Carbon Products Research Articles

Effect of Cu on Performance of Self-Dispersing Ni-Catalyst in Production of Carbon Nanofibers from Ethylene

The development of effective catalysts for the pyrolysis of light hydrocarbons with the production of carbon nanomaterials represents a relevant direction. In the present work, the influence of copper addition on performance of a self-dispersed Ni-catalyst and structural features of the obtained carbon nanofibers (CNFs) was studied. The precursors of Ni and Ni-Cu catalysts were prepared by activation of metal powders in a planetary mill. During contact with the C2H4/H2 reaction mixture, a rapid disintegration of the catalysts with the formation of active particles catalyzing the growth of CNFs has occurred. The kinetics of CNF accumulation during ethylene decomposition on Ni- and Ni-Cu catalysts was studied. The effect of temperature on catalytic performance was explored and it was shown that introduction of copper promotes 1.5–2-fold increase in CNFs yield in the range of 525–600 °C; the maximum CNFs yield (100 g/gcat and above, for 30-min reaction) is reached on Ni-Cu-catalyst at 575–600 °C. A comparative analysis of the morphology and structure of CNF was carried out using electron microscopy methods. The growth mechanism of carbon filaments in the shape of “railway crossties” on large nickel crystals (d > 250 nm) was proposed. It was found that the addition of copper leads to a decrease in the bulk density of the carbon product from 40–60 to 25–30 g/L (at T = 550–600 °C). According to the low-temperature nitrogen adsorption data, specific surface area (SSA) of CNF samples (at T < 600 °C) lies in the range of 110–140 m2/g, regardless of the catalyst composition; at T = 600 °C the introduction of copper contributed to an increase in the specific surface of CNF by 100 m2/g.

Promoting decarbonization in the power sector: How important is digital transformation?

The application of digital technologies to help improve new energy integration and generation efficiency is critical to decarbonizing the power sector. Many studies have explored the drivers of carbon emissions in the power sector, but the role of digitalization has been overlooked. To investigate digitalization's impact on electricity production's carbon intensity, this paper measures the level of digitalization in the electricity sector for 93 countries in 2010 and 2015–2019. A two-way fixed effects model was constructed to analyze the panel data. According to the empirical findings, digitalization can significantly reduce the carbon intensity of power generation. Optimizing the energy structure is an important mechanism for decarbonization. It is found that the energy structure enhances the carbon reduction effect of digitalization in the power sector. The impact of digitalization on reducing carbon intensity increases with the quantity of renewable energy. The heterogeneity analysis results suggest that digitalization's impact on reducing carbon emissions is stronger in nations with higher levels of digital investment, digital service investment, industrial proportion, or industrial electricity compared to residential electricity. The research offers empirical evidence and targeted policy recommendations for promoting decarbonization and digital transformation of the power sector.

Recent Advances on Single-Atom Catalysts for Photocatalytic CO2 Reduction.

The present energy crisis and environmental challenges may be efficiently resolved by converting carbon dioxide (CO2 ) into various useful carbon products. The development of more effective catalysts has been the main focus of current research on photocatalytic CO2 reduction. Due to their high atomic efficiency and superior catalytic activity, single-atom catalysts (SACs) have attracted considerable interest in catalytic CO2 conversion. This review discusses the current research developments, obstacles, and potential of SACs for photocatalytic CO2 reduction. And further, discusses the principle of photocatalytic carbon dioxide reduction. This work has compared and analyzed the effects of support materials and active site types in SACs on photocatalytic CO2 reduction performance. This work believes that by sharing these developments, some inspiration for the rational design and development of stable and effective photocatalytic CO2 reduction catalysts based on SACs can be provided.

Investigation of Carbon Products Produced by Catalytic Methane and Ethane Pyrolysis.

Investigation of Carbon Products Produced by Catalytic Methane and Ethane Pyrolysis.

Improvement of Ball Mill Performance in Recycled Ultrafine Graphite Waste Production for Carbon Block Applications.

