Deposition Current Efficiency Research Articles

Recovery of antimony from acidic and alkaline leaching solution of low-grade antimony ore by electrowinning process

With regards to the global continuous growth in consumption of base metals such as antimony (Sb), mining companies are currently looking to improve the productivity and extraction of Sb from low grade ore in order to economically process it. With this aim, in this study, an efficient protocol was developed to recover metallic Sb from the low grade Fe3Si2O5(OH)4. Sb3O6(OH). Sb2O3 ore of the Sefid-Abe mine in Zahedan province, Iran, utilizing selective acidic or alkaline leaching followed by Sb electrowinning. A process was developed to recover antimony from an Sb2O3 ore source, using selective acidic or alkaline leaching followed by antimony electrowinning. Sb could be leached with an efficiency of 85 % using 5 M NaOH and 87 % using 5 M hydrochloric acid/5 M sulfuric acid as the digestion solution at 80 °C for 8 h. The electrowinning process plays a significant role in recovery of highly pure Sb metal. Relying on this approach, a high deposition rate and current efficiency have been generated at a deposition potential 2 V at 30 °C (80 °C for alkaline medium). This was achieved by using anode electrode made of graphite and cathode electrode made of steel (two steel electrodes were used for alkaline electrowinning). Additionally, for acidic electrowinning, exploitation of Sb from the electrolyte solution was achieved by applying a current of 0.1 A, resulting in the highest yield equal to 89 %. On the other hand, for alkaline electrowinning, the highest efficiency corresponds to the current intensity of 0.5 A, which resulted in 97 % Sb extraction from the electrolyte solution. The XRD and ICP analysis performed for samples obtained from the electrolysis confirmed that the resulting antimony ingot has an exceptionally high purity.

Effect of bath temperature on electroplating of nickel on a copper substrate

ABSTRACT Nickel electroplating is known to be industrially effective for enhancing various substrate properties. In the present work, nickel coatings were developed on copper substrates by electroplating using standard nickel plating solution at various electrolyte bath temperatures ranging from 40 ± 2°C to 60 ± 2°C in steps of 10°C. Energy dispersive spectroscopy (EDS), X-ray diffraction (XRD) and field emission scanning electron microscopy (FESEM) were used to study the composition, phase structure and morphology of the coatings. The coatings were also analysed for hardness and porosity, and process current efficiency was measured. The electrolyte bath temperature has a profound effect on the nature of the developed nickel coatings, and is observed to have an impact on the surface morphology, crystallographic direction, and hardness, as well as deposition current efficiency.

Effect of bath temperature on electroplating of nickel on a copper substrate

ABSTRACT Nickel electroplating is known to be industrially effective for enhancing various substrate properties. In the present work, nickel coatings were developed on copper substrates by electroplating using standard nickel plating solution at various electrolyte bath temperatures ranging from 40 ± 2°C to 60 ± 2°C in steps of 10°C. Energy dispersive spectroscopy (EDS), X-ray diffraction (XRD) and field emission scanning electron microscopy (FESEM) were used to study the composition, phase structure and morphology of the coatings. The coatings were also analysed for hardness and porosity, and process current efficiency was measured. The electrolyte bath temperature has a profound effect on the nature of the developed nickel coatings, and is observed to have an impact on the surface morphology, crystallographic direction, and hardness, as well as deposition current efficiency.

Eco-Friendly Electrowinning for Metals Recovery from Waste Electrical and Electronic Equipment (WEEE)

The amount of waste electrical and electronic equipment (WEEE) has been intensely increasing over the recent decades. In this view, the efficient recovery of metals from WEEE will allow a secure supply of raw materials and will contribute to a circular economy. Among many factors currently affecting the contribution of recycling, is the lack of suitable technologies for WEEE treatment in an environmentally friendly way. Current trends in eco-friendly technologies applied for gold, silver, copper, and tin recovery by electrowinning are reviewed in this paper. In addition, a case study on the perspectives of tin electrowinning has been evaluated. Tin can be present in rather high quantities in WEEE; moreover, its price is about three times higher than that for copper. The electrorecovery of tin has been carried out in cooperation with JSC “Elektronikos perdirbimo technologijos”. The eco-friendly process based on electrowinning from citric acid-containing leachates is elaborated. The citrate-based solutions have been chosen because citric acid is considered to be an environmentally friendly component. A high deposition rate and current efficiency have been achieved at a deposition potential −0.85 V at 60 °C. However, additional steps would be beneficial to diminish the interference of metals present in the scraps, such as Pb(II) and Cu(II), on tin electrorecovery.

