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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 37 records · Page 2
All sourcesNASA NTRSDOE OSTI
DOE OSTI2025

Cradle-to-Gate greenhouse gas emissions of the production of ethylene from U.S. Corn ethanol and comparison to fossil-derived ethylene production

Conventional ethylene production heavily depends on fossil-derived feedstocks via steam cracking, a very energy- and emission-intensive process. Researchers have been exploring alternatives to reduce CO 2 emissions including producing ethylene from biobased feedstocks. This paper evaluates the cradle-to-gate greenhouse gas (GHG) emissions of bioethylene produced from U.S. corn ethanol. The analysis includes different pathways for the dehydration of corn ethanol to ethylene and co-processing routes via fluid catalytic cracking (FCC) processes. For the FCC co-processing route carbon-14 analysis is used to determine bioethanol yields. A 127% reduction in life cycle GHG emissions of bioethylene is estimated compared to fossil-derived ethylene for the base case. Additional case studies are also discussed to understand the reduction of GHG emissions due to sustainable corn farming and renewable power use, biogenic carbon capture, and fuel switch with biofuels at the ethanol plant, and its impact on bioethylene GHG emissions.

carbon footprint↗
DOE OSTI2025

Direct Comparison of the Activity and Selectivity of Rh 1 Cu and Ni 1 Cu Single-Atom Alloy Sites for Ethanol Decomposition

Ethanol is an important source of clean hydrogen, acetaldehyde, acetic acid, acetate esters, and light hydrocarbons. Controlling the divergent reaction pathways to these products requires understanding how different active sites influence the elementary steps involved. Herein, we present a combined surface science, theory, and nanoparticle catalysis study demonstrating how two single-atom dopants (Rh and Ni) in a Cu host can distinctively alter the selectivity of alcohol conversion. Specifically, our model studies reveal that ethanol reacts on Ni 1 Cu single-atom alloys to selectively produce acetaldehyde, whereas methane and CO are also formed on Rh 1 Cu single-atom alloys. Interestingly, these different reactivities are in contrast to the behavior of the pure metals as Ni(111) and Rh(111) surfaces favor methane/CO and surface carbon/CO, respectively. DFT calculations of reaction pathways and simulated product desorption based on microkinetic analyses explain these reactivity differences, demonstrating that C–C cleavage leading to methane formation has a lower barrier on Rh single-atom sites. To test the catalytic relevance of these fundamental results we synthesized and characterized supported Ni 1 Cu and Rh 1 Cu single-atom alloy nanoparticles with dopant:Cu ratios of 1:200. Flow reactor results revealed that both Ni and Rh increased ethanol conversion over Cu and that Ni 1 Cu catalysts were >99.9% selective to acetaldehyde, while Rh 1 Cu also produced 0.6%–2.6% of equimolar methane and CO between 433 and 493 K, demonstrating that C–C bond cleavage is enabled by isolated Rh sites. Furthermore, these catalytic results bridge the pressure and materials gaps, and together, this study provides insights into how different isolated dopant sites promote different catalytic pathways.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2025

Sustainable aviation fuel from ethanol: Techno-economic analysis and life cycle analysis

Sustainable aviation fuel (SAF) is crucial for improving energy security, enhancing domestic production, and reducing carbon emissions in the aviation sector. Among various SAF production technologies, the ethanol-to-jet (ETJ) pathway is a promising option due to its economic viability and technological maturity. This study integrates a techno-economic analysis (TEA) and a life cycle analysis (LCA) to evaluate emissions reduction strategies for SAF production via the ETJ pathway, considering use of ethanol derived from both corn grain and corn stover. Conventional corn grain-derived ETJ fuel reduces greenhouse gas (GHG) emissions by 22 % compared to fossil jet fuel, with potential reductions of 26 %–96 % when incorporating renewable energy sources, with a 6 %–32 % increase in the minimum fuel selling price (MFSP). Corn stover-derived ETJ achieves a 77 % GHG reduction but with higher MFSPs compared to corn grain ETJ. Carbon capture and storage (CCS without considering the cost for piping and sequestration, only compression) reduces the emissions of corn grain-derived ETJ by up to 32 gCO 2 e/MJ and enables negative emissions for corn stover-derived ETJ, with MFSP increases ranging from 1 % to 22 %. While carbon capture and utilization (CCU) increase ethanol yield by 47 %, it raises MFSPs by 54 % due to high electricity demand. Sustainable farming practices provide only limited carbon intensity (CI) reductions individually but do offer cumulative benefits when combined. These findings highlight the trade-offs between cost and environmental impact, providing insights to optimize SAF production strategies and support aviation sector goals for emissions reduction.

