共查询到20条相似文献,搜索用时 203 毫秒
1.
Electrochemical conversion of CO 2 into fuels using electricity generated from renewable sources helps to create an artificial carbon cycle. However, the low efficiency and poor stability hinder the practical use of most conventional electrocatalysts. In this work, a 2D hierarchical Pd/SnO 2 structure, ultrathin Pd nanosheets partially capped by SnO 2 nanoparticles, is designed to enable multi‐electron transfer for selective electroreduction of CO 2 into CH 3OH. Such a structure design not only enhances the adsorption of CO 2 on SnO 2, but also weakens the binding strength of CO on Pd due to the as‐built Pd–O–Sn interfaces, which is demonstrated to be critical to improve the electrocatalytic selectivity and stability of Pd catalysts. This work provides a new strategy to improve electrochemical performance of metal‐based catalysts by creating metal oxide interfaces for selective electroreduction of CO 2. 相似文献
2.
CO2 and steam/CO2 electroreduction to CO and methane in solid oxide electrolytic cells (SOEC) has gained major attention in the past few years. This work evaluates, for the very first time, the performance of two different ZnO–Ag cathodes: one where ZnO nanopowder was mixed with Ag powder for preparing the cathode ink (ZnOmix–Ag cathode) and the other one where Ag cathode was infiltrated with a zinc nitrate solution (ZnOinf –Ag cathode). ZnOmix–Ag cathode had a better distribution of ZnO particles throughout the cathode, resulting in almost double CO generation while electrolysing both dry CO2 and H2/CO2 (4:1 v/v). A maximum overall CO2 conversion of 48% (in H2/CO2) at 1.7 V and 700 °C clearly indicated that as low as 5 wt% zinc loading is capable of CO2 electroreduction. It was further revealed that for ZnOinf –Ag cathode, most of CO generation took place through RWGS reaction, but for ZnOmix–Ag cathode, it was the synergistic effect of both RWGS reaction and CO2 electrolysis. Although ZnOinf –Ag cathode produced trace amount of methane at higher voltages, with ZnOmix–Ag cathode, there was absolutely no methane. This seems to be due to strong electronic interaction between Zn and Ag that might have suppressed the catalytic activity of the cathode towards methanation. 相似文献
3.
Electrodes modified with iron porphyrin and carbon nanotubes (FeP–CNTs) were prepared and used for CO 2 electroreduction. The adsorption of iron porphyrin onto the multiwalled carbon nanotubes was characterized by scanning electron microscopy and ultraviolet and visible spectroscopy. The electrochemical properties of the modified electrodes for CO 2 reduction were investigated by cyclic voltammetry and CO 2 electrolysis. The FeP–CNT electrodes exhibited less negative cathode potential and higher reaction rate than the electrodes modified only with iron porphyrin or carbon nanotubes. A mechanism of the synergistic catalysis was proposed and studied by electrochemical impedance spectroscopy and electron paramagnetic resonance. The direct electron transfer between iron porphyrin and carbon nanotubes was examined. The current study shed light on the mechanism of synergistic catalysis between CNTs and metalloporphyrin, and the iron porphyrin–CNT-modified electrodes showed great potential in the efficient CO 2 electroreduction. 相似文献
4.
Hybrid electrodes with improved O 2 tolerance and capability of CO 2 conversion into liquid products in the presence of O 2 are presented. Aniline molecules are introduced into the pore structure of a polymer of intrinsic microporosity to expand its gas separation functionality beyond pure physical sieving. The chemical interaction between the acidic CO 2 molecule and the basic amino group of aniline renders enhanced CO 2 separation from O 2. Loaded with a cobalt phthalocyanine‐based cathode catalyst, the hybrid electrode achieves a CO Faradaic efficiency of 71 % with 10 % O 2 in the CO 2 feed gas. The electrode can still produce CO at an O 2/CO 2 ratio as high as 9:1. Switching to a Sn‐based catalyst, for the first time O 2‐tolerant CO 2 electroreduction to liquid products is realized, generating formate with nearly 100 % selectivity and a current density of 56.7 mA cm ?2 in the presence of 5 % O 2. 相似文献
5.