Magnetic field exposure on electroplating process of ferromagnetic nickel ion on copper substrate

In this research, nickel electroplating was carried out under a magnetic field. A constant magnetic field was used to influence the electroplating process. Its effects on surface morphology, deposition rate, current efficiency, crystal structure, hardness, and corrosion properties of nickel films were investigated. Inhomogeneous pyramidal-type structures without crevices were formed on all samples. Ni films electrodeposited under exposure of 0.14T of the magnetic field revealed the highest deposition rate, current efficiency, and hardness. Less crystallite size would produce higher hardness. Three major peaks of X-ray diffraction are observed, and the (111) crystal plane is the most affected by the magnetic field during the electroplating process. The presence of 0.14T of magnetic field on the electrodeposition process also decreases (111) plane, crystallite size, and microstrain. A magnetic field could improve the corrosion and hardness properties of Ni films.

Anion Modification and Theoretical Understanding for Improving Annealing-Free Electrochemistry Deposition of Perovskites under an Ambient Atmosphere

Organometallic halide perovskites have drawn tremendous attention for their remarkable photovoltaic properties. We report anion modification for improving annealing-free electrochemical deposition of perovskites under an ambient atmosphere and extending the applications. Relevant theoretical simulation based on the Butler–Volmer functions reveals the mechanism behind: introduced anions raise the exchange current and electrolyte conductivity, which promotes the deposition rate and current efficiency simultaneously. The crystallization and morphology of perovskites is conveniently and controllably improved by this strategy without additional annealing or N2 protection process. We extend this method onto fully textured silicon heterojunction solar cells, which optimizes the shape-preserving deposition of perovskites. Our article suggests a promising way toward low-cost perovskite/silicon monolithic tandem solar cells.

Electrodeposition of Cu-Mn Films as Precursor Alloys for the Synthesis of Nanoporous Cu

Cu-Mn alloy films are electrodeposited on Au substrates as precursor alloys for the synthesis of fine-structured nanoporous Cu structures. The alloys are deposited galvanostatically in a solution containing ammonium sulfate, (NH4)2SO4, which serves as a source of the ammine ligand that complexes with Cu, thereby decreasing the inherent standard reduction potential difference between Cu and Mn. The formation of the [Cu(NH3)n]2+ complex was confirmed by UV-Vis spectroscopic and voltammetric studies. Galvanostatic deposition at current densities ranging from 100 to 200 mA⋅cm−2 generally resulted in the formation of type I, crystalline coatings as revealed by scanning electron microscopy. Although the deposition current efficiency is (<30%) generally low, the atomic composition (determined by energy dispersive X-ray spectroscopy) of the deposited alloys range from 70–85 at% Mn, which is controlled by simply adjusting the ratio of the metal ion concentrations in the deposition bath. Anodic stripping characterization revealed a three-stage dissolution of the deposited alloys, which suggests control over the selective removal of Mn. The composition of the alloys obtained in the studies are ideal for electrochemical dealloying to form nanoporous Cu.

On the influence of magnetic field on electrodeposition of Ni–TiO2 composites from a citrate baths

In this paper, we present the results of the study on the influence of electrolysis conditions including external magnetic field on the properties of Ni–TiO2 composite materials synthesized from a citrate bath. The influence of electrode potential, TiO2 concentration in the electrolyte, as well as the value of magnetic field induction vector on the deposition rate, composition, current efficiency, structure, surface states and morphology of the synthesized coatings is reported. The obtained results indicate possibilities of synthesis of composites containing up to 1.39 wt % of TiO2. Dependent on the applied electrolysis condition current efficiency amounts to from 38.1 to 45.5% for B = 0 T and from 46.3 to 53.1 for B = 1 T. The results of electrochemical studies as well as further characterization of synthesized materials indicate that the presence of the magnetic field strongly influenced the kinetics of the processes responsible for materials formation. Voltammetric, XRD and XPS analyses indicate simultaneous formation of hydrides and hydroxides during electrolysis.

