Electrolyte Current Density Research Articles

Characteristics of Oxygen Electrode Supported Reversible Solid Oxide Cells

Oxygen-electrode-supported solid oxide cells (OESCs) have potential advantages over fuel-electrode-supported cells, including reduced fuel-electrode concentration polarization, better oxygen electrode current collection, and flexibility in the fuel electrode choice. However, there are serious drawbacks including the difficulty of co-firing the oxygen electrode and electrolyte, and oxygen electrode concentration polarization. This paper explores the characteristics of OESCs with La0.8Sr0.2MnO3−δ -Zr0.92Y0.16O2−δ (LSM-YSZ) electrode-support enhanced by SrTi0.3Fe0.6Co0.1O3−δ (STFC) infiltration, thin YSZ electrolyte, and SrTi0.3Fe0.7O3−δ (STF) fuel electrodes. The STFC infiltration increases fuel cell maximum power density by >1.5 times and electrolysis current density (at 1.3 V) by >2 times. Cell performance in pure oxygen is compared to that in air, exploring a possible reversible solid oxide cell system configuration where oxygen produced during electrolysis is stored and subsequently used during fuel cell operation. The fuel cell maximum power density is increased from 0.88 W cm−2 in air to 1.37 W cm−2 in oxygen, with limiting current increased from 1.7 to >5.6 A cm−2; the electrolysis performance is essentially unchanged, probably because the electrode air becomes enriched with oxygen during electrolysis.

Sono-assisted electrocoagulation treatment of rice grain based distillery biodigester effluent: Performance and cost analysis

Electrocoagulation process coupled with sonication is a type of advance oxidation process (AOP) to treat different type of waste waters. Biodigester effluent (BDE) generated from distillery industry contains very high chemical oxygen demand (COD=5500 mg/dm3) with high color (510 PCU) appearance. Organics reduction of biodigester effluent (BDE) in term of chemical oxygen demand (COD) and color have been investigated in a batch sono-electrocoagulation reactor with different electrode combinations such as Fe-Fe, Al-Al, Fe-Al, and Al-Fe at ultrasound frequency of 40 kHz. The impact of different operating parameters such as electrolyte concentration, electrode combination, pH and current density (CD) on COD and color removal are evaluated. The electrode combination of Fe-Fe has provided better results in sono-electrocoagulation process as compared to sonication and electrocoagulation alone. The maximum COD and color reduction efficiency of 99.1 % and 61.6 % was found at the electrode combination of Fe/Fe, CD 69.44 A/m2, pH 8, NaCl concentration 5 mg/dm3, and process time of 125 min. On the other hand the maximum COD and color removal efficiency of 98.3 % and 58.1 % was observed with the electrode combination of Al-Al at same operating conditions as described for Fe. Finally, sludge analysis and cost optimization are also incorporated in this article. It is found that at optimum condition (electrode combination of Fe/Fe, CD 69.44 A/m2, pH 8, NaCl concentration 5 mg/dm3, and process time of 125 min) the operating cost of the process is 1.39 $/m3. Sludge obtained after the treatment process contains anodic material (0.07 kg iron for the treatment 1 m3 of BDE) and also sludge had good heating value (5.5 MJ/kg). This work demonstrated that sono-electrocoagulation process is well applicable to treat BDE.

Syngas production through CH4-assisted co-electrolysis of H2O and CO2 in La0.8Sr0.2Cr0.5Fe0.5O3-δ-Zr0.84Y0.16O2-δ electrode-supported solid oxide electrolysis cells

High temperature co-electrolysis of H2O/CO2 allows for clean production of syngas using renewable energy, and the novel fuel-assisted electrolysis can effectively reduce consumption of electricity. Here, we report on symmetric cells YSZ-LSCrF | YSZ | YSZ-LSCrF, impregnated with Ni-SDC catalysts, for CH4-assisted co-electrolysis of H2O/CO2. The required voltages to achieve an electrolysis current density of −400 mA·cm−2 at 850 °C are 1.0 V for the conventional co-electrolysis and 0.3 V for the CH4-assisted co-electrolysis, indicative of a 70% reduction in the electricity consumption. For an inlet of H2O/CO2 (50/50 vol), syngas with a H2:CO ratio of ≈2 can be always produced from the cathode under different current densities. In contrast, the anode effluent strongly depends upon the electrolysis current density and the operating temperature, with syngas favorably produced under moderate current densities at higher temperatures. It is demonstrated that syngas with a H2:CO ratio of ≈2 can be produced from the anode at a formation rate of 6.5·mL min−1·cm−2 when operated at 850 °C with an electrolysis current density of −450 mA·cm−2.

