Stainless Steel Anode Research Articles

Novel application of electrochemical chloride extraction fixing polymer-modified conductive repair mortar as anode

Electrochemical chloride extraction (ECE) technique provides an effective technique to remove the chloride ions from concrete and realize reinforcements performance recovery. In this study, a novel type of polymer-modified conductive repair mortar (PCRM) was developed as the anode of ECE system, while the impacts of electrochemical parameters, anode types and reinforcements layout on the chlorides extraction efficiency were investigated, in addition, an innovative method is also proposed to further enhance the ECE efficiency. The results highlight that PCRM can be successfully fabricated with proper initial/final setting time, which presents the similar extraction efficiency compared with PC-based repair mortar and stainless-steel mesh anode. Furthermore, reinforcement cages provide target concrete with lower extraction efficiency inside the cage, and the efficiency can be remarkably increased by pulse current. Most importantly, the chloride extraction efficiency of PCRM anode is increased from 45.1% to 59.6% (electrochemical parameters), 53.7% (reinforcements layout), 60.2% (pulse current), respectively.

Polarity Effect of Stainless-Steel and Copper Electrode Materials for the Purification of Slaughterhouse Wastewater

Although electrochemical methods are one of the most efficient approaches for treating wastewater, the type of wastewater to be treated, the type of electrode material employed, and the polarity direction all significantly affect how well these systems work. The prospective application of the proposed materials for the purification of slaughterhouse effluent has not been sufficiently explored in earlier studies, despite the fact that the materials (copper and stainless-steel) are reasonably inexpensive and easily accessible, especially in low-income countries. It is also unfortunate that previous research has not taken into account the potential effect of polarity direction in stainless-steel and copper electrode materials used for the purification of slaughterhouse effluent. This study investigated the potential effect of polarity direction for the purification of slaughterhouse wastewater using stainless-steel and copper electrode materials. Two electrode polarities were used in the study; stainless-steel (anode) to copper (cathode) and copper (anode) to stainless-steel (cathode). The potential effect of the contact time on the pollutants’ removal was also taken into account. Generally, the copper-to-stainless-steel polarity showed a relatively high removal efficiency compared to the stainless-steel-to-copper electrode polarity. For instance, under 20 min of contact time, the removal efficiencies of copper (anode) to stainless-steel (cathode) were higher than that of stainless-steel (anode) to copper (cathode) in 11 out of 14 investigated water quality parameters. From 40 min contact time, the copper (anode) to stainless-steel (cathode) performed higher than that of stainless-steel (anode) to copper (cathode) in 8 out of 14 investigated water quality parameters. Moreover, from 60 min contact time, the copper (anode) to stainless-steel (cathode) performed higher than that of stainless-steel (anode) to copper (cathode) in 11 out of 14 investigated water quality parameters. Based on the findings, it is clear that, in order to obtain desired performance, contact time and polarity direction should be carefully considered when developing electrochemical wastewater treatment systems.

Activation of stainless steel 316L anode for anion exchange membrane water electrolysis

The increased emphasis on renewable energy has resulted in a surge of R&D efforts into hydrogen and battery research. The intensive electrochemical environment surrounding the anodic oxygen evolution reaction (OER) has plagued both the activity and stability of the catalytic layer, substrate and porous transport layer, ultimately affecting both these industries. Herein, we report the benefits of potential cycling (PC) a 316L stainless steel felt porous transport layer (PTL) for use in anion exchange membrane water electrolysis. The PC increased surface roughness and created a CrFe5Ni2-OxHy layer through the oxidation of iron as shown by SEM, EDS, XPS, XRD and Raman spectroscopy. Post-PC tests in a three-electrode setup reveal a ≈ 68% decline in polarisation resistance, which is reflected in its performance when employed as an anode in an anion exchange membrane water electrolyser (AEMWE). Overall, potential cycling the PTL under anodic conditions resulted in an improved performance when tested in a AEMWE. Implementing this treatment on stainless steel anodes could be considered to achieve an improved AEMWE performance.

