Enceladus' plume: Compositional evidence for a hot interior

Methane hydrate exists in huge amounts in certain locations, in sea sediments and the geological structures below them, at low temperature and high pressure. Production methods are in development to produce the methane to a floating platform. There it can be reformed to produce hydrogen and carbon dioxide, in an endothermic process. Some of the methane can be burned to provide heat energy to develop all needed power on the platform and to support the reforming process. After separation, the hydrogen is the valuable and transportable product. All carbon dioxide produced on the platform can be separated from other gases and then sequestered in the sea as carbon dioxide hydrate. In this way, hydrogen is made available without the release of carbon dioxide to the atmosphere, and the hydrogen could be an enabling step toward a world hydrogen economy.

Carbon dioxide and carbon monoxide hydrogenation over gold supported on titanium, iron, and zinc oxides

The synthesis of functional and complex organic compounds is majorly performed by the Claisen rearrangement method. Claisen rearrangement is one of [3,3] sigmatropic rearrangements, a complex method in the synthesis of organic compounds, where it is mostly used to construct stereoselective compounds. It can be combined with other synthesis methods to synthesize organic compounds giving satisfactory results based on the method used, temperature, time, and yield produced. This review aimed to summarize several recent advances in synthesizing organic compounds through Claisen rearrangement reactions. An understanding of the mechanism and applications of this reaction might improve the ability to synthesize innovative and useful organic compounds in various fields of life sciences.

Inorganic Compounds of Carbon, Nitrogen, and Oxygen

Combined effect of carbon monoxide mixed with carbon dioxide in air on the mortality of stored-grain insects

Forsøg på rekonstruktion af en fortidig jernudvindingsproces

Formation of carbon oxides during tobacco combustion: Pyrolysis studies in the presence of isotopic gases to elucidate reaction sequence

The photolysis of water vapor with carbon monoxide at 1849 A yields alcohols, aldehydes and organic acids, with an overall quantum yield of 3.3 x 10(-2). This rather high quantum yield could have led to a contribution of approximately 10(11) organic molecules cm-2 sec-1 to the pool of organic material on the primitive Earth. The reactions are initiated by the photolysis of water molecules and the resulting hydrogen atoms reduce the carbon monoxide to a variety of one and two carbon compounds. The organic molecules are dissolved in water and thus escape destruction by photolysis. Photolysis of water vapor with carbon dioxide did not yield organic compounds under these conditions.

Carburization of metal is a catalytic reaction that occurs on metal surfaces exposed to hydrocarbon atmosphere at high temperatures. This reaction is a form of the well-known Fischer-Tropsch synthesis and is immensely important to various industrial aspects, most notably metal dusting corrosion (MDC) [1] and catalytic conversions [2]. On Fe surfaces, carburization occurs at high temperature, initiated by adsorption of gaseous hydrocarbons and is responsible for triggering both MDC, a catastrophic failure of the structural integrity of metals and alloys and a severe threat to the petrochemical industries, and a central reaction in catalytic converters, that are purposefully designed to produce a high yield of carburization to reduce the emission of toxic gasses. One of the most abundant and widely-studied carburizing gas is carbon monoxide (CO) that has been observed to react with Fe surface and dissociate at temperatures 600–900 K. In a hydrocarbon environment, the reaction is given by, CO+H_(2) ( → ⊥ 800...

Investigation of electrochemical carbon monoxide sensor monitoring of anesthetic gas mixtures.

Observations from the Cassini spacecraft have shown that Saturn's small icy moon Enceladus ejects a plume of water vapor and small ice particles into Saturn's rapidly co-rotating magnetosphere. In this paper we show that the interaction of the moon with the magnetospheric plasma produces a number of electrodynamics effects that are remarkably similar to those observed in Earth's auroral regions and near Jupiter's moon Io. These include whistler-mode emissions similar to terrestrial auroral hiss, magnetic-field-aligned electron beams, and currents associated with a standing Alfven wave excited by the moon. Ray path analyses of the auroral hiss show that the electron beams responsible for the emissions are accelerated very close to the moon, most likely by parallel electric fields associated with the Alfven wave. However, other possibilities such as electric fields due to electrostatic charging of the moon's surface or of particles in the water vapor plume should be considered. Citation: Gurnett, D. A., et al. (2011), Auroral hiss, electron beams and standing Alfven wave currents near Saturn's moon Enceladus, Geophys. Res. Lett., 38, L06102, doi:10.1029/2011GL046854.