TYPE OF WEAR OF ALUMINIUM OXIDE LAYERS DEPENDING ON MANUFACTURING PARAMETERS

The article presents the type of wear of Al2O3 layers produced on the aluminium alloy EN AW-5251 depending on the production parameters. Oxide layers were produced by using DC anodizing in a ternary electrolyte at variable current density and electrolyte temperature. The layer scratch tests were carried out using a Micron- Gamma microhardness tester. The scratches of oxide layers were tested for the geometric structure of the surface using a Form TalySurf 2 50i contact profilograph. Contact thickness measurements were also made using a Dualscope MP40 device based on the eddy-current method. Using a scanning microscope (SEM), photos of the sample surfaces were taken to show and compare the surface morphology of the anodized layers in various parameters. Based on the research, it can be concluded that changes in the conditions of the production process of Al2O3 layers (electrolyte temperature and current density) have an impact on the type of tribological wear and changes in layer thickness. The largest thickness of the oxide layer (19.44 μm) was measured for Sample B produced at a current density of 3A/dm2 at an electrolyte temperature of 283 K, which was also characterized by the lowest value of the ratio of parameters f1 to f2 (0.584). The smallest thickness (5.32 μm) was measured for the Sample C anodized at 1 A/dm2 at 303 K, this sample had the largest ratio f1 to f2 (1.068) for the produced Al2O3 layers. Thanks to the parameters f1 and f2 and the calculation of their ratio, the wear process for Sample B was determined as scratching and microcutting, while for Sample C as grooving.

Effect of deposition temperature on mechanical properties of nanotwinned Cu fabricated by rotary electroplating

A rotary electroplating system was used to fabricate high-strength nanotwinned copper (nt-Cu) foils with slanted columnar grain structures, which may serve as the anode current collector in lithium ion batteries (LIBs). By controlling the temperature of electrolyte bath and current density during electroplating, it is possible to tune the nanotwinned microstructure to optimize mechanical properties of the electroplated nt-Cu foils. The ultimate tensile strength (UTS) of nt-Cu foils has been enhanced by 60% of the ordinary nt-Cu from 403 MPa to 637 MPa. We found that UTS of the electroplated nt-Cu foils increases with decreasing temperature of electrolyte bath. The tensile strength of the nt-Cu foils increases approximately by 10 MPa for 1 °C decrease in the electrolyte temperature. The highest UTS of 637 MPa was obtained in rotary-electroplated at 6 °C and a current density of 11 ASD.

Surface Modification of Titanium Alloy by Anodic Oxidation Method to Improve its Biocompatibility

Surface modification of titanium alloy (Ti-6Al-4V) has been performed by anodic oxidation method within various concentration ranges of sulphuric acid (H 2 SO 4 ) electrolyte. It describes the oxidation kinetics of the anodizing process and critical analysis of process parameters like concentration of electrolyte, voltage, time and anodic current density, was performed to obtain homogenized nano-sized porous structure on the titanium substrate. XRD (X-ray diffraction technique) and FE-SEM (field emission scanning electron microscopy) were utilized for phase analysis as well as for morphological survey. XRD report revealed that porous structure appeared at 0.4 M concentration of the electrolyte and at anodic voltage of 20 V. Anatase to rutile phase transformation was observed at 0.5 M of H 2 SO 4 . Tribological test of anodized as well as nonanodized surface performed on pin-on-disc type tribometer suggested that anodized surface possessed high wear resisting strength compared to bare metal surface. The present study tries to enhance the biocompatible features especially bone cell attachment or cell proliferation of titanium alloy by improved surface characteristics.

Electrochemical performance of La2NiO4+\u03b4-Ce0.55La0.45O2\u2212\u03b4 as a promising bifunctional oxygen electrode for reversible solid oxide cells

In this work, La2NiO4+δ-xCe0.55La0.45O2−δ (denoted as LNO-xLDC) with various LDC contents (x = 0, 10, 20, 30, and 40 wt%) were prepared and evaluated as bifunctional oxygen electrodes for reversible solid oxide cells (RSOCs). Compared with the pure LNO, the optimum composition of LNO-30LDC exhibited the lowest polarization resistance (Rp) of 0.53 and 0.12 Ω·cm2 in air at 650 and 750 °C, respectively. The enhanced electrochemical performance of LNO-30LDC oxygen electrode was mainly attributed to the extended triple phase boundary and more oxygen ionic transfer channels. The hydrogen electrode supported single cell with LNO-30LDC oxygen electrode displayed peak power densities of 276, 401, and 521 mW·cm−2 at 700, 750, and 800 °C, respectively. Moreover, the electrolysis current density of the single cell demonstrated 526.39 mA·cm−2 under 1.5 V at 800 °C, and the corresponding hydrogen production rate was 220.03 mL·cm−2·h−1. The encouraging results indicated that LNO-30LDC was a promising bifunctional oxygen electrode material for RSOCs.

