CO Conversion Rate Research Articles

Effect of different hydrogen evolution rates at cathode on bioelectrochemical reduction of CO2 to acetate

Microbial electrosynthesis (MES) offers a promising approach for converting CO2 into valuable chemicals such as acetate. However, the relative low conversion rate severely limits its practical application. This study investigated the impact of different hydrogen evolution rates on the conversion rate of CO2 to acetate in the MES system. Three potentials (−0.8 V, −0.9 V and −1.0 V) corresponding to various hydrogen evolution rates were set and analyzed, revealing an optimal hydrogen evolution rate, yielding a maximum acetate formation rate of 1410.9 mg/L and 73.5 % coulomb efficiency. The electrochemical findings revealed that an optimal hydrogen evolution rate facilitated the formation of an electroactive biofilm. The microbial community of the cathode biofilm highlighted key genera, including Clostridium and Acetobacterium, which played essential roles in electrosynthesis within the MES system. Notably, a low hydrogen evolution rate failed to provide sufficient energy for the electrochemical reduction of CO2 to acetate, while a high rate led to cathode alkalinization, impeding the reaction and causing significant energy wastage. Therefore, maintaining an appropriate hydrogen evolution rate is crucial for the development of mature electroactive biofilms and achieving optimal performance in the MES system.

Synergistic effect and coordination environment tuned water-gas shift reaction on MoS2 catalyst

CO conversion rate follows the order S edge > Mo edge > Cu/MoS2(001). Redox and associative routes are dominant on Cu/MoS2(001) and S edge, respectively, while both routes contribute to water-gas shift on Mo edge.

Different metal (Mn, Fe, Co, Ni, and Zr) decorated Cu/CeO2 catalysts for efficient CO oxidation in a rich CO2/H2 atmosphere.

In this work, CuM/CeO2 (M = Mn, Fe, Co, Ni, and Zr) catalysts with a low Cu content of 1 wt% were purposely designed and prepared using the co-impregnation method. The samples were characterized using various techniques (TG-DTA, XRD, N2-adsorption/desorption measurements, H2-TPR, XPS and Raman spectroscopy) and CO preferential oxidation (CO-Prox) under H2/CO2-rich conditions was performed. The results have shown that enhanced catalytic performance was achieved upon the introduction of Mn, Co and Ni, and little impact was observed with Zr doping, but Fe showed a negative effect, as compared with the Cu/CeO2 catalyst. Characterization data revealed that the M doping strongly changed the surface composition, revealing the decreased Cu/Ce ratios on the surface, which could be accounted for by the formation of more M/Cu-O-Ce solid solution, or strong Cu-M interactions. When Mn was used, the obtained CuMn/CeO2 catalyst revealed the highest concentration of the oxygen vacancies and Ce3+ ions, which could be correlated well with its superior catalytic performance. Compared with the Cu/CeO2 catalyst, the CO conversion rate increased by 24.7% at a low temperature of 90 °C over the CuMn/CeO2 catalyst. At 130 °C, the maximum CO conversion was 94.7% and the CO2 selectivity was 78.9%. Conversely, the Fe doped Cu/CeO2 catalyst demonstrated the poorest catalytic activity, which was due to the blockage effect of Fe species on Cu showing a high Fe/Cu ratio of 1.9 on the surface.

Catalytic conversion of carbon dioxide (CO2) using coal-based nano-carbon materials.

Carbon dioxide (CO2) is a prominent greenhouse gas and a widely available carbon resource. The chemical conversion of CO2 into high-value chemicals and fuels is a significant approach for mitigating carbon emissions and attaining carbon neutrality. However, enhancing CO2 adsorption and conversion rates remains a primary challenge in CO2 recycling. The development of high-performance catalysts is pivotal for the catalytic conversion of CO2. In this context, coal-based carbon materials, characterized by their extensive specific surface area and adaptable chemical composition, can offer more reactive active sites and have robust CO2 adsorption capabilities. They can function as either standalone catalysts or as components of composite catalysts, making them promising materials for CO2 reduction. The use of affordable and abundant coal as a precursor for carbon materials represents a crucial avenue for achieving clean and efficient coal utilization. This paper reviews the progress of research on coal-based carbon materials and examines their advantages and challenges as catalysts for CO2 reduction.