The electrochemical reduction of CO 2 on Sn, Cu, Au, In, Ni, Ru and Pt electrodes in methanol containing 0.1 M sodium perchlorate was studied by cyclic voltammetry and in-situ FTIR spectroscopy. Dissolved CO 2 increases the cathodic current at potentials below −1.3 V vs. Ag|0.01 M Ag + with Sn, Au, Cu, In and Ni electrodes. It is concluded from the FTIR spectra obtained that there is no reduction of CO 2 on any of the metals studied, and that the only reaction product detected by Fourier transform (FT) IR spectroscopy, i.e. CO 2−3, is formed by reaction of CO 2 with hydroxyl anions produced in the electroreduction of residual water.In order to identify the electroreduction products of CO 2 it was necessary to obtain the FTIR spectra of sodium oxalate and sodium carbonate in methanol. They were obtained by the electroreduction of oxalic acid and the alkalinization of CO 2-saturated methanol respectively. It could be proved that the electroreduction of carboxylic acids to carboxylate anions in organic solvents does not require either a H-chemisorbing metal electrode, or the presence of water in the solvent. 相似文献
6.
Co-electrolysis of CO_2 and H_2O using high-temperature solid oxide electrolysis cells(SOECs) into valuable chemicals has attracted great attentions recently due to the high conversion and energy efficiency,which provides opportunities of reducing CO_2 emission, mitigating global warming and storing intermittent renewable energies. A single SOEC typically consists of an ion conducting electrolyte, an anode and a cathode where the co-electrolysis reaction takes place. The high operating temperature and difficult activated carbon-oxygen double-bond of CO_2 put forward strict requirements for SOEC cathode. Great efforts are being devoted to develop suitable cathode materials with high catalytic activity and excellent long-term stability for CO_2/H_2O electro-reduction. The so far cathode material development is the key point of this review and alternative strategies of high-performance cathode material preparation is proposed. Understanding the mechanism of CO_2/H_2O electro-reduction is beneficial to highly active cathode design and optimization. Thus the possible reaction mechanism is also discussed. Especially, a method in combination with electrochemical impedance spectroscopy(EIS) measurement, distribution functions of relaxation times(DRT) calculation, complex nonlinear least square(CNLS) fitting and operando ambient pressure X-ray photoelectron spectroscopy(APXPS) characterization is introduced to correctly disclose the reaction mechanism of CO_2/H_2O co-electrolysis. Finally, different reaction modes of the CO_2/H_2O coelectrolysis in SOECs are summarized to offer new strategies to enhance the CO_2 conversion. Otherwise,developing SOECs operating at 300-600 °C can integrate the electrochemical reduction and the Fischer-Tropsch reaction to convert the CO_2/H_2O into more valuable chemicals, which will be a new research direction in the future. 相似文献
7.
One of the most effective ways to cope with the problems of global warming and the energy shortage crisis is to develop renewable and clean energy sources. To achieve a carbon-neutral energy cycle, advanced carbon sequestration technologies are urgently needed, but because CO 2 is a thermodynamically stable molecule with the highest carbon valence state of +4, this process faces many challenges. In recent years, electrochemical CO 2 reduction has become a promising approach to fix and convert CO 2 into high-value-added fuels and chemical feedstock. However, the large-scale commercial use of electrochemical CO 2 reduction systems is hindered by poor electrocatalyst activity, large overpotential, low energy conversion efficiency, and product selectivity in reducing CO 2. Therefore, there is an urgent need to rationally design highly efficient, stable, and scalable electrocatalysts to alleviate these problems. This minireview also aims to classify heterogeneous nanostructured electrocatalysts for the CO 2 reduction reaction (CDRR). 相似文献
8.
To be successfully implemented, an efficient conversion, affordable operation and high values of CO 2-derived products by electrochemical conversion of CO 2 are yet to be addressed. Inspired by the natural CaO-CaCO 3 cycle, we herein introduce CaO into electrolysis of SnO 2 in affordable molten CaCl 2-NaCl to establish an in situ capture and conversion of CO 2. In situ capture of anodic CO 2 from graphite anode by the added CaO generates CaCO 3. The consequent co-electrolysis of SnO 2 and CaCO 3 confines Sn in carbon nanotube (Sn@CNT) in cathode and increases current efficiency of O 2 evolution in graphite anode to 71.9 %. The intermediated CaC 2 is verified as the nuclei to direct a self-template generation of CNT, ensuring a CO 2-CNT current efficiency and energy efficiency of 85.1 % and 44.8 %, respectively. The Sn@CNT integrates confined responses of Sn cores to external electrochemical or thermal stimuli with robust CNT sheaths, resulting in excellent Li storage performance and intriguing application as nanothermometer. The versatility of the molten salt electrolysis of CO 2 in Ca-based molten salts for template-free generation of advanced carbon materials is evidenced by the successful generation of pure CNT, Zn@CNT and Fe@CNT. 相似文献
9.
