Metal–Organic Framework-Derived Carbon Nanorods Encapsulating Bismuth Oxides for Rapid and Selective CO2 Electroreduction to Formate

Carbon dioxide (CO₂) conversion is promising in alleviating the excessive CO₂ level and simultaneously producing valuables. This work reports the preparation of carbon nanorods encapsulated bismuth oxides for the efficient CO₂ electroconversion toward formate production. This resultant catalyst exhibits a small onset potential of −0.28 V vs. RHE and partial current density of over 200 mA cm⁻² with a stable and high Faradaic efficiency of 93 % for formate generation in a flow cell configuration. Electrochemical results demonstrate the synergistic effect in the Bi₂O₃@C promotes the rapid and selective CO₂ reduction in which the Bi₂O₃ is beneficial for improving the reaction kinetics and formate selectivity, while the carbon matrix would be helpful for enhancing the activity and current density of formate production. This work provides effective bismuth-based MOF derivatives for efficient formate production and offers insights in promoting practical CO₂ conversion technology.     

Metal–Organic Framework‐Derived Carbon Nanorods Encapsulating Bismuth Oxides for Rapid and Selective CO2 Electroreduction to Formate

Carbon dioxide (CO₂) conversion is promising in alleviating the excessive CO₂ level and simultaneously producing valuables. This work reports the preparation of carbon nanorods encapsulated bismuth oxides for the efficient CO₂ electroconversion toward formate production. This resultant catalyst exhibits a small onset potential of ?0.28 V vs. RHE and partial current density of over 200 mA cm^?2 with a stable and high Faradaic efficiency of 93 % for formate generation in a flow cell configuration. Electrochemical results demonstrate the synergistic effect in the Bi₂O₃@C promotes the rapid and selective CO₂ reduction in which the Bi₂O₃ is beneficial for improving the reaction kinetics and formate selectivity, while the carbon matrix would be helpful for enhancing the activity and current density of formate production. This work provides effective bismuth‐based MOF derivatives for efficient formate production and offers insights in promoting practical CO₂ conversion technology.     

Next steps for solvent-based CO2 capture; integration of capture,conversion, and mineralisation

In this perspective, we detail how solvent-based carbon capture integrated with conversion can be an important element in a net-zero emission economy. Carbon capture and utilization (CCU) is a promising approach for at-scale production of green CO₂-derived fuels, chemicals and materials. The challenge is that CO₂-derived materials and products have yet to reach market competitiveness because costs are significantly higher than those from conventional means. We present here the key to making CO₂-derived products more efficiently and cheaper, integration of solvent-based CO₂ capture and conversion. We present the fundamentals and benefits of integration within a changing energy landscape (i.e., CO₂ from point source emissions transitioning to CO₂ from the atmosphere), and how integration could lead to lower costs and higher efficiency, but more importantly how CO₂ altered in solution can offer new reactive pathways to produce products that cannot be made today. We discuss how solvents are the key to integration, and how solvents can adapt to differing needs for capture, conversion and mineralisation in the near, intermediate and long term. We close with a brief outlook of this emerging field of study, and identify critical needs to achieve success, including establishing a green-premium for fuels, chemicals, and materials produced in this manner.

In this perspective, we detail how solvent-based carbon capture integrated with conversion can be an important element in a net-zero emission economy.     

Efficient Photoelectrochemical Reduction of Carbon Dioxide to Formic Acid: A Functionalized Ionic Liquid as an Absorbent and Electrolyte

Photoelectrochemical (PEC) reduction of carbon dioxide (CO₂) is a potential method for production of fuels and chemicals from a C1 feedstock accumulated in the atmosphere. However, the low solubility of CO₂ in water, and complicated processes associated with capture and conversion, render CO₂ conversion inefficient. A new concept is proposed in which a PEC system is used to capture and convert CO₂ into formic acid. The process is assisted by an ionic liquid (1‐aminopropyl‐3‐methylimidazolium bromide) aqueous solution, which functions as an absorbent and electrolyte at ambient temperature and pressure. Within this PEC reduction strategy, the ionic liquid plays a critical role in promoting the conversion of CO₂ to formic acid and suppressing the reduction of H₂O to H₂. At an applied voltage of 1.7 V, the Faradaic efficiency for formic acid production is as high as 94.1 % and the electro‐to‐chemical efficiency is 86.2 %.     

