Showing papers on "Methanol published in 2022"
80 citations
TL;DR: In this article , the authors evaluated the effects of several commonly used quenchers (tert-butanol, methanol, ethanol, isopropanol, furfuryl alcohol, and L-histidine) on the mechanism of a cobalt mediated peroxymonosulfate (Co(II)/PMS) process.
80 citations
TL;DR: In this article , the authors demonstrate a process that grows and spreads Pt islands on Ru branched nanoparticles to create single-Pt-atom-on-Ru catalysts.
Abstract: Single Pt atom catalysts are key targets because a high exposure of Pt substantially enhances electrocatalytic activity. In addition, PtRu alloy nanoparticles are the most active catalysts for the methanol oxidation reaction. To combine the exceptional activity of single Pt atom catalysts with an active Ru support we must overcome the synthetic challenge of forming single Pt atoms on noble metal nanoparticles. Here we demonstrate a process that grows and spreads Pt islands on Ru branched nanoparticles to create single-Pt-atom-on-Ru catalysts. By following the spreading process by in situ TEM, we found that the formation of a stable single atom structure is thermodynamically driven by the formation of strong Pt–Ru bonds and the lowering of the surface energy of the Pt islands. The stability of the single-Pt-atom-on-Ru structure and its resilience to CO poisoning result in a high current density and mass activity for the methanol oxidation reaction over time. PtRu nanoparticles are the state-of-the-art catalysts for methanol electrooxidation—the anodic reaction in direct methanol fuel cells. Now, a method of dispersing single Pt atoms over Ru nanoparticles is presented and monitored in situ, thereby boosting the catalytic performance in the methanol oxidation reaction.
75 citations
TL;DR: In this article , a core-shell zeolitic imidazolate framework was used as the catalyst precursor, which was transformed into iron atoms dispersed in hollow porous nitrogen-doped carbon capsules through ion exchange and pyrolysis.
73 citations
TL;DR: In this paper , a single-atom Cu-Zr catalyst with isolated active copper sites for the hydrogenation of CO2 to methanol was reported, and it was shown that the presence of small copper clusters or nanoparticles with Cu-Cu structural patterns are responsible for forming the CO byproduct.
Abstract: Copper-based catalysts for the hydrogenation of CO2 to methanol have attracted much interest. The complex nature of these catalysts, however, renders the elucidation of their structure–activity properties difficult. Here we report a copper-based catalyst with isolated active copper sites for the hydrogenation of CO2 to methanol. It is revealed that the single-atom Cu–Zr catalyst with Cu1–O3 units contributes solely to methanol synthesis around 180 °C, while the presence of small copper clusters or nanoparticles with Cu–Cu structural patterns are responsible for forming the CO by-product. Furthermore, the gradual migration of Cu1–O3 units with a quasiplanar structure to the catalyst surface is observed during the catalytic process and accelerates CO2 hydrogenation. The highly active, isolated copper sites and the distinguishable structural pattern identified here extend the horizon of single-atom catalysts for applications in thermal catalytic CO2 hydrogenation and could guide the further design of high-performance copper-based catalysts to meet industrial demand. Copper-based catalysts are traditionally very effective for the hydrogenation of CO2 to methanol, although control over the active site has remained elusive. Here, the authors design a Cu1/ZrO2 single-atom catalyst featuring a Cu1–O3 site responsible for a remarkable performance at 180 °C.
61 citations
TL;DR: In this paper , an efficient, general, and expandable method is developed to synthesis two-dimensional (2D) ternary PtBiM nanoplates (NPLs), in which various M (Co, Ni, Cu, Zn, Sn) is severed as the third component to the binary PtBi system.
61 citations
TL;DR: In this article , a 3D crumpled Ti3C2Tx MXene balls with abundant Ti vacancies for Pt confinement via a spray-drying process are constructed and as-prepared Pt clusters/Ti3C 2Tx (Ptc/Ti 3C 2x) show enhanced electrocatalytic methanol oxidation reaction (MOR) activity, including a relatively low overpotential, high tolerance to CO poisoning, and ultrahigh stability.