The influence of zinc electrode substrate, electrolyte flow rate and current density on zinc-nickel flow cell performance

This work aims to identify a suitable material for use as a zinc electrode substrate material in alkaline media, then employ this to study the effect of electrolyte flow rate and current density on zinc-nickel flow cell performance. Three metallic and four graphite composite materials are investigated, with the coulombic efficiency of zinc electrode charge / discharge cycling found to increase as hydrogen evolution onset potentials become more negative. A graphite / PVDF composite substrate demonstrates the highest coulombic efficiency at 96.7% and the most negative hydrogen evolution onset potential at -1.595 V vs. Hg/HgO. Using this material, the effect of electrolyte flow rate and current density on a zinc-nickel flow cell is investigated. Zinc morphology and flow cell performance is related to the ratio of applied current density to limiting current density. At values between 0.47 and 1, boulder type zinc morphologies occur, with smooth and compact zinc deposits resulting from current density ratios of 0.39 and below. Stable zinc-nickel flow cell performance is achieved over 200 cycles with coulombic, voltaic and energy efficiencies of 98.3, 88.1 and 86.6%, respectively, at a current density of 20 mA cm−2.

Degradation of Acid Violet 19 textile dye by electro-peroxone in a laboratory flow plant

This paper deals with the degradation of Acid Violet 19 (AV19) textile dye by the electro-peroxone (E-peroxone) process in a laboratory flow plant using a filter press cell fitted with a 3D gas diffusion electrode (3D GDE) containing a graphite felt positioned on carbon-cloth PTFE as cathode, and a Ti|IrSnSb-oxides plate as anode. H2O2 was formed by the oxygen reduction reaction (ORR) in the cathode; the air was supplied by an external compressor. The O3 produced externally by an ozonator was added in the pipeline at the outlet of the electrolyzer to promote the reaction between the H2O2 and O3 to produce OH, which is the responsible for the mineralization of the dye. The effect of electrolyte flow rate (Q), current density (j), and initial concentration of AV19 dye on its degradation was addressed. The best electrolysis in a solution containing 40 mg TOC L−1, 0.05 M Na2SO4, at pH 3, was obtained at j = 20 mA cm−2, Q = 2.0 L min−1, using a pressure of the air fed to the 3D GDE of PGDE = 3 psi, and an ozone inlet mass flow rate of F03 = 14.5 mg L−1, achieving 100% discoloration, 60% mineralization, with mineralization current efficiency and energy consumption of 36% and 0.085 kWh(gTOC)−1. The degradation of AV19 dye was also performed by anodic oxidation plus H2O2 electrogenerated (AO-H2O2) and ozonation. The oxidation power was AO-H2O2 < ozonation < E-peroxone. Three carboxylic acids were quantified by chromatography as oxidation end products.

Ceftriaxone Degradation in the Presence of Sodium Halides Investigated by Electrochemical Methods Assisted by UV-Vis Spectrophotometry

The electrochemical stability of ceftriaxone (CFTX), belonging to the third generation of cephalosporin antibiotics, was studied by electrochemical measurements recorded on a platinum electrode (Pt) in aqueous solutions containing sodium halides. The electrochemical behavior of ceftriaxone was investigated by cyclic voltammetry (CV) and constant current density electrolysis assisted by UV-Vis spectrophotometry. Cyclic voltammetry highlighted that the addition of CFTX in sodium halide solutions leads to significant changes in the hysteresis characteristics due to specific interactions with active species from electrolytes, as well as with the platinum electrode surface. After CV, when an exterior electric stimulus in short time (40 s) was applied, the UV-Vis spectra illustrated that CFTX is stable in the presence of F− ions, it is electro(degraded/transformed) in the presence of Cl− and Br− ions and interacts instantly with I− species. Electrolysis at constant current density confirms the results obtained from cyclic voltammetry, showing that (i) in the presence of fluoride ions CFTX gradually decomposes, but not completely, in about 60 min, without identifying a reaction product; (ii) chloride and bromide ions determine the almost complete CFTX electro(degradation/transformation) in 10 and 5 min, respectively, with completion of the electro-transformation reaction after 60 and 30 min, respectively; (iii) instantaneous interactions between CFTX and the iodide ions occurred.