A novel magnetoelectrochemical method of synthesis of photoactive Ni-TiO2 coatings from glycinate electrolytes

This paper reports the results of analysis of magnetic field supported electrochemical deposition of Ni-TiO2 composite coatings from electrolytes containing nickel glycinate complexes. The effect of several parameters, including electrode potential, concentration of TiO2 in the electrolyte as well as value of magnetic field induction vector on deposition rate, composition, current efficiency, structure, surface states and surface morphology was described. Electrodeposited composites contained up to 1.43 wt% of TiO2. Depending on the applied electrolysis condition, current efficiency amounted to from 38 to 55.4% for B = 0 T and from 43.1 to 64.8 for B = 1 T. The electrochemical tests performed as well as determined diffusion coefficient values indicated that the magnetic field strongly influenced the kinetics of electrode processes. Voltammetric curves as well as further characterization of deposited coatings indicated that the deposition process is accompanied by precipitation of hydrides and hydroxides during electrolysis.

Cobalt electrowinning – A systematic investigation for high quality electrolytic cobalt production

The process of Minera y Metalúrgica del Boleo recovers cobalt from a complex oxide and sulfide ore by solvent extraction and electrowinning after the recovery of copper and zinc (as copper cathode and zinc sulfate monohydrate). As part of the process development, cobalt electrowinning was systematically studied with respect to temperature, pH, pitting behavior, deposit morphology, deposition stress and interfacial tension. Electrowinning test work was conducted in a bench scale diaphragm cell in a sulfate medium with control of the catholyte pH. Cobalt was deposited on a coated stainless-steel mandrel cathode with exposed circles to allow plating of disk shaped deposits over the surface of the cathode that could be easily stripped after 5–7 days of deposition. Limiting the area of plating prevents the detachment of the cobalt deposit from the cathode due to high deposition stress. The morphology and pitting behaviour varied for different commercial cobalt raw materials used for making cobalt sulfate solution as they contained different impurities or additives. The deposition behaviour changed after the solutions had an activation carbon treatment as some impurities (mainly organic compounds) were removed. In the temperature range from 50 to 65 °C, a higher temperature resulted in a brighter deposit with more pits and smaller lateral dendrites. The cobalt deposition current efficiency was around 98% at pH 3.0 and was not sensitive to temperature. With decreasing catholyte pH from 3.5 to 2.0, the cobalt current efficiency decreased from 99 to 88% and the growth of lateral dendrites were significantly suppressed. The formation of pits resulted from the adhesion of hydrogen bubbles on the cobalt deposit. The adhesion of hydrogen bubbles was determined by the prevailing surface and interfacial tensions. Anti-pitting agents were used to change the interfacial and surface tensions in such a way that the detachment of bubbles was facilitated, resulting in a pit-free cobalt deposit. The anti-pitting agents affected the deposit morphology and internal stress. The impact of the anti-pitting agents on the disengagement of organic and aqueous phases during cobalt solvent extraction was also investigated. The internal stress of the cobalt deposit as a function of temperature and anti-pitting agent dosage and the conductivities of the CoSO4-Na2SO4-H2SO4 system are reported.

Facile Synthesis of Capacitive Carbon Materials via Electrolyzing Carbonates Eutectic with Varying Metallic Anodes

The protocol of molten salts electrolysis provides a feasible close-loop solution to yield CO2 reduction and mitigate global climate change. In the present study, a typical Li2CO3-Na2CO3-K2CO3 eutectic is employed as the electrolyte and the electrolysis is performed in a two-electrode system. Three metallic materials of galvanized iron, nickel and copper are utilized as the counter electrode and assembled with the working electrode of galvanized iron in the molten salts electrolyzer to prepare electrolytic carbons. It is verified here that the hybrid carbonates electrolysis prefers the production of amorphous carbons with varying carbon structures. In particular, the electrochemical performance of the carbon products is studied in aqueous H2SO4 solution, and the carbon materials formed in Ni anode electrolyzer exhibit an ultrahigh specific capacity of 336 F/g at the charge/discharge current density of 1000 mA/g. Besides, current efficiency, reaction kinetics and electricity consumption for per kilogram carbon production are evaluated. The results demonstrate that the Ni anode electrolyzer provides the lowest voltage and electricity consumption, and simultaneously the maximum carbon deposition rate and current efficiency during the galvanostatic electrolysis process.