09 BIOMASS FUELS↗
DOE OSTI2026

Kinetic model development for single step ethanol to butene rich olefin process over Cu-Y/Beta catalysts

Here, this study presents the first intrinsic kinetic model for the single-step conversion of ethanol to butene-rich olefins over bifunctional Cu-Y/Beta catalysts, addressing a critical gap in the design and scale-up of Sustainable Aviation Fuel (SAF) processes. The reaction network comprises ten global steps involving dehydrogenation, aldol condensation, hydrogenation, and dehydration reactions, distributed across Cu and rare-earth (Y) active sites. The model incorporates dual-site functionality (Cu and Y site) and explicitly accounts for key intermediates such as crotonaldehyde and butanal. Reaction rates are formulated using Langmuir–Hinshelwood–Hougen–Watson (LHHW) kinetics. Kinetic parameters are extracted by fitting the model to lab-scale packed-bed reactor data across a wide range of temperatures and space velocities, demonstrating strong agreement in ethanol conversion and product selectivity. The reaction kinetics developed in this work provide a foundational basis for constructing reactor models that enable process optimization and scale-up of ethanol-to-jet fuel technologies.

Cu-Y/Beta catalyst↗
DOE OSTI2025

Techno-economic analysis of sugarcane bagasse and straw conversion into cellulosic ethanol via consolidated bioprocessing

Cellulosic biofuels offer a sustainable alternative to fossil fuels and a means to mitigate climate change. Consolidated bioprocessing (CBP) featuring engineered thermophilic bacteria, combined with mechanical disruption during fermentation (cotreatment), has potential to lower production costs compared to featuring thermochemical pretreatment and added cellulase. A techno-economic analysis was conducted (230 million L ethanol/year) from sugarcane bagasse and straw at stand-alone facilities generating electricity from residues. Three scenarios were evaluated: Conventional, featuring hydrothermal pretreatment, fungal cellulase, and yeast fermentation (current commercial standard); Mid-term CBP, relying on bagasse solubilization without pretreatment or cotreatment; and Mature CBP, incorporating cotreatment but no pretreatment. Results for these scenarios in this order were: fixed capital investment (CapEx) $\$$589M, $\$$658M, and $\$$472M; net annual revenue (EBITDA) $\$$56M, $\$$96M, and $\$$94M; and minimum ethanol selling price 0.73, 0.61, and 0.48 US$\$$/L. Payback periods were 10.5, 6.9, and 5.1 years, while all scenarios showed <5 years at European prices for scales >100M L/year. Sensitivity and risk analysis highlighted ethanol price as the most critical variable. It is notable that Mid-term CBP had shorter payback times and better overall economic feasibility compared to Conventional. Our results underscore opportunities for research-driven innovation on low-cost cellulosic ethanol technologies in Brazil and elsewhere.

Consolidated bioprocessing↗
DOE OSTI2026

Spin Polarization Enhanced Ethanol Selectivity in Electrocatalytic CO 2 Reduction on the Paramagnetic CuO Surface

We report an electrochemical CO 2 reduction reaction catalyzed by a paramagnetic and conductive CuO/Cu interface with spins polarized by a moderate external magnetic field (MF) of similar to 800 gauss, achieving a similar to 30% increase in CO 2 -to-C 2+ Faradaic efficiency (FE) compared to that in the absence of the MF in a flow cell electrolyzer. At a current density of 400 mA/cm 2 , the CO 2 -to-C 2+ FE reached 86.7 ± 2.7% with 47.9 ± 1.4% cathodic energy efficiency (EE) in contrast to the CO 2 -to-C 2+ FE of 67.6% with 36.4% of EE in the absence of MF. Notably, ethanol production exhibits a much higher response to the MF (similar to 55.6% increase in FE) than ethylene (similar to 6.4% increase in FE) at 400 mA/cm 2 . In situ surface-enhanced Raman spectroscopy (SERS) captured magnetic-field-enhanced *CO coverage and ethanol-forming C 2 intermediates on CuO/Cu, providing direct spectroscopic evidence of spin-modulated pathway selection. Here, computational study suggests that the enhancement of ethanol selectivity is due to the reduced reaction kinetic barrier under MF, while the ethylene selectivity is less affected, mainly due to the insensitivity of the kinetic barriers under MF.

