Reactant Loss Research Articles

Pure-Water-Fed Forward-Bias Bipolar Membrane CO2 Electrolyzer

Electrochemical CO2 reduction (ECO2R) has emerged as a promising approach to directly produce carbon-containing fuels from renewable sources and CO2, offering a practical opportunity to mitigate greenhouse-gas emissions and climate change. The key challenges to realize this vision are CO2 electrolyzers with high energy efficiency, faradaic efficiency (FE), carbon-conversion efficiency and can also maintain durable operations. As high alkalinity is beneficial for ECO2R reactivity and selectivity, flow cells or zero-gap devices supported by alkaline aqueous electrolytes are used to demonstrate outstanding ECO2R performance. However, this leads to two major challenges. First is the formation of (bi)carbonates (CO3 2-/HCO3 -) and subsequent CO2 crossover issue resulting in either reactant loss or additional energy penalty of regenerating and purifying CO2. Second is that alkali cations transfer through the membrane and build up on the cathode and result in carbonate salt precipitation, which leads to blockage of CO2 transport pathways, efficiency loss and device failure. Therefore, it is an urgent task to develop novel reactions to address both challenges. Herein, we design asymmetrical bipolar membranes assembled into a zero-gap CO2 electrolyzer fed with pure water, solving both challenges. By investigating and optimizing the anion-exchange-layer thickness, cathode differential pressure, and cell temperature, the forward-bias BPM CO2 electrolyzer achieves CO faradic efficiency over 80% with partial current density over 200 mA cm-2 at less than 3.0 V with negligible CO2 crossover. In addition, this electrolyzer achieves 0.61 and 2.1 mV h-1 decay rate at 150 and 300 mA cm-2 for 200h and 100h, respectively. Post-mortem analysis indicates that the deterioration of catalyst/polymer-electrolyte interfaces resulted from catalyst structural change and ionomer degradation at reductive potential shows the decay mechanism. All these results point to future research direction and show a promising pathway to deploy CO2 electrolyzers at-scale for industrial applications.

Photocatalysis of Adsorbed Catechol on Degussa P25 TiO2 at the Air-Solid Interface.

Semiconductor photocatalysis with commercial TiO2 (Degussa P25) has shown significant potential in water treatment of organic pollutants. However, the photoinduced reactions of adsorbed catechol, a phenolic air pollutant from biomass burning and combustion emissions, at the air-solid interface of TiO2 remain unexplored. Herein we examine the photocatalytic decay of catechol in the presence of water vapor, which acts as an electron acceptor. Experiments under variable cut-off wavelengths of irradiation (λcut-off ≥ 320, 400, and 515 nm) distinguish the mechanistic contribution of a ligand-to-metal charge-transfer (LMCT) complex of surface chemisorbed catechol on TiO2. The LMCT complex injects electrons into the conduction band of TiO2 from the highest occupied molecular orbital of catechol by visible light (≥2.11 eV) excitation. The deconvolution of diffuse reflectance UV-visible spectral bands from LMCT complexes of TiO2 with catechol, o-semiquinone radical, and quinone and the quantification of the evolving gaseous products follow a consecutive kinetic model. CO2(g) and CO(g) final oxidation products are monitored by gas chromatography and Fourier-transform infrared spectroscopy. The apparent quantum efficiency at variable λcut-off are determined for reactant loss (Φ- TiO2/catechol = 0.79 ± 0.19) and product growth ΦCO2 = 0.76 ± 0.08). Spectroscopic and electrochemical measurements reveal the energy band diagram for the LMCT of TiO2/catechol. Two photocatalytic mechanisms are analyzed based on chemical transformations and environmental relevance.