Abstract: Anchoring platinum catalysts on appropriate supports, e.g., MXenes, is a feasible pathway to achieve a desirable anode for direct methanol fuel cells. The authentic performance of Pt is often hindered by the occupancy and poisoning of active sites, weak interaction between Pt and supports, and the dissolution of Pt. Herein, we construct three-dimensional (3D) crumpled Ti3C2Tx MXene balls with abundant Ti vacancies for Pt confinement via a spray-drying process. The as-prepared Pt clusters/Ti3C2Tx (Ptc/Ti3C2Tx) show enhanced electrocatalytic methanol oxidation reaction (MOR) activity, including a relatively low overpotential, high tolerance to CO poisoning, and ultrahigh stability. Specifically, it achieves a high mass activity of up to 7.32 A mgPt-1, which is the highest value reported to date in Pt-based electrocatalysts, and 42% of the current density is retained on Ptc/Ti3C2Tx even after the 3000 min operative time. In situ spectroscopy and theoretical calculations reveal that an electric field-induced repulsion on the Ptc/Ti3C2Tx interface accelerates the combination of OH- and CO adsorption intermediates (COads) in kinetics and thermodynamics. Besides, this Ptc/Ti3C2Tx also efficiently electrocatalyze ethanol, ethylene glycol, and glycerol oxidation reactions with comparable activity and stability to commercial Pt/C.
60 citations
TL;DR: Using gold nanoparticles supported on the zeolite ZSM-5, a method to oxidize methane to methanol and acetic acid in water at temperatures between 120 and 240 °C using molecular oxygen in the absence of any added coreductant as discussed by the authors .
Abstract: The oxidation of methane, the main component of natural gas, to selectively form oxygenated chemical feedstocks using molecular oxygen has been a long-standing grand challenge in catalysis. Here, using gold nanoparticles supported on the zeolite ZSM-5, we introduce a method to oxidize methane to methanol and acetic acid in water at temperatures between 120 and 240 °C using molecular oxygen in the absence of any added coreductant. Electron microscopy reveals that the catalyst does not contain gold atoms or clusters, but rather gold nanoparticles are the active component, while a mechanism involving surface adsorbed species is proposed in which methanol and acetic acid are formed via parallel pathways.
60 citations
TL;DR: In this paper, NiIr-based metal-organic framework (MOF) nanosheet arrays are in situ grown on Ni foam and employed as a bifunctional self-supported electrocatalyst to oxidize small organic molecules of methanol to the value-added chemical formate while efficiently facilitating hydrogen production.
Abstract: The conventional water electrolysis system is seriously restricted by the sluggish kinetics of anodic oxygen evolution reaction. Electroreforming of organic substances coupling with electrochemical hydrogen evolution is an innovative strategy to achieve energy-saving co-generation of value-added chemicals and hydrogen. Herein, NiIr-based metal‐organic framework (MOF) nanosheet arrays are in situ grown on Ni foam (NiIr-MOF/NF) and employed as a bifunctional self-supported electrocatalyst to oxidize small organic molecules of methanol to the value-added chemical formate while efficiently facilitating hydrogen production. The constructed co-electrolytic system based on HER-methanol oxidation reaction (MOR) bifunctional NiIr-MOF/NF electrocatalyst possesses ultra-high energy conversion efficiency for electrochemically assisted overall water splitting, with a low cell voltage of only 1.39 V to achieve the current density of 10 mA cm−2. Especially, the Faradaic efficiencies of the cathode and anode could both reach nearly 100% for H2 and formate generated in 1 M KOH containing 4 M methanol.
58 citations
TL;DR: In this paper , a new method was utilized for epitaxial growth of gold quantum dots using atomically platinum chlorine species with porous graphdiyne as a support (PtCl2Au(111)/GDY), for obtaining successful multicomponent quantum dots with a size of 2.37 nm.
Abstract: The development of efficient and durable electrocatalysts is the only way to achieve commercial fuel cells. A new, efficient method was utilized for epitaxial growth of gold quantum dots using atomically platinum chlorine species with porous graphdiyne as a support (PtCl2Au(111)/GDY), for obtaining successful multicomponent quantum dots with a size of 2.37 nm. The electrocatalyst showed a high mass activity of 175.64 A mgPt-1 for methanol oxidation reactions (MORs) and 165.35 A mgPt-1 for ethanol oxidation reactions (EORs). The data for this experiment are 85.67 and 246.80 times higher than those of commercial Pt/C, respectively. The catalyst also showed highly robust stability for MORs with negligible specific activity decay after 110 h at 10 mA cm-2. Both structure characterizations and theoretical calculations reveal that the excellent catalytic performance can be ascribed to the chlorine introduced to modify the d-band structure on the Pt surface and suppression of the CO poisoning pathway of the MOR. Our results indicate that an atomically dispersed metal species tailoring strategy opens up a new path for the efficient design of highly active and stable catalysts.
