Slow Reaction Rate Research Articles

Atomic Doping and Anion Reconstructed CoF2 Electrocatalyst for Oxygen Evolution Reaction

AbstractElectrocatalytic water splitting is one of the most promising green solutions for large‐scale hydrogen production, which has developed rapidly in recent years. The slow reaction rate of oxygen evolution reaction (OER) has become the bottleneck to improve the electrocatalytic efficiency. Herein, Fe‐doped CoF2 nanowire arrays on 3D nickel foam are prepared by two steps of hydrothermal reaction and fluorination process. The increased catalytic activity sites and accelerated charge transfer rate make the self‐supported Fe‐doped CoF2 electrode show excellent OER performance in alkaline electrolyte. An overpotential of 230 mV is only required to release a current density of 10 mA cm−2. The Tafel slope derived from the polarization curves is 59 mV dec−1, indicating outstanding electrochemical kinetics performance. A stable output current density of 84 mA cm−2 for more than 96 h is achieved under an invariant overpotential of 338 mV, attributing to the anion reconstruction making part of CoF2 transform into cobalt hydroxide and further improving its electrocatalytic performance.

Illuminating a Practical Solution to Clothing Protection from Mustard Gas

Lee et al. reported the first metal-organic framework (MOF)-fiber composite for the catalytic detoxification of a mustard gas simulant. The development of such wearable catalytic materials is an important step toward developing protection equipment that can simultaneously detoxify several chemical warfare agents (CWAs) under ambient conditions.

Mathematical modelling of seed-mediated size-specific growth of spherical silver nanoparticles using Azadirachta indica leaf extract

ABSTRACT Spherical silver nanoparticles of required size were synthesized employing a seed-mediated approach using leaf extract of Azadirachta indica. Reaction pH was used to manipulate the rate of reduction of the precursor salt for achieving a fast rate of reaction needed during the synthesis of silver nanoparticles seeds and a slower rate of reaction needed for controlled growth and inhibition of secondary nucleation. A mathematical model was developed for staggered growth of silver nanoparticles using a multi-step growth approach. The developed model was used to predict the size of silver nanoparticles after various growth steps and was compared with the experimentally achieved results. Transmission electron microscope images were used for the determination of the size of the synthesized silver nanoparticles. The mathematical model appears to be a promising tool in enabling real-life application of green synthesized silver nanoparticles.

Ascorbic acid-mediated reductive disassembly of Fe3+-tannic acid shells in degradable single-cell nanoencapsulation.

Rapid degradation of Fe3+-tannic acid films is achieved under mild conditions via ascorbic acid-mediated Fe3+ reduction, which overcomes the problems in the disassembly of a metal-organic complex including slow reaction rates and reaction incompatibility with living cells. The strategy of reductive disassembly is applied to degradable single-cell nanoencapsulation, providing an advanced tool for tightly controlling and manipulating the cell-material interface.

Hydrolysis of ketene catalysed by nitric acid and water in the atmosphere

Environmental contextThe detailed mechanism of hydrolysis of gas-phase ketene to form acetic acid is critical for understanding the formation of certain atmospheric contaminants. This study explores the effect of nitric acid and water on the hydrolysis of ketene in the atmosphere. The calculated results show that nitric acid is an effective catalyst in the hydrolysis of ketene to form acetic acid in atmospheric water-restricted environments. AbstractThe gas-phase hydrolysis of ketene and the unimolecular reaction of 1,1-enediol catalysed by nitric acid and water have been investigated using quantum chemical methods and conventional transition state theory with Eckart tunnelling. The theoretical calculation results show that nitric acid exerts a strong catalytic effect on the hydrolysis of ketene in the gas-phase. The calculated energy barrier for the direct reaction mechanistic pathway is reduced from 42.10kcal mol−1 in the reaction of ketene with water to 3.40kcal mol−1 in the reaction of ketene with water catalysed by HNO3. The catalytic ability of nitric acid is further proven in the hydrogen shift reaction of 1,1-enediol because the energy barrier of the unimolecular reaction of 1,1-enediol is decreased from 44.92kcal mol−1 to −4.51kcal mol−1. In addition, the calculated results indicate that there is competition between the direct and indirect mechanistic pathways with the increase of additional water molecules in the reaction of ketene with water catalysed by HNO3 and (H2O)n (n=1, 2). The calculated kinetics results show that the CH2=C=O+H2O+HNO3 reaction is significant in the gas phase of the atmosphere and the other reactions are negligible owing to the slow reaction rates. However, compared with the CH2=C=O+OH reaction, the CH2=C=O+H2O+HNO3 reaction is very slow and cannot compete with the CH2=C=O+OH reaction. CH2=C=O+OH is the main elimination pathway of ketene in the gas phase of the atmosphere. Our findings reveal that acetic acid may be formed through the hydrolysis of ketene in atmospheric water-restricted environments of the surfaces of aqueous, aerosol and cloud droplets.