Open AccessCCS ChemistryMINI REVIEWS28 Dec 2022Electrocatalytic CO2 Reduction over Bimetallic Bi-Based Catalysts: A Review Wei Chen, Yating Wang, Yuhang Li and Chunzhong Li Wei Chen Key Laboratory for Ultrafine Materials of Ministry of Education, Shanghai Engineering Research Center of Hierarchical Nanomaterials, Frontiers Science Center for Materiobiology and Dynamic Chemistry, School of Materials Science and Engineering, East China University of Science and Technology, Shanghai 200237 , Yating Wang Key Laboratory for Ultrafine Materials of Ministry of Education, Shanghai Engineering Research Center of Hierarchical Nanomaterials, Frontiers Science Center for Materiobiology and Dynamic Chemistry, School of Materials Science and Engineering, East China University of Science and Technology, Shanghai 200237 , Yuhang Li *Corresponding authors: E-mail Address: [email protected] E-mail Address: [email protected] Key Laboratory for Ultrafine Materials of Ministry of Education, Shanghai Engineering Research Center of Hierarchical Nanomaterials, Frontiers Science Center for Materiobiology and Dynamic Chemistry, School of Materials Science and Engineering, East China University of Science and Technology, Shanghai 200237 and Chunzhong Li *Corresponding authors: E-mail Address: [email protected] E-mail Address: [email protected] Key Laboratory for Ultrafine Materials of Ministry of Education, Shanghai Engineering Research Center of Hierarchical Nanomaterials, Frontiers Science Center for Materiobiology and Dynamic Chemistry, School of Materials Science and Engineering, East China University of Science and Technology, Shanghai 200237 School of Chemical Engineering, East China University of Science and Technology, Shanghai 200237 https://doi.org/10.31635/ccschem.022.202202357 SectionsAboutAbstractPDF ToolsAdd to favoritesDownload CitationsTrack Citations ShareFacebookTwitterLinked InEmail Electrocatalytic reduction of carbon dioxide (CO2) to valuable fuels is an up-and-coming approach. Owing to the low cost, environmental friendliness, and high selectivity to formate single product at low overpotentials, bismuth (Bi)-based catalysts have attracted extensive research attention. In this review, the reaction mechanisms of Bi-based catalysts are first introduced, and the bimetallic Bi-based catalysts synthesized by alloying, doping, and loading strategies are reviewed from the aspects of catalyst component, morphology, synthesis procedure, and performance optimization for electrocatalytic CO2 reduction. We provide an in-depth discussion of the existing challenges and an outlook for this highly promising kind of electrocatalysis. Download figure Download PowerPoint Introduction The energy crisis and environmental pollution have been ongoing significant issues and the focus of the international community. Over the past few decades, the strong dependence and overuse of fossil fuels has resulted in a rapid increase in the concentration of carbon dioxide (CO2) in the atmosphere.1,2 When the World Meteorological Organization released its latest Greenhouse Gas Bulletin, they pointed out that the current CO2 concentration in the atmosphere is 149% of preindustrial levels.3 The Bulletin additionally noted that greenhouse gases have increased by 47% through radiative forcing, with CO2 accounting for 80% of this increase from 1990 to 2020. The emission of an oversized quantity of CO2 and other harmful gases has resulted in global warming and environmental pollution, documented in numerous studies related to the energy and environment around the world. CO2 emission reduction is urgently needed. Electrocatalytic CO2 reduction reaction In order to curtail the global warming trend, scientists conduct in-depth discussions and research on the issue of reducing CO2 emissions. There are four primary strategies: (a) developing new clean energy technologies; (b) upgrading existing processes to eliminate and replace the low-efficiency sectors and equipment in traditional technologies;1 (c) afforestation and forestation; and (d) carbon capture, utilization and storage.4,5 Research on carbon capture, carbon storage, and carbon utilization has produced many advances and breakthroughs in CO2 storage and conversion. Among them, carbon capture and storage technology have certain limitations. First of all, the technology is expensive. Second, storage equipment may leak and cause a series of other hidden safety problems, such as local seawater acidification. In contrast, carbon capture and utilization technology, which reduce CO2 and convert it into usable chemical value-added fuels, possesses greater development prospects.6–8 Not only can this technology reduce high CO2 concentrations in the atmosphere, but it also produces renewable fuels to combat the energy crisis. In recent years, numerous catalytic conversion methods have been developed successively. The methods used for CO2 reduction chiefly include biological (enzyme) catalysis, photocatalysis, thermocatalysis, and electrocatalysis.9–12 At present, electrocatalysis as an emerging energy technology for CO2 emission reduction and production of value-added fuels receives a great deal of research attention.7 Compared with traditional industrial processes, electrocatalytic CO2 reduction reaction (CO2RR) can be carried out under milder environmental conditions, improving electrochemical stability and selectivity in CO2RR via selecting appropriate electrocatalysts to manipulate reaction-tailored products.13 In this regard, reports in the literature demonstrate the exploration of various electrocatalysts and electrode reaction mechanisms for CO2RR. CO2RR also utilizes renewable energy for catalytic reactions to achieve large-scale energy storage and production of high-energy products.14 Generally, CO2RR is in a position to produce a variety of reduction products through electrocatalysis. The corresponding reduction products are different as electron-transferred numbers change. Electrocatalytic CO2RR products are categorized as formic acid (HCOOH),12 carbon monoxide (CO), methane (CH4), methanol (CH3OH) as C1, and ethanoic acid (CH3COOH), ethanol (C2H5OH)15 as C2.16,17 The above reduction products are obtained by various electron-transfer mechanisms and half-reactions, as