Pd-induced polarized Cu0-Cu+ sites for electrocatalytic CO2-to-C2+ conversion in acidic medium

The acidic CO2 reduction reaction (CO2RR) offers a promising approach to mitigate CO2 reactant loss and carbonate deposition, which are challenging issues in alkaline or neutral electrolytes. However, the hydrogen evolution reaction (HER) competes in the proton-rich environment near the catalyst surface as a side reaction, reducing the energy efficiency of generating multi-carbon (C2+) products. In this work, we proposed a palladium (Pd) doping strategy in a copper (Cu)-based catalyst to stabilize polarized Cu0-Cu+ sites, thus enhancing the CC coupling step during the CO2RR while suppressing HER. At an optimal doping ratio of 6%, the Pd dopants were well dispersed as single atoms without aggregation, allowing for the stabilization of subsurface oxygen (OSub), preserving the polarized Cu0-Cu+ active sites, and reducing the energy barrier of CC coupling. The Pd-doped Cu/Cu2O catalyst exhibited a peak Faradaic efficiency (FE) of 64.0% for C2+ products with a corresponding C2+ partial current density of 407.1 mA∙cm−2 at −2.18 V versus a reversible hydrogen electrode, a high CO2 single-pass conversion efficiency (SPCE) of 73.2%, as well as a high electrochemical stability of ∼ 150 h at industrially relevant current densities, thus suggesting a potential approach for tuning the electrocatalytic CO2 performances in acidic environments with higher carbon conversion efficiencies.

Carbon and Energy Efficient Ethanol Electrosynthesis By Acidic CO2 Reduction

The electrochemical CO2 reduction reaction (CO2RR) is one way of mitigating the rising levels of anthropogenic CO2 emissions. Most of the advancements in the CO2RR field have been implemented in basic or neutral electrolytes where a major fraction of the input CO2 converts to carbonate ions through reaction with OH– (Science 360, 783-787 (2018); Nat. Catal. 5, 564-570 (2022)). These approaches result in low carbon efficiency (the percentage of CO2 converted per total CO2 input), typically below 20% toward multicarbon products, resulting in severe energy and cost penalty (Nat. Sustain. 5, 563-573 (2022)).Performing CO2RR in acidic conditions reduces reactant loss to carbonates. In this condition, the (bi)carbonate ion crossover/formation is countered by the high proton concentration in the electrolyte. However, the unshielded cathode surface favors the hydrogen evolution reaction (HER) over CO2RR due to the high availability of protons and the fast kinetics of the HER (Science 372, 1074-1078, (2021); Nat. Catal. 4, 654-662 (2021)).Here, we have developed an interfacial cation matrix (ICM) to modulate the local microenvironment on the cathode surface. The ICM increases the local pH and electric field, promoting multicarbon production. Additionally, we have designed a Copper-Silver catalyst to tune the selectivity towards alcohol production. We improved the ethanol FE to 45% at 200 mA/cm2, which, to our knowledge, represents the highestethanol FE in membrane electrode assembly literature. The system maintains a high carbon efficiency (60%) resulting in a total energy cost of 263 GJ/tonne ethanol, which is the lowest value among current ethanol-producing CO2 electrolysers.

CO2 electroreduction to multicarbon products from carbonate capture liquid

CO2 electroreduction to multicarbon products from carbonate capture liquid

Experimental investigation of a packed bed membrane reactor for the direct conversion of CO2 to dimethyl ether

In this study, the performance of a packed bed membrane reactor (PBMR) based on carbon molecular sieve membranes for the one-step CO2 conversion to dimethyl ether (DME) is experimentally compared to that of a conventional packed bed reactor (PBR) using a CuO-ZnO-Al2O3/HZSM-5 bifunctional catalyst. The PBMR outperforms the PBR in most of the experimental conditions. The benefits were greater at lower GHSV (i.e., conditions that approach thermodynamic equilibrium and water formation is more severe), with both XCO2 and YDME improvements of +35–40 % and +16–27 %, respectively. Larger sweep gas-to-feed (SW) ratios increase the extent of water removal (ca. 80 % at SW=5), and thus the performance of the PBMR. Nevertheless, alongside the removal of water, a considerably amount of all products are removed as well, leading to a greater improvement in the CO yield (+122 %) than the DME yield (+66 %). Higher temperatures selectively improve the rWGS reaction, leading to a lower YDME with respect to the PBR at 260 °C, due to the significant loss of methanol. Furthermore, larger transmembrane pressures (∆P) were not beneficial for the performance of the PBMR due to the excess reactant loss (i.e., 98–99 % at ∆P = 3 bar). Finally, the reactor models developed in our previous studies accurately describe the performance of both the PBR and PBMR in the range of tested conditions. This result is of high relevance, since the reactor models could be used for further optimization studies and to simulate conditions which were not explored experimentally.

