Initial Current Density Research Articles

Modeling transport of membrane water in PEMFC and energy loss analysis at −20 °C based on mathematical boundedness

This work analyzes why the classic cold start-up model cannot match experimental data well in high initial membrane water content due to the unboundedness of membrane water content conservation equation, and a mathematical framework to ensure the boundedness of membrane water content is developed to solve these issues. Based on vehicle mechanism and Grotthuss mechanism, a “traffic jam” model is applied to describe the transport of membrane water reaching its maximum content. To keep the membrane water content within the upper bound, a new governing equation is proposed and the corresponding boundary conditions and discretization schemes are set. This model has been proved in eleven cases by comparing with experimental data including different initial membrane water content and different current density. Some of these cases are considered impossible to exist in classical cold start-up theory. The results illustrate that the boundedness model can show a clearer physical process and obtain more accurate and reasonable calculation results.

Understanding the key role of the surface structure of L11-ordered PtCu intermetallic electrocatalyst toward methanol oxidation reaction by dealloying methods

An accurate understanding of the surface structure–activity relationship is essential to rational designing highly efficient electrocatalysts for methanol oxidation reaction (MOR). Here, L11-ordered PtCu/C with rough and smooth Pt shells were obtained by electrochemically (ED) and chemically dealloying (CD) methods to investigate the difference in their MOR performances. The rough Pt shells (PtCu/C-700-ED) exhibited mass activity (MA) of 1625.2 mA mgPt−1 at peak potential, 2.19 and 2.74 times higher than smooth Pt shells (PtCu/C-700-CD) (743.1 mA mgPt−1) and commercial Pt/C (593.5 mA mgPt−1), respectively. DFT calculations indicate that PtCu with rough surfaces has a weaker CO binding energy than that with smooth surfaces, leading to better CO resistance and MOR activity. However, accelerated durability tests exhibit that the PtCu/C-700-CD catalysts obtained activity above the initial current density after 2000 cycles compared to PtCu/C-700-ED (36.48% loss) and commercial Pt/C (67.35% loss), indicating that smooth Pt shells have prominent structural stability. In addition, similar results were found simultaneously for other ordered Pt-based binary catalysts.

Bi-Phase NiCo2S4-NiS2/CFP Nanocomposites as a Highly Active Catalyst for Oxygen Evolution Reaction

Pursuing oxygen evolution reaction (OER) catalysts with high activity and stability is attracting many researchers. Here, we first designed and synthesized a biphasic three-dimensional structured catalyst of nickel–cobalt sulfide NiCo2S4-NiS2/CFP, which is a nickel–cobalt sulfide composite decorated on carbon fiber paper (CFP) by a one-step hydrothermal method. It exhibited an overpotential of about 165 mV at a current density of 10 mA cm−2 and a small Tafel slope of 81.54 mV dec−1. Furthermore, the long-term stability of the NiCo2S4-NiS2/CFP nanocomposite was 90.0% of the initial current density even after 12 h. The excellent catalytic performance of the NiCo2S4-NiS2/CFP nanocomposite can be attributed to several aspects. Firstly, the petal-like morphology of the NiCo2S4-NiS2 nanocomposite exposes more active sites. Secondly, the stability of the composite catalyst is significantly enhanced by its firm anchoring on the CFP. Thirdly, the catalytic performance was significantly improved by the addition of mixed valence of Ni or Co on the {111} plane of spinel NiCo2S4. Finally, the three-dimensional CFP substrate provides an efficient pathway and a stable integrated structure for the transmission of electrons and ions. Our one-step hydrothermal synthesis method provides a simple and economical way to obtain high-performance and robust OER catalysts.

Decolorization of reactive blue-2 dye in aqueous solution by electrocoagulation process using aluminum and steel electrodes