Tuning the selectivity of the CO2 hydrogenation reaction using boron-doped cobalt-based catalysts.

Direct CO2 hydrogenation to value-added chemicals is a promising path toward realizing the "carbon-neutral" goal. However, controlling the selectivity of CO2 hydrogenation toward desired products (e.g., CO and CH4) using non-precious metal-based catalysts is important but challenging. It is imperative to explore catalysts with high activity and stability. Herein, boron-doped cobalt nanoparticles supported on H-ZSM-5 were devised for CO2 hydrogenation to produce CO in a gas-solid flow system. Our results demonstrate that boron doping not only increases the CO2 adsorption capability of the catalyst but also optimizes the electronic state of Co for CO desorption during hydrogenation process. As a result, the boron-doped cobalt catalysts displayed an enhanced CO selectivity of 94.5% and a CO2 conversion rate of 45.6%, which is much higher than that of Co-ZSM-5 without boron doping. This study shows that the strategic design of metal borides is important for controlling the selectivity of desired products in the CO2 hydrogenation reaction.

Exsolved LaNiRuO3 perovskite-based catalysts for CO2 methanation reaction

Exsolved perovskite-based catalysts exhibiting high and stable CO2 conversion rates.

DUAL PROMOTION OF Cu/ZnO CATALYSTS MODIFIED BY ACETYLACETONE PRECURSORS FOR CO2 HYDROGENATION TO METHANOL

It is challenging to reveal the catalytic mechanism of Cu/ZnO catalysts with multivalent copper and improve the performance of CO2 hydrogenation to methanol. We synthesized Cu/ZnO catalysts with different Cu:Zn ratios using acetylacetone salts as the precursors, in which Cu, Cu2O, CuO coexist. The catalytic activity was significantly associated with the abundance of Cu+ active sites on the surface and the formation of more Cu+-ZnO interfaces. When the ratio of Cu:Zn = 5:4, the catalyst without reduction pretreatment showed good performance, with a CO2 conversion rate of 12.9%, methanol selectivity of 85.1%, and the space-time yield of 0.238 gMeOH gcat-1 h-1. It was suggested that Cu+ tends to closely bind with ZnO, and the preparation method leads to more Cu+-ZnO interfaces. The synergistic interaction between Cu+ and ZnO promoted the adsorption and dissociation of CO2 and H2, verifying its dual effect on CO2 and H2 and promoting CO2 hydrogenation to methanol.

Strong effect-correlated electrochemical CO2 reduction.

Electrochemical CO2 reduction (ECR) holds great potential to alleviate the greenhouse effect and our dependence on fossil fuels by integrating renewable energy for the electrosynthesis of high-value fuels from CO2. However, the high thermodynamic energy barrier, sluggish reaction kinetics, inadequate CO2 conversion rate, poor selectivity for the target product, and rapid electrocatalyst degradation severely limit its further industrial-scale application. Although numerous strategies have been proposed to enhance ECR performances from various perspectives, scattered studies fail to comprehensively elucidate the underlying effect-performance relationships toward ECR. Thus, this review presents a comparative summary and a deep discussion with respect to the effects strongly-correlated with ECR, including intrinsic effects of materials caused by various sizes, shapes, compositions, defects, interfaces, and ligands; structure-induced effects derived from diverse confinements, strains, and fields; electrolyte effects introduced by different solutes, solvents, cations, and anions; and environment effects induced by distinct ionomers, pressures, temperatures, gas impurities, and flow rates, with an emphasis on elaborating how these effects shape ECR electrocatalytic activities and selectivity and the underlying mechanisms. In addition, the challenges and prospects behind different effects resulting from various factors are suggested to inspire more attention towards high-throughput theoretical calculations and in situ/operando techniques to unlock the essence of enhanced ECR performance and realize its ultimate application.

