Combustion Of Fossil Fuels Research Articles

MetalFuel - Towards a full multi-scale understanding of zero-carbon metal fuel combustion

A large proportion of global energy demand is still met through burning fossil fuels such as oil and natural gas. Researchers in the MetalFuel project are exploring the potential of iron powders as an alternative carrier of energy, part of the wider goal of moving towards a more sustainable society, as Professor Philip de Goey explains.

Low-NOx thermal plasma torches: A renewable heat source for the electrified process industry

Industrial thermal plasma torches can heat a gas up to 5000–20,000 K, i.e., well above the temperature needed to replace the heat generated from the combustion of traditional fossil fuels (e.g., coal, oil, and natural gas) in large-scale process industry furnaces producing construction materials (e.g., iron, steel, lime, and cement). However, there is a risk for significant NOx emissions when air or N2 are used as plasma-forming gas since the temperature somewhere in the furnace always will be higher compared to the threshold NOx formation temperature of ∼1800 K. Torch NOx forms inside the high temperature region of the plasma torch (>5000 K) when air is used as gas. Process NOx forms instead when the hot gas (when air or nitrogen is used as plasma forming gas) from the plasma torch mixes with process air downstream the torch. By analysing the complex chemistry of both the torch- and process NOx formation with thermodynamic equilibrium and one-dimensional chemical kinetic calculations it was shown that adding H2 to the plasma-forming N2 gas significantly reduces the NOx emissions with more than 90 %. Verifying experiments with air, pure N2, and mixtures of H2 and N2 as plasma-forming gas were performed in a laboratory scale insulated laboratory furnace with different pre-heating temperatures of process air (293, 673, and 1073 K) which the plasma gas mixes with downstream the torch. Depending on the pre-heating temperature the NOx emissions were between 12,000–14,000 mg NO2/MJfuel when air was used as plasma forming gas. Substantial NOx emission reduction occurs both when N2 replaces air, where the NOx emissions was in the span of 8000–11,500 mg NO2/MJfuel and furthermore when H2 was mixed into the N2 gas stream. For the highest degree of H2 mixing (28.6 vol-%), the NOx emissions were between 450–1700 mg NO2/MJfuel depending on the pre-heat temperature of the process air, i.e., a reduction of 88–96 % and 85–94 %, respectively when air or N2 was used as plasma forming gas. The measured NOx emissions are then of the same order of magnitude as would be expected from the combustion of traditional fuels (coal, oil, biomass and pure H2). Finally, by analysing the aerodynamics in an axisymmetric furnace with an experimentally validated computational fluid dynamics (CFD) model using reduced chemistry for the NOx formation (19 species and 70 reactions), further guidelines into the process of NOx reduction from thermal plasma torches are given.

Novel C/MoS2 hollow nanocomposites enhance lithium storage in battery anodes

With society's rapid progress, there is an increasing need for electricity among individuals, but the prevailing source of electricity is still mainly obtained through the burning of nonrenewable fossil fuels, which are not renewable and pose serious environmental hazards. Lithium-ion batteries are used widely for excellent rechargeable capabilities and high energy density. Recently, researchers have become increasingly interested in transition metal sulfides owing to their cost-effectiveness and remarkable specific capacity. However, their commercialization has been hindered by the expansion of material volume and low electrical conductivity during charging and discharging. We have successfully designed and synthesized MoS2 nanosheets loaded on carbon spheres with a 3D hollow structure starting from SiO2 as a template. Due to the doping of carbon materials and particular 3D hollow structures, the optimal C/MoS2-0.3 hollow nanocomposites exhibit excellent electrochemical performance. Following exposure to over 900 cycles at a 0.5 A g-1 ampere density, the materials exhibited an exceptional 958.50 mAh g-1 reversible capacity, demonstrating their remarkable performance.

