Bare Carbon Cloth Research Articles

Electrochemical activation and characterization of carbon cloth

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

Biocompatible and capacitive PDA-Ov-Co3O4@CC anode augmented exoelectrogens enrichment and extracellular electron transfer in microbial fuel cells

Metal oxides rich in oxygen vacancies (Ov) possess excellent intrinsic conductivity, variable valence metal center and high capacitance, which were potential candidates as microbial fuel cells anode. However, their high bacterial toxicity greatly hindered the activity of biofilm. To solve this issue, in this work, polydopamine (PDA) covered capacitive Ov doped Co3O4 nanosheets were designed and successfully grown on carbon cloth (CC). The introduction of Ov significantly promoted the charge storage, the net charge and the accumulated charge were 217.1 and 2680.3 C/m2, respectively, surpassed Co3O4 anode without Ov. In addition, Ov also decreased the charge-transfer resistance (Rct), effectively accelerating EET. The Rct of PDA/Ov-Co3O4@CC was 29.51 Ω, lower than CC (382.10 Ω). The cover of PDA prevented the direct contact between metal ions and microorganisms, greatly enhanced the bacterial viability. The power density of MFCs with PDA/Ov-Co3O4@CC anode was 2.77 W/m2, 1.45 times higher than that of bare CC (1.90 W/m2). In addition, PDA/Ov-Co3O4@CC anode displayed excellent coulombic efficiency and daily COD removal amount (23.5 % and 147.6 mg/L/d), higher than the control groups. The community analysis showed the abundance of Geobacter on PDA/Ov-Co3O4@CC anode was 91 %, higher than other anodes. Present study developed a facile and effective PDA coating strategy to simultaneously enhance the biocompatibility and capacitance of Ov-rich metal oxides, which will be a promising method for the preparation of high performance MFCs anode.

Real direct urea fuel Fell operation using standalone Ni-based metal-organic framework prepared by ball mill at room temperature

Climate change and health issues are exacerbated by fossil fuel use. Efficient environmental energy conversion devices can reduce these effects. For the first time, we used a simple ball milling approach to manufacture a Nickel-based metal-organic framework (Ni-MOF) at ambient temperature directly onto a carbon cloth surface (Ni-MOF/CC) for a direct urea fuel cell (DUFC) anode. The prepared materials' crystaline structure, surface topography, and elemental content were studied using X-Ray diffraction and a scanning electron microscope with an EDS analyzer. Cyclic voltammetry, impedance electrochemical spectroscopy, and chronoamperometry were used in a three-electrode cell configuration to evaluate the material's electrochemical oxidation efficiency, particularly toward urea. In-Situ, under real fuel cell operation circumstances, we tested the electrodes in a two-electrode cell configuration. The Ni-MOF/CC exhibited a 0.35 V onset potential owed to Ni(OH)2 (Ni+2)/Ni+3 NiOOH active site. The electrode was stable for urea oxidation and operated well under real fuel cell conditions, producing 5 mW/cm2 using 1 M urea. The Ni-based MOF's fast charge and mass transfer capabilities, which was directly synthesized onto the carbon cloth surface, make the produced electrode operate well compared with bare carbon cloth. The results of the current work allow for more efficient environmental energy conversion devices that will reduce global warming.

Enhancing Extracellular Electron Transfer of a 3D-Printed Shewanella Bioanode with Riboflavin-Modified Carbon Black Bioink.

3D printing of a living bioanode holds the potential for the rapid and efficient production of bioelectrochemistry systems. However, the ink (such as sodium alginate, SA) that formed the matrix of the 3D-printed bioanode may hinder extracellular electron transfer (EET) between the microorganism and conductive materials. Here, we proposed a biomimetic design of a 3D-printed Shewanella bioanode, wherein riboflavin (RF) was modified on carbon black (CB) to serve as a redox substance for microbial EET. By introducing the medicated EET pathways, the 3D-printed bioanode obtained a maximum power density of 252 ± 12 mW/m2, which was 1.7 and 60.5 times higher than those of SA-CB (92 ± 10 mW/m2) and a bare carbon cloth anode (3.8 ± 0.4 mW/m2). Adding RF reduced the charge-transfer resistance of a 3D-printed bioanode by 75% (189.5 ± 18.7 vs 47.3 ± 7.8 Ω), indicating a significant acceleration in the EET efficiency within the bioanode. This work provided a fundamental and instrumental concept for constructing a 3D-printed bioanode.