Gas diffusion electrodes (GDEs), including GDE-In 0.90Sn 0.10, GDE-In 0.47Sn 0.53 and GDE-In 0.22Sn 0.78, were prepared by electrodeposition of In–Sn alloys on carbon fiber paper, and then used to explore the electroreduction of CO 2 to formate in aqueous solution. Compared with commercial indium or Sn foil catalysts, the GDE-In 0.90Sn 0.10 electrode in particular is shown to have excellent catalytic performance towards electroreduction of CO 2 to formate, with a high Faradaic efficiency (~ 92%). More importantly, the catalytic activity of GDE-In 0.90Sn 0.10 remained reasonably stable over a 22-hour period of electrolysis, and a relatively high electrolytic current density (15 mA cm − 2) was obtained in an aqueous medium, demonstrating its potential for electrochemical reduction of CO 2 to formate. 相似文献
10.
Controlling the selectivity in electrochemical CO 2 reduction is an unsolved challenge. While tin (Sn) has emerged as a promising non‐precious catalyst for CO 2 electroreduction, most Sn‐based catalysts produce formate as the major product, which is less desirable than CO in terms of separation and further use. Tin monoxide (SnO) nanoparticles supported on carbon black were synthesized and assembled and their application in CO 2 reduction was studied. Remarkably high selectivity and partial current densities for CO formation were obtained using these SnO nanoparticles compared to other Sn catalysts. The high activity is attributed to the ultra‐small size of the nanoparticles (2.6 nm), while the high selectivity is attributed to a local pH effect arising from the dense packing of nanoparticles in the conductive carbon black matrix. 相似文献
11.
Controlling the selectivity in electrochemical CO 2 reduction is an unsolved challenge. While tin (Sn) has emerged as a promising non‐precious catalyst for CO 2 electroreduction, most Sn‐based catalysts produce formate as the major product, which is less desirable than CO in terms of separation and further use. Tin monoxide (SnO) nanoparticles supported on carbon black were synthesized and assembled and their application in CO 2 reduction was studied. Remarkably high selectivity and partial current densities for CO formation were obtained using these SnO nanoparticles compared to other Sn catalysts. The high activity is attributed to the ultra‐small size of the nanoparticles (2.6 nm), while the high selectivity is attributed to a local pH effect arising from the dense packing of nanoparticles in the conductive carbon black matrix. 相似文献
12.
Highly efficient electrochemical reduction of CO 2 into value‐added chemicals using cheap and easily prepared electrodes is environmentally and economically compelling. The first work on the electrocatalytic reduction of CO 2 in ternary electrolytes containing ionic liquid, organic solvent, and H 2O is described. Addition of a small amount of H 2O to an ionic liquid/acetonitrile electrolyte mixture significantly enhanced the efficiency of the electrochemical reduction of CO 2 into formic acid (HCOOH) on a Pb or Sn electrode, and the efficiency was extremely high using an ionic liquid/acetonitrile/H 2O ternary mixture. The partial current density for HCOOH reached 37.6 mA cm ?2 at a Faradaic efficiency of 91.6 %, which is much higher than all values reported to date for this reaction, including those using homogeneous and noble metal electrocatalysts. The reasons for such high efficiency were investigated using controlled experiments. 相似文献
13.
The gradually increased concentration of carbon dioxide (CO 2) in the atmosphere has been recognized as the primary culprit for the rise of the global mean temperature. In recent years, development of routes for highly efficient conversion of CO 2 has received much attention. This Review describes recent progress on the design and synthesis of solid‐state catalysts for the electrochemical reduction of CO 2. The significance of this catalytic conversion is presented, followed by the general parameters for CO 2 electroreduction and a summary of the reaction apparatus. We also discuss various types of solid catalysts based on their CO 2 conversion mechanisms. We summarize the crucial factors (particle size, surface structure, composition, etc.) determining the performance for electroreduction. 相似文献
14.
Electrochemical reduction of CO 2 into value‐added product is an interesting area. MoP nanoparticles supported on porous carbon were synthesized using metal–organic frameworks as the carbon precursor, and initial work on CO 2 electroreduction using the MoP‐based catalyst were carried out. It was discovered that MoP nanoparticles supported on In‐doped porous carbon had outstanding performance for CO 2 reduction to formic acid. The Faradaic efficiency and current density could reach 96.5 % and 43.8 mA cm ?2, respectively, when using ionic liquid 1‐butyl‐3‐methylimidazolium hexafluorophosphate as the supporting electrolyte. The current density is higher than those reported up to date with very high Faradaic efficiency. The MoP nanoparticles and the doped In 2O 3 cooperated very well in catalyzing the CO 2 electroreduction. 相似文献
15.