Direct CO2 Electrolysis on Symmetric La0.8Sr0.2Cr0.5Fe0.5O3−δ -Zr0.84Y0.16O2−δ Electrode-Supported Solid Oxide Electrolysis Cells

La0.8Sr0.2Cr0.5Fe0.5O3−δ (LSCrF) is a mixed ionic and electronic conductor with excellent stability in both reducing and oxidizing atmospheres. Herein, we prepared a symmetric tri-layer structure of “porous YSZ-LSCrF ∣ dense YSZ ∣ porous YSZ-LSCrF” by the tape casting and lamination techniques. Porous scaffolds of 80 wt% LSCrF − 20 wt% YSZ showed good conductivities and reasonably high performance for direct CO2 electrolysis with a current density of 0.84 A·cm−2 at 850 °C. Infiltrating Sm0.2Ce0.8O2−δ (SDC) catalysts into both porous scaffolds enhanced their catalytic activities for CO2 reduction and oxygen evolution reactions, yielding an increased electrolysis current density of 1.3 A·cm−2 at 850 °C and 1.5 V. Impedance measurements showed a pronounced decrease in the total interfacial polarization resistance at 1.5 V, i.e., 0.34 vs 0.66 Ω·cm2. In addition, these symmetric cells exhibited good short-term stability at various voltages from 1.0 to 1.6 V.

Using electric flocculation to treat domestic laundry wastewater with different types of detergents

Laundry wastewater contains a large number of surfactants, suspended solids and other pollutants, and the COD value is high. If the wastewater is discharged into the water without harmless treatment, it will cause serious environmental pollution. The electrocoagulation process was selected as a promising environmentally friendly technology for treating domestic laundry wastewater. In this paper, the contribution of the liquid and powder detergents to the composition of domestic laundry wastewater was investigated. Combination of stainless steel and aluminum anode electrodes were compared. The effect of electrolysis time and current density on the removal of COD, LAS and turbidity of liquid detergent and powder detergent laundry wastewater were evaluated. The experimental results showed the electrocoagulation process has significant removal. It was found that the electrolysis time in 25 minute, current density in 5 mA/cm2 had optimum efficiency when considering efficient removal and economic energy consumption. For Liquid detergent laundry wastewater, COD, LAS and turbidity removal rates were 84%, 93% and 96%. For powder detergent laundry wastewater, COD, LAS and turbidity removal efficiency were 80%, 83% and 91%, respectively. Energy consumption in the optimum conditions for liquid detergent and powder detergent laundry wastewater by electrocoagulation were 7.324KWh/m3, 3.642KWh/m3, respectively, while using combination of stainless steel and aluminum anode electrodes equals 1 to 1.

Electrochemically controlled in situ conversion of CO2 to defective carbon nanotubes for enhanced H2O2 production.

Defects on carbon nanotubes (CNTs) can be used as active sites to promote the occurrence of catalytic reactions and improve the ability of catalysts. Although some progress has been made in the synthesis of defects on carbon nanotubes (CNTs), most of the defects are caused by acid etching or high-temperature pyrolysis of organics, which is detrimental to the environment, and the defects are uncontrollable. Herein, we report the eco-friendly and controllable synthesis of defective CNTs by reduction of CO2 under cathodic polarization in Li2CO3-based molten salts. The defective degree of CNTs can be tuned by changing the applied electrolysis current. The results show that low current is beneficial for the synthesis of CNTs with more defect sites. The most defect-rich carbon nanotubes synthesized under 300 mA cm-2 electrolysis (CNTs-B2O3-300) in a molten Li2CO3/B2O3 composite melt performed the best in the 2e- oxygen reduction reaction (ORR) compared with CNTs-B2O3-400 and CNTs-B2O3-500 obtained under higher current density electrolysis. This work provides an alternative strategy for the design and synthesis of defect-rich carbon materials for catalysis and energy applications.