In this study we have applied electrocoagulation process for the decolorization of synthetic wastewater containing Reactive Blue-2 (RB-2). Electrocoagulation is eco-friendly, cost-effective and low maintenance technique which is best wastewater technology to remove total suspended solids (TSS), soluble organic compounds and other contaminants from water. Experiments for decolorization of RB-2 solutions were performed by varying the types of electrode Aluminum (Al) and steel connected with DC power supply. Color removal of RB-2 solution was determined by double beam UV spectrophotometer. Significance of the data was determined by applying Two-way ANOVA. Synthetic wastewater samples were prepared in laboratory using RB-2 dye by dissolving its known concentrations in distilled water. In this study we had studied the effect of four experimental variables initial pH, electrolysis time and current density and dye concentration on efficiency of color removal of RB-2 dye. Optimum experimental conditions for RB-2 dye was found at 95% color removal efficiency i.e. electrolysis time = 6 min, initial pH = 3 and at current density = 16.6 mA/cm2 and dye concentration = 5 ppm using steel electrodes. Among both the electrodes, steel showed best results at all experimental variables. Chlorine quenching experiments reveals that active chlorine species had also significantly affects the color removal. It was confirmed from the ANOVA that the decolorization of RB-2 solutions were significantly affected by varying the types of electrodes and other experimental parameters. From overall results it can be concluded that this system can be apply for decolorization of real wastewater.

On the cone-to-jet transition region and its significance in electrospray propulsion

A novel method for identifying the cone-to-jet transition region is proposed to characterize the electrospray dynamics, and thus the Taylor cone, a fundamental principle of ion extraction from the tip of the Taylor cone in an electric field to produce μN thrust for nanosatellites' application. A numerical model is developed and validated against the droplet's diameter with a proper characterization of the cone-to-jet transition region based on the hydrodynamic pressure gradient at the cone-jet axis. The results show that the cone-to-jet transition region is reduced when the electric potential increases and the flow rate decreases. Moreover, the current density is found to be higher for the lower flow rate and large electric potential. Interestingly, the current density at the jet axis increases significantly at the flow rate of 1 cc/hr. This implies that below a certain droplet diameter, the current density carried by the jet interface is completely migrated into the jet, and the substantial change in the current density occurs within the cone-to-jet transition region. When comparing the current density along the jet axis, the small flow rate and large electric potential carry the maximum current density at the jet interface. The identification of cone-to-jet transition region is central in modeling the ion beam trajectory via initial current density profile required for particle-in-cell calculation for assuring the performance of a field emission electric propulsion thruster.

Cr(OH)3 nanosheets@ZIF67 electrocatalysts prepared by electrodeposition method for efficient oxygen evolution reaction

In this paper, a Cr(OH)3 NSs@ZIF67 (NSs = nanosheets) electrocatalyst is prepared on foam Ni via a simple and rapid electrochemical deposition method. Excellent electrocatalytic activity of Cr(OH)3 NSs@ZIF67 is demonstrated. It can use the overpotential of 281 mV and 390 mV respectively to drive 10 mA cm−2 and 50 mA cm−2. It is observed that the Cr(OH)3 NSs@ZIF67 electrode has the highest initial current density at 1.57 V compared with the other two monomer electrodes and shows excellent stability at the end of 60 000 s. It has the largest electrochemical activity specific surface and lowest charge-transfer resistance, and M–O bonds (M = Co, Cr) and shifting of binding energy peaks at the interface lead to more active sites and more efficient electron transfer for oxygen evolution reaction. This work highlights the construction of highly efficient composite electrocatalysts composted of low-dimensional non-precious transition metal compounds and metalorganic frameworks, promoting the development of low-cost non-noble metal composites in energy chemistry.

Removal of ammonium and phosphate from slaughterhouse wastewater by electrochemical method using magnesium electrodes

In this research, the treatability of slaughterhouse wastewater was investigated by using the electrochemical method with Mg electrodes. The influence of the variables such as initial pH (4, 5, 6, 7, 8, and 9), current density (15, 30, and 45 mA/cm2), and reaction time (20, 25, and 30 min) on the removal efficiency of ammonium and phosphate was studied. The highest phosphate removal efficiency was reached at 100% after 20 min of electrochemical treatment with 30 mA/cm2 of current density and initial pH 6. Meanwhile, the maximum removal percent of ammonium was approximately 52%. Thus, this method is feasible to apply for the removal of phosphate and ammonium in slaughterhouse wastewater.