Transitional bimetallic heterostructure catalyst modified anode for microbial fuel cell treatment of high-intensity wastewater

In this paper, transitional bimetallic catalysts (FeS2/MoS2) were prepared by a simple one-step hydrothermal method, which were directly applied to MFC anodes for the treatment of high-concentration wastewater with simultaneous biopower generation. The obtained catalysts were highly biocompatible and favorable for inducing the enrichment of electroactive microorganisms and shortening the initiation cycle. The maximum power density (Pmax) and current density of the obtained anode reached 2.87 W·m−2 and 4.37 A·m−2 under 4000 mg·L−1 influent, which were 171% and 65% higher than that of bare carbon cloth, respectively. The chemical oxygen demand (COD) removal rate reached 98.82%. 16 S rRNA gene sequence analysis showed that the main electrophilic microorganisms induced by FeS2/8%MoS2-modified anodes were Synergistota (30.94%) and Geoalkallbacter (15.93%) compared to CC anodes. The resulting anode possesses excellent redox activity and high biocompatibility, and is simple and inexpensive to prepare. More importantly, it accelerated the extracellular electron transfer rate at the interface between the electroactive bacteria and the anode, providing a new idea of choice for single-chamber microbial fuel cells for low-cost treatment of high-concentration wastewater.

In situ disinfection and green hydrogen production using carbon-based cathodes in seawater electrolysis

Electrolysis is an advanced oxidation process used to treat aquaculture effluents, commonly by employing precious-metal-based electrodes. However, such electrodes increase operation costs, prompting the need for novel electrodes. Low-cost carbon-based electrodes have been suggested as large-surface-area electrodes; however, their stability under long-term electrochemical operation, particularly in natural seawater, should be improved. Herein, carbon-based cathodes were applied in seawater electrolysis for in situ disinfection and green hydrogen production to recycle aquaculture effluents. Functionalized carbon black (CB) generated the highest hydrogen production of 46.6 ± 4 mL (purity ≥99.9 ± 0.05 %), which was 1.4 times higher than that for bare carbon cloth (CC). The production of sodium hypochlorous acid at >600 ± 50 mg/L was higher over functionalized CB/CC than that over bare CC. Within 1 min, the aquaculture effluent was disinfected with a high removal efficiency of 99.5 ± 0.05 %, which was similar to that for a platinum/titanium cathode. The cathodes exhibited higher potential stability (3.7 ± 0.5 V) than platinum/CB/CC under a constant current for 20 h owing to the control of inorganic fouling. Thus, these electrodes are efficient alternatives that can promote commercialization by reducing the costs and facilitate electrochemical and green production of hydrogen and oxidants.

One fell swoop strategized bipolar energy device for triboelectric energy harvesting and electrochemical energy storage

Bipolar energy devices are an essential feature due to the enlargement of intelligent and portable electronics in the present decade. In this work, we demonstrated a bipolar energy device using binder-free MnO2 deposited on carbon cloth (CC) by a one-step electrochemical deposition process (EDP), which was employed for solid-state supercapacitor device (SSCD) and another side of CC with Kapton (KP) as TENG device. The efficiency of the bare CC electrode was boosted by growing uniform porous MnO2 nanoballs on the surface of CC, the standalone CC electrode was aided as a positive tribo-layer, and the Kapton film as the negative tribo-layer in the TENG device. The constructed CC-KP TENG device generated a maximum peak power of 15.11 μW, whereas the MnO2 SSCD delivered energy/power density of 37.41 Wh kg−1/10000 W kg−1, respectively. Overall, the results conclude that these types of bipolar energy devices were splendid and could be used in miniatured low-power electronic devices.