Effects of Sodium Hypophosphite on the Behaviors of Electrodeposited NiWP Alloy Coatings

In this paper, ternary NiWP alloy coatings were prepared by electrodeposition, and the effects of sodium hypophosphite (NaH2PO2) concentration on the properties of the coatings, including the deposition rate, current efficiency, composition, surface morphology, corrosion resistance, and microhardness, were investigated. Results reveal that the deposition rate and current efficiency are mainly dependent on the NaH2PO2 concentration in the plating bath. The deposition rate reaches a maximum value of 8.70 μm/h with a NaH2PO2 concentration of 10 g/L, whereas the total current efficiency decreases from 33.10 to 27.80%. As the concentration of NaH2PO2 increases, the grain size of the obtained coatings gradually decreases. Moreover, when the NaH2PO2 concentration is 6 g/L, the NiWP alloy coatings possess a microhardness value of 663.7 HV.

Effect of pH on anomalous co-deposition and current efficiency during electrodeposition of Ni-Zn-P alloys

Electrodeposition of Ni-Zn-P alloy coatings was studied from an electrolyte containing hypophosphorous acid (H3PO2) as a source of phosphorus. In this study, the effect of electrolyte pH on deposit composition, current efficiency and anomalous codeposition was investigated in detail. With increase in pH of the electrolyte, the Zn and P-content of the NiZnP alloy coating decreased with commensurate increase in Ni-content. The faradic efficiency of deposition was found to increase with increase in pH and ultimately saturated beyond pH=10. At lower pH, the anomalous effect of Zn2+ was prominent which turned into non-anomalous at pH≥9.0. Evidence of simultaneous electroless deposition was noticed during electrodeposition and the corresponding deposition rate was nearly unaffected due to electrolyte pH variation. X-ray diffraction investigation confirmed the deposition of amorphous NiZnP alloys throughout the composition range studied here. Scanning electron microscope (SEM) examination of as-deposited surface showed smooth to nodular growth pattern with multiple cracks depending upon the pH values. The cross-section examination of deposited Ni-Zn-P alloy microstructure revealed growth of multiple layers with non-uniform thickness ranging from 100nm to 1μm along the growth direction. Corrosion experiments were performed in static as well as in potentiodynamic conditions in an electrolyte containing Na2SO4, H3BO3 under neutral condition. Coatings with Zn content in the range 18–22wt% were found to display open circuit potential (OCP) of −0.630 to −0.600V vs. SCE which are more active but close to steel substrate OCP and hence can be used as a sacrificial coating for the protection of steel for a longer duration.

Influence of Hydrogen Adsorption on Electrodeposition of Platinum from Chloro Complex Solution

Platinum (Pt) is widely used as insoluble and catalytic electrodes for electrolysis, automotive catalytic converters, and fuel cells. We have been investigating hydrogen incorporation in electrodeposited metal films and its influence on crystal structure of metals (1-3). It was reported that large amount of hydrogen (content in atomic ratio: x = H/Pt = 0.1) is incorporated in the Pt films electrodeposited from a solution including dinitrosulfatoplatinate(II) (H2Pt(NO2)2SO4, DNS) as a metal source. In this study, an electrochemical quartz crystal microbalance (EQCM) method (4) is used to examine influence of hydrogen adsorption on the electrodeposition and hydrogen incorporation into deposited films of Pt from a chloro complex solution. The current-potential and mass increase (Pt deposition rate)-potential curves in 0.024 mol dm-3 K2PtCl4solution adjusted at pH of 0.8 with HCl were measured using an EQCM system (Hokuto Denko, HQ-101D and HZ-5000). A quartz electrode coated with Au, an Ag/AgCl electrode, and a Pt wire were used as the working, reference, and counter electrodes, respectively. The hydrogen content of samples was measured by thermal desorption spectroscopy (TDS). Figure 1 shows the current density and mass increase rate versus electrode potential curves for the chloro complex solution. In the first forward potential sweep toward negative potentials of Fig. 1(a), the cathode current and deposition rate of Pt started increasing at +0.3 V vs. Ag/AgCl. Peaks for cathode current and deposition rate appeared at -0.19 V. The current efficiency was 74% at this peak. Then, as the potential was swept to lower potentials, the deposition rate and current efficiency decreased. This decrease in the current efficiency of Pt deposition is caused by hydrogen adsorption. In the return potential sweep (Fig.1 (b)), the cathode current and Pt deposition steeply increased by hydrogen desorption from the Pt surface, and the current efficiency was 113% at the potential of -0.25 V. The hydrogen content of Pt-electrodeposited Au foil (Pt: 1 μm and Au: 20 μm in thickness) increased as the deposition potential of Pt decreased from 0 to -0.3 V, and was much lower than that deposited from the DNS solution. Acknowledgements The present work was partly supported by JSPS KAKENHI (26289276). References N. Fukumuro, M. Yokota, S. Yae, H. Matsuda, Y. Fukai, J. Alloys Compd., 580, S55 (2013). N. Fukumuro, S. Kojima, M. Fujino, Y. Mizuta, T. Maruo, S. Yae, Y. Fukai, J. Alloys Compd., 645, S404 (2015). N. Hisanaga, N. Fukumuro, S. Yae, H. Matsuda, ECS Trans., 50, 77 (2013). T. Hagihara, K. Yaori, K. Iwakura, N, Fukumuro, S. Yae, Electrochim. Acta, 176, 65 (2015). Figure 1