Thermodynamic feasibility for molybdenum-based gaseous oxides assisted looping coal gasification and its derived power plant

Coal utilization in chemical looping reactions is a promising approach for fuel conversion with inherent CO2 separation, but is also hindered by kinetic limitations between the solid fuel and conventional oxygen carriers. Molybdenum oxides are considered as alternative oxygen carriers in a “gaseous oxide assisted looping” strategy, which can potentially resolve the problems of slow reaction rate in fuel reactors and the difficulty of separating oxygen carriers from ash in air reactors. For the novel conception, it is necessary to specify the chemical looping process and evaluate the thermodynamic feasibility. So, a molybdenum-based gaseous oxide assisted looping coal gasification (MoCLCG) process is designed in this study. The suitable temperature conditions of individual reactors are determined by analyzing the redox reaction characteristics and physical properties of molybdenum oxides. Furthermore, to verify the systemic feasibility, the MoCLCG technology is integrated with a hybrid solid oxide fuel cell/steam turbine power plant, which obtains energy/exergy efficiencies of 39.38% (LHV) and 36.32%, respectively. The most influence factor in the system performance is the heating efficiency of electric heating furnace. An optimal mass ratio of Mo-based oxygen carrier to coal is obtained as 6.84 and exists to achieve high energy and CO2 emission reduction efficiencies, simultaneously.

Strength, microstructure, efflorescence behavior and environmental impacts of waste glass geopolymers cured at ambient temperature

Abstract In this study, waste glass powder (d50 = 15.4 μm) obtained by crushing soda lime glass bottles was investigated as a raw material for geopolymer cement. The waste glass (WG) powder and class C fly ash (FC) were mixed at varying ratios (100:0, 75:25, 50:50, 25:75, 0:100) and activated by sodium hydroxide solutions of different concentrations (0 M, 2.5 M, 5 M, 7.5 M, 10 M). The geopolymer pastes were cured at ambient temperature and the compressive strengths at increasing curing ages were tested. The mechanical properties were analyzed with respect to the kinetics and Si/Al ratio of the reaction system. The experimental results suggested that the WG mostly acted as an inert filler at early ages due to the slow reaction rate. However, the strength performance improved significantly after the curing age of 14 days, which was attributed to the reaction between WG and FC. The geopolymer made by mixing WG and FC at a ratio of 1:3 (Si/Al = 3.038) and 5 Mol NaOH solution achieved a compressive strength of 34.5 MPa. The microstructure and minerology of the geopolymers analyzed by the SEM-EDX and XRD suggested the coexistence of sodium aluminate silicate hydrate (N-A-S-H) gel and calcium aluminate silicate hydrate (C-A-S-H) gel in geopolymer matrix. The results of leaching tests indicated the potential environmental impact caused by the leaching of excessive alkali, which should be carefully managed during the mix design. The sustainability analysis including the embodied energy and carbon footprint confirmed the environmental friendliness of WG geopolymer. This study exhibited the feasibility of producing WG geopolymer concrete at ambient temperature and the potential synergy between the waste glass recycling and geopolymer industry.