Escalating Global Threat of Heatwaves and Policy Options for Adaptation and Mitigation

This study evaluates the effects of intense and frequent heatwaves on human health, food security and infrastructure all having a direct bearing on sustainable development. It emphasizes that health issues such as cardiac and respiratory disorders, strokes, and mental health diseases are aggravated in harsh climates. This study focuses on the adverse implications of hot weather and the impact of said phenomenon on various fields of life. The aftermath of the excessive burning of fossil fuels and the emission of greenhouse gases have severely impacted the world by disrupting the economic stability of many countries around the globe. The heat waves are also responsible for low crop yield, fertilizer shortage and adverse impact on livestock. The intense and hot weather has not only caused power outages but also challenged infrastructure sustainability. The continuous usage of cooling systems is leading to urban heat islands adding more heat in the environment. This study highlights the challenges of climate change and brings attention to the need for sustainable development and practices to ensure proper heat management. After a deep insight into information and responses collected for the research, the study suggests some recommendations requiring all stakeholders including policymakers, implementing agencies, organizations and civil society to play their crucial role in devising and implementing suitable policy options and practices for adaptation and mitigation of climate change factors.

Overview of steam turbines and efficiency

Thermal power plants, which produce energy from the burning of fossil fuels that in turn generate turbine-turning steam, contribute a large proportion of energy in the world. Research on how we could apply fluid dynamic and thermodynamic principles in the design of turbines is crucial to improving their efficiency and fuel consumption. This paper mainly aims to explore and summarize how the power efficiency of turbines is maximized in thermal power plants and analyze the designs of turbines that increase proficiency. Literature and past paper review will be the primary method of this research. The main findings of this research are that efficiency in thermal turbines can be increased in three principal ways: a multi-stage expansion mechanism, the application of alternating blades, and in implementation of a reheating system. Using these methods, efficiency has been increased almost a million-fold in steam turbines. The purpose of this paper is to gain insights into how energy output in thermal power plant turbines is maximized and the specific designs of turbines that improve its efficiency.

Innovative Approaches for Climate-Resilient Farming: Strategies against Environmental Shifts and Climate Change

Climate change, driven predominantly by human activities such as burning fossil fuels and deforestation, is causing significant alterations to global weather patterns. This phenomenon results in more frequent and severe weather events, including prolonged droughts, intense rainfall, and shifting temperature regimes. Such changes pose a substantial threat to agriculture, a sector highly dependent on stable climatic conditions. Crop yields are increasingly unpredictable due to these extreme weather events and shifting growing seasons, impacting food security and livelihoods worldwide. To address these challenges, climate resilience agriculture has emerged as a pivotal solution. This approach involves adopting farming practices and technologies designed to withstand and adapt to changing climatic conditions. Strategies include diversifying crop varieties, precision agriculture, climate smart agriculture, nano biochar application, coated fertilizer applications, natural farming, site specific nutrient management, mulching, precise water management, seed bombing, direct seeding in rice, implementing soil conservation methods etc. Additionally, climate resilience agriculture promotes the integration of traditional knowledge with modern scientific advancements to enhance ecosystem robustness and productivity. By fostering adaptive capacity and reducing vulnerability, climate resilience agriculture aims to safeguard food systems and sustain agricultural productivity in the face of ongoing climate disruptions.

Hydrothermal synthesis of melamine-based porous organic polymer for the advanced adsorption of iodine

The release of carbon dioxide into the atmosphere from the combustion of fossil fuels to produce energy contributes to severe climate change. Transitioning from fossil fuels to nuclear energy, which is free of carbon emissions, presents its own set of challenges, particularly the potential release of radioactive iodine in handling nuclear waste and in the instance of a nuclear accident. The ongoing research aimed to harness the advantages of porous organic polymers to capture iodine generated during nuclear fission by synthesizing them in an environmentally friendly and cost-effective hydrothermal process. Herein, a melamine-based porous organic polymer (MPOP-4), possessing reliable thermal and chemical stability, highly porous (SABET=195.48 m2/g), designed for iodine capture, is reported. The synthesis of MPOP-4 using melamine and uracil as basic building blocks showed high iodine vapor capture capacities in various media (6.30 g/g at 80 °C, 4833.15 mg/g from aqueous solution, and 1.98 g/g at 25 °C), accompanied by good regeneration ability. A significant abundance of nitrogen content, conjugated π-electron arrangement, and porous network make it an efficient iodine adsorbent. This study suggests the green nature (metal-free) of MPOP-4 and its ability to adsorb iodine.