shown in Table 1.18,19 Table 1 | Electrochemical Potentials of Several CO2 Reduction Reactions CO2 Reduction Half-Reactions Electrode PotentialV (vs SHE) Electrode PotentialV (vs RHE) CO2 + 2H+ + 2e− → CO + H2O −0.52 −0.106 CO2 + 2H+ + 2e− → HCOOH −0.61 −0.250 CO2 + 4H+ + 4e− → HCHO + H2O −0.51 −0.070 CO2 + 6H+ + 6e− → CH3OH + H2O −0.38 0.016 CO2 + 8H+ + 8e− → CH4 + 2H2O −0.24 0.169 2CO2 + 12H+ + 12e− → C2H4 + 4H2O −0.34 0.064 2CO2 + 12H+ + 12e− → C2H5OH + 3H2O −0.33 0.084 During the electrocatalytic reduction process, not solely CO2RR but also other side reactions will occur, resulting in the complexity of the reaction. For instance, the hydrogen evolution reaction (HER) competes with CO2RR to generate H2, which decreases the performance of CO2RR20–22 in order to efficiently overcome the energy barrier of electron-transfer proton coupling, accelerate the catalytic reaction rate. and suppress the occurrence of side reaction processes. The development of ideal catalysts with remarkable CO2RR selectivity and activity is the focus of current research. Several parameters of electrocatalytic performance for CO2RR catalysts can primarily be evaluated, including Faradaic efficiency (FE), overpotential, current density, Tafel slope, stability, and so on.7,12,14 FE is the charge required as a percentage of the initial charge to cross the working electrode and facilitate the electrochemical reaction. In simple terms, FE is a significant indicator to measure the selectivity of electrocatalytic CO2RR products.23 Due to the complex reaction mechanism and sluggish kinetics, the actual reduction reaction working potential is more negative than the theoretical reduction potential. High reduction overpotentials lead to wasted energy and significant HER reactions. Therefore, overpotential is an important indicator in evaluating the electrocatalytic activity of CO2RR catalysts. Studies confirm that when current density goes above 300 mA cm−2, the production cost will be reduced as much as possible.24 The equation of Tafel (η = blgj + a) is able to directly reflect the rate of reaction dominated by kinetics. The smaller the Tafel slope of b in the equation, the faster the electrochemical reaction rate and the higher the catalytic activity, which is more favorable for the electrocatalytic reaction.25 Stability is an indicator of whether an excellent electrocatalyst possesses long-term stability and efficiency.26 The stability of electrocatalysts is usually effectively assessed with potentiostatic electrolysis or cyclic voltammetry. Bismuth-based electrocatalysts Recently, P-block electrocatalysts consisting of bismuth (Bi),27–30 tin (Sn),31–33 lead (Pb),34–36 and indium (In)37,38 have inarguably facilitated electrocatalytic CO2 reduction with remarkable selectivity for C1 products, especially formic acid or formate. The advantage of electrocatalytic generation of formate lies in the high selectivity and current density achieved by prohibiting competing side reactions. Compared with other value-added products from CO2 reduction, which are difficult to solely generate and low in yield, the FE of Bi-based CO2 toward formate can reach nearly 100%.39 In addition, formate is a liquid product with excellent chemical stability at room temperature for storage and transportation compared to gas-phase products such as CO. Experts evaluate various chemicals with economic viability in CO2RR and discovered that formate has considerable marketability.13 Moreover, converting CO2 toward formate is a 2-electron transfer process, leading to a low production cost of 1$US/0.59 kg, suggesting that CO2 electrolysis of formate is more cost-competitive than the C2 product production process.40 It may be difficult to attain widespread application of Pb and In metals on a marketable scale because of toxicity or low availability. However, Bi is a dramatic and promising electrocatalyst due to its low cost, nontoxicity, environmental safety, relatively single reduction product, and high formate generation activity. Bi-based catalysts can be traced back to the Bi electrocatalyst synthesized by Komatsu's team in 1995.41 In the following decades, research on Bi-based catalysts continued to deepen. Monometallic catalysts, including metallic Bi, are currently a hot topic in the field of electrocatalysis. Recently, with in-depth exploration and development of synthesis techniques, various nanostructured monometallic Bi catalysts have been designed, such as nanoparticles, nanowires, nanotubes, nanosheets, nanodendrites, and so on, in multidimensional aspects. However, monometallic Bi catalysts may be undesirable for the breakthrough of formate electrosynthesis, owing to the limited active sites on the catalyst surface. This means that monometallic Bi catalysts usually require high overpotential to achieve high formate FE and partial current density. Compared with the monometallic Bi catalysts that use advanced synthetic strategies or tedious structural optimization to enhance their performance, bimetallic Bi-based catalysts will further involve synergistic effects. The synergistic interaction between bimetals gives the bimetallic electrocatalyst a superior catalytic performance.42 The synergistic effects in bimetallic Bi-based catalysts can be broadly viewed as Bi acting as the active site and the other metals mainly playing three roles: (1) tailoring the electronic structures of Bi sites, (2) regulating the adsorption states of the key intermediates, and (3) generating interfacial active sites to further enhance performance. Through the electronic structure modulations by the second metal, the bimetallic Bi-based catalysts will boost the formation of the key intermediate OCHO*, thus improving the performance of CO2 electroreduction to formate. The activity, selectivity, and stability will be further improved via preparing bimetallic Bi-based materials through strategies such as alloying, surface doping, defect introduction, and nanoengineering. Here, in this review, the representative reaction pathways of Bi-based electrocatalysts are first introduced, and then the reaction mechanisms of bimetallic Bi-based heterogeneous CO2RR electrocatalysts are summarized with examples from the perspective of reaction