for supercapacitor applications. An additive-free aqueous electrolyte of 0.05 M nickel nitrate was used as the deposition bath, where the hydroxide film was prepared with only applying direct current of 10 mA/cm2 in a two-electrode system while a uniform electrical field was established through using two counter electrodes parallel to nickel foam cathode. The morphology, crystalline phase and also specific surface area of the deposited nickel hydroxide film onto Ni foam were analyzed using field-emission scanning electron (FE-SEM) and X-ray diffraction (XRD) techniques as well as BET and FT-IR spectroscopy. These analyses proved that a mixed alpha and beta phases of Ni(OH)2 with uniform nanosheets’ morphology are grown onto the nickel foam cathode. The electrochemical investigations using CV, GCD and electrochemical impedance spectroscopy (EIS) manifested the designed electrode provides specific capacitance of 2143 F g−1 at a current density of 0.5 A g−1 with high rate capability of 65% by increasing the current density from 0.5 to 20 A g−1 as well as 90% and 74% cycling stability at the current densities of 5 and 15 A/g, respectively. The excellent electrochemical performance of the as-prepared electrode is ascribed to the simultaneous deposition of both α and β phases through using a facile electrochemical deposition method. The presence of α and β phases guarantees the high specific capacitance and high cycling stability of the prepared electrode, respectively.

Unconventional electro-Fenton process operating at a wide pH range with Ni foam cathode and tripolyphosphate electrolyte

We propose an unconventional electro-Fenton (EF) system with a nickel-foam (Ni-F) cathode and tripolyphosphate (3-PP) electrolyte at near-neutral pH (EF/Ni-F-3-PP) to overcome pH restrictions in EF while preventing Ni-F corrosion. Response surface modelling was used to optimize the main operating parameters with a model prediction analysis (R2 = 0.99): pH = 5.8, Fe2+ = 3.0 mM and applied current = 349.6 mA. Among the three variables, the pH exerted the highest influence on the process. Under optimal conditions, 100 % of phenol removal was achieved in 25 min with a pseudo-first-order apparent rate constant (kapp) of 0.2 min−1, 3.2-fold higher than the kapp of EF/Ni-F with SO42− electrolyte at pH 3. A mineralization yield of 81.5 % was attained after 2 h; furthermore, it was found that 3-PP enhanced H2O2 accumulation by preventing bulk H2O2 decomposition. Finally, toxicity evaluation revealed the formation of toxic by-products at the early stages of treatment, which were totally depleted after 2 h, demonstrating the detoxifying capacity of the system. In conclusion, this study shows for the first time the potential of Ni-F as a cathode for EF under near-neutral conditions, rendered possible by the 3PP electrolyte. Under these conditions, the Ni-F corrosion issue could be alleviated.

A Bifunctional Electroactive Ti4O7-Based Membrane System for Highly Efficient Ammonia Decontamination

Herein, an electroactive filtration system, consisting of a Ti4O7 anode and a Pd-Cu co-modified nickel foam cathode, was developed and applied for the decontamination of ammonia from water. When assisted with an external electrical field, ClO• was generated on the surface of the Ti4O7 anode, which then reacted selectively with ammonia to generate N2. The anodic byproduct, NO3−, could also be reduced efficiently at the functional cathode to produce N2 as well. Electron paramagnetic resonance technique and radical scavenging tests synergistically verified the essential role of ClO• during the highly efficient ammonia conversion process. Relative to conventional batch systems, the developed flow-through design demonstrated enhanced ammonia conversion kinetics, thanks to the convection-enhanced mass transport. The proposed technology also showed desirable stability across a wide environmental matrix. This work provides new insights for the development of advanced and affordable continuous-flow systems towards effective decontamination of ammonia.

Quantitative evaluation of effects of different cathode materials on performance in Cd(II)-reduced microbial electrolysis cells

Three materials including stainless steel woven mesh (SSM), nickel foam (NF) and carbon cloth (CC) were conducted as cathode in Cd(II)-reduced microbial electrolysis cells (MECs), respectively. By using electrode potential slope (EPS) method, the experimental open circuit potentials of three cathodes were similar, while the SSM cathode showed the smallest resistance (6 ± 1 mΩ m2), following by NF cathode (18 ± 2 mΩ m2) and CC cathode (32 ± 5 mΩ m2). These values were analyzed to predicte higher current density and more positive cathode potential in the MEC with SSM cathode under subsequent operating conditions. Electrochemical performance was more likely to be limited by current density than cathode potential. Accordingly, the MEC with SSM cathode obtained better system performance than that with other cathodes. This study further expands the application of EPS method that quantitatively evaluating and effectively selecting cathode materials for better system performance in Cd(II)-reduced MECs.