54 citations
TL;DR: In this paper , the structural and surface properties of Cu-based catalysts and their functions on the reaction mechanisms are discussed, and further affecting on the catalytic selectivity, stability, and activity for the CO 2 hydrogenation to methanol.
TL;DR: In this article, a pyrolysis-induced-vaporization strategy was successfully employed to fabricate Co/g-C3N4 single-atom catalysts with surface Co atom loading up to 24.6%.
Abstract: Cobalt species as active sites for photocatalytic reduction of CO2 to valuable products such as methanol have received increasing attention, however, it remains a huge challenge to achieve the high activity. Herein, a pyrolysis-induced-vaporization strategy was successfully employed to fabricate Co/g-C3N4 single-atom catalysts (Co/g-C3N4 SACs) with surface Co atom loading up to 24.6 wt%. Systematic investigation of Co/g-C3N4 SACs formation process disclosed that concentrated-H2SO4 exfoliation of g-C3N4 nanosheets (g-C3N4 NSs) as the substrate followed by a two-step calcination process is essential to achieve ultrahigh metal loading. It was found that the ultrahigh-density of Co single-atom sites were anchored on the g-C3N4 substrate surface and coordinated with two nitrogen and one carbon atoms (Co-N2C). These single dispersed Co-N2C sites on the g-C3N4 surface were found to act not only as electron gathering centers but also as the sites of CO2 adsorption and activation, subsequently, boosting the photocatalytic methanol generation during light irradiation. As a result, the methanol formation rate at 4 h (941.9 μmol g−1) over Co/g-C3N4-0.2 SAC with 24.6 wt% surface Co loading was 13.4 and 2.2 times higher than those of g-C3N4 (17.7 μmol g−1) and aggregated CoOx/g-C3N4-0.2 (423.9 μmol g−1), respectively. Simultaneously, H2 (18.9 μmol g−1 h−1), CO (2.9 μmol g−1 h−1), CH4 (3.4 μmol g−1 h−1), C2H4 (1.1 μmol g−1 h−1), C3H6 (1.4 μmol g−1 h−1), and CH3OCH3 (3.3 μmol g−1 h−1) products were detected over Co/g-C3N4-0.2 SAC. Besides, the photocatalytic activity of the Co/g-C3N4-0.2 SAC for the reduction of CO2 to methanol was stable within 12-cycle experiments (~48 h). This work paves a strategy to boost the photoreduction CO2 activity via loading ultrahigh surface density single atomically dispersed cobalt active sites.
TL;DR: In this paper , NiIr-based metal-organic framework (MOF) nanosheet arrays are in situ grown on Ni foam and employed as a bifunctional self-supported electrocatalyst to oxidize small organic molecules of methanol to the value-added chemical formate while efficiently facilitating hydrogen production.
Abstract: The conventional water electrolysis system is seriously restricted by the sluggish kinetics of anodic oxygen evolution reaction. Electroreforming of organic substances coupling with electrochemical hydrogen evolution is an innovative strategy to achieve energy-saving co-generation of value-added chemicals and hydrogen. Herein, NiIr-based metal‐organic framework (MOF) nanosheet arrays are in situ grown on Ni foam (NiIr-MOF/NF) and employed as a bifunctional self-supported electrocatalyst to oxidize small organic molecules of methanol to the value-added chemical formate while efficiently facilitating hydrogen production. The constructed co-electrolytic system based on HER-methanol oxidation reaction (MOR) bifunctional NiIr-MOF/NF electrocatalyst possesses ultra-high energy conversion efficiency for electrochemically assisted overall water splitting, with a low cell voltage of only 1.39 V to achieve the current density of 10 mA cm −2 . Especially, the Faradaic efficiencies of the cathode and anode could both reach nearly 100% for H 2 and formate generated in 1 M KOH containing 4 M methanol. • The NiIr-MOF/NF composite was fabricated and served as a bifunctional electrocatalyst. • Replacing OER with MOR could achieve energy-saving electrochemical hydrogen evolution. • Methanol electroreforming at the anode could produce value-added chemical formate.