Application of nickel foam cathode modified by single-wall carbon nanotube in electro-Fenton process coupled with anodic oxidation: Enhancing organic pollutants removal

Herein, an electro-Fenton process combined with anodic oxidation was proposed to remove organic contaminants from water sources. Methylene blue (MB) was selected as the target contaminant for removal optimization of the system. Furthermore, to find the effectiveness of the system for pollutant degradation, some micro-pollutants were tested under optimum conditions. PbO2@Ti was used as the anode, and different types of carbonaceous materials such as single-wall carbon nanotube (SWCNT), multi-wall carbon nanotube (MWCNT), carbon black (CB), graphitic carbon nitride, and expanded graphite were coated on nickel foam cathode. FESEM, EDS, and XRD analyses were conducted for surface characterization of the electrodes. CB covered by SWCNT was observed on the surface of the optimally modified cathode. The amount of hydrogen peroxide generated in the system with both SWCNT and CB was 3.3, 7.3, and 11.5 times greater than in the system with just SWCNT, MWCNT, and CB, respectively. The effect of different parameters, such as initial pH, ferrous ion, and current density was investigated. After the degradation of the contaminant, the solution pH was adjusted to 7, and a significant amount of by-products was precipitated. Under the optimum conditions (pH: 3.0, Fe(Ⅱ): 0.5 mmol/L, and current density: 10 mA cm−2), 94.1 % of MB and 80.0 % of TOC were removed within an hour. Also, under the optimal conditions, removal efficiencies of 63.1, 70.2, 76.4, 84.0, and 97.3 % were obtained for tetracycline, phenol, bisphenol A, 4-chlorophenol, and amoxicillin, respectively, indicating that the proposed system is also able to remove other organic pollutants efficiently.

Response surface modeling of ceftriaxone removal from hospital wastewater.

In recent decades, an emerging concern of widespread antimicrobial resistance has been raised due to the existence of pharmaceutical samples such as antibiotics in an aqueous medium. Herein, antibiotic ceftriaxone (CTX) removal from hospital wastewater employing a hybrid process of electrocoagulation (EC) and adsorption (AD) was investigated. The response surface methodology (RSM) was employed to study the influences of main operating variables, including initial CTX concentration, pH, current density, reaction time, and chitosan dosage, on the removal efficiency of the treatment process. Under the optimum condition of the employed EC/AD hybrid treatment process, where initial CTX concentration, pH solution, the current density, adsorbent dosage, and reaction time were set at 20.0mg L-1, 7.5, 6.0mAcm-2, 0.75g L-1, and 12.5min, respectively, the removal efficiency of 100% was achieved. Analysis of variance (ANOVA) confirmed that the developed quadratic treatment model is highly significant. The applied EC/AD hybrid treatment process revealed the electrical energy consumption of 0.84 kWh m-3 and 0.2168 kWh (g Al)-1 per cubic meter of hospital wastewater and gram of consumed aluminum electrode, respectively. The second-order kinetic model with R2 of 0.9514 and the Langmuir isotherm model with R2 of 0.973 best fit the developed EC/AD hybrid treatment process, and qm was found to be 111.1mgg-1. The obtained experimental results confirmed that the CTX concentration of the hospital wastewater was reduced to zero after applying the EC/AD hybrid process.

Electrochemical performance of Paenibacillus profundus YoMME encapsulated in alginate polymer

Gram-positive bacterium Paenibacillus profundus YoMME, entrapped in an alginate polymer onto graphite paper, preserves its extracellular electron transfer capabilities. A current density of up to 30 mA m−2 was generated at an applied potential of −200 mV (vs. SHE). Fivefold higher initial current density values were recorded at applied potentials of +220 mV and +600 mV. The electrochemical behavior of the encapsulated bioelectrodes has been also explored by cyclic voltammetry, differential pulse voltammetry, and electrochemical impedance spectroscopy and evaluated by the parameters of the best-fitted equivalent electric circuit model. Over time the bacteria grow and divide within the alginate matrix, which affects considerably the capacitance and the charge transfer resistance of the coating. The impedance spectra follow the dynamics of the bacterial culture development within the alginate polymer and are useful for the prediction of the bioelectrode performance. A current density of 150 mA m−2 was achieved when the alginate was functionalized by a mixture of the redox dyes thiazolyl blue (MTT) formazan and phenazine methosulfate (PMS). It is supposed that the added artificial mediators facilitate the electron transfer from the bacteria to the electrode surface by forming conductive cascade conduits through the alginate matrix.

Honeycomb-Type TiO2 Films Toward a High Tolerance to Optical Paths for Perovskite Solar Cells.

