Carbon Monoxide Selectivity Research Articles

Electronic interactions between neighboring functionalized guest Sb single atoms and Pt clusters enhance CO tolerance

Platinum-based (Pt) catalysts are notoriously susceptible to deactivation in industrial chemical processes due to carbon monoxide (CO) poisoning. Overcoming this poisoning deactivation of Pt-based catalysts while enhancing their catalytic activity, selectivity, and durability remains a major challenge. Herein, we propose a strategy to enhance the CO tolerance of Pt clusters (Ptn) by introducing neighboring functionalized guest single atoms (such as Fe, Co, Ni, Cu, Sb, and Bi). Among them, antimony (Sb) single atoms (SAs) exhibit significant performance enhancement, achieving 99% CO selectivity and 33.6% CO2 conversion at 450 °C. Experimental results and density functional theory (DFT) calculations indicate the optimization arises from the electronic interaction between neighboring functionalized Sb SAs and Pt clusters, leading to optimal 5d electron redistribution in Pt clusters compared to other functionalized guest single atoms. The redistribution of 5d electrons weaken both the σ donation and π backdonation interactions, resulting in a weakened bond strength with CO and enhancing catalyst activity and selectivity. The redistribution of 5d electrons weaken both the σ donation and π backdonation interactions, resulting in a weakened bond strength with CO. In situ environmental transmission electron microscopy (ETEM) further demonstrates the exception thermal stability of catalyst, even under H2 at 700 ℃. Notably, the functionalized Sb SAs also improve CO tolerance in various heterogenous catalysts, including Co/CeO2, Ni/CeO2, Pt/Al2O3, and Pt/CeO2-C. This finding provides an effective approach to overcome the primary challenge of CO poisoning in Pt-based catalysts, making their broader applications in various industrial catalysts.

Light-Activated Artificial CO2-Reductase: Structure and Activity.

Light-dependent reduction of carbon dioxide (CO2) into value-added products can be catalyzed by a variety of molecular complexes. Here we report a rare example of a structurally characterized artificial enzyme, resulting from the combination of a heme binding protein, heme oxygenase, with cobalt-protoporphyrin IX, with good activity for the photoreduction of CO2 to carbon monoxide (CO). Using a copper-based photosensitizer, thus making the photosystem free of noble metals, a large turnover frequency value of ∼616 h-1, a turnover value of ∼589, after 3 h reaction, and a CO vs H2 selectivity of 72% were obtained, establishing a record among previously reported artificial CO2 reductases. Thorough photophysical studies allowed tracking of reaction intermediates and provided insights into the reaction mechanism. Thanks to a high-resolution crystal structure of the artificial enzyme, both in the absence and in the presence of the protein-bound CO2 substrate, a rational site-directed mutagenesis approach was used to study the effect of some modifications of the active site on the activity.

Reactive capture of CO2 via amino acid

Reactive capture of carbon dioxide (CO2) offers an electrified pathway to produce renewable carbon monoxide (CO), which can then be upgraded into long-chain hydrocarbons and fuels. Previous reactive capture systems relied on hydroxide- or amine-based capture solutions. However, selectivity for CO remains low (<50%) for hydroxide-based systems and conventional amines are prone to oxygen (O2) degradation. Here, we develop a reactive capture strategy using potassium glycinate (K-GLY), an amino acid salt (AAS) capture solution applicable to O2-rich CO2-lean conditions. By employing a single-atom catalyst, engineering the capture solution, and elevating the operating temperature and pressure, we increase the availability of dissolved in-situ CO2 and achieve CO production with 64% Faradaic efficiency (FE) at 50 mA cm−2. We report a measured CO energy efficiency (EE) of 31% and an energy intensity of 40 GJ tCO−1, exceeding the best hydroxide- and amine-based reactive capture reports. The feasibility of the full reactive capture process is demonstrated with both simulated flue gas and direct air input.