TL;DR: In this paper , a pyrolysis-induced vaporization strategy was successfully employed to fabricate Co/g-C 3 N 4 single-atom catalysts with surface Co atom loading up to 24.6 wt%.
Abstract: Cobalt species as active sites for photocatalytic reduction of CO 2 to valuable products such as methanol have received increasing attention, however, it remains a huge challenge to achieve the high activity. Herein, a pyrolysis-induced-vaporization strategy was successfully employed to fabricate Co/g-C 3 N 4 single-atom catalysts (Co/g-C 3 N 4 SACs) with surface Co atom loading up to 24.6 wt%. Systematic investigation of Co/g-C 3 N 4 SACs formation process disclosed that concentrated-H 2 SO 4 exfoliation of g-C 3 N 4 nanosheets (g-C 3 N 4 NSs) as the substrate followed by a two-step calcination process is essential to achieve ultrahigh metal loading. It was found that the ultrahigh-density of Co single-atom sites were anchored on the g-C 3 N 4 substrate surface and coordinated with two nitrogen and one carbon atoms (Co-N 2 C). These single dispersed Co-N 2 C sites on the g-C 3 N 4 surface were found to act not only as electron gathering centers but also as the sites of CO 2 adsorption and activation, subsequently, boosting the photocatalytic methanol generation during light irradiation. As a result, the methanol formation rate at 4 h (941.9 μmol g −1 ) over Co/g-C 3 N 4 -0.2 SAC with 24.6 wt% surface Co loading was 13.4 and 2.2 times higher than those of g-C 3 N 4 (17.7 μmol g −1 ) and aggregated CoO x /g-C 3 N 4 -0.2 (423.9 μmol g −1 ), respectively. Simultaneously, H 2 (18.9 μmol g −1 h −1 ), CO (2.9 μmol g −1 h −1 ), CH 4 (3.4 μmol g −1 h −1 ), C 2 H 4 (1.1 μmol g −1 h −1 ), C 3 H 6 (1.4 μmol g −1 h −1 ), and CH 3 OCH 3 (3.3 μmol g −1 h −1 ) products were detected over Co/g-C 3 N 4 -0.2 SAC. Besides, the photocatalytic activity of the Co/g-C 3 N 4 -0.2 SAC for the reduction of CO 2 to methanol was stable within 12-cycle experiments (~48 h). This work paves a strategy to boost the photoreduction CO 2 activity via loading ultrahigh surface density single atomically dispersed cobalt active sites. • The two-step calcination process induced bulk cobalt nitrate vaporization to avoid the aggregation of Co atoms during the pyrolysis process. • The g-C 3 N 4 nanosheets as the substrate was proven to afford rich exposed N sites for anchoring single Co atoms. • Formed ultrahigh density Co-N 2 C single dispersed active sites boost the photoreduction CO 2 to methanol by localization of photogenerated electrons.
TL;DR: In this article , the design and construction of dual-role catalysts for direct methanol fuel cells is reviewed and a discussion of the various dual role catalysts is given.
TL;DR: In this article , tiny Pd3 Cu nanoparticles are confined into a metal-organic framework (MOF), UiO-66, to afford a methanol production rate of 340 μmol g-1 h-1 at 200 °C and 1.25 MPa under light irradiation, far surpassing that in the dark.
Abstract: CO2 hydrogenation to methanol has attracted great interest while suffering from low conversion and high energy input. Herein, tiny Pd3 Cu nanoparticles are confined into a metal-organic framework (MOF), UiO-66, to afford Pd3 Cu@UiO-66 for CO2 hydrogenation. Remarkably, it achieves a methanol production rate of 340 μmol g-1 h-1 at 200 °C and 1.25 MPa under light irradiation, far surpassing that in the dark. The photo-generated electron transfer from the MOF to antibonding orbitals of CO2 * promotes CO2 activation and HCOO* formation. In addition, the Pd3 Cu microenvironment plays a critical role in CO2 hydrogenation. In contrast to the MOF-supported Pd3 Cu (Pd3 Cu/UiO-66), the Pd3 Cu@UiO-66 exhibits a much higher methanol production rate due to the close proximity between CO2 and H2 activation sites, which greatly facilitates their interaction and conversion. This work provides a new avenue to the integration of solar and thermal energy for efficient CO2 hydrogenation under moderate conditions.