Development of Ni-doped A-site lanthanides-based perovskite-type oxide catalysts for CO2 methanation by auto-combustion method.

Engineering the interfacial interaction between the active metal element and support material is a promising strategy for improving the performance of catalysts toward CO2 methanation. Herein, the Ni-doped rare-earth metal-based A-site substituted perovskite-type oxide catalysts (Ni/AMnO3; A = Sm, La, Nd, Ce, Pr) were synthesized by auto-combustion method, thoroughly characterized, and evaluated for CO2 methanation reaction. The XRD analysis confirmed the perovskite structure and the formation of nano-size particles with crystallite sizes ranging from 18 to 47 nm. The Ni/CeMnO3 catalyst exhibited a higher CO2 conversion rate of 6.6 × 10-5 molCO2 gcat -1 s-1 and high selectivity towards CH4 formation due to the surface composition of the active sites and capability to activate CO2 molecules under redox property adopted associative and dissociative mechanisms. The higher activity of the catalyst could be attributed to the strong metal-support interface, available active sites, surface basicity, and higher surface area. XRD analysis of spent catalysts showed enlarged crystallite size, indicating particle aggregation during the reaction; nevertheless, the cerium-containing catalyst displayed the least increase, demonstrating resilience, structural stability, and potential for CO2 methanation reaction.

Visible-light-responsive hybrid photocatalysts for quantitative conversion of CO2 to highly concentrated formate solutions.

Photocatalysts can use visible light to convert CO2 into useful products. However, to date photocatalysts for CO2 conversion are limited by insufficient long-term stability and low CO2 conversion rates. Here we report hybrid photocatalysts consisting of conjugated polymers and a ruthenium(ii)-ruthenium(ii) supramolecular photocatalyst which overcome these challenges. The use of conjugated polymers allows for easy fine-tuning of structural and optoelectronic properties through the choice of monomers, and after loading with silver nanoparticles and the ruthenium-based binuclear metal complex, the resulting hybrid systems displayed remarkably enhanced activity for visible light-driven CO2 conversion to formate. In particular, the hybrid photocatalyst system based on poly(dibenzo[b,d]thiophene sulfone) drove the very active, durable and selective photocatalytic CO2 conversion to formate under visible light irradiation. The turnover number was found to be very high (TON = 349 000) with a similarly high turnover frequency (TOF) of 6.5 s-1, exceeding the CO2 fixation activity of ribulose-1,5-bisphosphate carboxylase/oxygenase in natural photosynthesis (TOF = 3.3 s-1), and an apparent quantum yield of 11.2% at 440 nm. Remarkably, quantitative conversion of CO2 (737 μmol, 16.5 mL) to formate was achieved using only 8 mg of the hybrid photocatalyst containing 80 nmol of the supramolecular photocatalyst at standard temperature and pressure. The system sustained photocatalytic activity even after further replenishment of CO2, yielding a very high concentration of formate in the reaction solution up to 0.40 M without significant photocatalyst degradation within the timeframe studied. A range of experiments together with density functional theory calculations allowed us to understand the activity in more detail.

The CO2 Conversion in a DBD Plasma: A 1D Synergistic Catalysis Model

Objective: Plasma catalysis is regarded as a promising technology in mitigating atmospheric CO2, but there is still a gap between industrial demand and current efficiency. This paper aimed to investigate the synergistic effect between vibrational states and catalyst surfaces in plasma catalysis, and to offer a theoretical guide on how to maximize the effectiveness of the synergistic effect in a more energy-efficient way. Methods: A novel 1D dielectric barrier discharge plasma catalysis model has been developed. The Arrhenius equations were used to solve the surface catalytic chemistry. The influence of CO2 vibrational excitation on surface reaction rates were expressed in the framework of the theoretical-informational approach. Results: The simulation suggested that a lower electron temperature fosters vibrational excitation, while a higher electron temperature promotes electronic excitation, therefore, the CO2 conversion rate and energy efficiency were difficult to be improved simultaneously. Furthermore, our model elucidates the pivotal role of catalysts in achieving efficient decomposition of vibrationally excited CO2 (CO2v). However, under conditions of low vibrational density, this synergistic effect fails to yield substantial improvements in catalytic efficiency under low vibrational density conditions. Conclusion: By increasing the pulse voltage, using narrow pulses with rapid rise times, implementing rapid cooling techniques and enlarging the surface catalytic area, the concentrations of CO2v can be augmented. Consequently, the dissociation rate via the V-V process and surface processes can both be enhanced, thereby potentially enabling simultaneous improvements in the CO2 conversion rate and energy efficiency.