Microtubular Electrodes for Efficient Electrochemical CO2/CO Reduction to Value-Added Products

The conversion of carbon dioxide (CO2) or carbon monoxide (CO) to commodity fuels and chemicals, empowered by low-carbon electricity, has attracted much attention as an alternative to conventional routes of chemical production [1]. Numerous studies have focused on CO2 reduction to CO or formic acid and active/efficient electrocatalysts with high Faradaic efficiencies (FEs) have been developed [2]. However, CO2 reduction to higher value C2+ products needs the critical C-C coupling step, and to date, Cu has been the main electrocatalyst for this conversion [3]. Electrochemical carbon monoxide reduction (CORR) to C2+ products has advantages over electrochemical CO2 conversion (CO2RR) as issues such as carbonation, and CO2 loss during CO2RR are omitted in CORR due to the stability of CO in alkaline solutions. Facing common challenges as CO2RR, CORR suffers more from mass transport resistance and intrinsically lower aqueous CO solubility. Therefore gas-diffusion electrodes (GDEs) are desired to boost the formation of triple phases and active sites to obtain higher reaction rates.Herein for the first time we design Cu-based HFGDEs for efficient CORR to C2+ products with ethylene as the main product. The pristine Cu HFGDEs showed low selectivity towards C2+ products. Therefore, we tuned the Cu catalyst shape morphology and orientated growth of nanocubes on the outer surface of HFGDEs by electrodeposition. Due to the efficient C-C coupling and high C2+ _selectivity of copper nanocubes with dominant Cu(100), the HFGDEs showed exceptionally high current densities in the 1.0 M KOH electrolyte, outperforming conventional GDEs tested for CORR under similar conditions. Compared with CO2RR in a bicarbonate medium, significantly higher current densities and FEs of C2+ products (>90%) and ethylene (>65%) were achieved when the HFGDE were used for CORR. Moreover, lower partial current densities of C2+ were obtained when using the hollow fibers in the non-GDE mode, confirming the significant performance of HFGDEs for achieving high-rate and selective CO reduction through maximizing triple-phase interfaces and local CO concentration. By increasing the concentration of KOH, an ethylene partial current density of 472 mA cm2- was obtained using the flow-cell reactor, indicating the promises of HFGDEs as an emerging electrode configuration for efficient CORR to C2+ products. Figure 1

Modulating the electrocatalytic reduction of CO2 to CO via surface reconstruction of ZnO nanoshapes

The electrocatalytic conversion of carbon dioxide (CO2) into valuable chemicals presents a promising strategy for closing the carbon cycle. In this study, we synthesized zinc (Zn) catalysts through hydrothermal methods using either polyvinylpyrrolidone (PVP) or cetyltrimethylammonium bromide (CTAB) as stabilizing agents. These catalysts proved highly efficient in converting CO2 into carbon monoxide (CO). Our findings revealed that ZnO, synthesized with different morphologies—namely, nanoneedles (ZnO-NN) and nanorods (ZnO-NR)—underwent significant electro-reconstruction, ultimately leading to the formation of hexagonal metallic Zn crystals, regardless of their initial characteristics. Utilizing ex-situ operando techniques, we elucidated that metallic Zn serves as the active phase for the CO2-to-CO conversion process. In a comparison, ZnO-NN catalysts demonstrated superior selectivity and stability, achieving 91.3% CO selectivity at a potential of −0.88 V vs. RHE (Reversible Hydrogen Electrode) due to the facile transformation of ZnO to metallic Zn. Remarkably, these catalysts maintained this level of performance for more than 17 h. Conversely, ZnO-NR catalysts exhibited a lower CO selectivity of 62.5% at a relatively higher potential of −0.98 V vs RHE.