Glucose oxidation on monoclinic Co2V2O7 nanorods: Intuitions on cell potential reduction in hybrid electrolyzer

The deleterious impact of burning fossil fuels has led to a strategic shift towards exploring the environmentally benign energy generation technologies and renewable green sources. From the prospect of energy-saving hydrogen generation approach, alkaline hybrid electrolyzer using an anodic glucose oxidation reaction in conjunction with cathodic hydrogen evolution reaction catalyzed by monoclinic Co2V2O7 nanorods (NRs) is investigated. The Co2V2O7 was prepared by facile thermal treatment (500 °C/1 h) and displayed a nanorod-like morphology. The results derived from X-ray photoelectron spectroscopy confirmed the presence of multivalence states for both V (+4 and + 5) and Co (+2 and + 3) species. The Co2V2O7 exhibits superior glucose oxidation performance with very low onset potential of 1.2 V (vs RHE) and very high current density of 400 mA cm−2 at an overpotential of 1.51 V (vs RHE) in 1 M KOH. Furthermore, the Co2V2O7 exhibits an onset potential of −0.054 V (vs RHE) and an overpotentials of −75 mV and −190 mV to achieve the current densities of 10 mA cm−2 and 100 mA cm−2 respectively in hydrogen evolution reactions (HER). The Co2V2O7-NRs perform well in both the HER and glucose oxidation reactions, with a smaller hybrid water splitting potential of ∼1.46 V, which is 260 mV less than the analogous value in the conventional electrolyzer. The proposed electrocatalyst Co2V2O7 opens new possibilities for the production enediol together with hydrogen generation at low energy consumption.

Effects of energy sectors on the emission of carbon dioxide gas and environmental temperature

ABSTRACT In this paper, we have proposed a nonlinear mathematical model to study the dynamics of atmospheric carbon dioxide ( CO 2 ) and atmospheric temperature due to energy sectors. Energy sector is a major contributor of atmospheric carbon dioxide. We have studied the effects of energy consumption and human population on CO 2 level and temperature. Burning of fossil fuels results in an increase of CO 2 level and temperature. To curb the CO 2 level and temperature, efficient mitigation options are required. Mitigation options, which reduce emission rate of CO 2 , energy consumption rate and rate of increase in temperature, are considered in this model. By taking the efficiencies of mitigation options as control variables, the optimality system is derived. Numerical simulations are carried out to validate our analytical findings. The optimal profiles of control variables are plotted for different values of emission rate of CO 2 , energy consumption rate and rate of increase in temperature. Maximum efficiencies of mitigation options are also plotted against to reduce emission rate of CO 2 , energy consumption rate and rate of increase in temperature. It is found that mitigation cost of implementation of mitigation options can be minimized by implementing more efficient mitigation options.

The future of geoenergy – a perspective

Energy from Earth resources (geoenergy) in the form of coal, oil and gas has fuelled the global society since the Industrial Revolution began. Amongst the consequences of fuelling society and associated population growth, is climate change, driven by the emission of greenhouse gases liberated through unabated combustion of fossil fuels. There is much more to Earth energy systems, however, than just coal oil and gas. The Earth contains, in human terms, an unlimited supply of accessible heat and pressure (differences), as well as copious quantities of storage space, non-hydrocarbon gases and valuable solutes. These resources can be targeted to provide sustainable energy sources with low to zero carbon footprints. This report does not contain any new radical technologies that will deliver energy free from all environmental impacts but it does show that, when considering geoenergy, society needs to look at the whole system, which combines chemical, thermal, potential, kinetic, gravitational and other energy forms that could be used from individual developments to minimize waste, maximize efficiency and reduce unwanted impacts. We demonstrate that geoenergy will continue to play a key role in decarbonized energy systems for centuries to come.