TL;DR: In this paper , a heterostructure of nickel boride/nickel catalyst is developed to enable methanol electrooxidation into formate with a Faradaic efficiency of nearly 100%.
Abstract: Designing efficient catalysts and understanding the underlying mechanisms for anodic nucleophile electrooxidation are central to the advancement of electrochemically-driven technologies. Here, a heterostructure of nickel boride/nickel catalyst is developed to enable methanol electrooxidation into formate with a Faradaic efficiency of nearly 100%. Operando electrochemical impedance spectroscopy and in situ Raman spectroscopy are applied to understand the influence of methanol concentration in the methanol oxidation reaction. High concentrations of methanol inhibit the phase transition of the electrocatalyst to high-valent electro-oxidation products, and electrophilic oxygen species (O* or OH*) formed on the electrocatalyst are considered to be the catalytically active species. Additional mechanistic investigation with density functional theory calculations reveals that the potential-determining step, the formation of *CH2O, occurs most favorably on the nickel boride/nickel heterostructure rather than on nickel boride and nickel. These results are highly instructive for the study of other nucleophile-based approaches to electrooxidation reactions and organic electrosynthesis.
TL;DR: In this paper , a general strategy for preparing ultralight 3D porous medium-entropy aerogels with the lowest density of 39.3 mg cm−3 among the metal materials is reported, through combining auto-combustion and subsequent low-temperature reduction procedures.
Abstract: Medium‐entropy alloy aerogels (MEAAs) with the advantages of both multimetallic alloys and aerogels are promising new materials in catalytic applications. However, limited by the immiscible behavior of different metals, achieving single‐phase MEAAs is still a grand challenge. Herein, a general strategy for preparing ultralight 3D porous MEAAs with the lowest density of 39.3 mg cm−3 among the metal materials is reported, through combining auto‐combustion and subsequent low‐temperature reduction procedures. The homogenous mixing of precursors at the ionic level makes the short‐range diffusion of metal atoms possible to drive the formation of single‐phase MEAAs. As a proof of concept in catalysis, as‐synthesized Ni50Co15Fe30Cu5 MEAAs exhibit a high mass activity of 1.62 A mg−1 and specific activity of 132.24 mA cm−2 toward methanol oxidation reactions, much higher than those of the low‐entropy counterparts. In situ Fourier transform infrared and NMR spectroscopies reveal that MEAAs can enable highly selective conversion of methanol to formate. Most importantly, a methanol‐oxidation‐assisted MEAAs‐based water electrolyzer can achieve a low cell voltage of 1.476 V at 10 mA cm−2 for making value‐added formate at the anode and H2 at the cathode, 173 mV lower than that of traditional alkaline water electrolyzers.
TL;DR: In this article, different porous PtCu nanotubes constructed by hollow nanospheres, solid alloy, and Pt-rich skinned nanoparticles, respectively, were successfully synthesized for improving the methanol oxidation reaction (MOR) and oxygen reduction reaction (ORR).
Abstract: Platinum (Pt), as a commonly used electrocatalyst in direct methanol fuel cells (DMFCs), suffers from sluggish kinetics of both the methanol oxidation reaction (MOR) and oxygen reduction reaction (ORR). Geometric engineering has been proven effective for improving the MOR and ORR activities. Thus, by modulating the Pt precursor and poly(vinylpyrrolidone) (PVP) dosages, different porous PtCu nanotubes constructed by hollow nanospheres, solid alloy, and Pt-rich skinned nanoparticles, respectively, are successfully synthesized. Among them, the solid PtCu alloy nanoparticle coherent nanotubes exhibit the specific activity 9.42 times higher than Pt/C toward MOR, while the hollow PtCu alloy nanosphere coherent nanotubes show the specific activity 4.85 times higher than Pt/C toward ORR. The different Pt:Cu ratios of hollow nanospheres, solid alloy, and Pt-rich skinned nanoparticles cause the differences in electron transfer from Cu to Pt as well as electronic structures of Pt. As a result, the binding energies of intermediates can be regulated, leading to the enhancement in MOR and ORR.