A carbon block is a carbonaceous material used in various applications such as bearings, mechanical seals, and electrical brushes. This work aims to fabricate carbon blocks from industrial graphite waste, a residue from the cutting and tooling process of graphite block production. The ball milling process was used to fabricate ultrafine graphite waste to enhance the packing of carbon blocks. The milling performance was profoundly affected by dispersing agents in which sodium dodecyl sulfate (SDS), lignosulfonate (LS), and mixed dispersant (LS-SDS) were applied. The results showed that LS-SDS had the best milling performance, the greatest grinding index, and a flowable slurry, indicating the potentiality of this formulation for the environmentally friendly manufacture of ultrafine graphite waste. Carbon blocks were prepared from oven-dried ultrafine graphite waste, which was mixed with amorphous carbon and pitch. This carbon mixture was formed a block by compaction before carbonization and impregnation. The density of the fabricated carbon blocks increased from 1.76 to 1.83 g/cm3 after impregnation along with the increase in hardness, flexural strength, and reduction in electrical resistivity from 83, 62 MPa, and 40 μΩ m to 88, 81 MPa, and 39 μΩ m, respectively. The physical properties of carbon blocks prepared from ultrafine graphite waste were comparable to the properties of typical pristine carbon products.

Selective ethane production from carbon dioxide enabled by Cu-Ga plates with large-scale manufacturing capability

Catalysts for CO2 electroreduction to poly carbon products are urgently needed to mitigate the greenhouse effect. In this work, a simple method suitable for industry production has been proposed for manufacturing the Cu-5Ga alloy plates to achieve efficient CO2 reduction. The prepared Cu-Ga plates show uneven surfaces and pores to enhance the catalytic performance. Interestingly, the final catalyst can achieve a good selectivity of C2H6 product with a Faradaic efficiency of 36% at −0.45 VRHE, showing an average total current density of ∼−2.5 mA cm−2. Density functional theory calculations reveal that the favourable C2H6 selectivity by Cu-5Ga is due to the strong adsorption of *CO and the prominent carbon–carbon coupling on the alloy.

MetaFlux: Meta-learning global carbon fluxes from sparse spatiotemporal observations

We provide a global, long-term carbon flux dataset of gross primary production and ecosystem respiration generated using meta-learning, called MetaFlux. The idea behind meta-learning stems from the need to learn efficiently given sparse data by learning how to learn broad features across tasks to better infer other poorly sampled ones. Using meta-trained ensemble of deep models, we generate global carbon products on daily and monthly timescales at a 0.25-degree spatial resolution from 2001 to 2021, through a combination of reanalysis and remote-sensing products. Site-level validation finds that MetaFlux ensembles have lower validation error by 5–7% compared to their non-meta-trained counterparts. In addition, they are more robust to extreme observations, with 4–24% lower errors. We also checked for seasonality, interannual variability, and correlation to solar-induced fluorescence of the upscaled product and found that MetaFlux outperformed other machine-learning based carbon product, especially in the tropics and semi-arids by 10–40%. Overall, MetaFlux can be used to study a wide range of biogeochemical processes.

NMR-based quantification of liquid products in CO2 electroreduction on phosphate-derived nickel catalysts

Recently discovered phosphate-derived Ni catalysts have opened a new pathway towards multicarbon products via CO2 electroreduction. However, understanding the influence of basic parameters such as electrode potential, pH, and buffer capacity is needed for optimized C3+ product formation. To this end, rigorous catalyst evaluation and sensitive analytical tools are required to identify potential new products and minimize increasing quantification errors linked to long-chain carbon compounds. Herein, we contribute to enhance testing accuracy by presenting sensitive 1H NMR spectroscopy protocols for liquid product assessment featuring optimized water suppression and reduced experiment time. When combined with an automated NMR data processing routine, samples containing up to 12 products can be quantified within 15 min with low quantification limits equivalent to Faradaic efficiencies of 0.1%. These developments disclosed performance trends in carbon product formation and the detection of four hitherto unreported compounds: acetate, ethylene glycol, hydroxyacetone, and i-propanol.

Regenerable carbon honeycomb monoliths directly prepared from brown coal: A novel carbon product

A novel, straightforward and efficient method for preparing electrically regenerable carbon honeycomb monoliths (CHMs) directly from brown coal is described. Soft brown coal, which inherently contains relatively high oxygen functional group concentrations and high moisture contents, was kneaded with NaOH or KOH to achieve homogenised and smooth dough with plasticine consistency. This method of alkali salt addition leads to a high level of ion-exchange. The exchanged cations form a strong electrostatic network, strengthening the coal structure such that the dough can be directly extruded into high cell density CHMs (e.g., 227 cells/in2) which maintain their structural integrity throughout drying¸ carbonisation and activation processes.It was found that a modest temperature increase (to above 50 °C) enabled by the kneading, played an important role in developing the dough quality via an apparent irreversible, exothermic cross-linking reaction.The fabricated CHMs are structurally robust with high compressive strength (e.g., 40 MPa). They exhibit good electrical conductivity (e.g. 150 S/m) and high surface areas (e.g., 1175 m2/g), which can both be tailored for specific applications. The used CHM was fully regenerated by in-situ resistive heating after liquid adsorption in a short time (30 min) under atmospheric air, thanks to its optimal electrical conductivity and stable structure. These characteristics along with its low material and production cost make this CHM a promising material for a variety of applications, such as methane storage and phenol adsorption.