Economic framework for green shipping corridors: Evaluating cost-effective transition from fossil fuels towards hydrogen

Global warming's major cause is the emission of greenhouse-effect gases (GHG), especially carbon dioxide (CO2) whose main source is the combustion of fossil fuels. Fossil fuels serve as the primary energy source in many industries, including shipping, which is the focus of this study. One of the measures proposed to tackle GHG emissions is the development of green shipping corridors - carbon-free shipping routes that require the transition to alternative fuels, which are gaining competitiveness. One of the reasons for that is carbon pricing, which taxes CO2 emissions. However, the lack of consensus on the most cost-advantageous alternative fuel in the long run results in the delay of the implementation of green shipping corridors.To make it more accessible for stakeholders to conduct an economic analysis of the various options, a framework to determine and minimize the costs of transitioning from fossil fuels to any alternative fuel is proposed, over the period of one voyage, considering the lost opportunity cost, the deployment cost of bunkering vessels at the necessary call ports, the cost of converting the vessel, the car-bon emissions tax cost, and the fuel cost. This will allow stakeholders to choose the most economical alternative fuel, accelerating the development of green shipping corridor initiatives. To validate the effectiveness of the framework, it was applied in a case study involving a shipowner seeking to transition from heavy fuel oil (HFO) to Ammonia, Hydrogen, Liquefied Natural Gas (LNG), or Methanol. This study faced limitations due to the unknown costs of installing bunkering vessels for Ammonia and Hydrogen. However, it evaluates the cost-effectiveness of alternative fuels, providing insights into their short-term economic viability. The results showed that Hydrogen is the most cost-advantageous fuel until a deployment cost per bunkering vessel of 1,990,285$ for a sailing speed of 22 knots and 2,190,171$ for a sailing speed of 18 knots is reached, after which LNG becomes the most economical option regardless of variations in the carbon tax. Moreover, a sensitivity analysis was conducted to determine the effects of variations in parameters, such as carbon tax, fuel prices and vessel conversion costs in the total cost of each fuel option. Results highlighted that even though HFO remains the most economical fuel option, even when considering a high increase in carbon tax, the cost gap between HFO and alternative fuels narrows significantly with the increase in carbon tax. Furthermore, the sailing speed impacts the fuels’ competitiveness, as the cost difference between HFO and alternative fuels decreases at higher speeds.

The electrocatalytic reduction of nitrate to ammonia (NARR) using MOF-808 enhanced by the transition metal Fe (III) and H2PO4−/HPO42−

The combustion of fossil fuels has led to a surge in global CO2 emissions, causing environmental pollution and climate change issues that cannot be ignored. Ammonia, a green and carbon-free hydrogen energy, is emerging as a promising contender for new renewable fuels. Electrocatalytic nitrate-to-ammonia reduction reaction (NARR) is an emerging green synthesis method compared to the Haber-Bosch approach, and its performance is mainly controlled by selective hydrogenation. In this work, we report an efficient Fe@MOF-808-H2PO4−/HPO42− electrocatalyst (donated as Fe@MOF-808-P) for the electrocatalytic reduction of nitrate-to-ammonia. The results showed that the highest Faraday efficiency of NH3 (FENH3) is 90.8 ± 0.5 % at −0.9 V versus reversible hydrogen electrode (vs. RHE) in a 0.5 M potassium sulfate (K2SO4) solution containing nitrite (NO3−), the corresponding NH3 yield and specific activity are 420.4 ± 18.1 μmol h−1 cm−2 and 1035.9 ± 20.1 mgNH3 h−1 mgFe, respectively.Furthermore, a comparative analysis of the catalytic performance of Fe@MOF-808-H2O, MOF-808, MOF-808-P, and carbon cloth (CC) revealed that introducing P could accelerate the hydrogenation process of NO3− in the NARR process, confirming that Fe is the primary active center. Additionally, the cyclic electrolysis experiment demonstrated that the catalyst showed excellent stability. The results highlighted the promising potential of ammonia for future applications in renewable energy systems.