TL;DR: In this paper , a new black indium oxide with photothermal catalytic activity is successfully prepared, and it facilitates a tandem synthesis of methanol at a low hydrogen concentration (50%) and ambient pressure by directly using byproduct CO as feedstock.
Abstract: Abstract It has long been known that the thermal catalyst Cu/ZnO/Al 2 O 3 (CZA) can enable remarkable catalytic performance towards CO 2 hydrogenation for the reverse water-gas shift (RWGS) and methanol synthesis reactions. However, owing to the direct competition between these reactions, high pressure and high hydrogen concentration (≥75%) are required to shift the thermodynamic equilibrium towards methanol synthesis. Herein, a new black indium oxide with photothermal catalytic activity is successfully prepared, and it facilitates a tandem synthesis of methanol at a low hydrogen concentration (50%) and ambient pressure by directly using by-product CO as feedstock. The methanol selectivities achieve 33.24% and 49.23% at low and high hydrogen concentrations, respectively.
TL;DR: In this article , a convenient interfacial engineering strategy is developed to the design and construction of quasi-one-dimensional worm-shaped palladium nanocrystals strongly coupled with positively-charged polyelectrolyte-modified Ti3C2Tx MXene via the direct electrostatic attraction.
TL;DR: In this paper , an electrochemical CO2 reduction reaction (eCO2RR) was performed on two intermetallic compounds formed by copper and gallium metals (CuGa2 and Cu9Ga4).
Abstract: Electrochemical CO2 reduction reaction (eCO2RR) is performed on two intermetallic compounds formed by copper and gallium metals (CuGa2 and Cu9Ga4). Among them, CuGa2 selectively converts CO2 to methanol with remarkable Faradaic efficiency of 77.26% at an extremely low potential of −0.3 V vs RHE. The high performance of CuGa2 compared to Cu9Ga4 is driven by its unique 2D structure, which retains surface and subsurface oxide species (Ga2O3) even in the reduction atmosphere. The Ga2O3 species is mapped by X‐ray photoelectron spectroscopy (XPS) and X‐ray absorption fine structure (XAFS) techniques and electrochemical measurements. The eCO2RR selectivity to methanol are decreased at higher potential due to the lattice expansion caused by the reduction of the Ga2O3, which is probed by in situ XAFS, quasi in situ powder X‐ray diffraction, and ex situ XPS measurements. The mechanism of the formation of methanol is visualized by in situ infrared (IR) spectroscopy and the source of the carbon of methanol at the molecular level is confirmed from the isotope‐labeling experiments in presence of 13CO2. Finally, to minimize the mass transport limitations and improve the overall eCO2RR performance, a poly(tetrafluoroethylene)‐based gas diffusion electrode is used in the flow cell configuration.
TL;DR: In this paper , an operationally simple in situ dual doping strategy was proposed to construct efficient CO2-to-methanol electrocatalysts for methanol conversion.
Abstract: Methanol is a highly desirable product of CO2 electroreduction due to its wide array of industrial applications. However, the development of CO2-to-methanol electrocatalysts with high performance is still challenging. Here we report an operationally simple in situ dual doping strategy to construct efficient CO2-to-methanol electrocatalysts. In particular, when using Ag,S-Cu2O/Cu as electrocatalyst, the methanol Faradaic efficiency (FE) could reach 67.4% with a current density as high as 122.7 mA cm-2 in an H-type cell using 1-butyl-3-methylimidazolium tetrafluoroborate/H2O as the electrolyte, while the current density was below 50 mA cm-2 when the FE was greater than 50% over the reported catalysts. Experimental and theoretical studies suggest that the anion S can effectively adjust the electronic structure and morphology of the catalysts in favor of the methanol pathway, whereas the cation Ag suppresses the hydrogen evolution reaction. Their synergistic interactions with host material enhance the selectivity and current density for methanol formation. This work opens a way for designing efficient catalysts for CO2 electroreduction to methanol.