10 SYNTHETIC FUELS↗
DOE OSTI2025

Sustainable Tire Production: Catalytic Upgrading of Ethanol into Butadiene (CRADA 636) Abstract

Bridgestone aims to minimize resource depletion and greenhouse gas (GHG) emissions by using 100% sustainable materials by 2050. As part of this goal Bridgestone is working to develop a first-of-kind end-of-life recycling process for tire material circularity and the decarbonization of new tire production. Used tires can be gasified to produce intermediate syngas (H 2 + CO) that can be further converted into ethanol using mature technology. The ethanol can then be converted into butadiene, a key precursor of new tires, using patented PNNL technology, enabling circularity for end-of-life tires. Indeed, PNNL has developed a new patented thermocatalytic-based technology for the conversion of ethanol into butadiene that allows for high carbon efficiency and improved catalyst longevity compared to World War II baseline catalyst. The objective here is to continue the development of this processing with the goal of commercial deployment. This includes development of engineered catalysts (e.g., extrudates) and their evaluation under industrially relevant conditions for deployment of a pilot scale. If successful, Bridgestone will subsequently utilize this catalyst technology at pilot and then commercialization scale creating jobs in both construction sector and industry sector in a chosen location that promotes greater diversity, equity, and inclusion through key policies, training, and recruiting practices. Taken together, this work will support the U.S. Department of Energy goal for production of renewable chemicals with > 70% GHG emissions reduction relative to petroleum-derived counterparts and supporting > 1 MMT/ yr CO 2 e emissions reduction by 2030.

36 MATERIALS SCIENCE↗
DOE OSTI2025

Integrated Biorefinery of Brewer’s Spent Grain for Second-Generation Ethanol, Mycoprotein, and Bioactive Vinasse Production

Brewer’s spent grain (BSG), the main lignocellulosic by-product of the beer industry, represents an abundant yet underutilized resource with high potential for valorization. This study presents an integrated biorefinery approach to convert BSG into second-generation (2G) ethanol, bioactive vinasse for plant growth promotion, and fungal biomass as a potential mycoprotein source. The biomass was first subjected to biological delignification using the white-rot fungus Ganoderma lucidum, after which two valorization routes were explored: (i) evaluation of the fungal biomass as a mycoprotein candidate and (ii) alcoholic fermentation for ethanol production. For the latter, three pretreatment strategies were assessed (diluted sulfuric acid and two deep eutectic solvents (DESs) based on choline chloride combined with either glycerol or lactic acid) followed by a one-pot enzymatic saccharification and fermentation using Kluyveromyces marxianus SLP1. The highest ethanol yield on substrate (YP/S) was achieved with [Ch]Cl:lactic acid pretreatment (0.46 g/g, 89.32% of theoretical). Vinasse, recovered after distillation, was characterized for organic acid content and tested on Solanum lycopersicum seed germination, showing promising biostimulant activity. Overall, this work highlights the potential of BSG as a sustainable feedstock within circular economy models, enabling the production of multiple bio-based products from a single residue.

Ganoderma lucidum↗
DOE OSTI2026

Catalytic Bias of NADH-Dependent Reduced Ferredoxin: NADP+ Oxidoreductase (Nfn) and its Relevance to Ethanol Production in Thermoanaerobacterium Saccharolyticum

NADH-dependent reduced ferredoxin: NADP+ oxidoreductase (Nfn) enzyme catalyzes an energy-conserving flavin-based electron bifurcation (FBEB) reaction. In microbial metabolism, Nfn links redox pools of three electron carriers - ferredoxin (Fd), NAD(H), and NADP(H) - through the following FBEB reaction: 2 NADPH + NAD+ + 2 Fdox 2 NADP+ + NADH + 2 Fdred + H+ The forward reaction is termed electron bifurcation, and the reverse reaction is electron confurcation. Catalytic bias describes an enzyme's tendency to favor one direction of a reversible reaction over the other and is expressed as the ratio of activities in the two directions. Thermoanaerobacterium saccharolyticum (Tsac) is a thermophilic, ethanologenic bacterium that ferments hemicellulose to ethanol at yields above 90%. Its Nfn enzyme is known to support ethanol production, presumably by operating in the confurcating direction to balance cellular cofactors, but this has not previously been demonstrated. To investigate the Tsac Nfn further, we heterologously expressed, purified, and reconstituted the proteins NfnS (NfnA), NfnL (NfnB), and the putative partner Fd with iron-sulfur cluster and/or FAD cofactors. Activity assays monitoring the oxidation or reduction of Fd showed that, across pH 5-10, Tsac Nfn is catalytically biased towards the confurcating direction, favoring NADPH generation over NADPH oxidation by at least fivefold. Using protein electrochemistry, we also determined the reduction potentials of the cofactors in NfnL and Fd. These results indicate that the energetic landscape of FBEB in Tsac Nfn is similar to that in an ortholog. However, Tsac Fd has redox properties distinct from previously assayed Fds, suggesting that the identity and redox properties of Fd may help determine the catalytic bias of Nfn. Additionally, we confirmed the standalone ferredoxin: NADP+ oxidoreductase (FNOR) activity of NfnL but found it to be low and likely insignificant for in vivo redox conversion. We also show how the catalytic bias of Nfn integrates with the hydrogen cycling mechanism proposed in Tsac to better explain cofactor balancing for ethanol production. Our work advances the understanding of electron transfer processes within metabolic networks for the generation of valuable bioproducts.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2025