Direct Imaging of Local pH Reveals Bubble-Induced Mixing in a CO2 Electrolyzer.

Electrochemical CO2 reduction poses a promising pathway to produce hydrocarbon chemicals and fuels without relying on fossil fuels. Gas diffusion electrodes allow high selectivity for desired carbon products at high current density by ensuring a sufficient CO2 mass transfer rate to the catalyst layer. In addition to CO2 mass transfer, the product selectivity also strongly depends on the local pH at the catalyst surface. In this work, we directly visualize for the first time the two-dimensional (2D) pH profile in the catholyte channel of a gas-fed CO2 electrolyzer equipped with a bipolar membrane. The pH profile is imaged with operando fluorescence lifetime imaging microscopy (FLIM) using a pH-sensitive quinolinium-based dye. We demonstrate that bubble-induced mixing plays an important role in the Faradaic efficiency. Our concentration measurements show that the pH at the catalyst remains lower at -100 mA cm-2 than at -10 mA cm-2, implying that bubble-induced advection outweighs the additional OH- flux at these current densities. We also prove that the pH buffering effect of CO2 from the gas feed and dissolved CO2 in the catholyte prevents the gas diffusion electrode from becoming strongly alkaline. Our findings suggest that gas-fed CO2 electrolyzers with a bipolar membrane and a flowing catholyte are promising designs for scale-up and high-current-density operation because they are able to avoid extreme pH values in the catalyst layer.

Co–N2 Bond Precisely Connects the Conduction Band and Valence Band of g‐C3N4/CoCo‐LDH to Enhance Photocatalytic CO2 Activity by High‐Efficiency S‐Scheme

Precise regulation of photogenic electron transfer path plays an important role in improving photocatalytic carbon dioxide reduction efficiency and product selectivity. Herein, under the guidance of density functional theory calculation, the interface chemical bond (CoN2 bond) at the atomic level is designed, and g‐C3N4/CoCo‐layered double hydroxide (LDH) heterostructure is manufactured. CoCo‐LDH with water oxidation ability and g‐C3N4 were combined to construct S‐scheme heterojunction with redox ability. The valence band and conduction band of g‐C3N4 and CoCo‐LDH are precisely connected by the interfacial CoN2 bond, which realizes the high‐speed transfer of electron transport. Despite the absence of cocatalyst, the heterojunction exhibits high water oxidation and carbon reduction capacity due to the precise regulation of CoN2 bonds. Theoretical calculations and experimental results show that the addition of CoCo‐LDH: reduces the oxidation overpotential of water to provide more H protons; regulates the delocalization charge of g‐C3N4; and reduces the energy barrier of the CO2 intermediate (*COOH) in the reduction half‐reaction. The results show that the selectivity of carbon‐based substances in the products was 100%, and the optimal CO yield was 71.39 μmol g−1 h−1, which is among the highest values of g‐C3N4‐based photocatalysts.

Multi-scale observations of mangrove blue carbon ecosystem fluxes: The NASA Carbon Monitoring System BlueFlux field campaign

The BlueFlux field campaign, supported by NASA’s Carbon Monitoring System, will develop prototype blue carbon products to inform coastal carbon management. While blue carbon has been suggested as a nature-based climate solution (NBS) to remove carbon dioxide (CO2) from the atmosphere, these ecosystems also release additional greenhouse gases (GHGs) such as methane (CH4) and are sensitive to disturbances including hurricanes and sea-level rise. To understand blue carbon as an NBS, BlueFlux is conducting multi-scale measurements of CO2 and CH4 fluxes across coastal landscapes, combined with long-term carbon burial, in Southern Florida using chambers, flux towers, and aircraft combined with remote-sensing observations for regional upscaling. During the first deployment in April 2022, CO2 uptake and CH4 emissions across the Everglades National Park averaged −4.9 ± 4.7 μmol CO2 m−2 s−1 and 19.8 ± 41.1 nmol CH4 m−2 s−1, respectively. When scaled to the region, mangrove CH4 emissions offset the mangrove CO2 uptake by about 5% (assuming a 100 year CH4 global warming potential of 28), leading to total net uptake of 31.8 Tg CO2-eq y−1. Subsequent field campaigns will measure diurnal and seasonal changes in emissions and integrate measurements of long-term carbon burial to develop comprehensive annual and long-term GHG budgets to inform blue carbon as a climate solution.