Regulation of Stainless Steel Electrode Characteristics through Thermal Oxidation at Various Temperatures Induces Different Microbial Electrochemical Performances

The impact of thermal treatment at various temperatures on the properties of stainless steel (SS) anodes and subsequent bioelectricity generation is investigated in this study. It is observed that thermal oxidation at different temperatures significantly affects the characteristics of SS anodes. SS electrodes treated at 900 °C resulted in the best bioelectricity generation of Shewanella oneidensis MR-1 with a peak current density and power density of 0.36 ± 0.08 A m–2 and 1.15 ± 0.02 W m–2, respectively. Both experiments and molecular dynamics simulations indicate that such improvements may be due to not only the good biocompatibility of heat-treated SS electrodes but also the enhancement of direct extracellular electron transfer of S. oneidensis MR-1 to the anode. Moreover, using a home-made microfluidic device, we find that the biofilms on heat-treated SS electrodes exhibit better stability compared to unaltered ones. This study provides theoretical support for the application of SS electrodes in microbial electrochemistry technology.

Electrochemical treatment of hemodialysis wastewater including pharmaceutical products

Hemodialysis is an extracorporeal kidney replacement procedure to remove impurities or waste products from the blood that is used in the treatment of kidney failure. During this process, large amounts of water are used, which, lacking control, end up in sewage systems, potentially flushing high levels of organic and inorganic contaminants into the receiver's aqua biota. This research considered the treatment of synthetic hemodialysis water under acid and basic conditions. To better simulate the presence of organic compounds, 10 mg L−1 of amoxicillin, an antibiotic commonly present in wastewater from clinics and hospitals, was added. Laboratory and pilot tests were performed using coupled electrocoagulation and electro-oxidation. During electrocoagulation, the use of stainless steel and aluminum, as sacrificial anodes, were compared in acidic and basic pH. The stainless steel rod anode and a titanium mesh cathode were used during electrocoagulation in acidic conditions at a field strength of 3.0 V which was applied for 60 min. After electrocoagulation, the solution obtained was filtered to separate precipitates. The supernatant was then treated with electro-oxidation using an IrO2-Ta2O5|Ti anode and the titanium mesh cathode while applying 10 mA for 120 min. Wear of the stainless steel anode was identified by scanning electron microscopy and microanalysis. Removal of organic compounds including amoxicillin was significant. These results were confirmed by decreased contaminant concentration found by diode coupled chromatography detection. In the final analysis this coupled treatment system completely eliminated amoxicillin and significantly reduced entrained salts.

High-current density alkaline electrolyzers: The role of Nafion binder content in the catalyst coatings and techno-economic analysis.

We report high-current density operating alkaline (water) electrolyzers (AELs) based on platinum on Vulcan (Pt/C) cathodes and stainless-steel anodes. By optimizing the binder (Nafion ionomer) and Pt mass loading (mPt) content in the catalysts coating at the cathode side, the AEL can operate at the following (current density, voltage, energy efficiency -based on the hydrogen higher heating value-) conditions (1.0A cm-2, 1.68 V, 87.8%) (2.0A cm-2, 1.85 V, 79.9%) (7.0A cm-2, 2.38 V, 62.3%). The optimal amount of binder content (25wt%) also ensures stable AEL performances, as proved through dedicated intermittent (ON-OFF) accelerated stress tests and continuous operation at 1A cm-2, for which a nearly zero average voltage increase rate was measured over 335h. The designed AELs can therefore reach proton-exchange membrane electrolyzer-like performance, without relying on the use of scarce anode catalysts, namely, iridium. Contrary to common opinions, our preliminary techno-economic analysis shows that the Pt/C cathode-enabled high-current density operation of single cell AELs can also reduce substantially the impact of capital expenditures (CAPEX) on the overall cost of the green hydrogen, leading CAPEX to operating expenses (OPEX) cost ratio <10% for single cell current densities ≥0.8A cm-2. Thus, we estimate a hydrogen production cost as low as $2.06 kgH2 -1 for a 30 years-lifetime 1MW-scale AEL plant using Pt/C cathodes with mPt of 150μg cm-2 and operating at single cell current densities of 0.6-0.8A cm-2. Thus, Pt/C cathodes enable the realization of AELs that can efficiently operate at high current densities, leading to low OPEX while even benefiting the CAPEX due to their superior plant compactness compared to traditional AELs.

Electrocoagulation of Corrugated Box Industrial Effluents and Optimization by Response Surface Methodology.