Experimental and modeling study of CO2 absorption by L-Proline promoted potassium carbonate using hollow fiber membrane contactor

Recently, it has been shown that solutions of amino acid salts are suitable absorbents for CO2 separation. Potassium carbonate is an economic solvent; however, it has a slow reaction rate with CO2. In this work, potassium carbonate promoted with l-Proline, as an amino acid, is applied as a CO2 absorbent using a hollow fiber membrane contactor. Experimental results showed that recovery can rise up by adding l-Proline. Effects of parameters such as gas and liquid flow rates and concentration of absorbents on CO2 recovery and CO2 molar flux were investigated. The effect of wetting parameters, CO2 percent in feed gas and temperature on CO2 recovery were investigated by mathematical model. Results show that CO2 recoveries near 100 % can be reached at the l-Proline concentration of 0.1 mol/l, which reveals the potential of this amino acid as promoter of K2CO3.

Accelerating the Coupling of Maleated Polyolefins with Polyesters via Tin Compounds

Poly(ethylene terephthalate) (PET) and polyethylene (PE) are two of the most commonly used polymers in the packaging industry, and they make up a large portion of the recycling stream. Adhesion between these two immiscible polymers is poor without compatibilization. Maleic anhydride (MAH) grafted PE is a popular compatibilizer for PET/PE but is limited by the slow rate of reaction. In this study, we propose tin additives for improving adhesion and explore the mechanism of that improvement. We demonstrate that either dibutyltin oxide (DBTO) or di-n-octyltin oxide (DOTO) can dramatically enhance adhesion with only 60 s of contact time during lamination. A range of MAH and DOTO concentrations are examined, yielding adhesion up to 1300 J/m2. Possible reactions at the interface are investigated with small molecule model compounds, namely 1-hexadecanol, octylsuccinic anhydride (OSA), and ethylene glycol dibenzoate. DOTO does not improve the reaction rate in the hexadecanol–OSA system. This suggests that another...

Thermal Decomposition Reaction Kinetics of Hematite Ore

In order to understand the thermal decomposition kinetics of hematite particles in inert atmosphere, thermogravimetriy was employed for isoconversional analysis. The kinetic triplet was estimated from the experimental data and the isothermal reaction kinetics was predicted. The results indicated that the thermal decomposition could be divided into two stages, of which the activation energies were 636 kJ/mol and 325 kJ/mol, respectively. The exponential form of pre-exponential factor, ln(A/s−1), for the two stages were estimated to be 42.9±6.6 and 14.1±3.08. At last, the kinetic mechanism of the first stage was suggested to match Sestak-Berggren model as f(α)=(1−α)1.38. The relatively slow reaction rate of the second stage was due to the slag formation during the reaction.

Reaction of ribulose biphosphate carboxylase/oxygenase assembled on a DNA scaffold

Ribulose-1,5-biphosphate carboxylase/oxygenase (RuBisCO), an enzyme in the Calvin-Benson-Bassham cycle of photosynthesis, catalyzes the first step of CO2 fixation in plants, algae, and photosynthetic bacteria. Despite of the important function in the global carbon cycle, RuBisCO suffers from a slow reaction rate and a competing reaction with O2 which draw attentions to improve the enzyme efficiency. In this study, a RuBisCO dimer from Rhodospirillum rubrum was assembled on a DNA scaffold using a dimeric DNA binding protein as an adaptor. The enzyme assembly was characterized by atomic force microscopy and RuBisCO assembled on the DNA scaffold showed avid enzymatic activity with retaining its parent carboxylase function. To mimic the environment of the natural microcompartment in cyanobacterial carboxysome that encapsulate the second enzyme carbonic anhydrase (CA) with RuBisCO, RuBisCO was next co-assembled with CA on the DNA scaffold. Although the natural carboxysome assembly is believed to enhance the RuBisCO activity, the co-assembly of RuBisCO and CA reduced the RuBisCO activity, suggesting that the preferential CO2 dehydration by CA reduced the RuBisCO reaction rate. In line with the recent study, our results suggest that the proximity in the interenzyme distance of RuBisCO and CA is not the crucial determinant for the enhanced RuBisCO activity in carboxysome. The assembly of RuBisCO and CA on DNA scaffold provides a platform for further study on the spatial control of RuBisCO and associating enzymes.