Study on the impact of methanol steam reforming reactor channel structure on hydrogen production performance

The design and operation of embedded reactors involve chemical reaction efficiency issues, with the main consideration being heat and mass transfer characteristics. The contact area of the porous catalytic coating with methanol is affected by the reactor structure, to improve the hydrogen yield and reveal the mechanism of the channel structure on the hydrogen production performance, the hydrogen production performance of circle-triangle, circle-square, square-circle, square-square, and triangle-circle channels was investigated. The reasons for the differences in methanol conversion, hydrogen, and carbon monoxide selectivity were analyzed from the perspective of heat and mass transfer using a three-rate reaction mechanism. The results showed that the circle-triangle channel performed outstandingly in the hydrogen production from methanol steam reforming with 98.61 % methanol conversion, 88.74 % hydrogen selectivity, and 29.06 % CO selectivity. The shapes and sizes of the different channel structures affect the fluid flow pattern and velocity distribution, which in turn affect the mass transfer efficiency and lead to differences in hydrogen production performance. The circle-triangle channel exhibits superior heat transfer and material transport performance, which can improve the hydrogen production efficiency of methanol steam reforming and help provide an important reference for the embedded reactor design.

Rapid CO detection using MWCNTs/SnO2 hierarchical structure: Synthesis, characterization, and RT gas sensing features

Industrialization, modernization, and heavy car populations cause an extensive release of hazardous gases which impact the environment and human health. In this respect, employing gas sensors for detecting different concentrations of carbon oxides, nitrogen oxides, and other harmful gases is being advanced with much interest and necessity. In our current research, we have feasibly synthesized MWCNTs/SnO2 hierarchical structure through a hydrothermal process. The attained XRD diffraction pattern reflects the crystallinity with a crystallite size <10 nm. The FTIR results signify the presence of the functional group which verifies the successful interaction and connection for the composite network. Morphological features using SEM, HRTEM depict the hierarchical structure persistence. The adsorption/desorption curves are investigated using BET analysis acquiring a surface area of 189 cc/g. Numerous gases were included in the gas sensing study such as ethanol, methanol, acetone, ammonia, CO, and CO2. The sensing performance displays a remarkable result for carbon monoxide (CO) detection. The response time for CO detection was 5 s, while the recovery was 7s for 300 ppm at RT. The improved selectivity of CO amongst ethanol, CO2 and other gases is demonstrated. The proposed CO sensing structure combines feasible approach, low-cost, room temperature operation, and fast response/recovery times. The structure is promising for CO gas detection for versatile industrial applications.

Synthetic Leaves Based on Crystalline Olefin-Linked Covalent Organic Frameworks for Efficient CO2 Photoreduction with Water.

We report, for the first time, a new synthetic strategy for the preparation of crystalline two-dimensional olefin-linked covalent organic frameworks (COFs) based on aldol condensation between benzodifurandione and aromatic aldehydes. Olefin-linked COFs can be facilely crystallized through either a pyridine-promoted solvothermal process or a benzoic anhydride-mediated organic flux synthesis. The resultant COF leaf with high in-plane π-conjugation exhibits efficient visible-light-driven photoreduction of carbon dioxide (CO2) with water (H2O) in the absence of any photosensitizer, sacrificial agents, or cocatalysts. The production rate of carbon monoxide (CO) reaches as high as 158.1 μmol g-1 h-1 with near 100% CO selectivity, which is accompanied by the oxidation of H2O to oxygen. Both theoretical and experimental results confirm that the key lies in achieving exceptional photoinduced charge separation and low exciton binding. We anticipate that our findings will facilitate new possibilities for the development of semiconducting COFs with structural diversity and functional variability.

Multi-objective optimization of methanol reforming reactor performance based on response surface methodology and multi-objective particle swarm optimization coupling algorithm for on-line hydrogen production

The utilization of high-temperature exhaust to drive methanol steam reforming for on-line hydrogen production in engines is an effective approach to solving hydrogen storage and transportation challenges. In this work, the response surface methodology (RSM) is combined with the multi-objective particle swarm optimization (MOPSO) algorithm, and is first utilized for multi-objective optimization of the performance of a methanol reforming reactor. Regression models for optimization objectives are developed based on RSM, and the reliability and significance of regression models are determined through analysis of variance. The influence mechanism of the interaction between design variables on optimization objectives is elucidated by visual analysis of the response surface. A multi-objective optimization of reactor performance is performed utilizing the MOPSO algorithm, and the Pareto optimal solution is obtained from the Pareto optimal frontier based on the technique for order preference by similarity to ideal solution method. Optimization results demonstrate that the Pareto optimal solution is obtained at an exhaust temperature of 585.21 K, an exhaust flow rate of 0.0097 kg·s−1, a steam to methanol ratio of 1.48, and a weight hourly space velocity of 1.2. The hydrogen yield, methanol conversion and carbon monoxide selectivity corresponding to the Pareto optimal solution are 68.53 mol·h−1, 0.83 and 0.011, respectively. Under optimal operating parameters, the methanol reforming reactor achieves 21.92 % exhaust energy recovery.