Oxidation of Carbon Supports at Fuel Cell Cathodes: Differential Electrochemical Mass Spectrometric Study

The effects of O₂ and the supported Pt nano-particles on the mechanisms and kinetics of the carbon support corrosion are investigated by monitoring the CO₂ production using differential electrochemical mass spectrometry in a dual-thin layer flow cell. Carbon can be oxidized in different distinct potential regimes; O₂ accelerates carbon oxidation, the rates of CO₂ production from carbon oxidation in O₂ saturated solution are two times of that in N₂ saturated solution at the same potential; Pt can catalyze the carbon oxidation, with supported Pt nanoparticles, the overpotential for carbon oxidation is much smaller than that without loading in the carbon electrode. The mechanism for the enhanced carbon oxidation by Pt and O₂ are discussed.     

Pressurized CO<Subscript>2</Subscript>-enhanced gasification of coal

Carbon dioxide was considered as a co-gasifying agent in a coal gasification reactor. The work presented herein describes the simulation results for the process and the experimental data on coal char gasification with CO₂ addition as the rate-controlling step for the entire process. To study the potentially beneficial effect of the introduction of CO₂ into the gasification system, several simulations were conducted using the commercial process simulation software ChemCAD 6.3^®. The results of a Gibbs equilibrium reactor were evaluated. The Boudouard reaction is a critical path for the development of this process, and the kinetics were studied experimentally. Four chars derived from the pyrolysis of Polish coals of different origins were selected for the experiments. The kinetic characteristics of this system were examined using a custom-designed pressurized fixed-bed reactor. To determine the effect of pressure on the gasification rate, several preliminary studies on the gasification of coal chars were performed isothermally at the temperature of 950 °C and pressures of 1, 10, and 20 bars. In contrast to the thermodynamic calculations, the experimental data revealed that increasing the CO₂ pressure leads to a higher reaction rate for medium-rank coal chars and low-rank lignite coal char, resulting in higher efficiency for carbon monoxide production. The pressure influences the reactivity more strongly when varied from 1 to 10 bars; a further increase in pressure affects the rate almost insignificantly. The observed behavior representing the changes in carbon conversion degree during gasification is satisfactorily described by the grain model.     

Thermodynamic Feasibility of Enzymatic Reduction of Carbon Dioxide to Methanol

Production of valuable chemicals from CO₂ is highly desired for the purpose of controlling CO₂ emission. Toward that, enzymatic reduction of CO₂ for the production of methanol appeared to be especially promising. That has been achieved by reversing the biological metabolic reaction pathways. However, hitherto, there has been little discussion on the thermodynamic feasibility of reversing such biological pathways. The reported yields of methanol have been generally very low under regular reaction conditions preferred by naturally evolved enzymes. The current work examines the sequential enzymatic conversion of CO₂ into methanol from a thermodynamic point of view with a focus on factors that control the reaction equilibrium. Our analysis showed that the enzymatic conversion of carbon dioxide is highly sensitive to the pH value of the reaction solution and, by conducting the reactions at low pHs (such as pH 6 or 5) and ionic strength, it is possible to shift the biological methanol metabolic reaction equilibrium constants significantly (by a factor of several orders of magnitude) to favor the synthesis of methanol.     

Photocatalytic carbon dioxide reduction by photocatalyst innovation

The photocatalytic conversion of carbon dioxide into sustainable fuel methanol using carbon quantum dots is highlighted in this paper. The multifaceted roles of carbon quantum dots in photocatalytic reactions and future directions of CQD materials are outlined.     