Study on factors affecting the synthesis of selenium nanoparticles by solution plasma method

The solution plasma process (SPP) is a revolutionary approach for production of nanomaterials employing plasma discharge in liquid. The SPP can quickly deionize metal into the neutral state in the absence of a reducing agent. Selenium nanoparticles are created in solution plasma in this investigation. The approach is capable of producing selenium nanoparticles with uniform size in water and great stability without the use of a stabilizer. UV-Visible Spectrophotometry (UV-vis), X-Ray Diffraction (XRD), Dynamic Light Scattering Particle Size Analyzer (DLS), Scanning Electron Microscope (SEM) and Transmission Electron Microscope (TEM) techniques are used to analyze the produced selenium nanoparticles. In an ethanol/water mixture, the better solvent compares to distilled water, the SeNPs forms uniform flower-like nanostructures with diameters ranging from 50÷70 nm. Also, the effects of other parameters such as voltage, electrode spacing and reaction time on the production of nano selenium are investigated. The findings show that solution plasma can help form selenium nano particle in a very short time which is about 60 minutes. In addition, the electrodes must be separated by a minimum distance which is 0.5 mm . The ideal voltage to achieve a highly efficient process is 2 kV The higher voltage cause the reaction solution boil leading to the loss of reactants while the lower value cannot ignite the reaction. The reaction efficiency reaches 100% when applied those conditions. Also, those parameters help to shorten the reaction time which is an advantage of the synthesis method. As a result, the solution plasma method of synthesising nanoselenium makes it extremely promising for use in biomedical applications.

Transient power loss of electromagnetic waves in irreversible chemical reactions

In this paper, the general transient power loss in irreversible chemical reactions is derived. Based on the electrodynamic method, the power loss and stored electric energy density are separated compared with the electric energy conservation equation. The general transient power loss consists of the power loss of reactants, products and the coupling of reactants and products. Meanwhile, the general average power loss in a period is derived based on the general transient power loss when the reaction rate is slow. Numerical calculation is carried out to discuss the difference between the derived transient power loss and the average power loss.

A Detailed Process and Techno-Economic Analysis of Methanol Synthesis from H2 and CO2 with Intermediate Condensation Steps

In order to increase the typically low equilibrium CO2 conversion to methanol using commercially proven technology, the addition of two intermediate condensation units between reaction steps is evaluated in this work. Detailed process simulations with heat integration and techno-economic analyses of methanol synthesis from green H2 and captured CO2 are presented here, comparing the proposed process with condensation steps with the conventional approach. In the new process, a CO2 single-pass conversion of 53.9% was achieved, which is significantly higher than the conversion of the conventional process (28.5%) and its equilibrium conversion (30.4%). Consequently, the total recycle stream flow was halved, which reduced reactant losses in the purge stream and the compression work of the recycle streams, lowering operating costs by 4.8% (61.2 M€·a−1). In spite of the additional number of heat exchangers and flash drums related to the intermediate condensation units, the fixed investment costs of the improved process decreased by 22.7% (94.5 M€). This was a consequence of the increased reaction rates and lower recycle flows, reducing the required size of the main equipment. Therefore, intermediate condensation steps are beneficial for methanol synthesis from H2/CO2, significantly boosting CO2 single-pass conversion, which consequently reduces both the investment and operating costs.