Tailored SrFeO3-δ for chemical looping dry reforming of methane

Chemical looping dry reforming of methane (CL-DRM) is a highly efficient process that converts two major greenhouse gases (CH4 and CO2) into syngas ready for the feedstock of liquid fuel production. One of the major obstacles facing this technology now is creating oxygen carriers that are stable and reactive. We fabricated high-performance Sr0.98Fe0.7Co0.3O3-δ perovskite-structured oxygen carrier by combining A-site defects and B-site doping of SrFeO3-δ. During isothermal CL-DRM tests at 850 °C, Sr0.98Fe0.7Co0.3O3-δ achieved 87% CH4 conversion and 94% CO selectivity in the CH4 partial oxidation reaction, followed by a syngas yield of 8.5 mmol/g, and CO yield of 4.2 mmol/g in CO2 decomposition. A-site defect engineering of the perovskite creates abundant oxygen vacancies and enhances oxygen storage capacity (OSC). Co-doping of the B-site of Sr0.98FeO3-δ increases oxygen mobility and CH4/CO2 activation, resulting in high activity in the CL-DRM process. This methodology resulted in high ionic mobility and facilitated the rapid diffusion of oxygen in the bulk phase, thereby increasing the redox properties of SrFeO3-δ. The oxygen carrier exhibits excellent structural stability and regeneration ability in successive redox cycles. This strategy offers a simple but very effective pathway to tailor OSC, oxygen mobility, and oxygen vacancies of perovskite-structured materials for chemical looping or redox-involved processes.

Multi-objective optimization of steam methane reformer in micro chemically recuperated gas turbine

A kinetic theory, known as the Langmuir–Hinshelwood–Hougen–Watson adsorption model, is applied to describe the steam methane reforming (SMR) in a 500 kW scale micro chemically recuperated gas turbine (CRGT) cycle. The response surface models of important performance parameters, including the methane conversion, carbon monoxide selectivity, and chemically recuperated heat as a function of the temperature, pressure, steam-to-carbon ratio, and contact time are numerically obtained based on the cases selected by the central composite design. The factors affecting the SMR performance are analyzed, and the reformer performance is optimized using both the desirability function combined with the response surface methodology and the second generation non-dominated sorting genetic algorithm. Finally, performance of the optimized reformer and electrical efficiency of the micro CRGT cycle with the reformer are evaluated. Results reveal that the efficiency of the micro CRGT is 40.70%, which is much higher than the typical high-efficiency micro gas trubine without reformer.

Design of a novel tubular membrane reactor with a middle annular injector for enhancement of dry reforming towards high hydrogen purity: CFD analysis

This study introduces a novel design of a tubular porous membrane catalytic reactor (TPMCR) with a middle annular injector, which aims to improve the performance of a dry reforming of methane (DRM) process. A computational fluid dynamics (CFD) model is developed for a fundamental configuration and subsequently verified using experimental data. The validated CFD model is utilized to examine the influence of different parameters, such as feed composition, inlet gas temperature and pressure, and injection rate, on the reactor performance. The study findings reveal that the introduction of a secondary gas during the injection process has the potential to regulate the process and positively affect the production rates of hydrogen and carbon monoxide. The optimal inlet temperature to attain the highest rate of hydrogen production is determined to be 900 K. The hydrogen selectivity is found to increase from 0.96 to 1.60 with the injection of pure steam when the injection rate is increased from 50 to 500 kg/(m2.s). In addition, the carbon monoxide selectivity is decreased from 6.30 to 2.67. The implementation of a middle annular injector within the proposed TPMCR design offers the potential for enhancing the efficiency and sustainability of chemical reactors. Consequently, the introduced modification leads to more efficient and environmentally friendly chemical processes, specifically in the realms of syngas and hydrogen production through the DRM process, resulting in improved purity levels.