The electrocoagulation method using stainless steel anodes was applied to a corrugated cardboard box manufacturing plant’s wastewater with high COD content. The effects of current density, processing time and stirring speed on response functions were studied using the Response Surface Methodology (RSM). The removal efficiency of chemical oxygen demand (COD) and energy consumption were selected as response functions. The Central Composite Design (CCD) was chosen to explain the single and combined effects of independent variables on response functions. The COD concentration of the real industrial wastewater used in the experiments was 9130 mg L−1. The maximum COD removal efficiency of 91.6% is obtained with 19.78 Wh g−1 energy consumption. Current density and treatment time were effective parameters for both COD removal and energy consumption. Optimization for maximum COD removal with minimum energy consumption showed 80.9% of COD removal with 6.7 Wh g−1 of energy consumption at 15 mA cm−2, 700 rpm, and 28 min treatment time. The variables are optimized with a few experiments using the response surface method.Graphical abstract

Multiphase Alloy Nuclear Waste Forms Developed for Pyrochemical U-10Mo Scrap Recovery Waste Streams

The US High Performance Research Reactor (USHPRR) Conversion program is developing an Al-clad Zr-bonded U-10Mo nuclear fuel foil to enable the conversion of research reactors to high-assay low-enriched uranium (HALEU) alloy fuel. Fabrication scrap from the fuel manufacturing will be electrorefined to recover the HALEU, which will generate waste streams consisting of Zr, Mo, and residual U retained in the stainless steel anode basket used in the electrorefiner. Four alloys were formulated with different relative amounts of Zr, Mo, and 316L-SS to represent the expected range of waste compositions. Laboratory-scale ingots were made and metallurgically characterized to assess differences in the microstructures and distributions of the surrogate waste metals. Different amounts of the same dominant phases with similar compositions were formed in most materials: a γ-austenite based matrix, two ZrFe2 intermetallic phases that could host residual uranium, an FeCrMo sigma (σ) intermetallic phase, a chi (χ) phase, and a secondary austenite (γ2) phase. Electrochemical tests were conducted to compare the corrosion behaviors in acidic and alkaline brine solutions for a range of simulated environmental redox conditions. Corrosion of the Mo-rich γ and γ2 solid solutions and the σ and χ intermetallic phases occurred. The multiphase alloy waste form formulated with the lowest molybdenum and highest zirconium contents showed the highest corrosion resistance and has sufficient amounts of ZrFe2 to immobilize trace amounts of residual uranium in the waste stream. The alloy formulation strategy and testing approach will be presented with key results.Work conducted at Argonne National Laboratory is operated for the U.S. Department of Energy, Office of Science under contact DE-AC02-06CH11357.

Bio-electrocatalytic degradation of tetracycline by stainless-steel mesh based molybdenum carbide electrode.

In order to treat antibiotic wastewater with high efficiency and low energy consumption, this study proposed the coupling of electrocatalytic degradation and biodegradation, and explored a new modified electrocatalytic material in the coupling system. The stainless-steel mesh based molybdenum carbide (SS-Mo2C) was prepared by a low-cost impregnation method and showed superior electrocatalytic degradation ability for tetracycline (TC) when used as the anode in the electrocatalytic system. The degradation rate of TC with SS-Mo2C anode was 17 times higher than that of stainless-steel (SS) anode, and TC removal efficiency was 77% higher than that of SS anode. The electrocatalytic system prior to the biological reactor was proven to be the optimal coupling method. The external coupling system achieved a significantly higher TC removal (87.0%) than that of the internal coupling system (65.3%) and SS-Mo2C showed an excellent repeatable and stable performance. The fewer and smaller molecular weight intermediates products were observed in bio-electrocatalytic system, especially in the external coupling system. Alpha diversity analysis further confirmed that bio-electrocatalytic system increased the diversity of the microbial community. The stainless-steel mesh based molybdenum carbide (SS-Mo2C), which was prepared by a simple and low-cost impregnation method, significantly improved the electrocatalytic activity of anode, thus contributing to tetracycline removal in the bio-electrocatalytic system, especially in the external coupling system.

Development of polypyrrole nanotube coated with chitosan and nickel oxide as a biocompatible anode to enhance the power generation in microbial fuel cell