A multi-analytical approach for the identification of pollutant sources on black crust samples: Stable isotope ratio of carbon, sulphur, and oxygen

This study is focused on the identification of pollutant sources on black crust (BC) samples from the Monumental Cemetery of Milan (Italy), through a multi-analytical approach based on the determination of stable isotope ratios of carbon, sulphur, and oxygen. Six black crust samples, mainly developed on marble sculptures over a time span of 100–150 years, were analysed.For the first time, δ13C was measured for BC samples: δ13C values of the pulverized samples (from −1.2 to +1.3 ‰) are very close to the values obtained from the carbonate matrix, whereas after the removal of the matrix through acidification, δ13C values of BC samples from Milan range from −27.2 to −22.1 ‰, with no significant variation between samples with different ratios of organic carbon to elemental carbon. In sum, the δ13C values obtained for all BC samples fall within the range of anthropogenic emissions such as vehicle traffic, coal combustion and industrial emissions.δ34S and δ18O values of sulphate from BC samples range from −6.3 to +7.0 ‰ and from +7.6 to +10.5 ‰, respectively. Coupling the analysis of the oxygen isotope ratio with that of sulphur enables a more precise identification of the origin of sulphates: the observed isotopic composition falls in the range typical for anthropogenic emission of sulphur dioxide.Overall, in this study, C, S and O isotopes were combined for the first time to assess pollutant sources on black crust samples: this multi-stable isotope approach allowed to show that the BC formation on monuments from the Monumental Cemetery of Milan mostly results from anthropogenic emissions from fossil fuels combustion by road vehicles and factories, as well as domestic heating.

Influence of air temperature and interrelationship with greenhouse gases (CO2 and CH4) over Iraq using AIRS data

Global and regional observations of air temperature (AT) and specific atmospheric greenhouse gases (GHGs) such as methane (CH4) and carbon dioxide (CO2) are required for a variety of applications, including constraining global or regional estimates of their significant impacts on the climate system. The present study employs Atmospheric Infrared Sounder (AIRS) -Level3 monthly products for AT, CH4, and CO2, at two standard pressure levels (925 and 500 hPa) over Iraq during 2010–2016. Both CO2 and CH4 shows significant seasonal variation, with maximum (minimum) CO2 observed in June (October), while CH4 recorded three maximum peaks during April, August, and November, and a minimum in February. CH4 shows a negative correlation during winter (DJF), spring (MAM), summer (JJA), and autumn (SON) with correlation coefficients (R) −0.627, −0.734, −0.491, and −0.688, respectively. The P-value is below 0.05 (4.14 × 10−15, 2.13 × 10−22, 1.1 × 10−8, and 5.2 × 10−19) for the four seasons, indicating a negative linear relationship. CO2 shows a low negative correlation in DJF and SON, and a low positive correlation in MAM and JJA seasons, with R values equal to −0.315, −0.221, 0.059, and 0.079, for DJF, SON, MAM and JJA seasons, respectively. The P-value was greater than 0.05 (0.061, 0.728, 0.647, and 0.195) for the four seasons, respectively, indicating a nonlinear relationship with AT. The monthly averaged time-series for CH4 and CO2 shows an evident increase, with an annual average increase of 1.81% (4.75) ppbv/year and 3.31% (1.84) ppm/year, respectively. Analysis reveals that the major sink and sources for CH4 are the presence of hydroxyl (OH) radicals and vegetation, whereas the major sources for CO2 are anthropogenic emissions, burning fossil fuels, and land-use change. The satellite observations of AIRS can efficiently show the spatiotemporal variations of air temperature versus CH4 and CO2 for the study area.

Effects of in utero benzo[a]pyrene exposure on the testis of rats during puberty and the protective effect of atorvastatin.