Electrodeposition mechanism and characterization of Ni–Mo alloy and its electrocatalytic performance for hydrogen evolution

In the study, the electrodeposition mechanism of Ni–Mo alloy was investigated. Potentiostatic deposition showed that the presence of MoO42− could reduce the deposition overpotential of Ni, and the deposition current efficiency of Ni–Mo alloy was lower than pure Ni deposition as the potential moved negatively. Cyclic Voltammetry (CV) indicated that both the first reduction peak for Ni deposition and the deposition peak of Ni–Mo alloy moved to more positive potentials as the content of Ni2+ increased, but the deposition peak of Ni–Mo alloy moved to more negative potentials as the content of MoO42− increased. The cathodic polarization curve on Rotating Disc Electrode (RDE) presented that Ni–Mo codeposition was controlled by charge transfer. The morphology, composition and structure of Ni–Mo alloy were characterized by SEM, EDS and XRD. The results showed the Ni–Mo alloy coatings exhibited a spherical and cauliflower-like pattern, having a considerably rougher surface, with nano-crystal structure when the elements composition was Ni80.14Mo19.59. The electrochemical activity for hydrogen evolution of Ni–Mo alloy was studied in 30 wt.% KOH at 25 °C using steady-state polarization and electrochemical impedance spectroscopy (EIS) methods. The results clearly demonstrated that an increase in the electrochemical activity for hydrogen evolution of the Ni–Mo alloy coating can be attributed both higher exchange current density and larger real electrode area.

Electrodeposition and characterization of Ni–Mo–ZrO2 composite coatings

Ni–Mo–ZrO2 composite coatings were produced by electrodeposition technique from citrate electrolytes containing dispersed ZrO2 nanopowder. The influence of deposition parameters i.e. concentration of molybdate and ZrO2 nanoparticles in the electrolyte, bath pH and deposition current density on the composition and surface morphology of the coating has been investigated. The structure, microhardness and corrosion properties of Ni–Mo–ZrO2 composites with different molybdenum and ZrO2 content have been also examined. It was found that ZrO2 content in the deposit is increased by rising the nanoparticles concentration in the plating solution up to 20gdm−3. An increase in molybdate concentration in the electrolyte affects negatively the amount of codeposited ZrO2 nanoparticles. The correlation between the deposition current efficiency and ZrO2 content in the composite coating has been also observed. A decrease in deposition current efficiency leads to deposition of Ni–Mo–ZrO2 composite with low nanoparticles content. This may be explained by formation of higher amounts of gas bubbles on the cathode surface, which prevent the adsorption of ZrO2 nanoparticles on the growing deposit. The XRD analysis revealed that all the studied Ni–Mo–ZrO2 coatings were composed of a single, nanocrystalline phase with FCC structure. It was found that the incorporation of ZrO2 nanoparticles into Ni–Mo alloy matrix affects positively the microhardness and also slightly improves the corrosion properties of Ni–Mo alloy coating.