A BDD-BDD system was developed in the simultaneous conversion of CO 2 and wastewater purification in one electrochemical cell. 相似文献
16.
The electrochemical CO 2 reduction reaction (CO 2RR) to give C 1 (formate and CO) products is one of the most techno‐economically achievable strategies for alleviating CO 2 emissions. Now, it is demonstrated that the SnO x shell in Sn 2.7Cu catalyst with a hierarchical Sn‐Cu core can be reconstructed in situ under cathodic potentials of CO 2RR. The resulting Sn 2.7Cu catalyst achieves a high current density of 406.7±14.4 mA cm ?2 with C 1 Faradaic efficiency of 98.0±0.9 % at ?0.70 V vs. RHE, and remains stable at 243.1±19.2 mA cm ?2 with a C 1 Faradaic efficiency of 99.0±0.5 % for 40 h at ?0.55 V vs. RHE. DFT calculations indicate that the reconstructed Sn/SnO x interface facilitates formic acid production by optimizing binding of the reaction intermediate HCOO* while promotes Faradaic efficiency of C 1 products by suppressing the competitive hydrogen evolution reaction, resulting in high Faradaic efficiency, current density, and stability of CO 2RR at low overpotentials. 相似文献
17.
Hybrid electrodes with improved O 2 tolerance and capability of CO 2 conversion into liquid products in the presence of O 2 are presented. Aniline molecules are introduced into the pore structure of a polymer of intrinsic microporosity to expand its gas separation functionality beyond pure physical sieving. The chemical interaction between the acidic CO 2 molecule and the basic amino group of aniline renders enhanced CO 2 separation from O 2. Loaded with a cobalt phthalocyanine-based cathode catalyst, the hybrid electrode achieves a CO Faradaic efficiency of 71 % with 10 % O 2 in the CO 2 feed gas. The electrode can still produce CO at an O 2/CO 2 ratio as high as 9:1. Switching to a Sn-based catalyst, for the first time O 2-tolerant CO 2 electroreduction to liquid products is realized, generating formate with nearly 100 % selectivity and a current density of 56.7 mA cm −2 in the presence of 5 % O 2. 相似文献
18.
The increasing emission of carbon dioxide (CO 2) caused by the unrestrained consumption of fossil fuels in recent hundreds of years, has caused global environmental and social problems. Meanwhile, CO 2 is a cheap, abundant and renewable C1‐feedstock, which can be converted into alcohols, ethers, acids and other value‐added chemicals. Compared with the thermal reactions, electrochemical reduction of CO 2 is more attractive because of its advantages by using the seasonal, geographical and intermittent energy (tide, wind and solar) under mild conditions. In recent years, taking ionic liquids (ILs) as electrolytes in the CO 2 electrochemical reduction reaction has been paid much more attention due to the advantages of lowering the overpotential of CO 2 electroreduction and improving the Faradaic efficiency. In this paper, we summarized the recent progresses of electrochemical reduction of CO 2 in ILs electrolytes, and analyzed the reaction mechanism of CO 2 reaction in the electrode‐electrolyte interface region by experimental and simulation methods. Finally, the research which needs to be highlighted in this area was proposed. 相似文献
19.
Conversion of carbon dioxide (CO 2) into fuels and chemicals by electroreduction has attracted significant interest, although it suffers from a large overpotential and low selectivity. A Pd‐Sn alloy electrocatalyst was developed for the exclusive conversion of CO 2 into formic acid in an aqueous solution. This catalyst showed a nearly perfect faradaic efficiency toward formic acid formation at the very low overpotential of −0.26 V, where both CO formation and hydrogen evolution were completely suppressed. Density functional theory (DFT) calculations suggested that the formation of the key reaction intermediate HCOO* as well as the product formic acid was the most favorable over the Pd‐Sn alloy catalyst surface with an atomic composition of PdSnO 2, consistent with experiments. 相似文献
20.
Solid oxide fuel cell (SOFC) unit was constructed with Ni–GDC (gadolinia-doped ceria) as the anode, YSZ as the electrolyte, and Cu-added La 0.58Sr 0.4Co 0.2Fe 0.8O 3–δ–GDC as the cathode. Electrochemical CO 2 reduction occurs. The CO formation rate, the CO 2 conversion and the generated current density increase with increasing CO 2 concentration and temperature. The CO 2 conversion rate equals exactly the CO formation rate. No carbon deposition occurs. The activation energy is 2.72 kcal mol ?1. The electrochemical CO 2 reduction (dissociation) can have much lower activation barrier than the catalytic one. Simultaneous CO 2 reduction with power generation in SOFCs can be feasible. 相似文献
|