High Production Rate Research Articles

Accounting for the role of the gastro-intestinal tract in the ammonia and urea-N dynamics of freshwater rainbow trout on long-term satiation feeding

The contribution of the gut to the ingestion, production, absorption, and excretion of the extra ammonia and urea-N associated with feeding (“exogenous” fraction) has received limited prior attention. Analysis of commercial pellet food revealed appreciable concentrations of ammonia and urea-N. Long term satiation-feeding increased whole trout ammonia and urea-N excretion rates by 2.5-fold above fasting levels. Blood was sampled from the dorsal aorta, posterior, mid, and anterior sub-intestinal veins, as well as the hepatic portal vein in situ. Ammonia, urea-N, and fluid flux rates were measured in vitro using novel gut sac preparations filled with native chyme. The sacs maintained the extreme physico-chemical conditions of the lumen seen in vivo. Overall, these results confirmed our hypothesis that the stomach and anterior intestine+pyloric caecae regions play important roles in ammonia and urea-N production and/or absorption. There was a very high rate of urea-N production in the anterior intestine+pyloric caecae, whereas the posterior intestine dominated for ammonia synthesis. The stomach was the major site of ammonia absorption, and the anterior intestine+pyloric caecae region dominated for urea-N absorption. Model calculations indicated that >50% of the exogenous ammonia and urea-N excretion associated with satiation-feeding was produced in the anaerobic gut. This challenges standard metabolic theory used in fuel use calculations. The novel gut sac preparations gained fluid during incubation, especially in the anterior intestine+pyloric caecae, due to marked hyperosmolality in the chyme. Thus, satiation-feeding with commercial pellets is beneficial to the water balance of freshwater trout.

Thermal Conversion of Microalgae into Biochar: A Review on Processes, Properties, and Applications

AbstractGlobal energy consumption has drastically increased over the years due to population growth and industrialization. This has prompted an exploration for clean and renewable energy alternatives. Microalgae are widely recognized as a promising third‐generation energy source because they have the capability to generate biofuels, including biochar. The utilization of microalgal biomass has been gaining traction because of their advantages, such as fast growth, a high rate of production, and high carbon‐fixing efficiency. Thermochemical methods like hydrothermal carbonization, torrefaction, and pyrolysis can be employed to harness energy from microalgae. The different thermochemical methods employed for converting microalgal biomass into biochar have been discussed, as well as the factors affecting these methods. In addition, a dedicated section covered the components and properties of the generated biochar, including its thermal and surface properties. Furthermore, the economic analysis of the production of biochar from microalgae as well as the applications of microalgae‐derived biochar were presented and discussed, along with suggestions for further research.

A Possible Metal-dominated Atmosphere below the Thick Aerosols of GJ 1214 b Suggested by Its JWST Panchromatic Transmission Spectrum

Abstract GJ 1214b is the archetype sub-Neptune for which thick aerosols have prevented us from constraining its atmospheric properties for over a decade. In this study, we leverage the panchromatic transmission spectrum of GJ 1214b established by the Hubble Space Telescope (HST) and JWST to investigate its atmospheric properties using a suite of atmospheric radiative transfer, photochemistry, and aerosol microphysical models. We find that the combined HST, JWST/NIRSpec, and JWST/MIRI spectrum can be well explained by atmospheric models with an extremely high metallicity of [M/H] ∼ 3.5 and an extremely high haze production rate of F haze ∼ 10−8 to 10−7 g cm−2 s−1. Such high atmospheric metallicity is suggested by the relatively strong CO2 feature compared to the haze absorption feature or the CH4 feature in the NIRSpec-G395H bandpass of 2.5–5 μm. The flat 5–12 μm MIRI spectrum also suggests a small scale height with a high atmospheric metallicity that is needed to suppress a prominent ∼6 μm haze feature. We tested the sensitivity of our interpretation to various assumptions for uncertain haze properties, such as optical constants and production rate, and all models tested here consistently suggest extremely high metallicity. Thus, we conclude that GJ 1214b likely has a metal-dominated atmosphere where hydrogen is no longer the main atmospheric constituent. We also find that different assumptions for the haze production rate lead to distinct inferences for the atmospheric C/O ratio. We stress the importance of high-precision follow-up observations to confirm the metal-dominated atmosphere, as it challenges the conventional understanding of interior structure and evolution of sub-Neptunes.