A new catalyst mixture for synthesis of 1,3,5‐trioxane

AbstractBACKGROUNDA new catalyst mixture, namely trifluoromethanesulfonic acid + N‐methylimidazolium trifluoromethanesulfonate (CF3SO3H + [mim][CF3SO3]), is developed to overcome long‐standing problems of commercial catalysts and catalytic distillation for 1,3,5‐trioxane synthesis. CF3SO3H serves as a catalyst to accelerate the main reaction and [mim][CF3SO3] serves as an extractive distillation agent to promote phase separation. Unlike the conventional design methods whose purpose is to increase catalytic activity and selectivity, this catalyst mixture is designed to significantly enhance phase separation.RESULTSCompared to commercial catalysts, the new catalyst mixture significantly increases product concentration in distillate, and significantly decreases byproduct concentration in reaction liquid phase and volatilization loss of reactant in reaction liquid phase. This catalyst mixture also considerably decreases corrosion rate and salting out effect of catalyst.CONCLUSIONSOur design approach is of general significance for catalytic distillation. As a real example, it is used to markedly improve the performances of commercial catalysts for 1,3,5‐trioxane synthesis. © 2021 Society of Chemical Industry (SCI).

High Indirect Energy Consumption in AEM-Based CO2 Electrolyzers Demonstrates the Potential of Bipolar Membranes.

Typically, anion exchange membranes (AEMs) are used in CO2 electrolyzers, but those suffer from unwanted CO2 crossover, implying (indirect) energy consumption for generating an excess of CO2 feed and purification of the KOH anolyte. As an alternative, bipolar membranes (BPMs) have been suggested, which mitigate the reactant loss by dissociating water albeit requiring a higher cell voltage when operating at a near-neutral pH. Here, we assess the direct and indirect energy consumption required to produce CO in a membrane electrode assembly with BPMs or AEMs. More than 2/3 of the energy consumption for AEM-based cells concerns CO2 crossover and electrolyte refining. While the BPM-based cell had a high stability and almost no CO2 loss, the Faradaic efficiency to CO was low, making the energy requirement per mol of CO higher than for the AEM-based cell. Improving the cathode–BPM interface should be the future focus to make BPMs relevant to CO2 electrolyzers.

Design and control of novel reaction–separation–recycle processes for the production of 4-hydroxybutyl acrylate

Two chemistry routes are known for 4-hydroxybutyl acrylate production: the direct esterification of acrylic acid with 1,4-butanediol, and the transesterification of methyl acrylate with 1,4-butanediol. However, very scarce information in the literature is available about industrial production, or design and operation of production processes. In this study, we propose three novel reaction–separation–recycle processes for 4-hydroxybutyl acrylate production by direct esterification based on solid catalyst. Use of solid catalysts may avoid well-known issues of the liquid catalysts like recovery and re-use of the catalyst, difficult product recovery, and corrosion. Due to the nature of the chemical system and reactions conditions, the chemistry is not 100% selective towards the acrylate, important amounts of diacrylate by-product being formed. All processes use fixed-bed tubular reactors to perform the reactions and distillation-based equipment to achieve the required separations. While all processes have a similar separation sequence, each has its key particularities: the RSR-A process accepts the loss of reactants due to formation and elimination from the process of the diacrylate, RSR-B converts the diacrylate into its reactants in the esterification reactor, while RSR-C converts the diacrylate in a dedicated hydrolysis reactor. A key element in the separation sequence is the use of pressure-swing distillation to make the difficult split of the alcohol/acrylate/diacrylate ternary mixture. All processes are capital and energy intensive. The economic analysis shows that the RSR-A process has the most favorable economics: a total annualized cost of 2 million $/y and a specific annualized cost of 100 $/t of product. A control structure for the RSR-C process is presented, the dynamic simulations showing its efficiency in rejecting various disturbances.

Electroreduction of CO2/CO to C2 Products: Process Modeling, Downstream Separation, System Integration, and Economic Analysis.