Single‐Layered Imine‐Linked Porphyrin‐Based Two‐Dimensional Covalent Organic Frameworks Targeting CO2 Reduction

AbstractThe reduction of carbon dioxide (CO2) using porphyrin‐containing 2D covalent organic frameworks (2D‐COFs) catalysts is widely explored nowadays. While these framework materials are normally fabricated as powders followed by their uncontrolled surface heterogenization or directly grown as thin films (thickness &gt;200 nm), very little is known about the performance of substrate‐supported single‐layered (≈0.5 nm thickness) 2D‐COFs films (s2D‐COFs) due to its highly challenging synthesis and characterization protocols. In this work, a fast and straightforward fabrication method of porphyrin‐containing s2D‐COFs is demonstrated, which allows their extensive high‐resolution visualization via scanning tunneling microscopy (STM) in liquid conditions with the support of STM simulations. The as‐prepared single‐layered film is then employed as a cathode for the electrochemical reduction of CO2. Fe porphyrin‐containing s2D‐COF@graphite used as a single‐layered heterogeneous catalyst provided moderate‐to‐high carbon monoxide selectivity (82%) and partial CO current density (5.1 mA cm−2). This work establishes the value of using single‐layered films as heterogene ous catalysts and demonstrates the possibility of achieving high performance in CO2 reduction even with extremely low catalyst loadings.

The Research work of Dr. Ishida ‐ including Syntheses and Their Photocatalytic CO2 Reduction of Dinuclear Metal Complexes with Peptide Linkages project

The process of photosynthesis holds potential to be harnessed for addressing increasing CO2 levels, as well as for finding solutions for energy shortages resulting from depleted fossil fuel reserves. Professor Hitoshi Ishida, Laboratory on Functional Metal Complexes, Kansai University, has extensive expertise in creating artificial enzymes and is interested in developing techniques to emulate photosynthesis. The plan is to create a new photocatalyst by combining photochemical CO2 reduction catalytic reactions for artificial photosynthesis with the technology of functional molecule design using ‘peptide origami’, whereby proteins fold to form higher-order structures and exhibit functions. Ishida and his team are seeking to achieve artificial photosynthesis by using ruthenium complexes as catalysts in CO2 reduction reactions that can reduce CO2 to carbon monoxide (CO) and formic acid (HCOOH), which are useful as energy sources. Ishida has created functional molecules combining metal complexes with proteins, including artificial metalloproteins ‐ a type of protein containing a metal ion ‐ using synthetic bipyridyl amino acid 5Bpy. This focused on a rare transition metal called ruthenium as the ruthenium complexes the researchers are investigating have a selectivity for carbon monoxide and formic acid reduction products that change depending on the reaction conditions. The ultimate goal of Ishida’s work is to find a solution to the problem of pollution, while addressing the need for alternatives to fossil fuels.

Machine learning assisted prediction of copper-based catalysts towards carbon dioxide electroreduction into carbon monoxide

Copper-based catalyst is very active for electroreduction of carbon dioxide (CO2) to carbon monoxide (CO). However, the Faraday efficiency of copper-based catalysts for CO production can be affected by many complex factors, such as catalyst elemental composition, morphology, supporting substrate, synthesis method, catalyst size, electrolyte concentration, and test potential with unknown correlations, hindering the efficient exploration of active copper-based CO2 reduction catalysts with high CO Faraday efficiency. In this study, a machine learning (ML) model is proposed towards rapid screening of copper-based catalysts with high CO selectivity using experimental database. The significance of different catalyst-related features on the CO Faraday efficiency was evaluated using feature importance and Spearman correlation coefficients. The ML model predicted that the dendrite Pd-doped copper oxides catalyst electroless deposited on copper mesh has the highest CO Faraday efficiency (92.8%). This ML study provides a useful guidance for the screening of copper-based catalysts towards the reduction of CO2 to CO.