In this work, polypyrrole nanotubes (PPy-NT) are prepared by using a soft template of methyl orange and applied as anode catalyst in single chamber microbial fuel cell (SMFC). The coating of chitosan over PPy-NT (CHI@PPy-NT) provides good biocompatibility, proven by the increase in power density of the CHI@PPy-NT anode based SMFC compared to PPy-NT anode based SMFC. With the objective for further improvement in electrochemical efficiency, PPy-NT are coated with chitosan along with nickel oxide (NiO/CHI@PPy-NT) through hydrothermal method. XRD, FTIR, and XPS studies are used to characterize the structural and functional groups of the prepared nanocomposite. Morphological features reveal that nickel oxide is uniformly dispersed in chitosan coated on the surface of polypyrrole nanotubes. Cyclic voltammetry characterization shows high oxidation peak for CHI@PPy-NT (−0.0282 mA) and NiO/CHI@PPy-NT (−0.0286 mA), in comparison to PPy-NT (0.00860 mA). The coating of stainless steel mesh (SSM) anode with NiO/CHI@PPy-NT generates power density of 755 mW m−2, which is 4.4 times higher than the power density for bare stainless steel anode (170 mW m−2). Additionally, the charge transfer resistance obtained from the bare SSM is 817 Ω, 4.9 times high than the NiO/CHI@PPy-NT (165.3 Ω) modified SSM anode based MFC.

Electrochemical Advanced Oxidation of Lamotrigine at Ti/DSA (Ta2O5-Ir2O5) and Stainless Steel Anodes

The study presents kinetics of degradation and mineralization of an anti-epileptic drug Lamotrigine (LAM) in the aqueous matrix by electrochemical advanced oxidation process (EAOP) on Ti/DSA (Ta2O5-Ir2O5) and Stainless Steel (SS) anodes using sodium sulphate as supporting electrolyte. On both the anodes, kinetic behaviour was pseudo-first-order for degradation as well as mineralization of LAM. On Ti/DSA anode, maximum LAM degradation of 75.42% was observed at an associated specific charge of 3.1 (Ah/litre) at a current density of 1.38 mA/cm2 and 100 ppm Na2SO4 concentration. Maximum mineralization attained was 44.83% at an associated specific charge of 3.1 (Ah/litre) at a current density of 1.38 mA/cm2 and 50 ppm concentration of Na2SO4 with energy consumption of 2942.71 kWh/kgTOC. Under identical conditions on SS anode, a maximum of 98.92% LAM degradation was marked after a specific charge (Q) of 3.1 (Ah/litre) at a current density of 1.38 mA/cm2 and 100 ppm concentration of Na2SO4. Maximum LAM mineralization on SS anode was 98.53%, marked at a specific charge of 3.1 (Ah/litre) at a current density of 1.38 mA/cm2 and 75 ppm concentration of Na2SO4, with energy consumption of 1312.17 kWh/kgTOC. Higher Mineralization Current Efficiency (MCE) values were attained for EAOP on SS anode for both degradation and mineralization due to occurrence of combined electro-oxidation and electro-coagulation process in comparison to EAOP on Ti/DSA anode due to occurrence of lone electro-oxidation process.

The Effects of Surface Roughness of the Stainless-Steel Anode on Electricity Enhancement of Microbial Fuel Cell

Microorganisms actively catabolize substrate, and bioelectricity is generated. Microbial fuel cells (MFCs) could be utilized as a power generator in small devices. The discovery of species of microorganisms is called Rhodopseudomonas palustris KU-EGAT 13. The experiments have been conducted with the production of electricity from this type of microorganism in a single chamber microbial fuel cell. The study used 4 surface roughness of anode electrode single chamber micro fuel to study the performance of microbial fuel cell effect from the anode. Three stainless steel plates were polished to uniform roughness to the magnitude between 0.05 and 1 µm. After 24 h of experimentation, the rough electrode’s open-circuit voltage (OCV) and power densities were much higher than that produced by the smooth one. Moreover, the smooth surface is higher than the charge-transfer resistance of the rough electrode. The rough surface’s better electrochemical performance is due to denser biofilm grown on the surface, which was observed by scanning electron microscopy (SEM) and figuring out the microbial number in an image using an ImageJ program.&#x0D; HIGHLIGHTS&#x0D; &#x0D; The new discovery of species of microorganisms is called Rhodopseudomonas palustris KU-EGAT 13 which can produce electricity in a single chamber microbial fuel cell&#x0D; The performance of MFCs has gotten an effect from the different anode surface roughness.The biomass growth is larger than a rougher anode surface, which contributes to anode’s efficiency&#x0D; After observed by SEM, found that when it is in the highest anode surface roughness directed towards the number of microbes stick on the surface&#x0D; &#x0D; GRAPHICAL ABSTRACT

Treatment of livestock slaughterhouse wastewater by the electrochemical method using stainless steel and copper electrodes