pathways. Afterward, based on the Bi-based electrocatalysts in recent development, we divide bimetallic Bi-based catalysts into three categories: (1) alloyed Bi, (2) doped Bi, and (3) supported Bi. For each category, we describe in detail its performance-enhancing strategies and provide examples of catalysts, including descriptions of their preparation process, composition, morphology, catalytic activity, and product properties. Finally, we provide an in-depth analysis of the existing challenges and the current outlook for this field. Reaction Mechanisms of the Bi-Based Electrocatalysts Bi-based catalysts have high efficiency, selectivity, and stability to form formate via electrocatalytic CO2RR in aqueous solutions. They also possess the capacity to generate CO, according to some reports.43 The pathways of the formate and CO products are comparatively simple compared to that of other CO2RR products, and the essential difference is the intermediate products. An in-depth study of the electrocatalytic CO2RR process on the surface of Bi-based catalysts is required for a good understanding of the catalytic mechanism of Bi metals. In general, there are three types of steps involving the generation of products theoretically, consisting of: (1) reactant adsorption on the electrocatalytic surface, (2) transfer of electrons and protons to the reactant, and (3) the products desorption from the electrocatalyst surface.44 Research demonstrates that the first proton coupling determines the selectivity for a catalyst, which takes place at the C or O in CO2*− radical anion. Three reaction pathways for electrocatalytic CO2RR over Bi-based catalysts are displayed in Figure 1: (a) Generally, CO2 comes into contact with the catalyst via carbon or oxygen atoms. If the carbon atom binds to the catalyst electrode surface first, *COOH intermediate will be formed, which is the first intermediate for CO2 activation in this pathway. However, *COOH intermediate will have multiple pathways in the second proton coupling electron transfer (PCET) process, which is not conducive to promoting highly selective formate production. *COOH can lose H2O to form CO, or be reduced to form HCOOH. (b) Compared to pathway a, pathway b is different in that the oxygen is bound to the electrode surface, by which CO2* − hydrogenation forms the HCOO* intermediate.19 Based on the reaction mechanism of Bi-based catalysts, the second PCET process of the HCOO* intermediate can only generate HCOOH.(c) In the pathway c, CO2 forms the OCHO* intermediate during the first PCET when only one oxygen molecule is bound to the surface electrode. Formate is the only product obtained via a subsequent second PCET process. Theoretical analyses indicate that the formation energy barrier of OCHO* intermediate is lower than that of *COOH and HCOO* intermediates, leading to the importance of OCHO* intermediates in the Bi-based electroreduction process.45 Figure 1 | Possible electrochemical reaction pathways of CO2 over Bi-based catalysts. Download figure Download PowerPoint Theoretical calculations confirm that the CO2RR process of Bi-based catalysts follows the key intermediate of OCHO* from a PCET mechanism, facilitating highly selective formate production. The specific mechanism equations (1–5) for reducing CO2 pathway in solution to HCOOH are summarized as follows:46 CO 2 ( g ) → CO 2 * (1) CO 2 * + e − → CO 2 * − (2) CO 2 * − + e − + H + → OCHO * − (3) OCHO * − + e − + H + → HCOOH * (4) HCOOH * → HCOOH ( aq ) + * (5)where * denotes the catalytic surface or adsorption site, initially the CO2 molecules are dissolved in the solution and contact the electrode surface to form adsorbed CO2*. Afterwards, single electron is transferred to CO2* that forms the CO2* − radical anion. According to HCO3 − ↔ H+ + CO32−, electron transfer and proton coupling form OCHO* − intermediates. Ultimately, OCHO* − forms formic acid solution by PCET. Since the slow kinetics of the electrocatalytic CO2RR process, HER side reactions inevitably generate H2, and some reduction reactions are accompanied by CO generation, which negatively affects the highly selective production of formate from Bi-based materials. For the purpose of obtaining more formate, the production of H2 and CO is reduced as much as possible. The catalytic mechanism may be diametrically different in the same Bi-based alloy, depending on the content of two metal elements. Therefore, the reaction mechanism is manipulated via controlling different proportions of the two metals in bimetallic Bi-based electrocatalysts. For instance, Zhang et al.47 have developed CuO/Bi(OH)3 decorated on carbon nanotubes for CO2 electroreduction. CuBi#8 and CuBi#4 are bimetallic nanoparticles obtained via a two-step hydrolysis method and adjusted the Cu/Bi ratio. CuBi#8 and CuBi#4 exhibit CO and formate FE of 96% and 60% at −0.99 V versus reversible hydrogen electrode (RHE) (VRHE), respectively. It is found that with Bi content increasing, HER is well suppressed, and the products are mainly CO. By further increasing Bi content, FEHCOOH rapidly increases accompanied by the rapid decrease of FECO. FEHCOOH reaches the maximum of 96% at 12.5 mA cm−2. The conversion of intermediates from *COOH to OCHO* via increasing Bi content further illustrates the high selectivity of OCHO* to formate. Adjusting the optimal Cu/Bi ratio suppresses the production of CO and H2, leading to efficient production of formate. In addition, defects such as oxygen vacancies or doped atoms significantly improve the catalytic performance.12 Li et al.48 have prepared Sn atom-doped Bi2O3 nanosheet (NS) electrocatalysts by constant electrolysis. Three products can be detected during the electrolysis, including H2, CO, and HCOOH. The Sn-doped Bi2O3 NSs current density is significantly increased compared to the undoped Bi2O3 NSs. The 2.5% Sn-doped Bi2O3 NSs exhibit high selectivity for formate, obtaining a supreme FE of 93.4% at the potential of −0.97 V. The HER inhibition effect is significantly enhanced compared to the undoped Bi2O3 NSs. Moreover, the catalytic capacity is optimized by coping with significant HER and expanding its specific surface area. For the first time, metallic aerogel is a three-dimensional (3D) material that has attracted enormous