Self‐Stabilized Heterometallic Pair Sites for Selective Ethanol Dehydrogenation on Pt–Cr–Ag Alloy Catalysts

Self‐stabilized, heterometallic pair‐sites can enable fine‐tuning of catalytic functionality while also mitigating dynamic structural changes that degrade catalytic performance. This study demonstrates the development and characterization of trimetallic Pt x Cr x Ag 1‐2x ( x ≤ 0.1) alloys with active Pt–Cr pair‐ensembles for non‐oxidative ethanol dehydrogenation, leveraging predictions that favorable bonding stabilizes Pt–Cr pairs diluted in Ag. Operando X‐ray absorption spectroscopy confirms the preferential formation and stability of Pt–Cr pairings dispersed throughout the Ag matrix, and ambient‐pressure X‐ray photoelectron spectroscopy shows that Pt–Cr sites have significant activity for ethanol dehydrogenation, while suppressing reaction processes that deactivate binary Pt–Ag and Cr–Ag alloys. This work demonstrates that stabilizing heterometallic pair sites within trimetallic alloys provides a new avenue for designing catalysts with discrete active sites that are durable and highly selective.

36 MATERIALS SCIENCE↗
DOE OSTI2025

Methodology for Determination of Cellulosic Glucans and Hemicellulose Content in a Fuel Ethanol Production Facility (CRADA Final Report)

Develop a single methodology for determination of the total cellulosic glucan, including both cellulose and beta-glucans, along with hemicellulose content in corn kernel fiber which could be utilized by the dry grind corn ethanol production industry to determine the cellulosic converted fraction of the corn kernel fiber. The work will build upon a methodology already described in literature but will specifically focus on a more complete determination of the structural polysaccharides in corn kernel fiber to make it more applicable to the corn ethanol industry.

09 BIOMASS FUELS↗
DOE OSTI2026

Understanding_the_deactivation_mechanisms_of_ethanol_conversion_over_Cu-Y_Beta_catalyst

Direct conversion of bioethanol to C₃⁺olefins is a promising pathway for sustainable aviation fuel (SAF) production, but catalyst deactivation limits long-term operation. The stability and deactivation mechanisms of multifunctional Cu–Y/Beta zeolite catalysts were investigated for ethanol-to-olefins conversion over 300 h time-on-stream in the presence of H2. Catalytic testing reveals progressive losses in ethanol conversion and C₃⁺ olefin selectivity accompanied by increased acetaldehyde formation. The catalyst testing studies correlate with a suite of characterizations of fresh, spent, and regenerated catalysts to identify the deactivation factors. The loss of Y Lewis acid sites is the primary deactivation element. Reversible acid site deactivation is caused by coke deposition, which blocks Y-derived Lewis acid sites responsible for aldol condensation, MPV reduction, and alcohol dehydration. Minor irreversible deactivation is observed and possibly results from hydrothermal dehydroxylation of Y–silanol interactions, resulting in permanent loss of Lewis acidity without zeolite framework degradation or Y aggregation. Cu sites undergo limited agglomeration into small nanoparticles but contribute insignificantly to catalyst deactivation, under the investigated time frame. Oxidative regeneration removes coke and redistributes Cu sites, leading to full recovery of the initial catalytic performance though the Y Lewis acid sites are unable to fully recover. These findings establish Lewis acid site degradation as the primary deactivation mechanism impacting long-term catalyst stability

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2025

Mixing-Controlled Combustion of Ethanol Enabled by Prechamber Ignition (PC-MCC): A Preliminary Experimental Demonstration