Given the advantages of high power conversion efficiencies (PCEs), antisolvent-step free production, and suitability for device production in ambient conditions, perovskite solar cells (PSCs) based on ionic-liquid solvents have attained particular research interest. To further improve device performance, light management could be optimized to increase light harvesting in the perovskite layer. Here, ordered honeycomb-like TiO2 (Hc-TiO2 ) structures with a periodicity of around 450 nm were fabricated through a sacrificial template method. With this photonic crystal structure, the control to light flow and the confinement effect for perovskite growth were achieved simultaneously in the Hc-TiO2 , leading to improved light absorption as well as preferred crystal orientation. Furthermore, a reduced trap-state density and a well-aligned energy level induced by the perovskite/pore interlayer facilitated the charge-carrier extraction from the perovskite layer to electron transport layer. As a result, the structured devices performed better than the planar cells. And the angular dependent J-V sweeps show that the structured device reserved 76 % of its initial short circuit current density (Jsc ), whereas the planar cell showed more than a half loss under the incident light of 40°, demonstrating a reduced downward trend in Jsc with the presence of photonic crystal structures. This occurrence also suggests that the structured PSCs in this work have a high tolerance to optical path changes.

Performance evaluation and life cycle assessment of electrocoagulation process for manganese removal from wastewater using titanium electrodes

Excess manganese (Mn) concentrations can pose environmental and health risks. Currently, research on Mn removal by electrocoagulation (EC) using transition metal electrodes and the determination of its potential environmental impacts is limited. This study aims to assess the electrocoagulation process's performance with a titanium electrode as a sacrificial anode while also performing a life cycle assessment (LCA) of the process. The initial pH, current density (CD), electrode spacings, electrolyte types, concentrations, and electrode arrangement were all examined. For synthetic wastewater, most of the experiments used a concentration of Mn of 2 mg/L and sodium chloride as a supporting electrolyte at a concentration of 1 g/L. LCA software (OpenLCA 1.11) was used to assess the potential environmental impacts. Optimal operating conditions within the experimental range were as follows: initial pH = 7, CD = 10 mA/cm2, gap distance = 2 cm, and 1 g/L NaCl. Under these conditions, the maximum Mn removal efficiency was 96.5% after 60 min. There was an improvement of 2% rise after 60 min when the temperature increased from 20 °C to 40 °C. For real wastewater, the highest removal efficiencies for Mn and chemical oxygen demand after 60 min were 91.3% and 92%, respectively. The pseudo second order model provides the highest coefficient of determination for expressing the experimental data. Global warming, human non-carcinogenic toxicity, and terrestrial ecotoxicity were the most important categories of impact examined in this work according to the LCA (0.00064 kg CO2 eq, 0.00018 kg 1,4-DCB, and 0.00028 kg 1,4-DCB, respectively). To effectively remove Mn using EC with Ti electrodes, it appears that a period of electrolysis of 10 min would be sufficient under most of the conditions investigated in this study. The reduction in the electrolysis time will lead to a reduction in the operating costs of the system.

Highly active rGO/Ca-MOF loaded Pd-M (M = Fe, Sb, Pb, Sn, Ag) composite catalysts towards ethylene glycol electrooxidation

The combination of multi-metallic alloys and support materials is a promising approach for the design of electrocatalysts. In this study, Pd-M (M = Fe, Sb, Pb, Sn, Ag) bimetallic alloys embedded composites of 2D Ca-based metal–organic framework (Ca-MOF) nanosheets and reduced graphene oxide (rGO) were fabricated by a facile hydrothermal and impregnation reduction method, then applied as ethylene glycol oxidation reaction (EGOR) electrocatalysts. Remarkably, the forward peak current density of the best catalytic performer [email protected]/Ca-MOF is as high as 258.30 mA cm−2, which is 9.55 times greater than that of Pd/C. It also exhibits the biggest electrochemical active surface area of 3022.51 m2 g−1. After 3600 s chronoamperometry test, the retained current density of [email protected]/Ca-MOF is about 87.94 % of the initial current density. These results imply that bimetallic [email protected]/Ca-MOF have superior electrocatalytic activity and anti-CO poisoning capacity compared to monometallic and Pd/C for EGOR, especially [email protected]/Ca-MOF. The enhanced EGOR performance is due to the combined effect of Pd-M alloys and folded thin layer wrapped nanosheet rGO/Ca-MOF composites.