Fixation of CO2 by soil fungi: contribution to organic carbon pool and destination of fixed carbon products

Fixation of CO2 by soil fungi: contribution to organic carbon pool and destination of fixed carbon products

Research on low-carbon dual channel supply chain considering product substitution under government carbon tax and low-carbon subsidy.

Since dual channel supply chain has become one of the main modes of supply chain, its research has acquired great significance. This paper constructs a low-carbon dual channel supply chain composed of one manufacturer and one retailer. The manufacturer produces low-carbon product and high carbon product with substitution relationship. The retailer sells high carbon product in traditional channel. The manufacturer also sells low-carbon product in direct channel. The government, manufacturer and retailer conduct a three-level Stackelberg game. This paper studies the optimal decisions of the government, manufacturer and retailer under the three modes of carbon tax + subsidy, carbon tax only and subsidy only. It has been found that for social welfare, the carbon tax + subsidy model is higher than the subsidy model and carbon tax model. For manufacturer profit, the subsidy mode is the highest, followed by the carbon tax + subsidy mode. For retailer profit, the carbon tax + subsidy model is equal to the carbon tax model. The increase in the proportion of consumers who prefer high carbon product in the total market or product cost of low-carbon product, will increase the profit of traditional channel and reduce the profit of direct channel.

Production of combustible fuels and carbon nanotubes from plastic wastes using an in-situ catalytic microwave pyrolysis process

This study performed in-situ microwave pyrolysis of plastic waste into hydrogen, liquid fuel and carbon nanotubes in the presence of Zeolite Socony Mobil ZSM-5 catalyst. In the presented microwave pyrolysis of plastics, activated carbon was used as a heat susceptor. The microwave power of 1 kW was employed to decompose high-density polyethylene (HDPE) and polypropylene (PP) wastes at moderate temperatures of 400–450 °C. The effect of plastic composition, catalyst loading and plastic type on liquid, gas and solid carbon products was quantified. This in-situ CMP reaction resulted in heavy hydrocarbons, hydrogen gas and carbon nanotubes as a solid residue. A relatively better hydrogen yield of 129.6 mmol/g as a green fuel was possible in this process. FTIR and gas chromatography analysis revealed that liquid product consisted of C13+ fraction hydrocarbons, such as alkanes, alkanes, and aromatics. TEM micrographs showed tubular-like structural morphology of the solid residue, which was identified as carbon nanotubes (CNTs) during X-ray diffraction analysis. The outer diameter of CNTs ranged from 30 to 93 nm from HDPE, 25–93 nm from PP and 30–54 nm for HDPE-PP mixure. The presented CMP process took just 2–4 min to completely pyrolyze the plastic feedstock into valuable products, leaving no polymeric residue.

Fabrication of waste-derived porous geopolymer by community-scale carbonization and steam activation with potential copper adsorption

An integrated system for solid waste management in rural regions is presented in this study. Waste charcoal and activated carbon (AC) products were used for the production of absorbable geopolymers by subjecting municipal solid waste (MSW) and beachside waste (BSW) to a carbonization process (400 °C for 3 h) and steam activation (700, 800, and 900 °C for 1 h). The material characterization, mechanical property analysis, and copper adsorption performance were investigated. The results showed that the waste charcoal yields from MSW and BSW were 31.4% and 39.5%, respectively. The AC product yields of MSW and BSW were approximately 13.9–19.8% and 18.1–26.2%, respectively. Additional ingredients for geopolymer production are coal fly ash (FA) and rice husk bottom ash (RA). The results showed that the 45FARA10MSW and 50FA50BSW geopolymers had maximum compressive strengths of 188.78 and 130.94 ksc, respectively. The absorbable geopolymers 45FARA10MSW-AC and 50FA50BSW-AC, produced from waste charcoal-derived AC, exhibited Cu2+ removal performances of 68.5% and 98.3%, respectively. The high adsorption performance was owing to improved physical properties such as the surface area, pore size, and average porosity of the AC products. In summary, absorbable geopolymer products from waste could be a promising green materials for environmental applications.