Benzo[a]pyrene (BaP) is a contaminant that is generated in the environment through processes such as smoke, incomplete combustion of fossil fuels, vehicle exhaust emissions, entry into the body is through inhalation, and consumption of contaminated food. It is an omnipresent environmental pollutant with unavoidable exposure. BaP metabolites are observed in the male reproductive system, especially in the testes and epididymis of animals, and are responsible for reduced testicular and epididymal function. The protective effect of atorvastatin (ATV) on testicular damage was investigated previously. The aim of the present study was to investigate the protective effect of ATV on testicular toxicity induced by benzo[a]pyrene (BaP) during pregnancy in Wistar rats. This experimental laboratory study involved 40 adult rats, divided into seven groups and maintained under standard environmental conditions. The groups received different diets [control, corn oil, ATV (10 mg/kg), BaP (10 and 20 mg/kg), and ATV + BaP (10 and 20 mg/kg)] at gestation Days 7-16, orally. Male offspring were examined 10 weeks after birth. Testis and serum samples were collected, and testosterone level, malondialdehyde (MDA), and glutathione (GSH) were measured. Histological and immunohistochemical assays were performed under a light microscope. Statistical analysis was conducted using SPSS, with analysis of variance and Tukey tests to assess significant differences between groups. ATV significantly reduced MDA, a marker of lipid peroxidation and oxidative stress in rat testes following BaP administration. Treatment with ATV at doses of 10 mg/kg increased GSH levels, correcting disruptions in the antioxidant system caused by BaP. Testosterone concentration in rats treated with ATV and BaP substantially prevented the decrease induced by BaP. Histomorphometry revealed that ATV significantly prevented the detrimental effects of BaP on the thickness of spermatogenic epithelium and the diameter of seminiferous tubules. Under ATV treatment, testicular tissue histopathology improved, and spermatogenesis returned to a almost back to normal state. Caspase-3 expression decreased, and apoptosis activity in testicular tissue improved under ATV treatment, indicating a positive effect of ATV in reducing apoptotic damage caused by BaP. In conclusion, exposure to BaP can induce oxidative stress-related damage to testicular tissue, as evidenced by an increase in MDA levels, which ATV treatment can mitigate. Additionally, ATV enhances intracellular antioxidant GSH and protects the testes against BaP-induced damage while increasing testosterone levels, which are reduced due to exposure to BaP.

Role of reactive nitrogen species in changing climate and future concerns of environmental sustainability.

The nitrogen (N) cycle is an intricate biogeochemical process that encompasses the conversion of several chemical forms of N. Given its role in food production, the need for N for life on Earth is obvious. However, the release of reactive nitrogen (Nr) species throughout different biogeochemical processes contributes to atmospheric pollution. Several human activities generate many species, including ammonia, nitrous oxide (N2O), nitric oxide, and nitrate. The primary reasons for this change are the use of nitrogen-based fertilizers, industrial activities, and the burning of fossil fuels. N2O poses a significant threat to environmental sustainability on our planet, with its global warming potential approximately 298 times greater than that of CO2. It has direct or indirect impacts on the environment, agroecosystem, and human life on earth. Solar, hydroelectric, geothermal, and wind turbines must be used to reduce Nr emissions. In addition, enterprises should install catalytic converters to minimize nitrogen gas emissions. To reduce Nr emissions, strategic interventions like fertilizer balancing are needed. This work will serve as a comprehensive guide for researchers, academics, and policymakers. Additionally, it will also assist social workers in emphasizing the Nr issue to the public in order to raise awareness within worldwide society.