Pd-incorporated polyoxometalate catalysts for electrochemical CO2 reduction.

Polyoxometalates (POMs), representing anionic metal-oxo clusters, display diverse properties depending on their structures, constituent elements, and countercations. These characteristics position them as promising catalysts or catalyst precursors for electrochemical carbon dioxide reduction reaction (CO2RR). This study synthesized various salts-TBA+ (tetra-n-butylammonium), Cs+, Sr2+, and Ba2+-of a dipalladium-incorporated POM (Pd2, [γ-H2SiW10O36Pd2(OAc)2]4-) immobilized on a carbon support (Pd2/C). The synthesized catalysts-TBAPd2/C, CsPd2/C, SrPd2/C, and BaPd2/C-were deposited on a gas-diffusion carbon electrode, and the CO2RR performance was subsequently evaluated using a gas-diffusion flow electrolysis cell. Among the catalysts tested, BaPd2/C exhibited high selectivity toward carbon monoxide (CO) production (ca. 90%), while TBAPd2/C produced CO and hydrogen (H2) with moderate selectivity (ca. 40% for CO and ca. 60% for H2). Moreover, BaPd2/C exhibited high selectivity toward CO production over 12 h, while palladium acetate, a precursor of Pd2, showed a significant decline in CO selectivity during the CO2RR. Although both BaPd2/C and TBAPd2/C transformed into Pd nanoparticles and WO x nanospecies during the CO2RR, the influence of countercations on their product selectivity was significant. These results highlight that POMs and their countercations can effectively modulate the catalytic performance of POM-based electrocatalysts in CO2RR.

Integrated Capture and Electrochemical Conversion of CO2 into CO

The capture and electrochemical conversion of CO2, powered by renewable electricity, is an attractive method of sustainably producing valuable chemicals and fuels (e.g. carbon monoxide (CO)), reducing atmospheric CO2, and storing intermittent renewable energy. Integrated capture and conversion (reactive capture) of CO2 presents a CO2-to-CO electrolysis pathway that eliminates most of the upstream capital and energy costs by releasing CO2 directly inside the electrolyzer using an internal pH-swing. The reactive capture system readily allows for the collection of produced gas products via phase separation, thus minimizing downstream separation costs.Industrial-scale integration of reactive capture systems with upgrading processes require a pure and consistent product stream. Previous studies using bicarbonate electrolytes have demonstrated high selectivity towards CO. However, the limited CO2 capture capacity of bicarbonate electrolytes dilute the cathode product gas stream with excess CO2. This mandates a secondary CO2 capture unit and increases the cost of downstream separation. Other studies using carbonate or carbamate electrolyte as the inlet feed did not simultaneously achieve high CO selectivity and long-term stability.This study sought to improve the Faradaic efficiency (FE) toward CO in our carbonate electrolysis system by engineering a novel membrane electrode assembly structure. We designed a composite CO2 diffusion layer (CDL) between the cathode and the membrane that attains high CO selectivity by simultaneously achieving high alkalinity and sufficient CO2 availability at the cathode. We determined that the thickness, wettability, and permeability of the CDL affected species transport and were important optimization parameters. Applying this strategy, we produced syngas, a mixture of CO and hydrogen (H2), with an industrial H2/CO ratio of 1.16 at 200 mA cm-2. This corresponded to a CO Faradaic efficiency (FE) of 46% and energy intensity of 52 GJ tsyngas-1. The syngas produced in this system was not diluted by CO2 and contained sufficient CO content to meet industrial standards. We further increased the FE towards CO by exploring different capture solutions and designing selective catalysts for energy efficient CO production. System parameters such as temperature and pressure effects were also investigated to improve the CO2 concentration at the cathode. This study illustrated the potential for the industrial implementation of an energy efficient and capital cost effective CO2-to-CO pathway via reactive capture.

