Direct electrolysis of CO2 using an oxygen-ion conducting solid oxide electrolyzer based on La0.75Sr0.25Cr0.5Mn0.5O3 −  electrode

Zhang

et al. 2014

Sci Rep

Self Cite

In this paper, we report the in situ growth of NixCu1-x (x = 0, 0.25, 0.50, 0.75 and 1.0) alloy catalysts to anchor and decorate a redox-reversible Nb1.33Ti0.67O4 ceramic substrate with the aim of tailoring the electrocatalytic activity of the composite materials through direct exsolution of metal particles from the crystal lattice of a ceramic oxide in a reducing atmosphere at high temperatures. Combined analysis using XRD, SEM, EDS, TGA, TEM and XPS confirmed the completely reversible exsolution/dissolution of the NixCu1-x alloy particles during the redox cycling treatments. TEM results revealed that the alloy particles were exsolved to anchor onto the surface of highly electronically conducting Nb1.33Ti0.67O4 in the form of heterojunctions. The electrical properties of the nanosized NixCu1-x/Nb1.33Ti0.67O4 were systematically investigated and correlated to the electrochemical performance of the composite electrodes. A strong dependence of the improved electrode activity on the alloy compositions was observed in reducing atmospheres at high temperatures. Direct electrolysis of CO2 at the NixCu1-x/Nb1.33Ti0.67O4 composite cathodes was investigated in solid-oxide electrolysers. The CO2 splitting rates were observed to be positively correlated with the Ni composition; however, the Ni0.75Cu0.25 combined the advantages of metallic nickel and copper and therefore maximised the current efficiencies.

supporting

confidence: 60%

“…High-temperature electrolysis based on the redox-stable LSCM or LSTO cathode has been reported for the direct electrolysis of H 2 O, CO 2 or H 2 O/CO 2 , and promising electrode performances have also been observed1314151617. However, the LSCM, as a p-type conductor, is not well adapted to strong reducing potentials.…”

mentioning

confidence: 99%

In situ Growth of NixCu1-x Alloy Nanocatalysts on Redox-reversible Rutile (Nb,Ti)O4 Towards High-Temperature Carbon Dioxide Electrolysis

Wei

Zhang

et al. 2014

Sci Rep

Self Cite

“…However, this cathode is not ideally adapted to a strong reducing potential due to the p-type conduction mechanism of the LSCM, which results in a large electrode polarization resistance. In addition, our previous study demonstrated that strong reducing potentials can lead to adverse chemical and structural changes in LSCM under the electrolysis conditions12.…”

mentioning

confidence: 98%

“…Some reports have indicated that the deposition of carbon is likely caused by reactions that occur over the catalyst, and carbon deposition is likely to occur when hydrocarbons exist in the reactants1011. Recently, perovskite (La 0.75 Sr 0.25 ) 0.95 Mn 0.5 Cr 0.5 O 3 (LSCM) has been demonstrated to be an efficient ceramic cathode for direct CO 2 electrolysis in the absence of a reducing gas flowing over the composite cathode12. However, this cathode is not ideally adapted to a strong reducing potential due to the p-type conduction mechanism of the LSCM, which results in a large electrode polarization resistance.…”

mentioning

confidence: 99%

In situ formation of oxygen vacancy in perovskite Sr0.95Ti0.8Nb0.1M0.1O3 (M = Mn, Cr) toward efficient carbon dioxide electrolysis