AbstractElectrochemical methods provide one of the most effective approaches for wastewater treatment. However, the performance of these systems is highly dependent on the type of wastewater to be treated and the electrode material used (including some relatively cheap and readily available materials such as stainless‐steel and copper). Unfortunately, the applicability of stainless steel as anode and copper as cathode electrodes materials for the purification of livestock slaughterhouse wastewater has not been captured in the previous studies. This study investigated the potential of combining stainless steel (anode) and copper (cathode) as electrode materials for the purification of livestock wastewater. The influence of contact time (20, 40, and 60 min) on the pollutants’ removal efficiency was also investigated. From the analysis results, it was observed that the contact time and type of pollutant to be removed had a significant influence on the removal efficiency of the electrochemical treatment system. The highest removal efficiency was achieved from the combination of TSS and 60‐min contact time, with 92% removal efficiency. While the lowest removal efficiencies was observed from the combination of phosphates, nickel, aluminum, and ammonia and 10 min contact time; with removal efficiencies of 22.6%, 23.4%, 34.3%, and 34.3%, respectively. However, in terms of general removal efficiency (after 60 min of the contact time), the lowest removal efficiency was observed from ammonia with a removal efficiency of 62.2% . The treatment system also achieved high removal efficiencies for some other parameters such as Turbidity, Color, TSS, COD, BOD, and TOC ranging from 85.5% to 89.2% after 60 min of the contact time.

Cytotoxicity of a Cell Culture Medium Treated with a High-Voltage Pulse Using Stainless Steel Electrodes and the Role of Iron Ions.

High-voltage pulses applied to a cell suspension cause not only cell membrane permeabilization, but a variety of electrolysis reactions to also occur at the electrode–solution interfaces. Here, the cytotoxicity of a culture medium treated by a single electric pulse and the role of the iron ions in this cytotoxicity were studied in vitro. The experiments were carried out on mouse hepatoma MH-22A, rat glioma C6, and Chinese hamster ovary cells. The cell culture medium treated with a high-voltage pulse was highly cytotoxic. All cells died in the medium treated by a single electric pulse with a duration of 2 ms and an amplitude of just 0.2 kV/cm. The medium treated with a shorter pulse was less cytotoxic. The cell viability was inversely proportional to the amount of electric charge that flowed through the solution. The amount of iron ions released from the stainless steel anode (>0.5 mM) was enough to reduce cell viability. However, iron ions were not the sole reason of cell death. To kill all MH-22A and CHO cells, the concentration of Fe3+ ions in a medium of more than 2 mM was required.

Removal of salicylic acid by electrochemical processes using stainless steel and platinum anodes

Salicylic acid is an important pharmaceutic and widely used in plant hormones and personal care products. Peroxicoagulation (PC) method has recently been employed in treatment of various pollutants. In general, carbon-based cathode materials such as graphite and carbon fiber are used for in situ H2O2 production and stainless steel (SS316-L) anode for low iron production in PC studies as an efficient system modification. This study was conducted to investigate salicylic acid removal efficiency of electrochemical processes. Stainless steel was used as anode in this study. It was believed that the oxidation effect of stainless steel could be responsible for partial removal of salicylic acid. In this study, stainless steel anode and graphite or carbon fiber cathodes were employed in PC treatments for removing salicylic acid from aqueous solution, and some model trials were also made to investigate the in-situ Fe2+ and H2O2 production performance. Present findings revealed a total organic carbon (TOC) removal of 30.5% and salicylic acid removal of 69.5% at optimized conditions. The EF system modification used in the study can be proposed as an easy, low-cost and effective treatment alternative for treatment of pharmaceutical industry wastes such as salicylic acid.

Electrochemical Mineralization Kinetics of Metformin

Present work analyzes the kinetic study of mineralization during electro-oxidation on Ti/DSA (Ta2O5-Ir2O5) and combined electro-oxidation and electro-coagulation on stainless steel anode of an antidiabetic drug metformin hydrochloride (MET-HCl) in synthetic wastewater over a specific charge. Four different reaction orders (0.5, 1, 1.5 and 2) were tested using the integral analysis method by plotting TOC concentration terms over specific charges to determine the exact rate kinetics for the mineralization. The effect of applied current density was evaluated at 50 ppm of sodium sulphate as supporting electrolyte, and the effect of supporting electrolyte concentration was also assessed at a current density of 0.93 mA/cm2 in 50 ppm MET-HCl solution. As a result of (i) electro-oxidation experiments on MET-HCl, carried out on Ti/DSA anode, and (ii) combined electro-oxidation and electro-coagulation experiments carried out on stainless steel anode, based on the R-squared value of the mineralization curves, the first-order reaction rate was proposed.