Pt Atoms on the Surfaces of Ordered and Disordered Aucu/C for Oxygen Reduction Reaction: Comparison of Electrochemical Performance and Mechanism

To mitigate the effects of dwindling fossil fuel and the detrimental climate problems originating from the excessive CO2 emission, significant efforts are required to exploit alternative clean energy resources and advanced energy utilization strategies. Owing to its high energy density, high energy efficiency and low environmental impact, proton exchange membrane fuel cells (PEMFCs) are widely considered as the ideal alternatives to replace the traditional internal combustion engines. However, the slow rate of oxygen reduction reaction (ORR) in PEMFCs is the main limitation for automotive applications. This limitation could be eliminated if stable and active cathode catalysts could be developed. Nowadays, carbon supported platinum nanoparticles (Pt/C) still serve as the state-of-the-art ORR catalyst. The high cost and limited availability of Pt seriously impede its large-scale commercialization. Though tremendous efforts have been devoted to exploiting new Pt-free catalysts, there is still a large gap in the electrochemical performance between Pt/C and Pt-free catalysts in fuel cell. One strategy is to alloy Pt with other transition metals to form as PtM (M represents other transition metal) catalysts. The introduction of a secondary transition metal could change the environment of Pt atoms including: chemical composition, catalytic surface and coordination environment. What’s more, to maximize Pt utilization for fuel cell, various methods are explored to synthesize various structure of PtM catalysts, including hollow, cage, wire, dendrites and core-shell. Due to the so-called ligand effect and strain effect, the core-shell structure where the Pt atoms are usually arranged on the surface of the as-prepared alloy, is the most promising alternative to replace the traditional commercial Pt/C. However, few literature have studied if the structure ordering of the core materials has any effects on the catalytic performance of the outmost Pt atoms. The structure ordering refers to the different atomic arrangement in the unit cell. Taking the AuCu alloy as an example, in an ordered structure, the atoms only occupy the specific site of the unit cell, while the atoms of the disordered one will randomly distribute in the cubic of lattice. It means that in any nodes of the disordered unit cell, the atoms may exist statistically according to their mole ratios. Recently, there are several reports on the ordered alloys that they could have better ORR performance than their corresponding disordered samples. The enhanced activity and durability may be attributed to their different heteroatomic bonding, surface configuration and distribution of active sites. In our previous work, we obtained the ordered and disordered AuCu/C by a post-heating treatment at different temperatures. After a systematic comparison, we demonstrated the ordered AuCu/C catalysts could exhibit superior ORR performance, which is similar to that of Pt/C, than disordered ones in 0.1 M KOH solution. However, the Cu atoms are unstable in acid electrolyte which limited its further application in PEMFCs. In present work, Cu atoms on the surface of ordered AuCu/C nanoparticles were selectively replaced by Pt atoms by means of acid leaching and wet chemical deposition (denoted as O-Pts–AuCu/C) as shown in Figure 1. For comparison, the disordered AuCu/C was also used as core material to prepare D-Pts–AuCu/C. The high resolution transmission electron microscopy （HR-TEM）and high angle annular dark-field scanning transmission electron microscopy (HAADF-STEM) coupled with line scan demonstrated the formation of as O-Pts–AuCu/C and D-Pts–AuCu/C. The electrochemical characterization displayed the O-Pts–AuCu/C have a superior activity and remarkable stability in 0.1 M HClO4 solution with respect to commercial Pt/C and D-Pts–AuCu/C. To better understand their different electrochemical performance, X-ray photoelectron spectroscopy and X-ray absorption spectroscopic measurements were performed to study the electronic structure of O-Pts–AuCu/C and D-Pt s–AuCu/C. It was found that the ordered AuCu core could exert a compressive strain on the outmost Pt atoms. Compared to D-Pts–AuCu/C, lower d-band vacancy could be observed in O-Pts–AuCu/C which could account for its superior ORR performance. Figure 1

Boosting Photocatalytic Hydrogen Production by Modulating Recombination Modes and Proton Adsorption Energy.