An integrated Metagenomic-Pangenomic strategy revealed native microbes and magnetic biochar cooperation in plasticizer degradation

There has been growing concern over the release of plasticizers from plastic products, and the high levels of plasticizers in the environment have led to a threat to ecological security. Although some plasticizers may naturally degrade, their slow removal and prolonged life cycle remain challenges. To address this, this study explored a unique hybrid strategy using native field microorganisms and magnetic biochar (MBC) to support the upstream degradation of plasticizers. Diethyl phthalate (DP) was used as the test subject. The study found that MBC treatment led to high level of total organic carbon (TOC) and various organic products, demonstrating the degradation of DP. Analysis of the hybrid metagenomic model showed that several species of Pseudomonas can degrade downstream phenylmethanal and Pseudomonas nitroreducens has the ability to cooperate well with MBC due to its iron receptor and transporter. Additionally, a Pigmentiphaga species was found to have the ability to fully mineralize DP. Analysis of the Pigmentiphaga pangenome revealed that genes related to DP biodegradation were shared by members of this genus. Although some members of Pseudomonas is known to be pathogenic, the species identified in the study may not be harmful as they lack virulence factors. The study provides evidence regarding the cooperation between native biodegraders and MBC in mineralizing plasticizers, offering a new solution for removing phthalate plasticizers from soil and surface water.

Green Supply Chain Coordination Considering Carbon Emissions and Product Green Level Dependent Demand

As traditional supply chains face increasingly severe environmental issues, and as countries promote green development and sustainable development policy concepts, cultivating green supply chain operation models is gradually coming to be highly valued by governments and enterprises. Generally speaking, the production of green products incurs higher additional costs, and thus, their total production costs also increase. In this work, we studied the coordination mechanism, by considering carbon emissions and product green level dependent demand, in which the product green level is related to the random demand. Under the green supply chain buyback contract with the green product R&D cost sharing between the manufacturer and the retailer, both the product green level and the order quantity need to be decided, to maximize the channel profit. In order to coordinate the green supply chain, the manufacturer needs to share both the risk of good salvage and the green product R&D cost with the retailer. We found that both the wholesale price and the buyback price increase in the manufacturer’s proposition of the green product R&D cost, but decrease in the emission reduction efficiency coefficient or carbon trading price. In addition, the product green level, the optimal order quantity and the channel profit increase in the emission reduction efficiency coefficient, but decrease in the R&D cost coefficient of the product green level. Interestingly, we found that if the carbon trading price is low, the manufacturer will set a low product green level, and the product carbon emission trading is a cost for the supply chain. The increment of the carbon trading price leads to a higher cost, such that the channel profit is decreased. However, if the carbon trading price is high, the manufacturer will set a high product green level, and the product carbon emission trading is a revenue for the supply chain. The increment of the carbon trading price leads to a higher revenue, such that the channel profit is increased.

Applicability of hybrid aspen (Populus tremula L. × P. tremuloides Michx.) bark extract as a precursor of rigid carbon foam and activated carbon

Hybrid aspens have long attracted scientific interest, but the research on their use as feedstocks for chemical applications are still very limited. The bark biomass of the poplar species contains many valuable extractives that can be utilized as value-added products. This paper examines the applicability of hybrid aspen (Populus tremula L. × P. tremuloides Michx.) bark extract as a precursor of rigid carbon foam and activated carbon. To explore this, the study considers 1) the basic chemical composition of the bark in terms of added value potential, 2) the basic chemical composition of the bark extract and the effect of its pretreatment on the extract composition, 3) the production of rigid carbon foam, and 4) the chemical activation of carbon foam with different impregnating agents. The study determines that the bark extract of the hybrid aspen can be used as a precursor for rigid carbon foam and further processed into an activated carbon product. Therefore, the bark extract of Populus tremula L. × P. tremuloides Michx. can be assessed as a potential value-added product that increases the use value of the hybrid aspen biomass.

In-situ electrodeposited Ag/Cu for electrochemical reduction of acetic acid to nanodiamond under ambient conditions

Carbon nanostructured materials such as nanodiamonds and graphene are useful for various applications, but their low-energy production technologies remain an important challenge to overcome. Herein, the electrochemical reduction of acetic acid using in-situ electrodeposited Ag/Cu to nanocrystalline carbon products was investigated as a function of AgNO3 concentrations in the presence of water and [BMIM]+[BF4]- ionic liquid. Under the conditions used, the deposited Ag clusters could become negatively charged and were responsible for the reduction of acetic acid and the consequent crystalline carbon growth. Increasing Ag concentrations did not only result in higher amounts of Ag being deposited but also created significant local pressure on the atomistic level, where the crystalline carbon was formed, resulting in the re-ordering of carbon atoms into nanodiamond structure. The presence of nanodiamond with average crystallite size 27 nm was clearly evidenced by XRD, Raman, XPS, and TEM-EDX-SAED. The in-situ electrochemical reduction has shown to be an effective ultra-low energy strategy to produce crystalline solid carbon under ambient conditions.