Conductive and capacitive network for enriching the exoelectrogens and enhancing the extracellular electron transfer in microbial fuel cells

Although lots of nanomaterials modified anodes have been reported to improve the bacterial attachment and extracellular electron transfer (EET) in microbial fuel cells (MFCs), the lack of a three dimensional (3D) conductive and capacitive network severely limited MFCs performance. In this work, 3D conductive networks derived from mucor mycelia were grown on carbon cloth (CC), and capacitive FeMn phosphides/oxides were further anchored on these 3D networks by electrochemical deposition (denoted as FeMn/CMM@CC) to simultaneously address the above challenges. As a result, the multivalent metal active sites were evenly distributed on 3D conductive network, which favored the enrichment of exoelectrogens, mass transport and EET. Consequently, the as-prepared FeMn/CMM@CC anode displayed accumulated charge of 131.4C/m2, higher than bare CC. Meanwhile, FeMn/CMM@CC anode substantially promoted flavin excretion and the amounts of nano conduits. The abundance of Geobacter was 63 % on bare CC, and greatly increased to 83 % on FeMn/CMM@CC. MFCs equipped by FeMn/CMM@CC anode presented the power density of 3.06 W/m2 and coulombic efficiency (29.9 %), evidently higher than bare CC (1.29 W/m2, 7.3 %), and the daily chemical oxygen demand (COD) removal amount also increased to 92.6 mg/L/d. This work developed a facile method to optimize the abiotic-biotic interface by introducing 3D conductive and capacitive network, which was proved to be a promising strategy to modify macro-porous electrodes.

Carbon cloth modified by direct growth of nitrogen-doped carbon nanofibers and its utilization as electrode for zero gap flow batteries

The synthetic procedure and characterization of carbon nanofibers (CNFs) grown on carbon cloth (CC) are explored in this study, with a focus on their potential application as electrodes in vanadium redox flow batteries (VRFBs). CC offers an attractive platform for surface modification owing to its conductive properties and three-dimensional architecture, while the N-doped CNFs formed by nitrogen (N) rich composition of melamine precursor enhance wettability of electrolyte and redox reactivity of vanadium ions. Electrochemical assessments reveal that NCC electrodes significantly increase voltage efficiency (VE) and capacity retention in VRFBs compared to bare CC (BCC) electrodes. Notably, NCC demonstrates a VE of 65.9%, surpassing the 55.9% of BCC electrodes. Additionally, NCC maintains superior capacity retention under varying current densities, a crucial factor for VRFBs. Long-term stability tests over 1000 cycles highlight the NCC electrode's durability, with only a minimal decrease in VE. Post-experiment analysis confirms the structural integrity of the CNFs on the CC electrodes, validating their resilience in VRFB operations. In summary, the study introduces a novel approach for fabricating N-doped CNFs on CC, resulting in electrodes that significantly boost VRFB performance in terms of efficiency, capacity retention, and stability, marking a notable advancement in flow battery technology.

N-Doped Carbon Nanowire-Modified Macroporous Carbon Foam Microbial Fuel Cell Anode: Enrichment of Exoelectrogens and Enhancement of Extracellular Electron Transfer.

Microbial fuel cell (MFC) performance is affected by the metabolic activity of bacteria and the extracellular electron transfer (EET) process. The deficiency of nanostructures on macroporous anode obstructs the enrichment of exoelectrogens and the EET. Herein, a N-doped carbon nanowire-modified macroporous carbon foam was prepared and served as an anode in MFCs. The anode has a hierarchical porous structure, which can solve the problem of biofilm blockage, ensure mass transport, favor exoelectrogen enrichment, and enhance the metabolic activity of bacteria. The microscopic morphology, spectroscopy, and electrochemical characterization of the anode confirm that carbon nanowires can penetrate biofilm, decrease charge resistance, and enhance long-distance electron transfer efficiency. In addition, pyrrolic N can effectively reduce the binding energy and electron transfer distance of bacterial outer membrane hemin. With this hierarchical anode, a maximum power density of 5.32 W/m3 was obtained, about 2.5-fold that of bare carbon cloth. The one-dimensional nanomaterial-modified macroporous anodes in this study are a promising strategy to improve the exoelectrogen enrichment and EET for MFCs.