Polyurethane microplastics and associated tris(chloropropyl)phosphateadditives both affect development in larval fathead minnow Pimephales promelas.

Microplastics (< 5 mm) are a diverse class of contaminants ranging in morphology, polymer type, and chemical cocktail. Microplastic toxicity can be driven by one or a combination of these characteristics. Most studies, however, evaluate the physical effect of the most commercially available polymers. By disregarding other polymers with high consumption and/or production rates, and the chemical constituents of plastics, we fail to have a holistic understanding of the mechanisms of toxicity. Polyurethane is understudied in terms of effects testing yet considered one of the most hazardous polymers due to its chemical composition. Polyurethane is a high production polymer and is found in common consumer products ranging from packaging to spray foam insulation. To better understand the physico-chemical effects of polyurethane and a common additive in polyurethane products, we exposed larval fathead minnows for 28 days to polyurethane without chemical additives (i.e., plastic treatment), chemical leachate from polyurethane containing chemical additives (i.e., tris(chloropropyl)phosphate [TCPP]; i.e., chemical treatment) and polyurethane with chemical additives (i.e., plastic with chemical treatment) in a fully factorial experiment. We observed significant decreases in growth at 12 days posthatch (dph) in the plastic, chemical, and plastic with chemical treatments, suggesting a physical and chemical driver of toxicity. At 28 dph, we did not observe significant differences in growth, suggesting individuals can recover. We also observed concentrations of ΣTCPPs in fathead minnow exposed to the plastic with chemical treatment and the chemical only treatment, demonstrating TCPP uptake in exposed individuals. Combined, our data suggests the importance of both the physical and chemical components of microplastics when assessing effects, and thus emphasizing the need to evaluate the effects of microplastics in a multidimensional way.

Numerical and experimental investigation of resin flow, heat transfer and cure in a 3D compression resin transfer moulding process using fast curing resin

Compression resin transfer moulding (CRTM) has been widely used to manufacture automotive parts with reduced production cycle times. With the development of fast curing thermosetting resins, the CRTM process is a viable option for the high production rates in the transportation industry. However, the dynamic resin curing behaviour poses a potential risk of manufacturing defects in the part. In order to reduce the risk during the development of the tool and the process parameters, this paper proposes a modelling framework for the CRTM process when using fast curing resin systems. The work specifically focused on the coupling between heat transfer, resin cure, resin flow and preform compaction using a commercial code, PAM-RTM. The tool captures accurately the preform filling, temperature and resin pressure evolution during the injection and compression phase. The application of the framework was demonstrated for a complex 3D demonstrator. The predicted preform filling had an accuracy of 73% for the flow front evolution compared to the experimental results. This work demonstrates the validity of the framework proposed when dealing with resin systems that are challenging to process.

Machine Learning Boosted Entropy-Engineered Synthesis of CuCo Nanometric Solid Solution Alloys for Near-100% Nitrate-to-Ammonia Selectivity.

Nanometric solid solution alloys are utilized in a broad range of fields, including catalysis, energy storage, medical application, and sensor technology. Unfortunately, the synthesis of these alloys becomes increasingly challenging as the disparity between the metal elements grows, due to differences in atomic sizes, melting points, and chemical affinities. This study utilized a data-driven approach incorporating sample balancing enhancement techniques and multilayer perceptron (MLP) algorithms to improve the model's ability to handle imbalanced data, significantly boosting the efficiency of experimental parameter optimization. Building on this enhanced data processing framework, we developed an entropy-engineered synthesis approach specifically designed to produce stable, nanometric copper and cobalt (CuCo) solid solution alloys. Under conditions of -0.425 V (vs RHE), the CuCo alloy exhibited nearly 100% Faraday efficiency (FE) and a high ammonia production rate of 232.17 mg h-1 mg-1. Stability tests in a simulated industrial environment showed that the catalyst maintained over 80% FE and an ammonia production rate exceeding 170 mg h-1 mg-1 over a testing period of 120 h, outperforming most reported catalysts. To delve deeper into the synergistic interaction mechanisms between Cu and Co, in situ Raman spectroscopy was utilized for real-time monitoring, and density functional theory (DFT) calculations further substantiated our findings. These results not only highlight the exceptional catalytic performance of the CuCo alloy but also reflect the effective electronic and energy interactions between the two metals.