This experimental study presents preliminary investigations of prechamber-enabled mixing-controlled combustion (PC-MCC) at −2 bar brake mean effective pressure (BMEP) and 2200 rpm with fuel-grade ethanol (E98). Experimental results are conducted on a prechamber retrofitted single-cylinder Caterpillar C9.3B test engine. First, a series of prechamber-only experiments were conducted with a motored engine to evaluate the salient combustion trends in response to relevant prechamber operating parameters. Under firing conditions, the prechamber operating strategy was assessed with respect to the impact on ignition assistance of direct-injected E98 and overall engine performance. The preliminary results indicate the jet-induced ignition process is robust and prompts diffusion combustion of E98 at diesel-like boundary conditions. Here, the effect of external exhaust gas recirculation (EGR) on the residual tolerance of the prechamber combustion process was also investigated and showed stable combustion in both the main chamber and prechamber up to 30% EGR. Experiments were also conducted with the stock diesel engine for baseline comparison. At matched combustion phasing, mixing-controlled combustion of ethanol enabled by prechamber ignition was able to achieve heightened gross thermal efficiency while simultaneously reducing NOx and practically eliminating smoke emissions relative to diesel combustion. In addition, the covariance of load and standard deviation of combustion phasing was diesel-like and less than 2% and 1 CAD, respectively.

PC-MCC↗
DOE OSTI2025

Cu Evolution over Bimetallic Cu‐Y/Beta Zeolite Under H 2 and Ethanol Atmospheres: Unveiling the Role of Diatomic Metal–Metal Interactions

Understanding the dynamic evolution of Cu species under varying environmental conditions is critical for addressing challenges related to the activity and the stability of copper‐based catalysts in thermo‐, photo‐, and electrocatalysis. However, metal–metal interactions between dual single atoms and their effects on Cu evolution after exposure to different environmental molecules remain underexplored. Herein, we synthesized bimetallic Cu‐Y/Beta catalysts with dual single‐atom Cu and Y sites and monometallic Cu‐Beta catalysts with isolated Cu sites in dealuminated Beta zeolites. By varying Cu and Y compositions, diatomic interactions were studied under H 2 and ethanol atmospheres. With 6 wt% Y loading, approximately 0.4 wt% of Cu species in Cu‐Y/Beta remained partially oxidized as Cu(I) after reduction in pure H 2 at 350 °C, in contrast to the full transition to metallic Cu observed in Cu‐Beta. Combining X‐ray absorption spectroscopy with kinetic studies revealed that metallic Cu became the predominant species after reduction with H 2 as Cu loading increased from 0.4 to 1.7 wt%, quadrupling the initial ethanol dehydrogenation rate and demonstrating the dominant role of Cu(0) sites. In conclusion, scanning transmission electron microscopy and density functional theory simulations indicated spatial proximity between dual single‐atom Cu and Y sites and elucidated Cu speciation controlled by diatomic interactions.

Copper↗
DOE OSTI2026

A Comparative Study of Ethanol Upgrading to Butadiene Over Rare Earth Elements Incorporated in Dealuminated Beta Zeolites

Copper and rare earth element-containing dealuminated Beta zeolites (CuREE/deAlBeta) are promising catalysts for the conversion of ethanol to C 3+ olefins en route to sustainable aviation fuel. Product selectivities over CuREE/deAlBeta depend on the identity of the REE. Here, in this study, a suite of La/deAlBeta catalysts of varied La loading are prepared, and their reactivities, selectivities, and apparent C-C coupling kinetics in the cascade reaction between ethanol and acetaldehyde are reported. Ex situ and in situ titrations to quantify Lewis acidic La sites quantify distinct numbers of sites, suggesting a distribution of site types. Across a series of REE/deAlBeta catalysts (REE = Y, La, Lu, Yb, Gd), the selectivity to secondary products correlates with the pyridine heats of adsorption at REE Lewis acid sites. The turnover frequency (per Lewis acid site) for C–C coupling was similar across the series of REE/deAlBeta catalysts. Y/deAlBeta and La/deAlBeta, which have the most disparate secondary product selectivities, had similar kinetics for C–C coupling. These findings demonstrate the complexity of quantifying active sites in REE/deAlBeta zeolites, and the sensitivity of the selectivity, but not the reactivity for C–C coupling, to the identity of the REE atom in REE/deAlBeta zeolites.

alcohol upgrading↗
DOE OSTI2026

Protonation Dynamics of Confined Ethanol–Water Mixtures in H-ZSM-5 from Machine Learning-Driven Metadynamics