Vanadium nitride decorated carbon cloth anode promotes aniline degradation and electricity generation of MFCs by efficiently enriching electroactive bacteria and promoting extracellular electron transfer

To increase the colonization of electroactive bacteria and accelerate the rate of extracellular electron transfer, a simple coated anode of microbial fuel cell was designed. Here, we took advantage of vanadium nitride (VN) particles to modify the carbon cloth (VN@CC). Compared with bare carbon cloth, the designed VN@CC bioanodes exhibited a larger electrochemically active area, better biocompatibility, and smaller charge transfer impedance. The MFC with VN@CC bioanodes achieved the maximum power density of 3.89 W m−2 and chemical oxygen demand removal rate of 84% when 1000 mg L−1 aniline was degraded, which were about 1.88 and 2.8 times that of CC. The morphology of biofilm and 16s rRNA gene sequence analysis proved that the VN@CC bioanodes facilitated the enrichment of electroactive bacteria (99.02%) and increased the ratio of fast electron transfer in the extracellular electron transfer, thus enhancing the MFC performance of aniline degradation and power output. This work disclosed that it was feasible to increase the overall performance of MFC by enhancing the EET efficiency and presented valuable insights for future work.

Anode amendment with kaolin and activated carbon increases electricity generation in a microbial fuel cell

The bacterial anode is a key factor for microbial fuel cell (MFC) performance. This study examined the potential of kaolin (fine clay) to enhance bacteria and conductive particle attachment to the anode. The bio-electroactivity of MFCs based on a carbon-cloth anode modified by immobilization with kaolin, activated carbon, and Geobacter sulfurreducens (kaolin-AC), with only kaolin (kaolin), and a bare carbon-cloth (control) anodes were examined. When the MFCs were fed with wastewater, the MFCs based on the kaolin-AC, kaolin, and bare anodes produced a maximum voltage of 0.6 V, 0.4 V, and 0.25 V, respectively. The maximum power density obtained by the MFC based on the kaolin-AC anode was 1112 mW‧m−2 at a current density of 3.33 A‧m−2, 12% and 56% higher than the kaolin and the bare anodes, respectively. The highest Coulombic efficiency was obtained by the kaolin-AC anode (16%). The relative microbial diversity showed that Geobacter displayed the highest relative distribution of 64% in the biofilm of the kaolin-AC anode. This result proved the advantage of preserving the bacterial anode exoelectrogens using kaolin. To our knowledge, this is the first study evaluating kaolin as a natural adhesive for immobilizing exoelectrogenic bacteria to anode material in MFCs.

Construction of Zinc‐based Anodes for Electrolytic Zinc‐MnO2 Batteries with High Discharge Voltage and Good Durability

AbstractRechargeable aqueous zinc‐MnO2 batteries have attracted great attention owing to their advantages on safety, power density, and cost. In strong acidic environment, the capacity of MnO2‐based cathode can reach 616 mAh g−1 through a two‐electrons‐transfer process of Mn2+↔MnO2. However, in acidic environment, Zn corrosion, dendrites, and hydrogen evolution reaction (HER) on the anode are rather serious, resulting in low Columbic efficiency (CE) and poor durability. Towards these issues, ZnO with dual‐protection, including C and polyvinyl alcohol (PVA) coating (ZnO@C‐PVA), is developed as initial anode material herein. Compared with bare CC, ZnO, and ZnO@C, reversibility of the ZnO@C‐PVA electrode is largely enhanced. CE of an electrolytic full system using ZnO@C‐PVA as anode and bare carbon cloth (CC) as cathode can be as high as 90 % at 5 mA cm−2, and discharge voltage is up to 1.85 V (mid‐value), which can be maintained for 1,600 cycles, indicating rather good stability. It is believed that the existence of initial ZnO can tune the local pH around the anode, resulting in the decrease of HER and the enhancement of Zn plating. Besides, corrosion and Zn dendrites also can be inhibited effectively by the PVA layer.