Construction of Biogas Digester and Produce Biogas from Cow Dung and Chicken Droppings as an Alternative Source of Heat to the Existing LPG Gas

The study analyzed the compositions of cow dung and chicken droppings, revealing that cow dung has a higher proximate composition, containing more organic waste, leading to increased biogas output. Anaerobes break down raw materials through hydrolysis, acidification, and methanization processes. The densities of both materials were found to be different, with cow dung having a larger density than chicken droppings. This results in varying chances of becoming soluble in the digester's contents during fermentation periods. The calorific values of the two raw materials were 7.8 mj/kg for cow dung and 7.9 mj/kg for goat dung. Both materials have a high rate of biogas production and a decent calorific value. The pH values of the slurry for cow dung and chicken droppings were 7.8 and 7.9, respectively. For fermentation and regular gas generation, a pH of 7 to 8.5 is ideal. The modest pH variations between the two substrates might be explained by the type of organic feeds given to animals as ruminants. Gas production was usually started from the 5th day. The pH of the slurry was adjusted to the required value (5-8) by adding 1 N sodium bicarbonate solution. The daily production over 30 days' retention period for the slurry with different pH levels showed that biogas gas production was higher during initial days and decreasing gradually as the day passed. The maximum gas yield was obtained for pH 7 on the 16th day and 8th and 19th in 10 and 20% of cow dung and chicken droppings, followed by 33, 22, and 33, 38 ml for pH 5 on the 25th, 23rd, and 16th, 13th days in 10 and 20% of cow dung and chicken droppings, and 14, 22, and 15, 26.1 cm3 for pH 8 on the 20th, 23rd, and 11th, 18th days in 10 and 20% of cow dung and chicken droppings, respectively

Exploring the relationship between leaf color, canopy architecture,photosynthesis and pigment composition in guava mapping population

Leaf color is a crucial parameter in determining the photosynthetic productivity of a plant. We examined 150 intervarietal guava hybrids from the cross Arka Poorna x Purple Local, that were segregating for leaf color (green and greyed purple). Variations in tree morphology, gas exchange parameters and pigment contents were investigated to understand the impact of leaf color on plant growth and physiology. Significant differences were observed in tree morphology between green and purple leaves, with green leaf plants showing better growth and vigor than purple leaf individuals. Photosynthetic rate, stomatal conductance, and transpiration rates were significantly higher in green plants than in purple leaf plants. In contrast, chlorophyll b, total chlorophyll, carotenoids, and anthocyanins were significantly higher in the purple plants. These results suggest that the presence of high anthocyanin and carotenoid pigments in purple plants have a masking effect that resulted in high chlorophyll production and low photosynthetic rates due to reduced incident light. The segregating population is an important repository for mapping QTLs associated to photosynthetic attributes.

Enhancing D-lactic acid production from non-detoxified corn stover hydrolysate via innovative F127-IEA hydrogel-mediated immobilization of Lactobacillus bulgaricus T15.

The production of D-lactic acid (D-LA) from non-detoxified corn stover hydrolysate is hindered by substrate-mediated inhibition and low cell utilization times. In this study, we developed a novel temperature-sensitive hydrogel, F127-IEA, for efficient D-LA production using a cell-recycle batch fermentation process. F127-IEA exhibited a porous structure with an average pore size of approximately 1 μm, facilitating the formation of stable Lactobacillus bulgaricus clusters within the gel matrix. It also maintains excellent mechanical properties. It also maintains excellent mechanical properties. F127-IEA immobilized Lactobacillus bulgaricus T15 (F127-IEA-T15) can be used in cell-recycle fermentation for over 150 days from glucose and 50 days from corn stover hydrolysate, achieving high production rates of D-LA from glucose (2.71 ± 0.85 g/L h) and corn stover hydrolysate (1.29 ± 0.39 g/L h). F127-IEA-T15 enhanced D-LA production by adsorbing and blocking toxic substances present in corn stover hydrolysate that are detrimental to cellular activity. The newly developed hydrogels in this study provide a robust platform for large-scale extraction of D-LA from non-detoxified corn stover.