Climate Change Causes Food Insecurity for Developing Countries

At the moment, climate change is one of the most urgent issue worldwide. This is due to long-term climate trends and changes in social lifestyle. Another reason is the greenhouse gases produced by excessive fuel use. The intensity of weather, the decline in human health, and the devastation of natural ecosystems are all contributing factors. Intergovernmental Panel on Climate Change (IPCC) suggests controlling the avaeage temperate rise at 1.5 degrees Celsius to reduce global warming's intensity. The three major green house gasses responsible for global warming are carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O) emitted from burning fossil fuels. Climate change is affecting the entire world, but poor and developing countries are suffering the most. The effects of climate change are all-encompassing. It affects agriculture, human health and crop productivity. A decrease have been observed in maize and wheat production in worst cases of climate change. This deficiency can lead to a food crisis. Poor and developing countries do not have the necessary resources to cope with the situation. They can't mould themselves quickly enough. Due to the lack of resources, they cannot discover new seeds to increase food production and are unable to improve their irrigation system. Climate change and rising temperatures contribute to the rapid growth of harmful bacteria and pathogens. These microbes have become a source of food contamination. Changes in rainfall patterns is also an important issue that affects the agricultural sector and the quality of irrigation water used. The risk of water pollution also increases. The gases produced from food waste, like greenhouse gases, are also harmful. Food waste in neighbourhoods releases methane gas, harming the environment. Commodity shortage and rising prices are major problems for people in poor and developing countries. The best strategy to deal with all these problems is to find new methods for agriculture that cope with climate change. To solve all these problems, government and international organizations should come forward and work together to help poor nations.

Electrochemical CO2 Reduction to Methane with Remarkably High Faradaic Efficiency in the Presence of a Proton Permeable Membrane

The combustion of fossil fuels is a major contributor to rising levels of anthropogenic carbon dioxide (CO2) in the atmosphere. Due to the adverse effects of climate change caused in large part by CO2, new technologies must be developed that contribute to a global renewable energy supply. Electrochemical reduction of CO2 offers a viable pathway to generating value-added products and synthetic fuels to meet our future energy demands while decreasing greenhouse gas emissions. By constructing electrocatalysts capable of modulating proton transfer, we are able to tune product selectivity. Previous studies have demonstrated that two-electron products (CO and HCOOH) can be produced with high selectivity, but multiple-electron transfer products (CH4, CH3OH, and C2+ products) typically are produced at much lower Faradaic efficiencies. In this work, we construct polymer-modified Cu electrodes that exhibit extraordinarily high CH4 production (88% Faradaic efficiency). These electrodes afford a new strategy for increasing the selectivity of CO2 reduction electrocatalysts, an attribute that is key in developing industrially-relevant CO2 conversion devices. Nafion is a widely used fluoropolymer that is often mixed with electrocatalysts to facilitate proton transport. In contrast to these Nafion-catalyst composites, this work studies electrodes covered by Nafion overlayers for the CO2 reduction reaction. By varying the thickness, substrates, and voltage, we perform a detailed study of the effect of Nafion overlayers on metal and carbon mesh electrodes for CO2 reduction. Depending on the thickness of the Nafion membrane, CO2 reduction occurs at either the polymer–electrolyte interface or electrode–polymer interface. A Nafion overlayer of 15 μm on a Cu electrode enables an extraordinarily high yield of CH4 production (88% Faradaic efficiency) at a low overpotential (540 mV) via the stabilization of metal-bound CO intermediates. To the best of our knowledge, this yield is the highest for electrocatalytic CO2 reduction to CH4 production at room temperature reported.