Online Monitoring of Electrochemical Carbon Corrosion in Alkaline Electrolytes by Differential Electrochemical Mass Spectrometry

Carbon corrosion at high anodic potentials is a major source of instability, especially in acidic electrolytes and impairs the long‐term functionality of electrodes. In‐depth investigation of carbon corrosion in alkaline environment by means of differential electrochemical mass spectrometry (DEMS) is prevented by the conversion of CO₂ into CO₃^2?. We report the adaptation of a DEMS system for online CO₂ detection as the product of carbon corrosion in alkaline electrolytes. A new cell design allows for in situ acidification of the electrolyte to release initially dissolved CO₃^2? as CO₂ in front of the DEMS membrane and its subsequent detection by mass spectrometry. DEMS studies of a carbon‐supported nickel boride (Ni_xB/C) catalyst and Vulcan XC 72 at high anodic potentials suggest protection of carbon in the presence of highly active oxygen evolution electrocatalysts. Most importantly, carbon corrosion is decreased in alkaline solution.     

Carbon Dioxide Capture and Use: Organic Synthesis Using Carbon Dioxide from Exhaust Gas

A carbon capture and use (CCU) strategy was applied to organic synthesis. Carbon dioxide (CO₂) captured directly from exhaust gas was used for organic transformations as efficiently as hyper‐pure CO₂ gas from a commercial source, even for highly air‐ and moisture‐sensitive reactions. The CO₂ capturing aqueous ethanolamine solution could be recycled continuously without any diminished reaction efficiency.     

A mass and energy balance to provide microbial growth yield efficiency in soil

The control on the CO₂ coming from soil handling, makes necessary the introduction of new methodologies that inform about the capacity of the soil as a carbon sink and about the carbon decay. It can be performed through the microbial growth yield efficiency concept by calorimetry and enthalpy balances. Here it is examined the sensitivity of these indicators to two metal layering phosphates, AZP [(NH)₄Zn₂(PO)₄(HPO)₄] and AIP [(NH)₄Fe(PO)₄H₂O] to assess about their soil impact. Both compounds caused metabolic changes on soil microbial biomass when compared to appropriated references indicating that the proposed methodology is sensitive to different inorganic sources of microbial growth.     

Overall Carbon-neutral Electrochemical Reduction of CO2 in Molten Salts using a Liquid Metal Sn Cathode

An overall carbon-neutral CO₂ electroreduction requires enhanced conversion efficiency and intensified functionality of CO₂-derived products to balance the carbon footprint from CO₂ electroreduction against fixed CO₂. A liquid Sn cathode is herein introduced into electrochemical reduction of CO₂ in molten salts to fabricate core–shell Sn−C spheres (Sn@C). An in situ generated Li₂SnO₃/C directs a self-template formation of Sn@C. Benefitting from the accelerated reaction kinetics from the liquid Sn cathode and the core–shell structure of Sn@C, a CO₂-fixation current efficiency higher than 84 % and a high reversible lithium-storage capacity of Sn@C are achieved. The versatility of this strategy is demonstrated by other low melting point metals, such as Zn and Bi. This process integrates energy-efficient CO₂ conversion and template-free fabrication of value-added metal-carbon, achieving an overall carbon-neutral electrochemical reduction of CO₂.     

Enhanced photocatalytic CO2 hydrogenation with wide-spectrum utilization over black TiO2 supported catalyst

Light-driven conversion of CO₂into chemicals/fuels is a desirable approach for achieving carbon neutrality using clean and sustainable energy.However,its scale-up application is restricted due to insufficient efficiency.Herein,we present a photothermal catalytic hydrogenation of CO₂into CH₄over Ru/black Ti O₂catalysts,aiming to achieve the synergistic use of light and heat in solar energy during CO₂conversion.Owing to the desirable spectral ...     