attention due to its abundant specific surface area, contributing to the generation of more catalytic centers.49 In addition, adjusting the partial pH can also improve the selectivity of CO2RR, and proper control of pH into acidity facilitates the formation of formate.50 Advanced Bi-Based Electrocatalysts for CO2 Reduction In recent decades, various Bi-based CO2 reduction electrocatalysts have been exhaustively studied, mainly with formate as the end product. Especially, the preparation of bimetallic catalysts via different synthetic methods is the focus of most current studies. Bimetallic Bi-based catalysts can mainly be classified into three types: (1) alloyed Bi, (2) doped Bi, and (3) supported Bi. Detailed CO2RR performances of bimetallic Bi-based electrocatalysts are summarized in Table 2. Table 2 | Performance of Bimetallic Bi-Based Catalysts in Electrocatalytic CO2RR Catalyst Electrolyte Major Products FE (%) Potential at FEMax (V) Current Density (mA cm−2) Stability (h) References Bi5Sn60 0.1 M KHCO3 Formate 94.8 −1.0 (vs RHE) 34 20 52 BixSny/Cu 0.1 M KHCO3 Formate 90.4 −0.84 (vs RHE) 30 12 53 Bi-Sn aerogel 0.1 M KHCO3 Formate 93.9 −1.0 (vs RHE) 9.3 10 57 Cu-Bi 0.1 M KHCO3 Formate 90 −0.8 (vs RHE) >2 — 60 CuBi-100 0.5 M KHCO3 Formate 94.7 −1.0 (vs RHE) 12.8 8 61 CuBi 0.5 M KHCO3 Formate 94.4 −0.97 (vs RHE) 38.5 — 62 CuBi 0.5 M KHCO3 Formate 98.3 −1.07 (vs RHE) 56.6 — 62 Bi/Cu 0.5 M KHCO3 Formate 95 −0.9 (vs RHE) 59.7 12 64 CuBi75 0.5 M KHCO3 Formate 100 −0.77 (vs RHE) 33.65 24 66 Cu1-Bi/Bi2O3@C 0.5 M KHCO3 Formate 93.4 −0.94 (vs RHE) 10.1 10 67 Pd3Bi-IMA 0.1 M KHCO3 Formate >90 −0.35 (vs RHE) 3 8 68 a-NPSB 0.1 M KHCO3 Formate 88.4 −1.15 (vs RHE) 21.2 18 70 Bi–Pt complex 0.1 M TBAPF6/THF CO 82 −1.25 (vs NHE) 0.125 — 71 Mo-Bi BMC/CP 0.5 M [Bmim]BF4 CH3OH 71.2 −0.7 (vs SHE) 12.1 — 72 Sn-doped Bi2O3 NSs 0.5 M KHCO3 Formate 93.4 −0.97 (vs RHE) 24.3 8 48 Bi/Bi(Sn)Ox NWs 1 M KOH Formate ∼100 −0.7 (vs RHE) 301.4 20 77 Cu-Bi2Se3 0.5 M NaHCO3 Formate 65.31 −1.3 (vs RHE) 24.1 24 78 Ce–[email protected]x/C 0.5 M KHCO3 Formate 96 −1.7 (vs SHE) 15.2 10 79 BiIn5[email protected] 0.5 M KHCO3 Formate 97.5 −0.86 (vs RHE) 13.5 15 81 Bi-Sn/CF 0.5 M KHCO3 Formate 96 −1.1 (vs RHE) 45 100 82 Sn0.80Bi0.20@Bi-SnOx 0.5 M KHCO3 Formate 95.8 −0.88 (vs RHE) 74.6 — 83 Bi-SnO/Cu 0.1 M KHCO3 Formate 93 −1.7 (vs Ag/AgCl) — 30 84 [email protected] 0.5 M NaHCO3 Formate 95 (vs RHE) 15 12 45 NSs 0.5 M KHCO3 Formate −0.86 (vs RHE) 8 90 0.5 M KHCO3 Formate −0.8 (vs RHE) 0.5 M KHCO3 Formate −0.8 (vs RHE) 10 [email protected] 0.5 M KHCO3 Formate (vs RHE) 10 M Formate (vs RHE) 34 Bi The is one of the methods to enhance the electrocatalytic performance of Bi-based effects facilitate the catalytic reaction by a between two different metal elements. P-block catalysts have CO2 conversion that is highly selective for Among them, Bi-Sn bimetallic is the most is a and method for the preparation of The method a of two metallic elements. Bimetallic obtained via are or and possess such as high density and can improve the catalytic activity of the catalyst Li et have two Bi and on the an In this different electrode The at different of This structure is to the surface and more catalytic When the of metal Bi and the of metal Sn 60 the catalytic performance the as the of −1.0 with mA partial current density, the FE of formate it excellent formate yield, which superior to most electrocatalysts. The of bimetallic is to the OCHO* intermediate and suppress the HER process. Li et have also electrocatalysts on and discovered that the FE of formate enhanced by the Bi content in the BixSny/Cu electrode. is an emerging in electrocatalytic due to their structure and the of the catalyst, contributing to the generation of more catalytic Bimetallic prepared by the method it to compared with methods such as or solution et have prepared Bi-Sn bimetallic under with and abundant Bi and Sn the of via controlling the ratio. with with a electron as shown in Figure abundant of that favorable for and abundant active sites during electrocatalysis. The of the Bi-Sn aerogel well with of Sn and Bi suggesting that the obtained aerogel is a Bi-Sn The that the are and corresponding to the and of Bi and This that the Sn and Bi are and more reaction sites are during the catalytic process. The the of Sn and Bi in the The electrochemical performance displayed compared with Sn and Bi catalysts, Bi-Sn aerogel excellent performance for formate with FE as high as Density that electronic between Bi and Sn the energy barrier for formate, the electrocatalytic performance In can indicate the reaction pathway of Bi-Sn aerogel bimetallic catalyst in CO2RR. shown in Figure the at at V and more as the potential increased from to V. This is to the that in the formate intermediate HCOO* is in suggesting that the synergistic effects between Bi-Sn bimetals can the generation of Figure 2 | (a) of the synthesis of Bi-Sn (b) of (c) of (d) and the corresponding of the catalytic mechanism of the of Bi-Sn with various with from Download figure Download PowerPoint is a and catalyst in the field of electrocatalysis. The product selectivity of catalysts is C1 products such as formate and CH4 and value-added fuels such as The of the Bi and to form a Cu-Bi usually formate conversion and the HER The reaction intermediates with of the between bimetallic Cu-Bi facilitate the catalytic reaction. et have synthesized bimetallic Cu-Bi electrocatalysts with Owing to the difference between Bi and the of bimetallic defect sites with high density, leading to the formation of more catalytic Cu-Bi exhibit lower current for HER and CO evolution thus the higher selectivity of Cu-Bi for formate. At −0.8 the FE of the formate product In to materials obtained by have numerous and catalytic activity will be Through the of bimetallic catalysts, the of reaction sites of electrocatalysts are increased as much as and the electrochemical of product selectivity is For instance, et have synthesized bimetallic Cu-Bi electrocatalysts by at room temperature In the by the of CuBi-100 the electrochemical performance At the potential from −0.8 V to CuBi-100 excellent selectivity for formate and FE of more than The supreme at the potential of −1.0 electron that CuBi-100 on carbon and a The of CuBi-100 has