Isotopic Signatures and Fluxes of N2O Emitted from Soybean Plants and Soil During the Main Growth Period of Soybeans

Soil microorganisms have long been recognized as primary producers of biogenic N2O in terrestrial ecosystems. Terrestrial plants can contribute to N2O emissions by transporting N2O produced in soils, and there is also evidence that plants may serve as direct producers of N2O. However, to date, direct evidence for N2O production by plants remains limited. To exclude N2O emissions resulting from soil-to-plant transport, this study conducted incubation experiments using cut soybean branches and leaves (cSBF) and intact soil cores under an N2O-free air background. The natural isotopic signatures (δ15N and δ18O) and fluxes of N2O produced by cSBF and soil were compared across different soybean growth stages over two growing seasons. The observed δ15N and δ18O values of N2O from soil ranged from −26.7‰ to −5.3‰ and −24.1‰ to 22.8‰, respectively. In contrast, the values for N2O produced from cSBF ranged from −4.7‰ to 33.1‰ and from 23.7‰ to 88.8‰, respectively. Notably, N2O emitted from plants exhibited significantly higher δ15N and δ18O values than soil-derived N2O (p &lt; 0.05). These findings indicate that the pathways and mechanisms of N2O production and emission in soybean plants differ from those mediated by soil microorganisms and nitrogen transport processes. Additionally, a significantly higher amount of N2O emission was observed during early growth stages compared to late growth stages (p &lt; 0.01), suggesting that plant N2O production may be associated with elevated water content and oxygen-limited conditions within plant cells. In addition to the N2O uptake by plants observed in some literature, the positive relationship between δ15N values and N2O fluxes suggests that N2O could be consumed in plant cells (p &lt; 0.01), with a high consumption rate often associated with a high production rate. The results of this study provide compelling evidence that plants may represent an overlooked source of N2O in terrestrial ecosystems.

Plastic Waste Management Strategies to Reduce Negative Impacts on the Environment and Human Health in Padang City

Plastic waste has become one of the major problems threatening the environment and human healthIn Indonesia, the use of plastics in daily life, such as shopping bags, water bottles, and food packaging, contributes greatly to the increasing amount of plastic waste (Ditjen PPKL, 2018). This research aims to analyse effective plastic waste management strategies to reduce negative impacts on the environment. The research uses a mixed-method approach, a combination of quantitative and qualitative methods, to gain a comprehensive understanding of the condition of plastic waste and identify the factors that influence the effectiveness of such management. This method is relevant for evaluating waste management policies, the role of the community, and the application of environmentally friendly technologies. This study will be conducted in several areas that have high plastic waste production rates, such as urban, coastal, and areas with community-based waste management initiatives. The results show that community awareness level participation in recycling high 60% p = 0.001 This shows that environmental education is very important to increase community participation. Community-based education is needed to raise this awareness. A massive education campaign is needed, involving community leaders to strengthen positive social norms.

Cobalt coordinated olefin-linked covalent organic frameworks toward highly efficient photocatalytic hydrogen production

Covalent organic frameworks (COFs) have emerged as a crystalline porous materials for photocatalytic hydrogen production. However, the design of efficient COF-based catalyst for satisfactory solar-to-hydrogen energy conversion is still challenging. Here, cobalt was anchored on the bipyridine moieties in the framework of olefin-linked sp2c-COFdpy by convenient post-metalation (sp2c-COFdpy-Co). Experimental results showed that sp2c-COFdpy-Co exhibited wider visible light absorption region and quicker photogenerated e-/h+ separation efficiency than sp2c-COFdpy. Photocatalytic experiments revealed that sp2c-COFdpy-Co was highly efficient for H2 production after photodeposition of Pt co-catalyst (Pt@sp2c-COFdpy-Co). The optimized Pt@sp2c-COFdpy-Co exhibited a high photocatalytic H2 production rate of 324.4 μmol/h under visible light irradiation in the presence of 1.0 wt% Pt as co-catalyst, which was higher than Pt@sp2c-COFdpy-Fe and Pt@sp2c-COFdpy-Ni, and it was much higher than that of its counterparts and many reported works. This work provides new insights into design of highly efficient COF-based catalyst for photocatalytic H2 production.

Hydrogen Production and Li-Ion Battery Performance with MoS2-SiNWs-SWNTs@ZnONPs Nanocomposites.