Enhanced microorganism attachment and flavin excretion in microbial fuel cells via an N,S-codoped carbon microflower anode

Commonly used dense arrays of nanomaterials on carbon cloth (CC) are not suitable to accommodate microorganisms in microbial fuel cells (MFCs) due to their unmatched size. To simultaneously enrich exoelectrogens and accelerate the extracellular electron transfer (EET) process, SnS2 nanosheets were selected as sacrificial templates to prepare binder-free N,S-codoped carbon microflowers (N,S-CMF@CC) by polymer coating and pyrolysis. N,S-CMF@CC showed a cumulative total charge of 125.70C/m2, approximately 2.11 times higher than that of CC, indicating its better electricity storage capacity. Moreover, the interface transfer resistance and diffusion coefficient in bioanodes were 42.68 Ω and 9.27 × 10-10 cm2/s, respectively, superior to CC (141.3 Ω and 1.06 × 10-11 cm2/s). Remarkably, N,S-codoped carbon microflowers excreted more flavin than CC, as confirmed by continuous fluorescence monitoring. Biofilm and 16S rRNA gene sequence analysis revealed that exoelectrogens were enriched, and nanoconduits were generated on the N,S-CMF@CC anode. In particular, flavin excretion was also promoted on our hierarchical electrode, effectively driving the EET process. MFCs equipped with the N,S-CMF@CC anode could deliver a power density of 2.50 W/m2, coulombic efficiency of 22.77 %, and chemical oxygen demand (COD) removal amount of 90.72 mg/L/d, higher than that of bare CC. These findings not only demonstrate that our anode is capable of solving the cell enrichment issue, but it may also increase EET rates by bound flavin with outer membrane c-type cytochromes (OMCs) to simultaneously boost the power generation and wastewater treatment performance of MFCs.

A carbon cloth with a coating layer containing aluminum fluoride as an interlayer for lithium metal batteries

Problems in safety and cell performance from dendritic growth of lithium and formation of dead lithium on the surface of electrode during charge has impeded commercialization of lithium metal as an electrode of lithium rechargeable batteries. To solve these problems, use of lithiophilic materials on lithium metal electrode has been suggested. Herein, we propose an interlayer for lithium metal battery composed of carbon cloth with a coating layer containing lithiophilic aluminum fluoride (AlF3). The positive effects of AlF3-containing layer on the carbon cloth on the performance of lithium metal anode are investigated through cycling of Li||Li symmetric and LiCoO2||Li half-cells. We demonstrate that the enhanced cycling stability with the interlayer is attributed to the LiF-rich SEI layer in-situ formed from the reaction between AlF3 and lithium-ions in cycling and suppressed formation of dendrites and dead lithium during lithium plating process. The LiF-rich SEI layer on the carbon cloth induces uniform plating of lithium above and inside the interlayer while the bare carbon cloth results in irregular and local plating of lithium. The reduced decomposition of the electrolyte by the AlF3-containing layer is also considered to be the reason for the improved cycling stability of the lithium metal anode.

Porous reduced-graphene oxide supported hollow titania (rGO/TiO2) as an effective catalyst for upgrading electromethanogenesis

Microbial electrochemical system (MES) for enhancing methane production has gained significant interest during the recent years, but the practical applications of MES are still far away due to several limitations such as low efficiency of cathodic electrochemical kinetics. In this study, novel porous reduced-graphene oxide/hollow titania (rGO/TiO2) was successfully synthesized to be used as cathode catalyst for promoting electrochemical reduction of CO2 to methane. The MES operation with rGO/TiO2 catalyst exhibited 15.4% higher methane yield (0.383 ± 0.01 LCH4/gCOD) and 13.4% higher production rate (152.38 mL/L.d) compared to control MES with bare carbon cloth cathode. The MES-rGO/TiO2 produced around 33% higher in total Coulomb at 3837.9 ± 351.5C compared to the pristine cathode at 2887.92 ± 254.6C. Substrate degradation and volatile fatty acids conversion were significantly improved in the presence of rGO/TiO2 catalyst. By using cyclic voltammetry and electrochemical impedance spectroscopy analysis, rGO/TiO2 was proved to ease the electron transfer efficiency of working cathode for the conversion of electron to methane. The results suggest that porous rGO/TiO2 can be a promising cathode catalyst to upgrade the performance of a scalable methane-producing MES-AD system.