Direct electrochemical reduction of CO2 to C2 products such as ethylene is more efficient in alkaline media, but it suffers from parasitic loss of reactants due to (bi)carbonate formation. A two-step process where the CO2 is first electrochemically reduced to CO and subsequently converted to desired C2 products has the potential to overcome the limitations posed by direct CO2 electroreduction. In this study, we investigated the technical and economic feasibility of the direct and indirect CO2 conversion routes to C2 products. For the indirect route, CO2 to CO conversion in a high temperature solid oxide electrolysis cell (SOEC) or a low temperature electrolyzer has been considered. The product distribution, conversion, selectivities, current densities, and cell potentials are different for both CO2 conversion routes, which affects the downstream processing and the economics. A detailed process design and techno-economic analysis of both CO2 conversion pathways are presented, which includes CO2 capture, CO2 (and CO) conversion, CO2 (and CO) recycling, and product separation. Our economic analysis shows that both conversion routes are not profitable under the base case scenario, but the economics can be improved significantly by reducing the cell voltage, the capital cost of the electrolyzers, and the electricity price. For both routes, a cell voltage of 2.5 V, a capital cost of $10,000/m2, and an electricity price of <$20/MWh will yield a positive net present value and payback times of less than 15 years. Overall, the high temperature (SOEC-based) two-step conversion process has a greater potential for scale-up than the direct electrochemical conversion route. Strategies for integrating the electrochemical CO2/CO conversion process into the existing gas and oil infrastructure are outlined. Current barriers for industrialization of CO2 electrolyzers and possible solutions are discussed as well.

Is Hydroxide Just Hydroxide? Unidentical CO2 Hydration Conditions during Hydrogen Evolution and Carbon Dioxide Reduction in Zero-Gap Gas Diffusion Electrode Reactors

The implementation of gas diffusion electrodes is a prerequisite to achieving industrially relevant reaction rates in gas-phase electrochemical CO2 reduction (CO2RR). In the state-of-the-art anion exchange membrane flow electrolyzers, however, there is a substantial loss of reactants due to a nonelectrochemical CO2 consumption at the cathode and the transport of its products to the anode. Our detailed analysis of CO2 crossover in a zero-gap CO2-to-CO flow electrolyzer showed a change in the chemical nature of the transported ionic species through the membrane. With the increasing reaction rate, a continuous shift from HCO3– to CO32– conduction was found to be similar to pure carbonate conduction in the high current density region (>100 mA cm–2). As competing hydrogen evolution takes over the cathodic reaction in a CO2-rich environment, hydroxide conduction becomes more pronounced. This reveals an alteration in the chemical CO2 consumption, the so-called CO2 hydration (CO2 + OH– ↔ HCO3– + OH– ↔ CO32–), implying an unidentical environment for the hydroxide ions generated in CO2RR and hydrogen evolution reaction under a CO2 atmosphere. Our work draws attention to the incomplete description of CO2 hydration at the confined cathode/membrane interface in membrane electrode assembly-type zero-gap CO2 electrolyzers.

Reducing the crossover of carbonate and liquid products during carbon dioxide electroreduction

Membrane electrode assembly (MEA) electrolyzers can perform stable, high-rate carbon dioxide (CO2) electroreduction for renewable fuels and chemicals, thereby realizing effective carbon utilization to mitigate anthropogenic CO2 emissions. Here, we present a numerical, multiphysics model, computationally intensified 60-fold with a machine learning analysis of computational and experimental data, to address the most urgent systems challenges in CO2 MEA electrolyzers: mitigating carbonate and liquid product crossover to increase CO2 utilization and energy efficiency. We explore the effect of varying the applied potential, CO2 partial pressure, ion-exchange membrane thickness, membrane porosity, and membrane charge on these three metrics. By selectively tuning these physical system parameters, we identify conditions that realize negligible CO2 reactant loss, a 2-fold enhancement in CO2 utilization, and a 2-fold decrease in Nernstian overpotential, corresponding to a multi-carbon, full-cell energy efficiency of 21%. These results may direct future MEA system designs and motivate thin anion-exchange membrane structures.