This study explores the hydrogen generation potential via water-splitting reactions under UV-vis radiation by using a synergistic assembly of ZnO nanoparticles integrated with MoS2, single-walled carbon nanotubes (SWNTs), and crystalline silicon nanowires (SiNWs) to create the MoS2-SiNWs-SWNTs@ZnONPs nanocomposites. A comparative analysis of MoS2 synthesized through chemical and physical exfoliation methods revealed that the chemically exfoliated MoS2 exhibited superior performance, thereby being selected for all subsequent measurements. The nanostructured materials demonstrated exceptional surface characteristics, with specific surface areas exceeding 300 m2 g-1. Notably, the hydrogen production rate achieved by a composite comprising 5% MoS2, 1.7% SiNWs, and 13.3% SWNTs at an 80% ZnONPs base was approximately 3909 µmol h-1g-1 under 500 nm wavelength radiation, marking a significant improvement of over 40-fold relative to pristine ZnONPs. This enhancement underscores the remarkable photocatalytic efficiency of the composites, maintaining high hydrogen production rates above 1500 µmol h-1g-1 even under radiation wavelengths exceeding 600 nm. Furthermore, the potential of these composites for energy storage and conversion applications, specifically within rechargeable lithium-ion batteries, was investigated. Composites, similar to those utilized for hydrogen production but excluding ZnONPs to address its limited theoretical capacity and electrical conductivity, were developed. The focus was on utilizing MoS2, SiNWs, and SWNTs as anode materials for Li-ion batteries. This strategic combination significantly improved the electronic conductivity and mechanical stability of the composite. Specifically, the composite with 56% MoS2, 24% SiNWs, and 20% SWNTs offered remarkable cyclic performance with high specific capacity values, achieving a complete stability of 1000 mA h g-1 after 100 cycles at 1 A g-1. These results illuminate the dual utility of the composites, not only as innovative catalysts for hydrogen production but also as advanced materials for energy storage technologies, showcasing their potential in contributing to sustainable energy solutions.

Current Advances in the Photoconversion of Plastics: the Catalysts and Reaction Pathways.

Plastic waste has caused severe global environmental pollution and health issues due to the high production rate and lack of proper disposal technology. Traditional methods to deal with plastic waste, such as incineration and landfilling, are deemed unsustainable and energy-intensive. A promising alternative is the photocatalytic conversion of plastic waste, using sunlight as a sustainable and carbon-neutral energy source to break down plastic waste under ambient pressure and low temperatures. This review aims to provide a comprehensive summary of recent advancements in plastic photoconversion, with an emphasis on the catalysts and reaction pathways. The mechanisms and reaction routes are first reviewed, followed by a detailed discussion of strategies to design catalysts for improved performance in photoconversion. Then, examples of photothermal degradation processes are presented. Finally, current strategies, challenges, and possible future directions of plastic photoconversion are summarized and discussed.

Facet-dependent spatial separation of dual cocatalysts on MOF photocatalysts for H2O2 production coupling biomass oxidation with enhanced performance

Cooperative coupling of photocatalytic two-electron oxygen reduction reaction (2e-ORR) with oxidative organic synthesis holds great promise for sustainable production of valuable chemicals. To achieve high performance, the rational design of photocatalysts with effective electron-hole separation and redox capability is crucial. Herein, a MOF-based photocatalyst with crystal facet-dependent spatial separation of dual cocatalysts is constructed for photocatalytic 2e-ORR coupled with vanillyl alcohol oxidation reaction (VAOR). The facet-dependent growth of reductive Pd and oxidative CoOx cocatalysts respectively on the {100} and {001} facets of MIL-125-NH2 enables the directional migration of photogenerated carries, facilitating the charge separation for redox reactions. Additionally, the interaction between Pd and MIL-125-NH2 modulates the Pd sites into electron-sufficient state with upshifted d-band center, promoting the O2 activation and *OOH intermediate formation. The rationally designed composite photocatalyst delivers an excellent H2O2 yield of 74.8 mM g−1 h−1 and a high vanillic acid production rate of 80.9 mM h−1 g−1 with the conversion and selectivity of 96.8 % and 91.1 %, respectively.