A series of ice mixtures containing carbon monoxide (CO), carbon dioxide (CO(2)), and molecular oxygen (O(2)) with varying carbon-to-oxygen ratios from 1 : 1.5 to 1 : 4 were irradiated at 10 K with energetic electrons to derive formation mechanisms and destruction pathways of carbon monoxide (CO), carbon dioxide (CO(2)), and carbon trioxide (CO(3)) in extraterrestrial, low temperature ices. Reactants and products were analyzed on line and in situ via absorption-reflection-absorption FTIR spectroscopy in the solid state, while the gas phase was sampled by a quadrupole mass spectrometer (QMS). Additionally, isotopically mixed ices consisting of (i) (13)CO ratio C(18)O ratio CO(2), (ii) CO(2)ratio C(18)O(2), and (iii) CO(2)ratio(18)O(2) were irradiated in order to derive mechanistical and kinetic information on the production and destruction pathways of the following species: (i) (13)CO, C(18)O, CO(2), CO, (13)CO(2), (18)OCO, and (13)CO(3) (C(2v)), (ii) CO(2), C(18)O(2), CO, C(18)O, (18)OCO, CO(3) (C(2v)), OC(18)OO (C(2v)), OC(18)O(2) (C(2v)), (18)OCO(2) (C(2v)), (18)OC(18)OO (C(2v)), and C(18)O(3) (C(2v)), and (iii) CO(2), CO, (18)OCO, C(18)O, and C(18)O(2).