TL;DR: In this paper, the combined injection of kinetic and thermodynamic hydrate inhibitors (KHIs and THIs) is considered as a promising method to prevent the blockage of oil and gas pipelines caused by the accidental formation of methane hydrate.
TL;DR: In this paper , the authors used x-ray photoelectron spectroscopy at 180 to 500 millibar to probe the nature of Zn and reaction intermediates during CO2/CO hydrogenation over Zn/ZnO/Cu(211), where the temperature is sufficiently high for the reaction to rapidly turn over, thus creating an almost adsorbate-free surface.
Abstract: The active chemical state of zinc (Zn) in a zinc-copper (Zn-Cu) catalyst during carbon dioxide/carbon monoxide (CO2/CO) hydrogenation has been debated to be Zn oxide (ZnO) nanoparticles, metallic Zn, or a Zn-Cu surface alloy. We used x-ray photoelectron spectroscopy at 180 to 500 millibar to probe the nature of Zn and reaction intermediates during CO2/CO hydrogenation over Zn/ZnO/Cu(211), where the temperature is sufficiently high for the reaction to rapidly turn over, thus creating an almost adsorbate-free surface. Tuning of the grazing incidence angle makes it possible to achieve either surface or bulk sensitivity. Hydrogenation of CO2 gives preference to ZnO in the form of clusters or nanoparticles, whereas in pure CO a surface Zn-Cu alloy becomes more prominent. The results reveal a specific role of CO in the formation of the Zn-Cu surface alloy as an active phase that facilitates efficient CO2 methanol synthesis. Description Zinc’s state in methanol synthesis Methanol can be synthesized from carbon monoxide (CO), carbon dioxide (CO2), and molecular hydrogen (H2) over copper–zinc (Cu–Zn) catalysts, but studies have disagreed about the chemical state of Zn. Although x-ray photoelectron spectroscopy (XPS) can determine its oxidation state, many studies have been limited to reaction pressures of a few millibars, where the rates are low. Amann et al. performed XPS at 180 to 500 millibars for CO2 and CO hydrogenation over a Zn/ZnO/Cu(211) surface at high turnover rates. Stoichiometric mixtures of CO2 and H2 formed ZnO, but for CO and H2, Zn became more metallic and formed Cu alloys. In industrial synthesis, CO2 and H2 are mixed with CO, and the presence of CO would generate Cu–Zn alloy sites active for CO2 reduction to methanol. —PDS CO induces Zn–Cu surface alloy sites that are active for CO2 hydrogenation in catalytic methanol synthesis.
TL;DR: A detailed review of methanol production and its impact on engine emissions in the context of carbon neutrality is presented in this paper . But the authors do not consider the impact of the combustion process on IC engines.
TL;DR: The obtained results emphasize the advances in effective precious material utilization and fabricating techniques of active electrocatalysts for direct alcohol oxidation fuel cell applications.
Abstract: The development of efficient and highly durable materials for renewable energy conversion devices is crucial to the future of clean energy demand. Herein, cage‐like quasihexagonal structured platinum nanodendrites decorated over the transition metal chalcogenide core (CoS2)‐N‐doped graphene oxide (PtNDs@CoS2‐NrGO) through optimized shape engineering and structural control technology are fabricated. The prepared electrocatalyst of PtNDs@CoS2‐NrGO is effectively used as anodic catalyst for alcohol oxidation in direct liquid alcohol fuel cells. Notably, the prepared PtNDs@CoS2‐NrGO exhibits superior electrocatalytic performance toward alcohol oxidation with higher oxidation peak current densities of 491.31, 440.25, and 438.12 mA mgpt–1 for (methanol) C1, (ethylene glycol) C2, and (glycerol) C3 fuel electrolytes, respectively, as compared to state‐of‐the‐art Pt‐C in acidic medium. The electro‐oxidation durability of PtNDs@CoS2‐NrGO is investigated through cyclic voltammetry and chronoamperometry tests, which demonstrate excellent stability of the electrocatalyst toward various alcohols. Furthermore, the surface and adsorption energies of PtNDs and CoS2 are calculated using density functional theory along with the detailed bonding analysis. Overall, the obtained results emphasize the advances in effective precious material utilization and fabricating techniques of active electrocatalysts for direct alcohol oxidation fuel cell applications.