Effects of Oxygen Cathode Substrates with Various Carbon Catalysts on the Discharge Capacity of Lithium-Oxygen Battery

Lithium-oxygen batteries have been considered strong candidates to supersede current rechargeable batteries especially lithium-ion batteries. Despite having tremendously high theoretical energy density, the practically achievable energy density is far from commercial application till date. The oxygen electrode is one of the major bottlenecks in maximizing the battery capacity. It is comprised of a porous structure (mainly carbon) with high surface area and sufficient reaction sites. High porosity facilitates lithium ion and oxygen mass transfer and results in high storage capacity for the insoluble discharge product during discharging. The cathode electrode is fabricated by coating a catalyst layer on a porous carbon substrate. The substrate, which contacts with oxygen channels, plays a vital role in mass transfer of oxygen from outside to the reaction sites. Therefore, it is important to select a substrate that does not clog with deposition of Li2O2 particles immediately after discharging begins and allows oxygen to reach the catalyst side for longer period of time.This study investigates the effects of oxygen electrode substrates with various coating materials on the discharge capacity of lithium-oxygen battery. For this purpose, we have compared the discharge capacity of plain carbon cloth, plain carbon paper and carbon cloth or carbon paper coated with carbon catalysts including Vulcan XC, Super P and Graphene Oxide. 1.5mg/cm2 (+/-0.3mg/ cm2) is used as catalyst loading. The electrolyte used in this study is 1M LiTFSI in TEGDME. PTFE (30wt%) is used as a binder. All experiments are conducted at room temperature with pure oxygen supply.With carbon cloth as a substrate, the discharge capacities obtained were 3 to 6 times higher (depending on the carbon catalysts coated) than the capacities obtained with carbon paper. The bare carbon cloth, Vulcan XC, Super P and Graphene oxide with carbon cloth as a substrate have discharge capacities of 0.11 mAh/mg, 13 mAh/mg, 6.8 mAh/mg, 1.5 mAh/mg respectively. On the other hand, the discharge capacities achieved with bare carbon paper, Vulcan XC, Super P and graphene oxide with carbon paper as substrate were 0.02 mAh/mg, 2.4 mAh/mg, 2.7 mAh/mg, 0.28 mAh/mg respectively. The results clearly indicate that the cathode with carbon cloth as a substrate yields significantly higher discharge capacity with all the coating materials as compared with the carbon paper. The different performances of two substrates can be attributed to their structure and pore size distribution. Carbon cloth is composed of flexible woven threads with longer lengths ( ̴ 30µm) and broader pore size distribution (5-200 µm) with peaks at 10, 70 and 100 µm. This type of structure is favorable in reducing tortuosity, enhancing mass transport of oxygen and lithium ion and improving ionic conductivity. On the other hand, the structure of carbon paper comprises of non-woven short carbon fibers ( ̴ 15µm) and smaller pore size distribution range (10-70 µm) with a peak at 50 µm. This renders poor transport of oxygen from outside to the reaction sites leading to lower discharge capacity.The primary function of coating materials is to increase surface area of cathode thereby providing more reaction sites and creating tri-phase boundaries for reaction to take place. These catalysts also have different pore size distributions and resistance to mass transfer. Therefore, various carbon catalysts used yield different discharge capacity with same substrate.

Nickel-incorporated electrochemical activated carbon cloth for efficient and robust water oxidation activity

Carbon cloth is treated with a moderate electrochemical activation strategy to enrich its surface functional groups. In result, the hydrophilicity and intrinsic activity of carbon cloth (CC) can be enhanced. Furthermore, the activated carbon cloth (ACC) can adsorb massive transition-metal like nickel ions with a wet chemistry method. Combined with a low temperature thermal reduction under the atmosphere of Ar/H2, nickel-incorporated activated carbon cloth (Ni-ACC) can be obtained. In comparison with bare CC and nickel-incorporated carbon cloth (Ni-CC), the Ni-ACC displays more superior activity and durability of water oxidation in alkaline environment. The overpotential at the current density of 10 mA cm−2 (η10) is maintained at 245 mV after chronopotentiometry (CP) test for 24 h. The electrochemical activated method can serve as a simple approach for fabricating various metal-incorporated ACC.