Zeolites are indispensable heterogeneous catalysts in industrial chemical processes, valued for their strong Brønsted acidity, well-defined microporous frameworks, and tunable pore structures. Their catalytic activity arises primarily from Brønsted acid sites (BAS), typically present as bridging hydroxyl groups (Si–OH–Al). Under aqueous reaction conditions, these protons interact dynamically with water and alcohol molecules, leading to complex solvation and protonation behavior within confined pores. In this study, we investigate the protonation equilibrium occurring between ethanol and water at the BAS of acidic zeolites under varying hydration levels, i.e., C2H5OH–(H2O)n, n=1–4. Local structure was analyzed through an adaptive-learning global optimization algorithm, while enhanced sampling molecular dynamics simulations with Well-Tempered Metadynamics (WMetaD) and machine learning interatomic potentials (MLPs) provide free-energy surfaces (FES) at variable hydration levels. The results reveal a strong dependence of proton localization on the degree of hydration. At low hydration (1 water molecule), the proton resides predominantly on ethanol; with 2 water molecules, it shifts toward water, and at higher hydration (3 or more water molecules), it becomes extensively delocalized over the water cluster. These findings underscore the critical role of solvation in modulating acid site behavior and suggest that a minimum of three water molecules is necessary to fully stabilize the proton on water within the zeolite framework. This solvation threshold has significant implications for catalytic processes, particularly in biomass conversion reactions where alcohol protonation is a key step in dehydration mechanisms.

machine learning↗
DOE OSTI2025

Ethanol as a hydrogen carrier with a value-added co-product

Traditional liquid organic hydrogen carriers rely on return/re-charge of the carrier and financial subsidy. We show that ethanol, available at scale from fermentation, can be a revenue-positive hydrogen carrier, owing to the value of its potassium acetate co-product, itself an emerging fertilizer. Traditional liquid organic hydrogen carriers (LOHCs) rely on return/re-charge of the carrier and financial subsidy. We show here that ethanol, available at scale from fermentation, can be a revenue-positive hydrogen carrier, owing to the value of its potassium acetate co-product, itself an emerging fertilizer.

Rander, Andrew R↗
DOE OSTI2026

In situ catalyst activation and regeneration enable energy-efficient high-current CO 2 reduction to ethanol-rich C 2+ mixtures

Electrochemical conversion of dissolved CO 2 in bicarbonate electrolytes, i.e., bicarbonate electrolysis, offers distinct advantages over gas diffusion electrode systems by enabling direct utilization of the CO 2 capture electrolyte while bypassing the energy-intensive CO 2 release step. However, bicarbonate electrolysis faces challenges such as CO 2 mass-transfer limitation, local pH-driven CO 2 depletion, and high cathodic potentials. The higher potential often causes catalyst surface reorganization, leading to a gradual loss of active sites and variations in selectivity during CO 2 reduction. Here, we report a directed, in situ activation and regeneration method that allows precatalysts to equilibrate under dynamic (pulsed) electrolysis conditions. We demonstrate in situ activation of a scalable Cu 2 O/Cu mesh that, under short-width (t = 4 s) pulsed electrolysis, provides stable mixed oxidation states of Cu, favoring the formation of an ethanol-rich crude mixture. The pulsed electrolysis waveform, consisting of six distinct segments, is tuned to form Cu + oxides, which are then reduced to generate local alkaline conditions favoring C–C coupling. This synergistic effect results in FEs of 73% for C2+ products and 39% for ethanol at an applied current density of −150 mA cm −2 and a cathodic potential of −1.45 V (vs. RHE). The overall half-cell energy efficiency is ∼30% for C 2+ products. The in situ Raman experiments confirm the role of pCO 2 R in dynamically regenerating Cu+-containing surface species during pulsed operation, thereby steering selectivity towards C 2+ products. A comprehensive multiscale, multiphysics model is developed to investigate the dynamic behavior of copper surface species (Cu, Cu + , and Cu 2+ ) and local microenvironmental conditions during the pCO 2 R. The results reveal that the coexistence of different copper oxidation states, especially the Cu+ intermediate, is critical in steering selectivity towards multicarbon (C 2+ ) products. The dynamic modulation of surface redox states via tailored pulsing strategies favors C–C coupling pathways by inducing localized alkaline conditions and stabilizing reactive intermediates. This work establishes a predictive modeling platform that links pulse waveform design with mechanistic insights into catalyst state evolution and product selectivity. Overall, this study provides valuable insights into the synergistic effect of in situ activation of pre-catalysts and pulsed electrolysis for higher selectivity towards C 2+ products.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