The catalytic oxidation of toxic carbon monoxide (CO) into carbon dioxide (CO 2 ) is one of the most significant reactions in heterogeneous catalysis and industrial chemistry. Hence, finding efficient and cost‐effective catalysts for CO oxidation is very critical. In this study, the electronic and catalytic properties of a Co atom incorporated B 36 cluster (Co@B 36 ) are investigated by means of first‐principles calculations. The results show that the Co atom can seriously tune the properties of the B 36 cluster due to significant hybridization between the 3d states of the Co atom and the B‐2p states of the surrounding B atoms. This induces a significant positive charge on the Co atom, providing an active site for O 2 and CO molecules to attack. Furthermore, the well‐known mechanisms for CO oxidation, namely the Eley‐Rideal (ER), Langmuir‐Hinshelwood (LH), termolecular Eley‐Rideal (TER), and new Eley‐Rideal (NER), are taken into account in this work. According to our findings, the LH and TER mechanisms are the most energetically efficient routes for CO oxidation; however, the favored mechanism may be depending on the relative concentrations of CO and O 2 molecules in the reaction mixture. The obtained activation energies through the TER and LH mechanisms are also comparable with those reported on noble metals. The findings of this work might help in the design and manufacture of noble‐metal free single atom catalysts for the removal of harmful CO molecules from the environment.