Lithium Recovery from Geologic Brines by Advanced Cation-Exchange Ionomers

As of today a massive restructuring of the energy system is taking place at the global level to curtail the use of fossil fuels and foster the large-scale implementation of renewable sources such as the sun and the wind. This is a crucial stepping stone to minimize the emissions of the greenhouse gases associated with the combustion of fossil fuels, with the ultimate goal to slow down global warming and ensure that the development of humankind could become compatible with the conservation of the natural environment.A major drawback of most renewable sources (e.g., the sun and the wind) is that they are intermittent and non-programmable. Hence, energy storage and distribution technologies are necessary to close the spatial and temporal gaps between the production of energy and its exploitation by end users. In this regard, lithium batteries (LiBs) are becoming one of the most promising tools to profitably use the energy obtained from renewable sources to power to a broad variety of applications, from portable electronics to light-duty (LD) vehicles.After decades of R&D efforts a large-scale rollout of LD vehicles powered by LiBs is currently taking place worldwide. Consequently, the production of massive amounts of LiBs is underway, straining the traditional supply chains of lithium and leading to a huge increase in the cost of this element, now listed by the European Union as a Critical Raw Material [1]. Accordingly, major efforts are dedicated at the global level to identify new and unexploited sources of lithium. In recent years it was acknowledged the potential of geologic brines to supply lithium. Geologic brines are widely available and abundant worldwide. However, an effective and inexpensive technology to selectively extract Li from a brine (that is typically much richer in other cations such as Na+, and Ca2+) is still not available.In this contribution a family of very inexpensive and chemically-stable cation-exchange ionomers is proposed. The physicochemical features of the ionomers are elucidated, with a particular reference to the cation-exchange capacity, the morphology (probed by scanning electron microscopy) and the porosimetric features (investigated by nitrogen physisorption techniques). In a second step it is studied the kinetics of cation binding upon immersing the ionomers into a suitable synthetic brine closely mimicking a natural specimen and including the following cations: Li+, Na+, K+, Ca2+ and Mg2+. The kinetic information is then used in experiments meant to determine the binding features at equilibrium of the various cations present in the synthetic brine to the ionomers.The following binding features of the ionomers are determined: (i) number of distinct binding sites; (ii) number of cations that can be coordinated to each binding site; and (iii) maximum theoretical binding of each cation to the ionomer, with a particular reference to Li+ [2]. The physicochemical properties of the ionomers are finally correlated to the binding parameters, allowing to suggest new strategies to devise enhanced ionomers able to extract selectively and cheaply Li+ from the brines.

Key Factors for Electrochemical Carbon Dioxide Reduction at Ni-N-C Catalysts

Electrochemical carbon dioxide reduction reaction (CO2RR) has the potential to adequately contribute to addressing the energy and environmental challenges faced by the humanity today. The surplus of CO2 produced by burning fossil fuels can be transformed into valuable products by CO2RR. An effective use of this approach on a large scale requires active, selective, and stable CO2 reduction electrocatalysts. Additionally, insightful understanding of interfacial behavior such as water wetting and carbonate formation at the electrode is required to enhance the performance and durability of CO2RR electrocatalysts.1 Atomically dispersed Ni-N-C materials have attracted attention due to their superior selectivity for CO generation.2 Their activity and selectivity of CO2RR are influenced by the metal center and local atomic defects in M-N-C catalysts.3 In addition to catalyst structures, electrode composition and structure have also substantial impact on the activity and selectivity of CO2RR. Particularly, ionomer compositions and the electrode fabrication process can alter the hydrophobicity of the electrode and the local pH on the catalyst, resulting in considerable changes in CO2RR activity and selectivity.In this presentation, we will report on the performance of various electrodes fabricated with the Ni-N-C catalyst, using different types of ionomers and measured in a flow cell and zero-gap electrolyzer at > 100 mA/cm2 current densities for CO2RR. We will also introduce an approach that aims at reducing carbonate formation at the CO2RR electrolyzer cathode by the modifications to the electrolyte composition, the CO2 inlet humidity, and the electrochemical cell temperature. Acknowledgement Research presented in this work was supported by the Laboratory Directed Research and Development program of Los Alamos National Laboratory under project number 20230065DR. References (1) Sa, Y. J.; Lee, C. W.; Lee, S. Y.; Na, J.; Lee, U.; Hwang, Y. J. Catalyst–electrolyte interface chemistry for electrochemical CO2 reduction. Chemical Society Reviews 2020, 49 (18), 6632-6665.(2) Wu, J.; Sharifi, T.; Gao, Y.; Zhang, T.; Ajayan, P. M. Emerging Carbon-Based Heterogeneous Catalysts for Electrochemical Reduction of Carbon Dioxide into Value-Added Chemicals. Advanced Materials 2019, 31 (13), 1804257.(3) Liang, S.; Huang, L.; Gao, Y.; Wang, Q.; Liu, B. Electrochemical Reduction of CO2 to CO over Transition Metal/N-Doped Carbon Catalysts: The Active Sites and Reaction Mechanism. Advanced Science 2021, 8 (24), 2102886.