Insights into carbon production by CO2 reduction in molten salt electrolysis in coaxial-type reactor

With carbon capture and utilization (CCU) technologies, it is possible to take CO2 from air and transform it into valuable carbon products, such as graphene and nanotubes. In this study, CO2 was reduced to solid carbon by molten lithium carbonate salt electrolysis. The reactor used for the electrolysis was a coaxial-type unit, where a cylindrical nickel cathode was placed inside a cylindrical stainless steel vessel; such a coaxial-type reactor has not been used before for molten salt electrochemical reduction of CO2. This reactor design allows studies of voltage-current characteristics, which have previously not been conducted for this specific process. As a result, voltage efficiency of this process could be determined along with effect of temperature to cell voltage. Based on these results it is evident that accurate temperature control is crucial in terms of energy efficiency of the process. Data monitoring revealed a high accuracy of temporal temperature control. Great temperature differences were observed spatially. Thermoneutral voltage from the process was determined to be 1.02 V. For this electrochemical process studied, carbon nano-onions (CNOs) were obtained as a main product. Identification of the product was carried out based on Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM) and X-Ray Diffraction (XRD) analyses. Results also showed that iron, chromium and nickel metals are released during electrolysis. Iron and chromium can only be released from the stainless steel anode, as nickel can come from anode or cathode.

Enhancement of thermionic emission and conversion characteristics using polarization- and band-engineered n-type AlGaN/GaN cathodes

Enhanced thermionic emission (TE) and conversion characteristics are observed by controlling spontaneous and piezoelectric polarization and the band diagram of n-type AlGaN/GaN thermionic cathodes. Reduction in the electron affinity and work function by the insertion of an N-polarity thin n-type AlGaN (n-AlGaN) film including tensile biaxial strain is confirmed by an ultraviolet photoemission spectroscopy analysis. The obtained TE current from N-polarity n-AlGaN films grown on an n-type GaN (n-GaN) substrate is 0.29 mA at 500 °C in a Cs gas atmosphere in the vacuum gap between the cathode and a stainless steel anode. This TE current is 5.0 times and 1.6 times higher than that from the surface of Ga-polarity n-GaN substrate and that of the Ga-polarity n-AlGaN film on the substrate, respectively.

Study on fabrication of MnO2/CNTs composite by electrolysis in neutral solution and its applicability as cathode materials in Mg‐ion batteries

AbstractEffects of electrolysis conditions such as Mn2+ ions, and CNTs concentration, temperature, and solution stirring on electrochemical precipitation of MnO2/CNTs composite on SS 304 stainless steel anode electrodes were studied by cyclic voltammetry (CV) method. Results show that the MnO2/CNTs was fabricated at the electrode potential was more positive than 0.8 V/SCE with a suitable solution composition of 0.5 M Na2SO4, 0.4 M MnSO4 and CNTs 0.2 g/L, at 80 oC, and stirring speed ranging from 100 to 200 rpm. The obtained MnO2/CNTs composite materials contained a crystalline phase of MnO2 akhtenskite. The presence of CNTs in the composite was observed by FESEM image. Electrochemical properties of the MnO2/CNTs composites were studied by CV method and galvanostatic charge‐discharge. The composite materials have good discharge capacity, its specific capacity was 92 mAh/g, after 35 charge‐discharge cycles the specific capacity of the material decreased to 69.2 mAh/g, equal to 75 % of the first cycle.

Water Electrolysis Accompanied by Side Reactions

Water electrolysis is used to teach important and fundamental concepts in chemistry. In practical water electrolysis experiments, it is difficult to achieve the ideal 2:1 ratio of hydrogen to oxygen. This work demonstrates an experimental setup comprising multiple water electrolysis cells connected in series to simultaneously visualize the effects of various electrode materials and electrolytes on water electrolysis. The volumes of oxygen were lower when using stainless steel and graphite anodes, which corrode in the electrolytes containing SO42– and NO3– anions, compared to those in the presence of the noncorroding Pt electrode. In addition, the volumes of hydrogen in the presence of NO3– anions, which are catalytically reduced on the cathodes of stainless steel and graphite, were remarkably lower than those obtained with the noncatalyzing Pt cathode. These phenomena are attributed to side reactions which consume portions of the electrons intended for water electrolysis. This demonstration can help students to realize that the experimental results of water electrolysis should be carefully interpreted as they may include a contribution from electrode side reactions.