Solar-driven production of renewable energy (e.g., H2) has been investigated for decades. To date, the applications are limited by low efficiency due to rapid charge recombination (both radiative and nonradiative modes) and slow reaction rates. Tremendous efforts have been focused on reducing the radiative recombination and enhancing the interfacial charge transfer by engineering the geometric and electronic structure of the photocatalysts. However, fine-tuning of nonradiative recombination processes and optimization of target reaction paths still lack effective control. Here we show that minimizing the nonradiative relaxation and the adsorption energy of photogenerated surface-adsorbed hydrogen atoms are essential to achieve a longer lifetime of the charge carriers and a faster reaction rate, respectively. Such control results in a 16-fold enhancement in photocatalytic H2 evolution and a 15-fold increase in photocurrent of the crystalline g-C3N4 compared to that of the amorphous g-C3N4.

Kinetics underpinning the C-CO2 gasification of waste tyre char and its interaction with coal char upon co-gasification

This study includes a thorough investigation of the char structure, the potential catalytic influence of minerals, the carbon conversion rate, the kinetic behavior and parameters of the CO2 – gasification reaction for waste scrap tyre char and its blends with coal chars. Kinetic modelling was also attempted based on the two classical methods, random pore model (RPM) and grain model (GM) using the isothermal gasification results collected from thermogravimetric analysis (TGA). As has been found, tyre char is characterised with a macroporous structure with a very low reactivity. The catalytic role of the inherent minerals within tyre char is only influential at lower temperatures below ~1373 K. As opposed to the generally assumed first order reaction, the tyre char exhibits a reaction order between 0.62 (for an intrinsic reaction at 1273 K) and 0.92 referring to a dominant diffusion control at 1573 K. The slow intrinsic reaction rate of tyre char was also found to be comparable with the gas diffusion rate, thereby exhibiting a large activation energy of 174.87 kJ/mol that is considerably higher than coal chars. The coal char – tyre char blends displayed declining reactivity with increasing tyre char content, due to the enhanced ash melting and diffusion against the inward gas diffusion towards the unreacted carbon that is encapsulated inside. This was further explained by the experiments of blending tyre char ash with coal chars, and the observation of ash residues collected from the gasification of blends. Furthermore, the grain model was found more suitable to fit the blending conversion data, agreeing with the hypothesised molten ash layer surrounding the unreacted char blend.

Rapid removal of diclofenac in aqueous solution by soluble Mn(III) (aq) generated in a novel Electro-activated carbon fiber-permanganate (E-ACF-PM) process

Electrolysis and permanganate (PM) oxidation are two commonly used technologies for water treatment. However, they are often handicapped by their slow reaction rates. To improve the removal efficiency of refractory contaminants, we combined electrolysis with PM using an activated carbon fiber (ACF) as cathode (E-ACF-PM) for the first time to treat diclofenac (DCF) in aqueous solution. Up to 90% DCF was removed in 5 min by E-ACF-PM process. In comparison, only 3.95 and 27.35% of DCF was removed by individual electrolysis and PM oxidation at the same time, respectively. Acidic condition was more conducive to DCF removal. Surprisingly, soluble Mn(III) (aq) formed on the surface of ACF was demonstrated as the principal oxidizing agent in E-ACF-PM process. Further studies showed that all three components (electrolysis + ACF + PM) were necessary to facilitate the heterogeneous generation of reactive Mn(III) (aq). Moreover, SEM images and XPS spectra of ACF before and after treatment revealed that the morphologies and elemental compositions of reacted ACF were nearly unchanged during the E-ACF-PM process. ACF can be remained active and utilized to the rapid degradation of DCF in E-ACF-PM process even after reused for 20 times. Therefore, the E-ACF-PM process may provide a novel and effective alternative on the generation of reactive Mn(III) (aq) in situ for water treatment by green electrochemical reactions.