Li-Mediated Electrochemical NH3 Synthesis Utilizing H2o As a Proton Source

Electrochemical ammonia (NH3) synthesis is a promising technology for sustainable NH3 production that does not require H2 extraction from natural gas or coal which results in significant amounts of CO2 emissions. However, in aqueous electrolytes, the kinetics of H2O reduction (or proton coupling) into H2 is much faster than that of N2 reduction, leading to the dominance of the H2 evolution reaction. To address these challenges, the Li-mediated electrochemical N2 reduction reaction (Li-NRR) has been investigated in polar aprotic organic solvents, and a high NH3 production rate and faradaic efficiency (F.E.) have been obtained. Although significant progress has been made in the Li-NRR, the sustainability of the reaction system remains questionable. As an anode reaction, sacrificial oxidation of the THF-based electrolyte is exploited and the electrolyte undergoes oxidative chemical transformations. To prevent electrolyte degradation at the anode, the H2 oxidation reaction has been derived by supplying additional H2. However, such a methodology is a paradoxical approach to the original purpose of electrochemical NH3 synthesis to replace the proton source for NH3 with H2O from H2. Nevertheless, the absence of H2O (or a low concentration of H2O) is a prerequisite for the Li-NRR; thus, attempts to provide H2O as a proton source for NH3 have not yet been made. In this presentation, we show a biphasic hybrid electrolyte system consisting of an organic solvent catholyte and aqueous anolyte to supply the proton from H2O oxidation (O2 evolution reaction) for electrochemical NH3 synthesis. A comparable NH3 production rate and F.E. could be achieved in the hybrid system using H2O as the proton source, similar to those of the conventional one-compartment Li-NRR system. The hybrid electrolyte system maintains ~60% of NH3 F.E. for 50 h without the electrolyte degradations at a current density of −5 mA cm−2. We expect that this hybrid electrolyte system holds the potential to extend the applications of electrochemical conversion reactions beyond the Li-NRR system.

Boosting Hydrogen Production: Non-Noble Metal Catalysts Optimize Electrodes in Anion Exchange Membrane Water Electrolysis

As the world transitions to renewable energy sources, efficient energy storage is crucial for managing power fluctuations and decarbonize crucial high temperature processes. Achieving grid balance and optimizing renewable energy capacity requires innovative solutions. One promising option is the conversion of electrical energy into hydrogen through Anion Exchange Membrane Water Electrolysis (AEM-WE).AEM-WE combines high hydrogen production rates per electrode area and little production site footprint of Proton Exchange Membrane Water Electrolysis (PEM-WE) with cost-effectiveness of non-noble electrode materials utilized in Alkaline Water Electrolysis (A-WE). To further optimize AEM-WE, it is essential to improve hydrogen production while reducing material costs. This can be achieved through innovative approaches to electrocatalyst and electrode design. However, developing cost-effective catalysts that combine superior efficiency and robustness in aqueous environments, ideally in alkaline conditions, remains a big challenge. In this work, two electrode preparation approaches are investigated. For the anodic OER a corrosion synthesis is been developed to form highly active NiFe-layered double hydroxide (LDH) structures on nickel non-woven porous transport layers (PTL). A highly active cell can be combined with a cathodic HER catalyst, prepared by electrochemical deposition Ni-S on a stainless steel non-woven PTL.In single cell AEM water electrolysis using 1 M KOH-solution utilizing the prepared NiFe-LDH anode and Pt/C cathode, 2.7 A/cm² at 2 V were achieved, surpassing commercially available powder catalysts like NiFe-oxide. Comparative analysis of Ni-S cathode with NiFe-LDH, integrated into a membrane electrode assembly demonstrated superior AEM-WE performance, outperforming the mentioned platinum on carbon catalysts. Electrochemical impedance spectra indicated higher charge transfer activity of Ni-S cathode compared to Pt/C. Importantly, the electrodes prepared in this study exhibited stability under accelerated electrochemical stress tests for 1000 cycles.These approaches provide a simple, inexpensive, scalable and therefore industry-relevant fabrication method with improved active areas and excellent catalytic activity during AEM water electrolysis. Figure 1

Molybdenum-Catalyzed Electrochemical Ammonia Synthesis Using Zero-Gap Electrolysis Cell

Ammonia, which is a valuable material not only as a fertilizer but also as a potential alternative to fossil fuels has been conventionally synthesized under high temperature and pressure conditions by the Haber-Bosch method. Recently, an innovative method for the synthesis of ammonia from water and nitrogen under ambient conditions using Mo complexes has been reported.[1] In this study, a cathode supported by the Mo complex was prepared and the electrochemical production of ammonia was demonstrated using a zero-gap electrolysis cell.A catalyst layer consisting of porous carbon was spray coated on carbon paper. The Mo complex [MoI3(PCP)] (PCP: 1,3-bis((di-tert-butylphosphino)methyl)benzimidazol-2-ylidene) was supported on the carbon substrate by immersion. A 4-cm2 zero-gap electrolysis cell was constructed using the cathode, an ion-exchange membrane and IrOx-loaded Ti nonwoven fabric as the anode.The nitrogen reduction reaction (NRR) was performed at constant current by supplying nitrogen gas to the cathode and K2SO4 electrolyte to the anode. Ammonia produced at the cathode was collected by a H2SO4 trap at the cathode outlet, which was changed every 5 minutes. When 50 mA/cm2 was applied, the ammonia production rate was maximized in the 10-15 minutes, with an ammonia production partial current density of 2.9 mA/cm2, a Faraday efficiency of 5.7%, and a cell voltage of 3.1 V. A high ammonia production rates (over 1000 µg mg-1 h-1) was achieved among aqueous electrochemical NRR.[2] Further improvements of the NRR electrolyzer and results of XAFS analysis of Mo complexes are also presented.This paper is based on results obtained from a project, JPNP21020, commissioned by the New Energy and Industrial Technology Development Organization (NEDO).[1] Y. Ashida, K. Arashiba, K. Nakajima et al., Nature 568, 536 (2019).[2] H. Shen, C. Choi, J. Masa et al., Chem 7, 1708 (2021). Figure 1