Ascorbic-acid-assisted in-situ construction of S-scheme CuO/Cu2O hetero-nanosheets with active Cu(II)-O-Cu(I) bridges for efficient CO2 photoreduction

Efficient charge transfer across interfaces is highly desirable, but remains challenging in engineering semiconductor heterojunctions for photocatalysis. In this work, hybrid hetero-nanosheets (HNSs) of CuO/Cu2O bridged with interfacial Cu(II)-O-Cu(I) have been constructed via an in-situ topotactic transformation strategy, in which CuO nanosheets are partially reduced by ascorbic acid and transformed into Cu2O. The interfacial Cu(II)-O-Cu(I) bridges are found to provide fast transfer channels for photogenerated carriers transporting from CuO to Cu2O in an S-scheme pathway, leading to enhanced separation of photogenerated carriers. Furthermore, the bond bridges can tune the kinetic and thermodynamic processes of the CO2-to-CO conversion at interfacial Cu(I) catalytic sites by altering the rate-determined step and shifting downwards d-band center of the Cu(I) sites. Owing to the interfacial Cu(II)-O-Cu(I) bridges, the optimized CuO/Cu2O HNSs significantly expedite the CO2 photoreduction to CO, delivering a CO2 conversion rate of 22.14 μmol g−1 h−1 with a CO selectivity of 94.4%, outperforming the state-of-the-art copper oxide-based photocatalysts. This work demonstrates an effective in-situ topotactic transformation strategy to create interfacial bond bridges at heterogeneous interfaces for boosted photocatalysis as well as the critical roles of interface catalytic sites for CO2 conversion.

Synergistic Integration of Zr-MOF (UiO-66) and Bi Electrocatalysts for Enhanced CO2 Conversion to Formate

The utilization of renewable energy-driven CO2 conversion technology has garnered considerable attention as a potential remedy for both the energy crisis and climate change. Among various methods, the electrocatalytic CO2 reduction reaction (CO2RR) has received particular focus due to its mild reaction conditions and its ability to produce various valuable products. Specifically, formic acid holds great promise for CO2 electrolysis due to its potential for energy storage and transportation, as well as its commercial viability as indicated by techno-economic assessments. Bi, In, and Sn are several metal catalysts that have been reported for formic acid production, with Bi catalysts demonstrating favorable properties in terms of both cost-effectiveness and selective production of formic acid. However, despite efforts to enhance the intrinsic catalytic activity of Bi through methods such as nanostructuring and alloying, it has yet to achieve the desired level of performance. In light of recent findings by Nam et al. on the ability of a metal-organic framework (MOF) to regulate reaction intermediates for Ag catalyst, resulting in higher CO production, we draw inspiration from MOF's versatility and demonstrate the successful coupling of Bi with UiO-66, a Zr-MOF, to achieve higher CO2 reduction rates and thus increase formic acid production [1]. We synthesized MOF materials, UiO-66 and NH2-functionalized UiO-66 (UiO-66-NH2), and deposited Bi catalysts on the MOF structures using the NaBH4 reduction method, resulting in Bi/UiO-66 and Bi/UiO-66-NH2 samples. To compare the catalytic activity, we also synthesized Bi particle samples using the same method (Bi). Prior to CO2 reduction examination, all electrocatalysts were pre-treated in a 1.0 M KOH solution for 5 minutes, and then CO2 electrolysis was performed in a flow-cell reactor. Among the synthesized samples, Bi/UiO-66 demonstrated excellent CO2 reduction properties, exhibiting about 5 times higher current density (-220 mA/cm2) at an applied potential of -0.7 V vs. the reversible hydrogen electrode (RHE) than Bi alone (-44 mA/cm2), despite the identical electrochemically active surface area (ECSA) for both samples. On the other hand, Bi/UiO-66-NH2 showed an almost identical ECSA-normalized current density compared to Bi/UiO-66, indicating the negligible effect of NH2 functionalization on UiO-66 for CO2RR. Nevertheless, it is evident that the utilization of Zr-MOF (UiO-66) is beneficial in increasing the CO2 conversion rate of metallic Bi catalyst. To comprehend the reason behind the superior catalytic activity exhibited by the Bi/UiO-66 sample, we conducted various characterizations, such as SEM, TEM, FTIR, Raman, and XPS. Our results revealed that the structural evolution of UiO-66 occurs by the formation of carbonate-coordinated Zr-hydroxide during CO2 electrolysis, contributing to the high CO2 reduction current density. Moreover, the disappearance of the carbonate-relevant peak in the C 1s from XPS analysis after the decline in catalytic activity suggests that the carbonate species formed at Zr-MOF site, which is the captured form of CO2 molecules, play a crucial role in efficient CO2 capture and conversion. These findings suggest that Zr-MOF can be used for CO2 capture and conversion with high efficiency.[1] Nam et al., J. Am. Chem. Soc. 2020, 142, 51, 21513–21521.