Freestanding Cactus-Like Dual-Phase Bimetallic Metal–Organic Framework as a High-Efficiency Electrocatalyst for Water Oxidation

Realizing a high-efficiency electrochemical oxygen evolution reaction (OER) is a great challenge in water splitting and metal–air battery fields due to the slow reaction kinetics. Herein, a synchronous dual-phase synthetic strategy is developed to successfully construct a cactus-like dual-phase bimetallic metal–organic framework (MOF) on a nickel foam (NF) substrate (noted as NiFe-MOF@NF). It is constituted by Ni-main NiFe-MOF and Fe-main NiFe-MOF. When functioning as an anode, the freestanding cactus-like dual-phase NiFe-MOF@NF catalyst merely requires a lower overpotential of 277 mV to supply 100 mA cm–2 with robust stability (90% retainment of initial current density after 24 h chronoamperometry measurement). Density functional theory calculations on the NiFe-MOF@NF catalyst reveal that the combination of Ni and Fe has efficiently modulated the electron configuration of metal centers and optimized the absorption/desorption of OER oxygen-containing intermediates. Thus, we demonstrate a novel synchronous dual-phase synthetic strategy to engineer freestanding dual-phase electrocatalysts, which feature multiple synergetic effects considerably boosting OER performance for optimizing the energy conversion and storage system.

Electro‐oxidation of pistachio processing wastewater using Ti/Pt mesh‐type anodes in batch system

AbstractIn this study, the treatment of pistachio processing wastewater (PPW) by electro‐oxidation method was investigated. Ti/Pt‐plated electrodes were used for the anode material, and stainless steel electrodes were used for cathode material. Experimental studies were carried out in batch mode. Stirring speed, supporting electrolyte species and concentration, initial pH value, current density, temperature and dilution ratio were selected as experimental parameters effecting removal efficiency. In Ti/Pt electrode experimental studies on the optimum conditions, chemical oxygen demand (COD), total organic carbon (TOC) and total phenols (TP) removal efficiencies were obtained, respectively, as 99.98%, 70.74% and 100%, and energy consumption value was obtained as 297.5 kW‐h/m3 (12.39 kW‐h/kg COD, 51.29 kW‐h/kg TOC and 64.68 kW‐h/kg TP). As a result of the experimental studies, the PPW can be treated by electro‐oxidation. Given the results of removal efficiency and energy consumption values, it was concluded the electro‐oxidation using Ti/Pt anode very appropriate treatment of PPW.

The Effects of Biofouling and Corrosion Products on Impressed Current Cathodic Protection System Design for Offshore Monopile Foundations

The robustness of the cathodic protection systems utilized for offshore wind monopile foundations depends on the surface condition of the steel as well as the environmental conditions. This study investigated how preexisting biofouling and corrosion products on vertical uncoated steel surfaces extending from the intertidal zone to the buried zone affected the cathodic protection requirements when impressed current cathodic protection (ICCP) was applied under tidal conditions. The comparative results between initially clean and previously fouled and corroded panel sets showed that the fouling and corrosion products increased both the initial and mean current densities. They also altered the composition, slowed the formation, and reduced the protective properties of cathodic chalks during nine weeks of deployment in seawater at Port Canaveral, Florida.

Hydroxyzine removal from the polluted aqueous solution using the hybrid treatment process of electrocoagulation and adsorption; optimization, and modeling

The current work investigated the efficacy of the hybrid treatment process of electrocoagulation and adsorption in removing hydroxyzine (HDZ) from polluted aqueous solutions. Response surface methodology (RSM) was used to optimize the operating parameters based on the sub-category of central composite design (CCD). The significance of variables, interactions, and quadratic effects was investigated through analysis of variance (ANOVA). The value of determination coefficient (R2), Adjusted R2 (Adj.R2) and predicted R2 (Pred.R2) were 0.9855, 0.9791, and 0.9743, respectively; also, p-value of P < 0.0001, and F-value of 65.91 were obtained. The obtained results revealed that the removal efficiency of 99.3% and electrical energy consumption of 0.438 kWh m−3 were achieved at the optimum treatment condition of initial HDZ concentration of 25.0 mg L−1, pH solution of 8.0, the current density of 12.0 mA cm−2, reaction time of 15.0 min, and chitosan dosage of 0.03 g L−1. According to the Pareto analysis, the initial HDZ concentration, solution pH, current density, and reaction time’s contribution to the HDZ removal were 22.61%, 38.99%, 19.36%, and 9.43, respectively. Furthermore, the contributions of solution pH and reaction time with the quadratic effects were 3.43% and 6.19%, respectively. Thus, the pH solution revealed the highest contribution to the removal process. Overall, HDZ removal by the hybrid treatment process of EC and AD revealed a good efficiency; also, it can be potentially presented as a promising process for treating polluted water.