Process Simulations and Technoeconomic Analysis of Ethylene Production By Electrochemical Reduction of Carbon Capture Solutions

Electrocatalytic reduction offers an alternate route for production of olefins from non-traditional feedstocks such as CO2, resulting in a lower carbon footprint if coupled with renewable sources of energy.Electrolyzer architectures employing bipolar membranes (BPMs) to convert aqueous alkaline carbonates (carbon capture solution) into hydrocarbons are a potential solution to overcome the limitations of high H2 production and crossover rates that limit CO2 conversion in conventional CO2 gas-fed electrochemical systems. Current literature lacks a full process analysis of such a system for C2+ hydrocarbons production, especially the inclusion of direct air capture of CO2 as part of the process and identification of the key tradeoffs involved in such systems. To address this important issue, here we present comprehensive process simulations, process design analysis, and technoeconomic evaluation of integrated electrolysis-based systems (beginning with CO2 capture and ending in electrolyzer product separation and stream recycling) for ethylene production from carbonates. Process simulations revealed the importance of upstream concentration of the captured carbonate feed stream by a membrane system operable at alkaline conditions, which makes the overall process economically feasible. Electrolyzer sizing, scale-up, and configuration are examined in more detail. Costing of the electrolyzer was approached with nonlinear scaling to better account for economies of scale relevant for electrochemical systems. Three different scenarios were considered for a 2 million metric tons (MMT)/yr ethylene plant. A set of key projected performance metrics has been determined for future profitable large-scale production of ethylene from alkaline carbonates. This BPM-based conversion process was evaluated with both direct air capture (DAC) and flue gas capture scenarios for carbonate production, demonstrating roughly equivalent economic feasibility (<8% difference between the 2 cases). Ongoing improvements in BPM-based processes can lead to ethylene minimum selling prices (MSPs) comparable to MSPs from naphtha-based processes, which are also projected to be lower than those of more conventional CO2 gas-fed electrochemical processes.

Electrocatalytic Synthesis of Pure Aqueous Hydrogen Peroxide Using a Porous Proton Exchange Membrane

Hydrogen peroxide (H2O2) is a valuable and useful chemical, but its manufacturing process has environmental and cost challenges. Polymer electrolyte membrane-based electrochemical cells have been reported for 2-electron oxygen reduction reactions to produce pure aqueous H2O2. However, state-of-the-art 3-chamber cells with high production rates suffer from large cell resistance. Herein, we developed a novel 2-chamber cell employing a porous proton exchange membrane to facilitate oxygen supply from the anode to the cathode side. The generated H2O2 is easily collected with water flow on the cathode chamber, achieving higher Faradaic efficiency compared to conventional 2-chamber cells. Minimizing the water flow rate at 40 mA cm−2 resulted in an H2O2 concentration of 6000 mg L−1, sufficient for wastewater treatment applications. Continuous electrosynthesis of pure aqueous H2O2 was also demonstrated for 50 hours without cell voltage increase or H2O2 concentration decline. This result indicates that the porous proton exchange membrane was not flooded with liquid water after 50 hours of operation even though water flowed on the cathode chamber. Additionally, electrochemical impedance measurement revealed a cell resistance of 4.2 Ω cm2, which is much lower than that of the 3-chamber cell. The developed electrolyzer, in which oxygen is supplied from the anode side through the porous membrane, offers a novel approach to establish a gas–liquid–solid triple-phase boundary, facilitating electrocathodic H2O2 production with high selectivity and low cell resistance. Figure 1