NiFeP-MoO2 hybrid nanorods on nickel foam as high-activity and high-stability electrode for overall water splitting

The research about inexpensive and efficient electrocatalyst plays a significant role in electrocatalyzing H2 production from water splitting. We herein report a novel hybrid 1D heterogeneous nanorods based on nickel–iron phosphide and molybdenum dioxide (NFPMO) grown on nickel foam that presents highly outstanding electrocatalytic performance in electrochemical overall water splitting, both hydrogen evolution reaction (HER) and oxygen evolution reaction (OER). The applied cell voltage of employing NFPMO electrode in overall water splitting merely require 1.41 V and 1.65 V at 10 mA cm−2 and 100 mA cm−2 working electrolysis current density, respectively, and it can bear high stably upon hundreds of hours long-term electrolysis operation. The synergistic effects of heterogeneous structure in 1D nanorods obviously accelerate the electrocatalytic activity, as demonstrated by not only electrochemical tests but also coupling systematic electrochemical study with density functional theory (DFT) calculation.

Electrochemical stability of stainless-steel-made anode for alkaline water electrolysis: Surface catalyst nanostructures and oxygen evolution overpotentials under applying potential cycle loading

We investigated electrochemical stability of the NiFe-hydroxide/oxide-catalyst-layer covered stainless-steel(SS)-anode (NiFe-HyOx/SS) for alkaline water electrolysis. The NiFe-HyOx catalyst layer was synthesized through constant current density electrolysis of 30 mA/cm2 in 1 M KOH solution of a 316 SS plate at 75 ℃ for 5 h. The initial overpotential of oxygen evolution reaction (OER) was estimated to be ca. 270 mV at 100 mA/cm2 and the potential kept almost constant during applying the 20,000 potential cycles (PCs) of 0.5 and 1.8 V vs. reversible hydrogen electrode in 7 M KOH at 20 ℃. Scanning transmission electron microscopic observations conducted before and after the PCs loading revealed that the 50 nm-thick, nanofiber-like NiFe-HyOx catalyst layer remained unchanged in structure and in thickness, while the ca. 850 nm-thick, relatively dense NiFe-(hydro)oxide interlayer was generated under the catalyst layer. The results suggest that the superior OER property of the NiFe-HyOx/SS anode is originated from the surface catalyst layer.

Study on electrolyte supply strategy for energy storage system of multi zinc nickel single flow battery stack loaded with single pump

Zinc nickel single flow battery (ZNB) has the advantages of low cost, low toxicity and long life, which is considered as one of the ideal choices for large-scale fixed energy storage. The efficient operation of ZNB is a necessary condition for maximizing system efficiency and safe operation. In this paper, a dynamic model of ZNB of single pump loaded with multi stack considering electrochemical reaction, mass transfer and hydraulic loss is constructed. Based on the principle of minimizing charging energy and maximizing discharge energy, the effects of electrolyte flow rate and current density on potential window and morphology of zinc deposition are considered, an adaptively adjusted electrolyte flow supply scheme is proposed. By considering the effect of flow rate on zinc deposition, the optimized electrolyte supply strategy can not only improve the system efficiency, but also effectively extend the service life of ZNB.

Electrolytic Formation of Solid Crystalline UO2–ThO2 and UO2–ThO2–ZrO2 Solutions from Salt Melts

For the first time, crystalline solid solutions of UO2–ThO2 and UO2–ThO2–ZrO2 have been electrolytically prepared. The mechanism of their formation in molten halides is presented. The influence of the electrolysis current density on the compositions of the cathode deposits has been established and explained. We also established the effect of zirconium ions on the ThO2 content in the UO2–ThO2–ZrO2 cathode deposits.

Highly Efficient Alkaline Water Splitting with Ru-Doped Co-V Layered Double Hydroxide Nanosheets as a Bifunctional Electrocatalyst.

Active electrocatalysts for the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) are decisive for achieving efficient energy conversion from electricity to hydrogen fuel through water electrolysis. In this study, tremella-like Ru-doped Co-V layered double hydroxide nanosheets on Ni Foam (Ru-CoV-LDH@NF) was fabricated by a one-pot solvothermal reaction. As-prepared Ru-CoV-LDH@NF, with a nominal Ru loading of around 51.6 μg cm-2 exhibits excellent bifunctional catalytic activity towards HER and OER in alkaline media. To accomplish a current density of 10 mA cm-2 , it demands 32 mV and 230 mV overpotentials for HER and OER, respectively. The alkali electrolyzer utilizing Ru-CoV-LDH/NF as bifunctional electrocatalyst affords 10 mA cm-2 electrolytic current density at an extremely low cell voltage of 1.50 V, showing excellent performance compared to a Pt/C-RuO2 -based electrolyzer and many other bifunctional electrocatalyst-based ones. The incorporation of Ru changes the morphology of the resultant nanosheets to offer high electrochemical surface areas for electrocatalysis; at the same time, it significantly boosts the intrinsic HER/OER electrocatalytic activity. For HER, the energy barrier of the Volmer step is efficiently reduced upon Ru doping, whereas the Ru dopants optimize the absorption strength of *O intermediates to facilitate the OER process. This work offers a feasible means to optimize the Co-based hydroxide materials for improved electrocatalysis in overall water splitting.