Performance Evaluations of Biofuel Cells Using Biocatalysts Consisting of Mediator and Enzyme Immobilized Carbon Nanotube Based Substrate

Enzyme based biofuel cells (BC) utilizing glucose and oxygen fuels are devices converting chemical energy of the fuels to electrical energy with a help of the enzyme based biocatalysts. Because the BC can run even in the physiological conditions, the glucose and oxygen which are flowed in human body can be considered as the fuels for the devices implanted into the human body. In spite of that, there are still problems to be resolved. Especially, the slow reaction rate issue of the biocatalyst should be improved. To address the issue, adopting mediator with the enzyme and substrate materials is a plausible way. When the appropriate mediator is introduced, electron transfer rate for the anodic reactions including glucose oxidation reaction (GOR) and the cathodic reactions including oxygen reduction reaction (ORR) is promoted and as a result, the generated current will increase. To maximize the electron transfer rate and elucidate the electron transfer mechanism, we propose a new electron transfer mechanism, so called, a mediator embedded electron transfer (EMET). With this EMET mechanism, the corresponding mediator that is cheap and has a low-overpotential range for redox reaction is well immobilized on the enzyme and substrate materials, such as carbon nanotube (CNT). More specifically, in terms of anode, glucose oxidase (GOx) enzyme and dye mediators were considered for the purpose, while in cathode, GOx and iron porphyrin mediator were utilized for the goal. The use of the redox couple induced superior catalytic activity of the biocatalysts and BC performance. In this conference, I will explain the related electron transfer theory, the synthetic procedure of corresponding biocatalysts and the configuration and performance of BC utilized.

Assay-Guided Extraction and Kinetics of Radical Scavenging Activity of Curcumin from the Rhizome of Curcuma longa Linn

Extraction of phytoceuticals from medicinal plants need to be optimized to produce standardized, dose-dependent and reliable extracts to meet food or drug administration regulations for translation into approved nutraceutical or pharmaceutical products. Effect of selected limiting extraction variables on yield and antiradical activity of curcumin-rich extract from Curcuma longa rhizomes was investigated. Assay-guided response (free radical scavenging activity) was used to determine the optimized set of extraction parameters. Curcumin-rich extract was produced using solvent boiling process at 65 oC with absolute methanol of weight ratio 1:50 (w/v) within 1 h. Relative radical scavenging activity of the extract derived using the optimized set of parameters recorded an IC50 of 497 μg/ml and its total antiradical capacity determined within 6 h (76 - 85 % at a concentration of 400 – 600 μg/ml) was not significantly different from that of commercially available natural curcumin used as reference. Time-dependent kinetic analysis revealed an initial fast burst in rate of activity (2.27 – 7.77 min-1) followed by a slow reaction rate in a steady second phase (0.12 – 0.54 min-1). Conclusively, appreciable amount of curcumin-rich extract of enhanced antiradical activity was extracted from the rhizome of C. longa using assay-guided procedure.

Effect of passive film on the galvanic corrosion of titanium alloy Ti60 coupled to copper alloy H62

Ti alloys exhibit high potential because of the compact passive film. However, the effect of passive film on galvanic corrosion is not clear. On the one hand, the great potential difference can accelerate the galvanic corrosion of other metals with low potential. On the other hand, the passive film can hinder the electrochemical reactions, inhibiting the galvanic corrosion. To clarify this question, the galvanic corrosion of titanium alloy Ti60 coupled to copper alloy H62 was studied using zero‐resistance ammeter, scanning vibrating electrode technique, scanning electron microscopy, and potentiodynamic polarization measurements. The chemical composition and electrical properties of the passive film on Ti60 were detected using X‐ray photoelectron spectroscopy and Mott‐Schottky plots. The results indicate the galvanic corrosion of Ti60‐H62 coupling is ignorable in spite of the great galvanic potential difference between them. It can be attributed to the low electron donor density of passive film, which inhibits the electron charge transfer process at the film/solution interface, causing the slow cathodic reaction rate on Ti60.

In Situ Forming, Dual-Crosslink Network, Self-Healing Hydrogel Enabled by a Bioorthogonal Nopoldiol–Benzoxaborolate Click Reaction with a Wide pH Range

The use of click chemistry as a hydrogel cross-linking reaction is often limited by slow reaction rates and harsh conditions, such as exposure to UV light and/or use of nonspecific or toxic reagent...

