Browsing by Author "Jiao, Feng"
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Item Best practices for electrochemical reduction of carbon dioxide(Nature Sustainability, 2023-01-02) Seger, Brian; Robert, Marc; Jiao, FengCarbon capture, utilization and storage, a fundamental process to a sustainable future, relies on a suite of technologies among which electrochemical reduction of carbon dioxide is essential. Here, we discuss the issues faced when reporting performance of this technology and recommend how to move forward at both materials and device levels. Electrochemical reduction of CO2 into value-added chemicals has attracted considerable attention recently1,2,3. However, reporting the performance of a new CO2 electrocatalyst or a new reactor design is not trivial because of the complex nature of the CO2 electroreduction reaction. In many cases, the results are presented in a confusing manner, rendering it difficult to assess the true performance of the catalyst and/or device. In this Comment, we first discuss common problems in reporting the performance of a new electrocatalyst (including both heterogeneous and molecular catalysts) in the literature and then extend the discussion to how the products should be properly measured and quantified. Finally, we comment on the issues associated with full-cell level studies and recommend the best practices for electrochemical CO2 reduction.Item A hybrid inorganic–biological artificial photosynthesis system for energy-efficient food production(Nature Food, 2022-06-23) Hann, Elizabeth C.; Overa, Sean; Harland-Dunaway, Marcus; Narvaez, Andrés F.; Le, Dang N.; Orozco-Cárdenas, Martha L.; Jiao, Feng; Jinkerson, Robert E.Artificial photosynthesis systems are proposed as an efficient alternative route to capture CO2 to produce additional food for growing global demand. Here a two-step CO2 electrolyser system was developed to produce a highly concentrated acetate stream with a 57% carbon selectivity (CO2 to acetate), allowing its direct use for the heterotrophic cultivation of yeast, mushroom-producing fungus and a photosynthetic green alga, in the dark without inputs from biological photosynthesis. An evaluation of nine crop plants found that carbon from exogenously supplied acetate incorporates into biomass through major metabolic pathways. Coupling this approach to existing photovoltaic systems could increase solar-to-food energy conversion efficiency by about fourfold over biological photosynthesis, reducing the solar footprint required. This technology allows for a reimagination of how food can be produced in controlled environments.Item Techno-Economic Assessment of Green H2 Carrier Supply Chains(Energy Fuels, 2023-01-19) Crandall, Bradie S.; Brix, Todd; Weber, Robert S.; Jiao, FengGreen hydrogen can play a key role in affordably decarbonizing society. However, storage and transmission costs pose significant barriers to green hydrogen distribution. These limitations may be overcome with liquid green hydrogen carriers like ammonia, methanol, and toluene/methylcyclohexane, as well as formic acid, which has only recently received limited attention. A techno-economic assessment of these hydrogen carriers is presented across a wide range of scales. Green formic acid is identified to be the most cost-effective carrier when the entire supply-chain cost is considered. Additional analysis shows that formic acid is the only green carrier that is more affordable to produce than its fossil-based counterpart and is the safest of the studied carriers. Finally, research and policy outlooks are provided to guide efforts toward the realization of a green hydrogen economy. This work provides information on the selection of a suitable green hydrogen carrier, which is essential to decarbonize at the rate needed to avoid climate catastrophe.Item Turning Carbon Dioxide into Sustainable Food and Chemicals: How Electrosynthesized Acetate Is Paving the Way for Fermentation Innovation(Accounts of Chemical Research, 2023-06-20) Crandall, Bradie S.; Overa, Sean; Shin, Haeun; Jiao, FengConspectus The agricultural and chemical industries are major contributors to climate change. To address this issue, hybrid electrocatalytic–biocatalytic systems have emerged as a promising solution for reducing the environmental impact of these key sectors while providing economic onboarding for carbon capture technology. Recent advancements in the production of acetate via CO2/CO electrolysis as well as advances in precision fermentation technology have prompted electrochemical acetate to be explored as an alternative carbon source for synthetic biology. Tandem CO2 electrolysis coupled with improved reactor design has accelerated the commercial viability of electrosynthesized acetate in recent years. Simultaneously, innovations in metabolic engineering have helped leverage pathways that facilitate acetate upgrading to higher carbons for sustainable food and chemical production via precision fermentation. Current precision fermentation technology has received much criticism for reliance upon food crop-derived sugars and starches as feedstock which compete with the human food chain. A shift toward electrosynthesized acetate feedstocks could help preserve arable land for a rapidly growing population. Technoeconomic analysis shows that using electrochemical acetate instead of glucose as a fermentation feedstock reduces the production costs of food and chemicals by 16% and offers improved market price stability. Moreover, given the rapid decline in utility-scale renewable electricity prices, electro-synthesized acetate may become more affordable than conventional production methods at scale. This work provides an outlook on strategies to further advance and scale-up electrochemical acetate production. Additional perspective is offered to help ensure the successful integration of electrosynthesized acetate and precision fermentation technologies. In the electrocatalytic step, it is critical that relatively high purity acetate can be produced in low-concentration electrolyte to help ensure that minimal treatment of the electrosynthesized acetate stream is needed prior to fermentation. In the biocatalytic step, it is critical that microbes with increased tolerances to elevated acetate concentrations are engineered to help promote acetate uptake and accelerate product formation. Additionally, tighter regulation of acetate metabolism via strain engineering is essential to improving cellular efficiency. The implementation of these strategies would allow the coupling of electrosynthesized acetate with precision fermentation to offer a promising approach to sustainably produce chemicals and food. Reducing the environmental impact of the chemical and agricultural sectors is necessary to avoid climate catastrophe and preserve the habitability of the planet for future generations.Item Voltage Loss Diagnosis in CO2 Electrolyzers Using Five-Electrode Technique(ACS Energy Letters, 2022-12-09) Hansen, Kentaro U.; Cherniack, Luke H.; Jiao, FengCO2 electrolysis is a promising carbon utilization technology. Currently, energetic efficiency still requires a significant improvement for commercialization. To rationally design a more efficient CO2 electrolyzer, diagnostic tools are necessary to pinpoint the source of voltage losses across the full cell at work. Here we develop a five-electrode technique to probe voltage drops at the cathode, anode, membrane, and their interfaces in a typical zero-gap cell. We show that the cathode/membrane ionic interface is the major source of overpotential, contributing 720 mV voltage loss at 600 mA cm–2. This loss can be mitigated by coating the catalyst directly onto the membrane to lower ionic resistances, reducing this voltage loss to 80 mV at the same current density. The improved design enables us to achieve a full cell performance of 3.55 V and >95% CO Faradaic efficiency at 800 mA cm–2, representing the highest performance for CO2 electrolysis with a dilute bicarbonate electrolyte. The insights provided by the five-electrode technique may guide the rational design of future membrane-based electrochemical cells.