(Invited) Effects of PrOx and Gd-Doped CeOx Infiltration: Enhancement of Solid Oxide Cell Performance and Stability

PrOx-infiltrated oxygen electrodes can yield relatively low polarization resistances even at reduced operating temperature. Similarly, Gd-doped Ceria (GDC) infiltration into Ni-YSZ fuel electrodes has been shown to reduce polarization resistance while also helping to maintain stable electrolysis operation. Here we review the literature on these electrodes and discuss recent results on electrochemical impedance spectroscopy (EIS) studies of PrOx-infiltrated La0.6Sr0.4Co0.2Fe0.8O3 (LSCF) and SrTi0.3Fe0.55Co0.15O3 (STFC) oxygen electrodes and GDC-infiltrated Ni-YSZ. Physically-based equivalent circuit models are developed using the distribution of relaxation times method and used to fit the symmetric cell EIS data, comparing PrOx- and GDC-infiltrated electrodes with un-infiltrated electrodes. The results suggest that PrOx improves oxygen dissociative adsorption/desorption, oxygen surface exchange, and transport of oxygen in the perovskites; while GDC reduces the reaction resistance associated with three-phase boundaries and improves oxygen transport in Ni-YSZ. Full cells employing the PrOx-infiltrated STFC and Ni-YSZ:GDC electrodes achieve high performance (e.g. fuel cell power density nearly 3 W/cm2 at 750 oC and > 1 W/cm2 at 600 oC; and electrolysis current density at 1.3 V of nearly 4 A/cm2 at 750 oC), while exhibiting promising stability. Combining the equivalent circuit models from the symmetric cell data for each electrode provides a detailed explanation and fit of the full cell EIS results.

Electroreduction of CO2 on Modified Graphene Supported Sn Nanoparticles in Half-Cell and Full Cell Configuration

Electrochemical reduction of CO2 is a process that can reduce carbon dioxide from the atmosphere and simultaneously produce useful, value-added chemicals, specifically solar fuel [1]. Depending on the catalyst materials, CO2 can be reduced to single carbon or multi carbon products [2]. Sn nanoparticle was used to catalyze CO2 reduction to produce formate in alkaline medium. Sn nanoparticles were synthesized by the sol-gel method with different precursors at room temperature and supported with carbon black and conductive graphene nano-sheets. Graphene nano-sheets were synthesized by the conventional modified Hammer method [3]. X-ray diffraction (XRD) and transmission electron microscope (TEM) enabled insights into phase formation, shape, and size of the Sn nanoparticles. Reference materials included commercial Sn nanoparticles with carbon support (Sn:C_com), commercial Sn nanoparticles with graphene support (Sn:GN_com), Sn nanoparticle synthesised using Sn (II) 2-ethylhexanoate and Sn (II) chloride as tin precursor with carbon support as respectively (Sn:C_Tin-2-hexa) and (Sn:C_SnCl2). Three-electrode chronoamperometry showed that Sn:GN_com enabled high CO2 electrolysis current density (see Figure 1(a)). Electrochemical impedance spectroscopy (EIS) of the prepared catalysts in CO2-saturated 0.1 M KHCO3 was recorded in a three-electrode rotating disk electrode (RDE) configuration (see Figure 1(b)). The charge-transfer resistance was smallest for Sn:GN_com sample, as well. CO2 reduction was performed in a full electrochemical cell using the same architecture as a low temperature polymer electrolyte fuel cell (PEFC) in alkaline medium with anion exchange membrane. Polarization plots show a unique feature (two different slopes); this change in slope is dominated by a distinct change in the area specific resistance (ASR) value (see Figure 1(c)).In this work, we mainly focus on the CO2 electroreduction to produce formate in a full cell with RDE (rotating disc electrode) measurements providing additional insights into catalytic properties. Our primary goal is to understand the basic underlying physical processes during CO2 reduction in the full cell set up and also find inexpensive and efficient catalytic active materials for the reduction process. Figure 1: CO2 electrolysis (a) and impedance spectra (b) in RDE configuration with different catalyst. (c) Polarisation plots for CO2 reduction in full cell configuration with different flow rate