Efficiency of CO<Subscript>2</Subscript> Dissociation in a Radio-Frequency Discharge

One possible solution to mitigating the effects of high atmospheric concentrations of carbon dioxide (CO₂) is the use of a plasma source to break apart the molecule into carbon monoxide (CO) and oxygen. This work experimentally investigates the efficiency of dissociation of CO₂ in a 1-kW radio-frequency (rf) plasma source operating at 13.56-MHz in a low-pressure discharge. Mass spectrometry diagnostics are used to determine the species present in the discharge, and these measurements are used to calculate the energy efficiency and conversion efficiency of CO₂ dissociation in the rf plasma source. Experimental results have found that the conversion efficiency of CO₂ to CO can reach values near 90%, however energy efficiency reaches a maximum of 3%. A theoretical energy cost analysis is also given as a method to evaluate the effectiveness of any plasma system designed for CO₂ emissions reduction.     

Pure and Metal-confining Carbon Nanotubes through Electrochemical Reduction of Carbon Dioxide in Ca-based Molten Salts

To be successfully implemented, an efficient conversion, affordable operation and high values of CO₂-derived products by electrochemical conversion of CO₂ are yet to be addressed. Inspired by the natural CaO-CaCO₃ cycle, we herein introduce CaO into electrolysis of SnO₂ in affordable molten CaCl₂-NaCl to establish an in situ capture and conversion of CO₂. In situ capture of anodic CO₂ from graphite anode by the added CaO generates CaCO₃. The consequent co-electrolysis of SnO₂ and CaCO₃ confines Sn in carbon nanotube (Sn@CNT) in cathode and increases current efficiency of O₂ evolution in graphite anode to 71.9 %. The intermediated CaC₂ is verified as the nuclei to direct a self-template generation of CNT, ensuring a CO₂-CNT current efficiency and energy efficiency of 85.1 % and 44.8 %, respectively. The Sn@CNT integrates confined responses of Sn cores to external electrochemical or thermal stimuli with robust CNT sheaths, resulting in excellent Li storage performance and intriguing application as nanothermometer. The versatility of the molten salt electrolysis of CO₂ in Ca-based molten salts for template-free generation of advanced carbon materials is evidenced by the successful generation of pure CNT, Zn@CNT and Fe@CNT.     

生物质焦油组分甲苯在镍/凹凸棒石上的二氧化碳催化重整

 以大比表面积的天然纳米矿物材料凹凸棒石 (PG) 为载体, 采用等体积浸渍法制备了 Ni/PG 催化剂. 运用 X 射线衍射、透射电镜和 CO₂ 程序升温脱附对 Ni/PG 催化剂进行了表征, 并用于以甲苯为生物质焦油模型化合物的 CO₂ 催化重整反应. 考察了反应温度、CO₂ 浓度以及催化剂中 Ni 负载量对甲苯与 CO₂ 重整性能的影响. 结果表明, 吸附在催化剂表面的 CO₂ 存在三个脱附峰, 其中高温脱附 CO₂ 与反应密切相关; 随着 CO₂ 浓度、Ni 负载量和反应温度的增加, 甲苯转化率和 H₂ 产率升高. 在 800 ^oC, CO₂/PhCH₃ 摩尔比为 0.2~0.26 时, 甲苯转化率达最高; 而在 CO₂/PhCH₃ 摩尔比为 0.2 时, H₂ 产率最高. 催化剂上积炭量随 CO₂ 浓度的增加和反应温度的升高而显著降低.     

Metabolic heat and CO2 evolution rates measured by calorimetry during different in vitro induction processes of cineraria

Explanted cotyledons from cineraria ‘Jester Pink’ seeds were cultured in vitro on a modified Murashige-Skoog medium containing (in μM): 13.5 NAA, 13.5 2,4-D, 4.4 BAP, 13.5 NAA + 4.4 BAP, 13.5 2,4-D + 4.4 BAP or no plant growth regulators (control). Photographs were taken at 7-day intervals for 35 days to follow the embryogenic/organogenic development of the explanted cotyledons. Calorespirometric (metabolic heat rate, R_q and respiration rate, RCO₂) measurements were made in triplicate on the cultured cotyledons at the same interval as the photographs. Results showed a close correlation between the embryogenic/organogenic response of the tissues and R_q values. Cotyledons on a medium containing 2,4-D + BAP had the highest R_q values while those cotyledons that failed to develop or those of control, that suffered deterioration, had the lowest. This work showed that calorespirometric data may be useful in estimating early responses of tissues/organs in vitro embryogenic/organogenic culture systems.     