Synergy of Co0-Co2+ in cobalt-based catalysts for CO2 hydrogenation: Quantifying via reduced and exposed atoms fraction

Cobalt (Co)-based catalysts exhibit exceptional versatility in CO2 hydrogenation, yielding valuable fuels and chemicals like methane, methanol, and ethanol. Generally, the Co0–Co2+ synergy plays a vital role in promoting this process, yet a quantifying descriptor remains absent. This study presents a series of CoAl-CO32− layered double hydroxide (LDH) derived catalysts synthesized through coprecipitation. By tuning precipitation pH and reduction temperature, various Co-based catalysts with distinct reduction degrees and dispersions were obtained. By introducing the descriptor "fraction of reduced and surface exposed Co (FCo,r,s)", the Co0–Co2+ synergy is effectively quantified for CO2 hydrogenation. The balanced Co0–Co2+ synergy in catalysts yields a moderate FCo,r,s, resulting in high turnover frequencies (TOFs) for CO2 conversion via HCOO intermediate formed at the Co0–Co2+ interfaces. The HCOO species can be hydrogenated to form methane and methanol, as well as coupled with CHx intermediate followed by hydrogenation to form ethanol. Conversely, catalysts with excessively high or low FCo,r,s display poor Co0–Co2+ synergy and consequently lower TOFs. A clear volcano-shaped relationship between FCo,r,s and TOFs for CO2 conversion, methane, methanol, and ethanol formation underscores its significance as a key determinant of Co-based catalysts' CO2 hydrogenation performance. The catalyst with optimized Co0–Co2+ synergy (precipitated at pH 8.5 and reduced at 750 oC) possesses a high CO2 conversion rate of 26.8 mmol gcat−1 h−1 at a low temperature (i.e., 180 oC).

Effects of preparation methods on the size and interface of Ni–W bimetallic catalysts for dry reforming of methane

One of the most effective methods of utilizing CH4 and CO2 resources is the dry reforming of methane (DRM). However, the small particle size and the metal-support interactions of Ni–W bimetallic catalysts are key factors affecting activity and carbon deposition. This article evaluates the effect of Ni–W bimetallic catalysts synthesized by different preparation methods on their catalytic performance in DRM reactions. The results show that the bimetallic catalyst prepared by the solid-state grinding method exhibits excellent catalytic performance and anti-carbon deposition performance. The conversion rate of CH4 and CO2 remain unchanged during 1450 min, which is 58% and 66%, respectively. Through various characterization methods, it has been proven that the bimetallic catalyst prepared by the solid-state grinding method effectively reduces the size of Ni particles and increases the number of exposed active sites. In addition, this method also enhances the metal-support interactions, which helps to improve the stability of the catalyst.