Highly selective electrocatalytic reduction of nitrate to nitrogen in a chloride ion-free system by promoting kinetic mass transfer of intermediate products in a novel Pd–Cu adsorption confined cathode

The mass transfer on the catalyst surface has a great influence on the selectivity of electrocatalytic nitrate reduction to nitrogen. In this study, a Pd–Cu adsorption confined nickel foam cathode is designed in the absence of both proton exchange membranes and chloride ions. The repulsion of the cathode enables intermediate products such as nitrite to accumulate in the confined region, resulting in an increase in the possibility of a second-order reaction to form nitrogen. The system can obtain more than 92% continuous N2 selectivity when it is used to treat 200 mg L−1 NO3−-N under a current density of 8 mA cm−2, which is not only higher than those of semiconfined and nonconfined systems but also significantly better than the results obtained by Pd–Cu directly modified cathodes prepared by electrodeposition or impregnation. It is found that a high initial nitrate concentration and low current density are more beneficial for the accumulation of intermediates on Pd–Cu catalysts, thus improving the formation of nitrogen. A mechanism study reveals that the intermediates can completely occupy the active sites on the surface of Pd, avoiding the generation of active hydrogen, and therefore inhibiting the first-order reaction to produce ammonia. Moreover, the reducibility of Pd–Cu can also be gradually improved under the function of the cathode so that the system exhibits good stability. This study demonstrates an environmentally friendly and promising method for total nitrogen removal from industrial wastewater with high conductivity.

Influence of surface finishing and heat treatments on the corrosion resistance of LPBF-produced Ti-6Al-4V alloy for biomedical applications

Additive manufacturing (AM) technologies are gaining increasing attraction for biomedical applications due to the granted customizability and optimal surface topography for osteointegration. Ti-6Al-4V is one of the most promising materials due to its biocompatibility. However, excessive ions release can occur, leading to a relevant immunologic response in the surrounding tissues. Despite the corrosion behavior of the conventionally-manufactured material being well known, it should be assessed for AM-processed components, as the effect of the unique superficial and microstructural features granted by the process is still quite unknown. The aim of this paper is the electrochemical evaluation of the passive current density of the laser powder bed fusion (LPBF)-processed Ti-6Al-4V alloy via potentiostatic tests, carried out at typical in-service potentials for biomedical implants. This parameter is correlated with the ion release rate of the alloy, a fundamental phenomenon to address to prevent possible inflammations caused by the implant. Different manufacturing conditions (surface finishing, heat treatment) and exposure time (0, 60 and 6000 h) were considered. The importance of performing these measurements over a long period (> 8 months) was demonstrated. In fact, despite the initial current densities being significantly affected by the surface and microstructural differences, the ion release rates converged for long-time exposures. The results also underlined the good corrosion resistance of the material. Poor corrosion performances, alongside with significant current densities development, were observed in the as-built condition. A pickling treatment demonstrated to mitigate such effect without compromising the unique surface finishing granted by the manufacturing technology.

(Digital Presentation) Electrodeposition of Uranium Dioxide from Li2MoO4-K2MoO4-MoO3 Based Melts: An Effect of Melt Composition

The effect of electrolysis conditions on the composition of cathodic products formed in Li2MoO4–K2MoO4–MoO3–UO2MoO4 melts was investigated. The experiments were performed in the melts based on (1–x)(0.605Li2MoO4–0.395K2MoO4)–xMoO3 mixtures (x = 0.3–0.5) at 550–800 oC. Electrolysis was performed in the galvanostatic mode on platinum cathode. The initial current density was varied between 0.05–1 A/cm2. Depending on the electrolysis conditions the cathodic deposits consisted of UO2+x, U4O9–y, U1,5Mo10O32, Mo2UO8 and MoO2 phases. Phase composition and oxygen-to-uranium ratio were determined for the products obtained. Conditions allowed obtaining uranium oxide with minimal molybdenum contamination were determined, and confirmed by the bulk electrolysis runs.