Highly sensitive and selective chemiresistive sensor for detection of carbon monoxide based on iron substituted octaethylporphyrin-functionalized reduced graphene oxide

We report an ultrasensitive and selective carbon monoxide (CO) chemiresistive sensor based on iron-octaethylporphyrin (FeOEP)-functionalized reduced graphene oxide (rGO) (rGO/FeOEP). The graphene oxide (GO) was synthesized using Hummers’ improved method and was thermally reduced to obtain rGO, which was then drop-cast onto copper electrodes on a glass substrate. The sensors based on rGO/OEP and rGO/FeOEP were prepared by functionalizing rGO with OEP and FeOEP, respectively. GO, rGO, and rGO/FeOEP were characterized using various techniques such as Fourier transform infrared spectroscopy, UV–visible spectroscopy, Raman spectroscopy, X-ray diffraction, current–voltage characteristics, and scanning electron microscopy. The rGO/FeOEP-based sensor exhibited a superior sensing performance in the chemiresistive modality, with response and recovery times of 55 s and 120 s, respectively. The rGO/FeOEP sensor exhibited high sensitivity, selectivity, stability, repeatability, and reproducibility for CO, with a limit of detection of 1 ppm, which is far below the permissible exposure limit suggested by the Occupational Safety and Health Administration, USA.

Fabrication of Heterostructural FeNi3-Loaded Perovskite Catalysts by Rapid Plasma for Highly Efficient Photothermal Reverse Water Gas Shift Reaction.

Metal-semiconductor heterostructured catalysts have attracted great attention because of their unique interfacial characteristics and superior catalytic performance. Exsolution of nanoparticles is one of the effective and simple ways for in-situ growth of metal nanoparticles embedded in oxide surfaces and their favorable dispersion and stability. However, both high-temperature and a reducing atmosphere are required simultaneously in conventional exsolution, which is time-consuming and costly, and particles often agglomerate during the process. In this work, Ca0.9Ti0.8Ni0.1Fe0.1O3-δ (CTNF) is exposed to dielectric blocking discharge (DBD) plasma at room temperature to fabricate alloying FeNi3 nanoparticles from CTNF perovskite. FeNi3-CTNF has outstanding catalytic activity for photothermal reverse water gas shift reaction (RWGS). At 350°C under full-spectrum irradiation, the carbon monoxide (CO) yield of FeNi3-CTNF (10.78mmol g-1 h-1) is 11 times that of pure CaTiO3(CTO), and the CO selectivity is 98.9%. This superior catalytic activity is attributed to the narrow band gap, photogenerated electron migration to alloy particles, and abundant surface oxygen vacancies. The carbene pathway reaction is also investigated through in-situ Raman spectroscopy. The present work presents a straightforward method for the exsolution of nanoalloys in metal-semiconductor heterostructures for photothermal CO2 reduction.

Quasi-open Cu(I) sites for efficient CO separation with high O2/H2O tolerance.

Carbon monoxide (CO) separation relies on chemical adsorption but suffers from the difficulty of desorption and instability of open metal sites against O2, H2O and so on. Here we demonstrate quasi-open metal sites with hidden or shielded coordination sites as a promising solution. Possessing the trigonal coordination geometry (sp2), Cu(I) ions in porous frameworks show weak physical adsorption for non-target guests. Rational regulation of framework flexibility enables geometry transformation to tetrahedral geometry (sp3), generating a fourth coordination site for the chemical adsorption of CO. Quantitative breakthrough experiments at ambient conditions show CO uptakes up to 4.1 mmol g-1 and CO selectivity up to 347 against CO2, CH4, O2, N2 and H2. The adsorbents can be completely regenerated at 333-373 K to recover CO with a purity of >99.99%, and the separation performances are stable in high-concentration O2 and H2O. Although CO leakage concentration generally follows the structural transition pressure, large amounts (>3 mmol g-1) of ultrahigh-purity (99.9999999%, 9N; CO concentration < 1 part per billion) gases can be produced in a single adsorption process, demonstrating the usefulness of this approach for separation applications.