Electro-Fenton Degradation of Selected Antiretroviral Drugs Using a Low-Cost Iron-Modified Carbon-Cloth Electrode

Human immunodeficiency virus (HIV) and acquired immune deficiency syndrome (AIDS) causes morbidity and mortality in infected patients. These epidemics are significantly reduced and treated globally with antiretroviral drugs (ARVDs). However, the eventual disposal of the ARVDs, either by excretion or otherwise enables them to end up as emerging hazardous contaminants in our environment. Of all the available methods to remove ARVDs from our water bodies, electrochemical methods are reckoned to be the most effective. As a result, it is imperative to acknowledge the interactive behavior of these pharmaceuticals on the surface of the electrode. In this study, iron particles were deposited on the carbon-cloth electrode by electrodeposition using chronoamperometry techniques. The synthesized electrode was characterized using scanning electron microscopy (SEM) with energy-dispersive X-ray spectroscopy (EDS) and X-ray photoelectron spectroscopy (XPS) analysis. The electrochemical characterization of the material was also carried out using cyclic voltammetry (CV) and electrical impedance spectroscopy (EIS). Applicability of iron-supported carbon-cloth (CC) electrode was investigated by the electrochemical degradation of neivrapine (NVP), lamivudine (LVD), and zidovudine (ZDV) in wastewater as a model for organic pollutants in 50 mM K2SO4 electrolyte at a pH of 3. The SEM and EDX analysis showed the formation of iron nanoparticles within the matrix structure of the CC electrode. The XPS enlightened the presence of oxygen functional groups in the electrode’s structure. EIS results are indicative that the modified electrode has a decreased charge transfer resistance (Rct) value as compared to the bare CC electrode. On the other hand, a CV result fosters good conductivity, enhanced current and large surface area of the modified electrode. Electrochemical studies with the modified CC electrode by electro-Fenton (EF) process show a decrease in the initial ARVDs concentration (20 mg/L) as compared with a bare electrode. Their rate constants were 1.52 × 10–3 mol−1 min−1 for ZDV, 1.20 × 10–3 mol−1 min−1 for NVP, and 1.18 × 10–3 mol−1 min−1 for LVD. The obtained removal efficiencies indicate that the iron particle in the synthesized improves the degradation efficiency.

MnO2/reduced graphene oxide nanohybrids as a cathode catalyst for the microbial reduction of CO2 to acetate and isobutyric acid

Microbial electrochemical synthesis (MES) can promote an electro-reduction of CO2 to value-added products with nanohybrid catalysts for efficient electron and mass transfer. This study aimed to develop a novel electrode made of nanowires interconnected with flower-like morphology of MnO2 decorated over reduced graphene oxide (rGO) for the conversion of CO2 to volatile fatty acids (VFAs) in a single-chamber MES. The carbon cloth modified with MnO2/rGO nanohybrids could increase CO2 absorption capacity and reduce electron transfer resistance by 70% compared to bare carbon cloth. This modified cathode catalyst enhanced the production of isobutyric acid (15.9 mM) and acetate (3.5 mM), which were 2.09 and 2.91 times higher, respectively, then bare carbon cloth, and the maximum columbic efficiency of 66.4% was obtained for both products. Linear sweep voltammetery of the MnO2/rGO nanohybrids cathode electrode indicated a positive shift of the onset potential under turnover condition. Scanning electron microscopy revealed a diverse enhanced bacterial biofilm growth on the surface of the modified electrode. This study suggests that the MES system with modified cathode using a nanostructured MnO2/rGO nanohybrids catalyst can be used to enhance the CO2 electro reduction to high-value VFAs, which can be further developed as carbon capture and utilization (CCU) technology.