Effects of Flame Temperature and Absorption Coefficient on Premixed Flame Interactions with Radiation

The effects of the flame temperature and the absorption coefficient on interactions between radiative heat transfer and the flame behavior were numerically investigated using high-fidelity numerical code with the discrete ordinates method. To study the effects of the flame temperature and the absorption coefficient, three different flame temperatures and four different absorption coefficient conditions were selected, so twelve test cases were studied in total. In the numerical test results, radiation effects resulted in preheating of the reactant gases and heat loss from the product gases. A higher flame temperature resulted in stronger preheating effects in reactants near the flame. Due to the preheating effects, with the appropriate absorption coefficient, the peak temperature appeared at the flame front. Lower flame temperatures resulted in larger reabsorption effects in the product zone. The peak temperature at the flame front and the flame speed were influenced by the combined effects of preheating and radiative heat loss at the flame front. Depending on the conditions, due to those effects, the peak temperature and the flame speed could increase or decrease. When the absorption coefficient was sufficiently large, the temperature decrease was reduced in the product zone.

Stabilization of acid-rich bio-oil by catalytic mild hydrotreating.

Although liquid products derived from the pyrolysis of biomass are promising for the production of petroleum-like hydrocarbon fuels, the catalytic burden of hydrodeoxygenation must be reduced to achieve feasible upgrading processes. Herein, mild hydrotreating of an acid-rich biomass pyrolysis oil (bio-oil) with an unusually high total acid number (588mg KOH/g bio-oil) was performed to stabilize the low-quality bio-oil. Ru-added TiO2-supported transition metal catalysts stabilized the bio-oil by reducing its acidity more compared to what could be achieved by Ru-free catalysts; this process also leads to lower loss of organic compounds compared to when using a Ru/TiO2 catalyst. Based on the performance of transition metal catalysts, including Ni, Co, and Cu, supported on TiO2, tungstate-zirconia, or SiO2, supported bimetallic catalysts were prepared by adding Ru to the TiO2-supported metal catalysts. The bimetallic catalysts Ru/Ni/TiO2 and Ru/Co/TiO2 exhibited good decarboxylation activity for the removal of carboxylic acids and a higher yield of organic compounds compared to that provided by Ru, which can be deemed appropriate for feedstocks when hydrodeoxygenation needs to suppress the loss of organic reactants. Using these catalysts, the carboxylic acid concentration was reduced to 319-323mg KOH/g bio-oil with organic yields of 62-63wt% at reaction temperatures 150-170°C lower than the temperature required for direct conversion of carboxylic acids to alcohols or deoxygenates. The improved catalytic hydrotreating activity of Ru-added transition metals can be attributed to the high acid site densities of these catalysts along with their improved hydrogenation activities.

Probing ultracold chemistry using ion spectrometry.

Rapid progress in atomic, molecular, and optical (AMO) physics techniques enabled the creation of ultracold samples of molecular species and opened opportunities to explore chemistry in the ultralow temperature regime. In particular, both the external and internal quantum degrees of freedom of the reactant atoms and molecules are controlled, allowing studies that explored the role of the long-range potential in ultracold reactions. The kinetics of these reactions have typically been determined using the loss of reactants as proxies. To extend such studies into the short-range, we developed an experimental apparatus that combines the production of quantum-state-selected ultracold KRb molecules with ion mass and kinetic energy spectrometry, and directly observed KRb + KRb reaction intermediates and products [M.-G. Hu and Y. Liu, et al., Science, 2019, 366, 1111]. Here, we present the apparatus in detail. For future studies that aim for detecting the quantum states of the reaction products, we demonstrate a photodissociation based scheme to calibrate the ion kinetic energy spectrometer at low energies.