Carbon Dioxide Destruction with Methane Reforming by a Novel Plasma-Catalytic Converter

A novel plasma-catalyst converter (NPCC) was engineered in applying the carbon capture utilization technology for the destruction of carbon dioxide (CO₂), which is a cause of global warming and is generated from the combustion of fossil fuels. The NPCC has an orifice-type baffle to improve an amount of gas feed with the higher CO₂ destruction for a stationary point sources application . To examine its ability for the CO₂ destruction, the performance analysis was conducted on the effects of methane additive, nozzle injection velocity, total gas feed, and catalyst type. The product gas from the NPCC was combustible components like CO, H₂, CH₄, THCs. The CO₂ destruction and the CH₄ conversion at a 1.29 CH₄/CO₂ ratio were 37 and 47 %, respectively, and the energy decomposition efficiency was 0.0036 L/min W. The nickel oxide catalyst among other catalysts showed the most effectiveness for the CO₂ destruction and CH₄ conversion at a lower temperature. The carbon-black produced without the catalytic bed has carbon nanoparticles with diverse shapes, such as spherical carbon particles and carbon nanotubes; and its high conductivity and specific surface area were suitable for special electronic materials, fuel cells, and nanocomponents.     

Silver and Copper Nitride Cooperate for CO Electroreduction to Propanol

The need of carbon sources for the chemical industry, alternative to fossil sources, has pointed to CO₂ as a possible feedstock. While CO₂ electroreduction (CO₂R) allows production of interesting organic compounds, it suffers from large carbon losses, mainly due to carbonate formation. This is why, quite recently, tandem CO₂R, a two-step process, with first CO₂R to CO using a solid oxide electrolysis cell followed by CO electroreduction (COR), has been considered, since no carbon is lost as carbonate in either step. Here we report a novel copper-based catalyst, silver-doped copper nitride, with record selectivity for formation of propanol (Faradaic efficiency: 45 %), an industrially relevant compound, from CO electroreduction in gas-fed flow cells. Selective propanol formation occurs at metallic copper atoms derived from copper nitride and is promoted by silver doping as shown experimentally and computationally. In addition, the selectivity for C₂₊ liquid products (Faradaic efficiency: 80 %) is among the highest reported so far. These findings open new perspectives regarding the design of catalysts for production of C₃ compounds from CO₂.     

Enhancing CO2 Electroreduction to Methane with a Cobalt Phthalocyanine and Zinc–Nitrogen–Carbon Tandem Catalyst

Developing copper-free catalysts for CO₂ conversion into hydrocarbons and oxygenates is highly desirable for electrochemical CO₂ reduction reaction (CO₂RR). Herein, we report a cobalt phthalocyanine (CoPc) and zinc–nitrogen–carbon (Zn-N-C) tandem catalyst for CO₂RR to CH₄. This tandem catalyst shows a more than 100 times enhancement of the CH₄/CO production rate ratio compared with CoPc or Zn-N-C alone. Density functional theory (DFT) calculations and electrochemical CO reduction reaction results suggest that CO₂ is first reduced into CO over CoPc and then CO diffuses onto Zn-N-C for further conversion into CH₄ over Zn-N₄ site, decoupling complicated CO₂RR pathway on single active site into a two-step tandem reaction. Moreover, mechanistic analysis indicates that CoPc not only generates CO but also enhances the availability of *H over adjacent N sites in Zn-N₄, which is the key to achieve the high CH₄ production rate and understand the intriguing electrocatalytic behavior which is distinctive to copper-based tandem catalysts.