Sodium Promoted FeZn@SiO2-C Catalysts for Sustainable Production of Low Olefins by CO2 Hydrogenation

A prepared FeZnNa@SiO2-C catalyst with graphitized carbon (C)-modified mesoporous SiO2 supports metal nanoparticles with the sol–gel method. The effect of adding metal Na and Zn promoters as a dispersion on the CO2 hydrogenation to low olefins was systematically studied. The results showed that Zn–Na, as a combination, could promote the absorption of CO2 and improved the conversion rate of CO2. Na as an alkaline substance can improve the absorption of more acidic CO2, which could increase the conversion rate of CO2 to 59.03%. Meanwhile, the addition of secondary metal Zn to Fe-based catalysts to form a surface alloy could alter the adsorption of CO2 and the activation of C-O bonds, inhibit the subsequent hydrogenation of olefins to paraffins, and facilitate the reduction of Fe2O3 and the formation of active Fe5C2 species. The formation of active Fe5C2 species was found in TEM and XRD, and the selectivity of the target product was 41.07%. The deep hydrogenation of olefins was inhibited, and the space–time yield (STY) of low olefins was raised again by inhibiting their deep hydrogenations, up to 0.0436. However, the corresponding STY did not increase infinitely with the increase of Na doping, and higher catalytic performance for CO2 hydrogenation could be exhibited when the Na doping reached 6.4%. Compared with Fe@SiO2-C catalyst, Na- and Zn-promoted Fe-based catalysts, prepared by the modified sol-gel method, can be used directly for highly efficient CO2 hydrogenation to low olefins and thus has a more promising application prospect in the future.

Surface modification of dual-phase ceramic membrane reactor for coupling catalytic CO2 conversion with partial oxidation of methane

The oxygen transport membrane (OTM) reactor is a particularly promising process for CO2 conversion and utilization through coupling the thermochemical decomposition of CO2 with the partial oxidation of methane (POM). However, its low CO2 decomposition efficiency and poor operational stability in corrosive atmospheres are the main challenges for practical application. In this work, the porous layers of LaMO3-δ (M = Fe, Co, Ni) and Ce0.8Zr0.2O2-δ (CZ), with different functions separately, were coated on both sides of the Ce0.9Pr0.1O2-δ-Pr0.6Sr0.4Fe0.9Al0.1O3-δ (CP-PSFA) dual-phase membrane. The presence of oxygen vacancy and transition ions M with the valence of +2/+3 in the LaMO3-δ is conducive to catalyzing CO2 conversion. The LaCoO3-δ porous layer exhibits the best oxygen permeability and CO2 conversion, and the performance of POM is greatly enhanced by the in situ Ni-doped CZ porous layer. After a long-term test at 925 °C, the oxygen permeation flux of the LaCoO3-δ/CP-PSFA/CZ-Ni maintains at 0.96 mL cm−2 min−1, the conversion rate of CH4 and CO2 maintains at 23 % and 45 % respectively, and the syngas yield reaches 6.3 mL cm−2 min−1. The sandwich-like OTM reactor with functional porous layers has broad research prospects in the CO2 conversion and utilization field.

A review of mechanistic insights into CO2 reduction to higher alcohols for rational catalyst design

The utilization of captured CO2 for chemical synthesis could play an important role in reducing CO2 emissions. Higher alcohols stand out among various products of CO2 reduction due to high market prices and diverse applications, e.g., as fuel additives. However, developing catalysts for this reaction requires a profound understanding of the reaction mechanisms and catalyst design principles, which are discussed in the present review. Depending on the catalytic sites, higher alcohol synthesis could proceed via vastly different pathways. Herein, we outline how various proposed reaction mechanisms lead to different catalyst design strategies for optimizing the rate of CO2 conversion into reactive C1 intermediates (CO, CHx, CHxO, and HCOO) and their coupling into C2+ intermediates that are eventually converted into higher alcohols. Lastly, we discuss knowledge gaps in achieving rational catalyst design for higher alcohol synthesis and the breakthrough potential of machine-learning techniques for catalyst discovery.