A biochar modified nickel-foam cathode with iron-foam catalyst in electro-Fenton for sulfamerazine degradation

A nickel-foam cathode modified by a self-nitrogen-doped biochar derived from waste giant reed was synthesized. The fabricated cathode (B@Ni-F) proved to be with high oxygen reaction reactive (ORR) reactivity and H2O2 selectivity (70.41%) owing to the enrichment of oxygen functional groups and pyridinic N when low-temperature pyrolyzed biochar was incorporated. The charge transfer resistance of B@Ni-F decreased to 7.18 Ω, which was 95.7 Ω for the original nickel-foam, proving by electrochemical impedance spectroscopy (EIS). Expectedly, Its H2O2 accumulation improved 14 times, thus making it comparable with commonly used electrodes like carbon cloth and graphite plate. Subsequently, B@Ni-F cathode and iron-foam (Fe-F) catalyst were firstly used in the electro-Fenton (EF) process for sulfamerazine (SMR) degradation. Double-functional polyphosphate electrolytes including tetrapolyphosphate (4-TPP), tripolyphosphate (3-TPP), pyrophosphate (PP) and Na3PO4 were compared with the conventional Na2SO4 electrolyte in EF for SMR degradation. The absolute rate constant for oxidation of SMR by OH was determined to be (3.4 ± 0.09) × 109 M−1 s−1. SMR degradation enhancement in the presence of polyphosphate-based electrolytes is associated with bulk OH generation from Fe2+- polyphosphate ligand complexes via O2 activation. The Fe2+-3-TPP complexes have relatively higher oxidation ability compared to Fe2+-PP, Fe2+-PO4 species. A plausible SMR oxidation pathway is proposed based on the by-products detected by UPLC-MS/MS and density functional theory (DFT) calculations. The dominant SMR degradation pathway was hydroxylation of aniline residue of SMR, followed with the cleavage of SN and then breakage of aromatic rings.

A Facile Preparation of Hierarchical β-Ni(OH)2@NiAl-LDHs Nanosheets on 3D Nickel Foam as Ultra High Rate Capability Cathode without Binder for Nickel Based Batteries

Designing of economical and high-efficiency electrode materials are received much attention for high-performance rechargeable batteries. Herein, we designed and grown the β-Ni(OH)2@NiAl-LDHs nanostructures on 3D nickel foam (NF) as substrate via a simple in-situ complexation-precipitation method with the one-pot process. More interestingly, the β-Ni(OH)2@NiAl-LDHs are uniformly covered on NF with a hierarchical nanosheets-shaped morphology. The attained β-Ni(OH)2@NiAl-LDHs/NF suggested as advanced cathode without binder in nickel-based batteries. It implies that β-Ni(OH)2@NiAl-LDHs/NF cathode provided the high specific capacities of 423 and 357 mAh g−1 at 20 and 100 A g−1, respectively. Besides, the β-Ni(OH)2@NiAl-LDHs/NF cathode maintains 94.6% of capacity over 10,000 cycles at an ultra-high current density of 100 A g−1, indicating its outstanding rate ability and superb durability. The achieved electrochemical properties are ascribed to its special structure with enhanced binding interaction within the β-Ni(OH)2@NiAl-LDHs and 3D NF. Thus, the reported new material will be a rational way toward the designing of high-performance cathode for nickel based batteries.

Electrocatalytic sulfathiazole degradation by a novel nickel-foam cathode coated with nitrogen-doped porous carbon

A new nickel-foam (Ni-F) based cathode was elaborated by coating nitrogen-doped porous carbon (CN/Ni-F) and applied to the electro-Fenton (EF) treatment of sulfathiazole (STZ, a target pollutant). Both Fourier transform infrared spectra (FITR) and X-ray photoelectron spectroscopy (XPS) results confirmed the abundant presence of surface oxygen/nitrogen-containing functional groups after nitrogen-doped porous carbon (CN) introduction. Linear sweep voltammetry (LSV) showed an improvement of the electroactive surface area, while according to electrochemical impedance spectroscopy (EIS), the charge transfer resistance decreased from 95.7 Ω to 19.7 Ω after CN modification. Results showed that the modified CN/Ni-F cathode, achieved a 15 times improvement of H2O2 accumulation, which represented 13.8 times higher current efficiency (CE) for H2O2 generation via two-electron oxygen reduction. Its H2O2 generation ability was comparable to other carbonaceous cathodes like graphite and carbon cloth. Furthermore, CN/Ni-F also enhanced the electrocatalytic reduction of Fe3+. Regarding STZ degradation by EF, the apparent kinetic rate constant (kapp = 1.15 × 10−2 min−1) was 5.22 times higher than the kinetic rate constant obtained with the unmodified Ni-F cathode (kapp = 2.2 × 10−3 min−1), thus confirming the superiority of CN/Ni-F electrode. In addition, a possible STZ degradation pathway was proposed according to the intermediates identified during EF (aromatic by-products and inorganic ions (SO42−, NH4+ and NO3−)). Finally, 5 cycles experiments showed that the CN/Ni-F cathode had a good stability in terms of H2O2 accumulation and STZ degradation.