Integrated reaction-separation processes sequencing and screening at early stages of design

Process intensification and selection of the most efficient chemical process provides resources conservation and decreases the energy consumption to minimize CO2 emissions. Distillation Sequence Efficiency (DSE) method is extended to chemical processes also considering the reactors to provide a very simple and useful process design tool. A minimum amount of input data and computation power is required for a fast screening providing a basis for other more rigorous methods, i.e. including a cost assessment. The method considers, in a rough approach but at very early stages of process design, three factors related to environmental impact resources conservation and catalyst costs.The input data required is the vapour-liquid equilibrium represented by a proper thermodynamic model and some other predictable basic thermodynamic data. As it is an early stage approach, the reactor outputs can be assumed at chemical equilibrium minimizing the free Gibbs Energy. The 8/8 analysis is used to check the feasibility and calculate the stream flow rates and compositions. The distillation column output streams are at boiling point, and therefore the input data for the DSE method is available, which quantifies the process efficiency and therefore it is related to its environmental impact. A resources conservation factor, considering reactant losses, relates the product quantity generated to the amount that could be generated. A catalyst cost factor, considering catalyst deactivation, relates the feed raw materials to the system with the total feed stream to the reactor.ETBE (Ethyl Tert-Butyl Ether) production process is used as a case study. According to the results, the best alternative is the intensified process, i.e. reactive distillation, followed by the process proposed in the BREF. Other five alternative process schemes values are all in agreement with Recker et al. (2015) cost assessment results. However, there is disagreement between methods only in one case due to catalyst cost.

(Invited) Development of a Multiscale Approach for Modeling Fuel Cell Electrodes

Porous electrodes form a critical part of electrochemical energy systems such as polymer electrolyte fuel cells (PEFCs). In order to improve their performance and reduce cost, novel designs for porous electrodes are being envisioned, e.g., non-PGM catalyst layers, ultra-thin Pt/Pt-Ni based catalyst layers, or NSTF catalyst layers.1 These electrodes have features spanning multiple length scales: from nano-scale catalyst particles to micrometer thick catalyst layers; with meso-scale porous structure in between. In order to understand the impact of these new designs on cell performance, a detailed understanding of the multi-scale structure is required. Furthermore, the physical processes at each length scale must be understood and up-scaled in order to evaluate the macro-scale cell performance. The aim of this work is to develop multi-scale models which can account for the effect of micro and meso scale structure on macro-scale performance. Figure 1 shows a schematic of the multi-scale approach for modeling PEM fuel cells. This approach can be used for conventional Pt based electrodes, or for non-PGM based electrodes where large catalyst particles induce significant local flooding and reactant losses. The microstructure is generated using stochastic techniques.2,3 The crucial micro-structural properties such as pore sizes, ECSA, phase distributions are obtained using physical characterization methods such as imaging, Cyclic voltammetry, and BET. The generated microstructures will be used to simulate pore-level physics, where local transport, and reactions will be modeled. The pore scale performance will then be upscaled and used with macro-scale models to simulate system level performance. To analyze critical parameters for fuel cell performance, sensitivity studies will be performed using the macro-scale model. The aim is to identify parameters which affect the cell performance significantly and therefore must be measured accurately and provide a way to optimize cell performance. Apart from macro-scale parameters, the multi-scale sensitivity study can also be used to optimize ionomer and catalyst distribution. Acknowledgements The work is funded under the Fuel Cell Performance and Durability Consortium (FC-PAD), by the Fuel Cell Technologies Office (FCTO), Office of Energy Efficiency and Renewable Energy (EERE), of the U.S. Department of Energy under contract number DE-AC02-05CH11231. References P. K. Sinha, W. Gu, A. Kongkanand and E. Thompson, J. Electrochem. Soc., 158, B831 (2011).F. C. Cetinbas, R. K. Ahluwalia, N. N. Kariuki and D. J. Myers, J. Electrochem. Soc., 165, F1051 (2018).L. M. Pant, S. K. Mitra and M. Secanell, Phys. Rev. E, 92, 063303 (2015). Figure 1