Copper deposition on stainless steel sheets in copper nitrate solution

The aim of this study was to examine factors that influence copper nitrate based electrorefining of copper and to search the best process parameters for high-purity copper deposition on AISI 316L steel blanks. Considering impurities, the most important goal was to minimize sulfur content in a copper cathode. The effect of Cu 2+ concentration, current density, temperature and pH were studied. The best parameters for the best copper purity were sorted out. The most important factors for quality copper deposition are sufficiently low Cu 2+ concentration, low current density, right zone and careful control of pH. Active nitrate ion reduction reactions catalyzed by copper ions are suggested to affect detrimentally both copper deposition current efficiency and purity. Furthermore, nitrate ion reactions seem to elevate an electrolyte pH so that the deposition appears to be dark brow copper oxide. The 6N purity for copper was not reached with this cell construction and it felled behind about 7 ppm (99.9993% Cu). Both, sulfur and silver concentration were slightly above 1 - 2 ppm. To minimize the impurities, electrolyte circulation and filtration are needed. Also, either a separate silver cementation cell or cementation membrane is needed.

Effects of saccharin and anions (SO4 2−, Cl−) on the electrodeposition of Co–Ni alloys

The electrodeposition of Co–Ni alloys is investigated to examine the mechanistic effects of chloride, sulfate and saccharin on the resulting alloy composition, deposition current efficiency and partial current densities of the cathodic reactions. When deposition is carried out in chloride, sulfate or mixed sulfate-chloride solutions without saccharin, the influence of hydrogen evolution (HER) becomes dominant and deleterious at higher overpotentials, leading to very low metal deposition current efficiency and the formation of a hydroxide/oxide film on the substrate. This problem is significantly reduced when saccharin is added to the mixed sulfate-chloride plating bath and to a lesser extent the sulfate-only solution. Although saccharin is ineffective in suppressing H+ reduction at low overpotentials, it is very effective at inhibiting H2O reduction at high overpotentials and enabling metal deposition to more easily occur. The system follows anomalous behavior at all current densities both in the absence and presence of saccharin, although it approaches normal behavior as the current density increases toward −1,000 A m−2 due to Co(II) reduction being mass transfer-controlled.

Nanostructured tin electrodeposited in ionic liquid for use as an anode for Li-ion batteries

Nanostructured tin (Sn) is fabricated via electrodeposition in an ionic liquid (IL). The advantages of electrodeposition in IL (compared to that in conventional aqueous solution) include increased deposition current efficiency and suppressed corrosion of the Cu current collector. The former is associated with the elimination of hydrogen evolution during the cathodic deposition and the latter is attributed to the chemical benignity of ILs. It is found that the Sn morphologies can be effectively manipulated by adjusting the deposition potential in the IL plating solution. The higher the deposition overpotential, the better is the electrochemical performance of the Sn electrode for Li-ion batteries. The electrode deposited at −2.4 V, consisting of Sn nanospheres, shows a reversible discharge (delithiation) capacity of 980 mA h g−1 (at 0.1 A g−1). When the charge–discharge rate is increased to 15 A g−1, the measured capacity is as high as 588 mA h g−1. These properties are clearly superior to those of the Sn electrode deposited in aqueous solution.

Indirect electrochemical reduction of carbon dioxide to carbon nanopowders in molten alkali carbonates: Process variables and product properties

Carbon was deposited on a mild steel cathode during electrolysis in the molten mixture of Li2CO3 and K2CO3 (mole ratio: 62:38) under CO2 or mixed N2 and CO2 atmospheres at 3.0–5.0V and 540–700°C. In a three-electrode cell, cyclic voltammetry was applied on a platinum working electrode to study the reduction and deposition processes. A two-electrode cell helped correlate electrolysis variables, e.g. temperature and voltage, with the deposition rate, current efficiency, and properties of the deposited carbon powders. High current efficiency (>90%) and deposition rate (>0.11gcm−2h−1) were achieved in the study. Elemental analysis of the electro-deposits, following washing with HCl solutions (2.3–7.8molL−1), showed carbon as the dominant element (75–95wt.%) plus oxygen (5–10wt.%) and small amounts of other elements related to materials of the electrolytic cell. Thermogravimetry detected fairly low onset combustion temperatures (310–430°C), depending on the electrolysis and acid washing conditions. Amorphous and various nanostructures (sheet, rings and quasi-spheres) were revealed by electron microscopy in carbon samples deposited under different process conditions. The specific surface area of the carbon deposited at 5.0V and 540°C was as high as 585m2g−1. An analysis of the energy consumption suggests several ways for efficiency improvement so that the electrolytic carbon from CO2 will become commercially attractive.