Three-dimensional nickel foam electrode for efficient electro-Fenton in a novel reactor

ABSTRACTOne of the bottlenecks often encountered in electro-Fenton technology is its low ability to produce hydrogen peroxide (H2O2). Thus, the hunt of suitable electrodes and reactor are a must to be tackled in order to improve the efficiency of the system. In this study, three-dimensional nickel foam was selected as cathode for in situ generating H2O2 efficiently and graphite was the control group in an enhanced oxygen mass transfer reactor. The micro-structure and electrochemical performance of electrodes were tested by scanning electron microscopy (SEM), X-ray diffraction (XRD), cyclic voltammetry (CV), electro-chemical impedance spectroscopy (EIS) and Tafel polarization techniques, respectively. The concentration of H2O2 produced by nickel foam cathode was 780.63 μmol/L and the removal efficiency of rhodamine B (RhB) was reached to 92.5% in 60 min. SEM and Tafel results showed that both nickel foam and graphite electrodes were porous structure cathodes. Moreover, CV and EIS experimental results indicated nickel foam electrode was controlled by charge transfer process while had a better transfer than graphite electrode. Electron spin resonance (ESR) spectra results demonstrated that the main oxidant species involved was ·OH, accounting for RhB degradation in electro-Fenton progress. Therefore, in terms of pollutant degradation in the electro-Fenton process, nickel foam electrode together with novel reactor was a promising technique.

A Cu[sbnd]Ni bimetallic cathode with nanostructured copper array for enhanced hydrodechlorination of trichloroethylene (TCE)

To address the challenges of low hydrodechlorination efficiency by non-noble metals, a CuNi bimetallic cathode with nanostructured copper array film was fabricated for effective electrochemical dechlorination of trichloroethylene (TCE) in aqueous solution. The CuNi bimetallic cathodes were prepared by a simple one-step electrodeposition of copper onto the Ni foam substrate, with various electrodeposition time of 5/10/15/20 min. The optimum electrodeposition time was 10 min when copper was coated as a uniform nanosheet array on the nickel foam substrate surface. This cathode exhibited the highest TCE removal, which was twice higher compared to that of the nickel foam cathode. At the same passed charge of 1080C, TCE removal increased from 33.9 ± 3.3% to 99.7 ± 0.1% with the increasing operation current from 5 to 20 mA cm−2, while the normalized energy consumption decreased from 15.1 ± 1.0 to 2.6 ± 0.01 kWh log−1 m−3. The decreased normalized energy consumption at a higher current density was due to the much higher removal efficiency at a higher current. These results suggest that CuNi cathodes prepared by simple electrodeposition method represent a promising and cost-effective approach for enhanced electrochemical dechlorination.

High efficiency microbial electrosynthesis of acetate from carbon dioxide using a novel graphene–nickel foam as cathode

AbstractBACKGROUNDMicrobial electrosynthesis (MES) is a biocathode‐driven process, producing high‐value chemicals, from CO2. However, the low efficiency of the biocathode hinders the MES process efficiency significantly.RESULTSA novel 3D graphene–nickel foam (G‐NF) cathode has been fabricated, by hydrothermal approach for the improvement of microbially‐catalyzed reduction at the MES cathode. An increase of 1.8 times in the volumetric acetate production rate was obtained, compared with the untreated nickel foam. In MES with G‐NF, a volumetric acetate production rate of 3.11 mmol L‐1 day‐1 has been achieved; 70% of the electrons consumed were recovered and the final acetate concentration reached 5.46 g L‐1 within 28 days.CONCLUSIONThe hierarchical porous G‐NF cathode improved bacterial colonization and the efficiency of mass, nutrients and protons transfer due to its 3D composition; the graphene coating considerably increased the effective surface area for microbial adhesion, as well as the electron transfer rate of biofilm in the MES. This study attempted to improve the efficiency of the biocathode, and provides a promising large electrode for large‐scale MES devices. © 2017 Society of Chemical Industry