Hydrogen-rich carbon recycling complex system establishment and comprehensive evaluation

Hydrogen-rich carbon recycling complex system coupling CO2 reduction with waste heat conversion efficiently is becoming a vigorous horizon stepping forward carbon peak and carbon neutrality with great strides in metallurgical industrial sectors. This article originally proposes an in-situ waste plastics gasification complex system utilizing blast furnace flue gas waste heat for hydrogen-rich preparation and CO2 reduction simultaneously, and the effect of parameters such as temperature, pressure, etc. on syngas yield, CO2 conversion rate, etc. are systemically discussed in detail, furthermore, the techno-economic analysis and priorities of this complex system are obtained through originally comparing intensifying factor and substitution coke ratio. The results show that waste plastics conversion rate, hydrogen and syngas yield have a positive relationship with temperature, but opposite with pressure. Hydrogen preparation is intensifying when water vapor is feeding into, and CO yield is augmented when flue gas is injected. The maximum H2 plus CO preparation efficiency is 61.3–77.4% and H2 yield is 95.9–135.5%,when pressure, temperature, H2O/P ratio and CO2/P ratio should be controlled in 1 bar, 800–1000 °C, 1.5–3.0 and 0.1–0.5, respectively, meanwhile, CO2 conversion rate is 28.4%.Otherwise, this complex system has a maximum CO2 reduction efficiency 73.6–99.0%, when 1 bar, 800–1000 °C, 0.1–0.2, 0.1–3.0 are adopted. Under the optimum conditions above, CO2 reduction efficiency is 171.1 kg/t for an ironmaking sector with capacity 54,000 tons, hydrogen preparation efficiency is 15.6 kg/t at 800 °C, corresponding coke ratio substitution amount is 460.0 kg/t. Besides, the maximum H2 preparation intensifying factor is 8.3% at 1000 °C and the maximum CO2 emission reduction intensity factor is 91.0%, which increases by 49.6–71.3% comparing to predecessors. Through this researches above, hydrogen-rich carbon recycling complex system has unique advantages for CO2 deep reduction and coke ratio decrease, and has a significant contribution suppling with a new horizon and methodology for low-carbon metallurgical process development in the future.

Revealing Co-N4 @Co-NP Bridge-Enabled Fast Charge Transfer and Active Intracellular Methanogenesis in Bio-Electrochemical CO2 -Conversion with Methanosarcina Barkeri.

To significantly advance the bio-electrochemical CO2 -conversion rate and unfold the correlation between the abiotic electrode and the attached microorganisms, an atomic-nanoparticle bridge of Co-N4 @Co-NP crafted in metal-organic frameworks-derived nanosheets is integrated with a model methanogen of Methanosarcina barkeri (M. barkeri). The direct bonding of N in Co-N4 and Fe in member protein of Cytochrome b (Cytb) activates a fast direct electron transfer path while the Co nanoparticles further strengthen this bonding via decreasing the energy gap between the p-band center of N and the d-band center of Fe. This multiorbital tuning operation of Co nanoparticles also enhances the coenzyme F420-mediated electron transfer by enabling the electron flow direct to the hydrogenation sites. Particularly, the increased surface electric field of the Co-N4 @Co-NP bridge-based nanosheet electrode facilitates the interfacial Na+ accumulation to expedite ATPase transport for powering intracellular CO2 conversion. Remarkably, the self-assembled M.barkeri-Co-N4 @Co-NP biohybrid achieves a high methane production rate of 3860mmol m-2 day-1 , which greatly outperforms other reported biohybrid systems. This work demonstrates a comprehensive scrutinization of biotic-abiotic energy transfer, which may serve as a guiding principle for efficient bio-electrochemical system design.