Introduction The carbon monoxide (CO) in hydrogen fuel is known to degrade the fuel cell performance [1-4]. The allowable concentration of CO is 0.2 ppm in the quality standards for hydrogen fuel of fuel cell vehicles [5]. The allowable concentration of impurities would be revised in accordance with the development of the fuel cell components, such as reduction of platinum loadings and thinning of the membrane. In order to discuss the allowable concentration of CO, the understanding of the performance degradation mechanism by CO and the evaluation in conditions close to the actual environment are required. In our previous work, we showed that the low anode platinum loadings would decrease the fuel cell performance significantly at the CO concentration as low as 1 ppm in the hydrogen [4]. But the CO adsorption behavior of near the allowable concentration remain incompletely understood. In this study, the adsorption behavior of low concentration CO on the polymer electrolyte fuel cell was investigated by gas analysis at the anode outlet. Experimental Commercial Pt/C catalyst (TEC10E50E, Tanaka Kikinzoku Kogyo) and electrolyte membrane (Nafion NR211, DuPont) were used for the single cell tests. The platinum loading on the anode / cathode was set at 0.1/ 0.3 mg cm-2, respectively. The MEAs were assembled into a JARI standard cell (25 cm2 of electrode area). The cell temperature was 60ºC, and the dew point temperatures of the anode and the cathode were 47ºC and 40ºC , respectively. The anode gas was hydrogen mixed with CO (0.2 - 1.0 ppm), and the cathode gas was purified air. The stoichiometry of fuel and air was 1.4 and 2.5, respectively. The CO and carbon dioxide (CO2) at the anode outlet concentrations were analyzed by a gas chromatograph with a pulse discharged helium ion detector. Results and Discussion The cell voltage at 1000 mA cm-2 and the CO and CO2 exhaust rate at the anode outlet (R CO, out and R CO2, out, respectively) during the 0.4 ppm of CO exposure test were shown in Fig. 1. The cell voltage started to drop after 5 hours and became stable after 25 hours. The exhaust rate of CO and CO2 rose when the cell voltage dropped, and became stable after 25 hours. The sum of CO and CO2 exhaust rate after 30 hours was nearly equal to the CO supply rate (R CO, in). The effect of CO concentration was investigated at the ranges from 0.2 to 1.0 ppm. The amount of CO adsorption was calculated from the results of the CO and CO2 measurement. Firstly, the CO adsorption rate (q CO) can be determined from the molar balance of carbon in the gas phase at the inlet and the outlet, that is q CO = R CO, in - (R CO, out + R CO2, out). Then, the amount of CO adsorption was obtained by time integration of q CO. The amount of CO adsorption during the CO exposure tests were shown in Fig. 2. At the beginning, the amount of CO adsorption increased proportional to time, and the slope correspond approximately to the CO supply rate. This indicates that most of the CO species were adsorbed on the anode. Then, the amount of CO adsorption were come to steady regardless of the cumulative CO supply amount. The saturated adsorption of CO was increased with the increase of CO concentration at cell inlet. The increase of saturated adsorption of CO will cause the voltage degradation of the cell. From these results, the adsorption behavior of CO near the allowable concentration was analyzed. The relationship between the voltage drop and the amount of CO adsorption will be discussed at the meeting. Acknowledgements This work was partly supported by the New Energy and Industrial Technology Development Organization (NEDO).