Electrochemical Production of Formic Acid / Formate By CO2 Electrolysis Using High Performance Gas Diffusion Electrodes

Electrochemical low-temperature conversion of CO2 is a promising way to reduce GHG emissions and to valorize CO2 as a carbon-source to produce basic chemicals and/or to store excess electricity from renewable resources. The most widely studied products for these purposes are formic acid/formate, carbon monoxide and methane. In contrast to carbon monoxide and methane, aqueous formic acid/formate solutions show advantages in terms of handling, storage, toxicity and safety. The stored energy can thereby be recovered either in direct formate or formic acid fuel cells (DFFC or DFAFC), or by upstream hydrogen production from dehydrogenation and subsequent use in a H2-fuel cell. Besides the energetic use, formic acid may also serve as precursor for the decentralized production of synthesis gas as it can be decomposed to hydrogen or carbon monoxide. Formatotrophic bacteria might also use formic acid as substrate in fermentation towards higher hydrocarbons like isobutene or propane.[1] CO2 + H2O + 2e- --> HCOO- + OH- φ0=-0.665 V (vs. SHE, pH=10) Two of the biggest problems to overcome in electrochemical CO2 reduction reaction (CO2RR) is its low energetic efficiency and the sluggish reaction kinetics, which strongly limits the achievable current density. The energetic efficiency not only suffers from a high overpotential, which might be greatly reduced by state-of-the-art electrocatalysts, but also by several sources of ohmic losses throughout the whole electrolysis cell. Thus, for industrial application these resistances are to minimize by choosing an appropriate reactor design, but also by optimizing the used electrodes and reaction conditions. In order to overcome the slow reaction rates caused by the low solubility of CO2 in aqueous media, gas diffusion electrodes (GDEs) have become the number one solution. Their highly porous structure provides a huge three-phase boundary between gaseous CO2, electrolyte and catalyst. As most groups use layered GDEs with a supporting gas diffusion layer as backbone and the active component bound on top by a hydrophobic binding agent (mostly PTFE or Nafion®), we want to emphasize single-layer GDEs (SLGDE) that comprise all of these three components in one homogenous layer. SLGDEs in CO2RR have already been proven to show one of the highest current densities in literature of 400 mA cm-2 while maintaining a faradaic efficiency of at least 75 %.[2] Optimizing such SLGDEs is one of our current subject of research. It includes multiple aspects, like the catalyst’s nature, dispersion and loading [3], electrode composition, including type of carbon, porosity and hydrophobicity, as well as the extent of electrolyte intrusion during the reaction. Besides the electrodes properties, reaction conditions are of upmost importance. This includes temperature, type of electrolyte and concentration, but also controlling the electrochemical stress, especially during start-up phase. The results shown in figure 1 demonstrate the importance of these parameters. Acetylene black based gas diffusion electrodes, loaded with SnOx nanoparticles were screened for their maximum current density (defined as minimum 80 % formate faradaic efficiency for 45 min), showing a temperature depended maximum in performance at 1000 mA cm-2. This maximum results from slow intrinsic reaction kinetics and little mass transport coefficients at lower temperatures and decreasing CO2 solubility at higher temperatures. Optimizing the used electrolyte and carefully starting-up the GDE helps to further raise the performance up to 1200 mA cm-2. A comparison with values from literature (figure 1, right side) illustrates the high performance of such SLGDEs. Further investigations need to focus on transferring these results into continuous mode of operation and stabilization of the three-phase boundary for industrial relevant lifetimes.[4] [1] www.eforfuel.eu [2] D. Kopljar, N. Wagner, E. Klemm, Chem. Eng. Technol., 39 (11), 2016, p. 2042-2050. [3] D. Kopljar, A. Inan, P. Vindayer, N. Wagner, E. Klemm, J. Appl. Electrochem., 44 (10), 2014, p. 1107-1116 [4] D. Kopljar, A. Inan, P. Vindayer, R. Scholz, N. Frangos, N. Wagner, E. Klemm, Chem. Ing. Techn., 87 (6), 2015, p. 855-859 The authors would like to thank the German BMWi (Bundesministerium für Wirtschaft und Energie - support code: 03ET1037B) for the financial support. Figure 1