Zhang

Wei

et al. 2014

Sci Rep

Self Cite

In this work, redox-active Mn or Cr is introduced to the B site of redox stable perovskite Sr0.95Ti0.9Nb0.1O3.00 to create oxygen vacancies in situ after reduction for high-temperature CO2 electrolysis. Combined analysis using X-ray diffraction, X-ray photoelectron spectroscopy, transmission electron microscopy and thermogravimetric analysis confirms the change of the chemical formula from oxidized Sr0.95Ti0.9Nb0.1O3.00 to reduced Sr0.95Ti0.9Nb0.1O2.90 for the bare sample. By contrast, a significant concentration of oxygen vacancy is additionally formed in situ for Mn- or Cr-doped samples by reducing the oxidized Sr0.95Ti0.8Nb0.1M0.1O3.00 (M = Mn, Cr) to Sr0.95Ti0.8Nb0.1M0.1O2.85. The ionic conductivities of the Mn- and Cr-doped titanate improve by approximately 2 times higher than bare titanate in an oxidizing atmosphere and 3–6 times higher in a reducing atmosphere at intermediate temperatures. A remarkable chemical accommodation of CO2 molecules is achieved on the surface of the reduced and doped titanate, and the chemical desorption temperature reaches a common carbonate decomposition temperature. The electrical properties of the cathode materials are investigated and correlated with the electrochemical performance of the composite electrodes. Direct CO2 electrolysis at composite cathodes is investigated in solid-oxide electrolyzers. The electrode polarizations and current efficiencies are observed to be significantly improved with the Mn- or Cr-doped titanate cathodes.

“…17 To date, there have been some reports confirming the feasibility and superiority of direct electrolyzing CO 2 without feeding reducing gas. [29][30][31] Gorte et al 29 found that SOE with La 0.8 Sr 0.2 Cr 0.5 Mn 0.5 O 3 (LSCM) composite electrode can operated in pure CO 2 . However, the large reducing potential required for CO 2 reduction can cause structural change of LSCM, leading to a large polarization resistance.…”

mentioning

confidence: 99%

Electrolysis of Carbon Dioxide in a Solid Oxide Electrolyzer with Silver-Gadolinium-Doped Ceria Cathode

Xiao

Liu

et al. 2015

J. Electrochem. Soc.

Splitting CO 2 into CO and pure O 2 at high temperature through solid oxide electrolyzers (SOEs) could provide an efficient way for energy storage and CO 2 utilization. Tubular solid oxide electrolysis cells, with yttrium-stabilized-zirconia (YSZ) as electrolyte, strontium-doped lanthanate (LSM) as anode, cermet of Ag-GDC (gadolinium-doped-ceria) as cathode, is fabricated and operated as SOEs for electrolysis of pure CO 2 . Such an SOE shows a minimum electrolyzing voltage of 0.70 V and a current density of 1359 mA cm −2 at 2 V. Its CO production rates are 3.1, 6.6 and 10.0 mL min −1 at electrical currents of 0.5, 1.0 and 1.5 A, respectively, at 800 • C. The corresponding Faraday efficiencies are 88.6%, 94.3%, and 95.2%, and the electrical energy conversion efficiencies are 75.4%, 65.2%, and 56.5%, respectively. An SOE with Ag-GDC electrode is steadily operated at 1.59 V for pure CO 2 electrolysis at 800 • C for 18 h, suggesting that Ag-GDC is a promising cathode material for SOEs of CO 2 electrolysis. Energy storage plays an extremely important role in peak load shifting of traditional power plant and in effective application of intermittent renewable energies such as solar, wind, and tide, etc.1,2 Solid oxide electrolyzers (SOEs) have attracted more and more attention in recent years due to their environmental-friendliness and high efficiency in storing energy by converting electrical energy into chemicals such as hydrogen or carbon monoxide through electrolysis of water or carbon dioxide. [3][4][5][6] In principle, SOEs work in the reverse manner of high temperature solid oxide fuel cells (SOFCs). 6 A cathode of an electrochemical cell is the electrode where reduction reaction occurs, and an anode is where oxidation reaction occurs. An electrode functioning as the anode of an SOFC will work as the cathode when the cell is operated in an SOE mode. At the same time, the cathode of the SOFC is shifted to be the anode of the SOE. Nevertheless, the electrode on the air or oxygen side always has a higher potential than that on the fuel (or CO 2 rich or H 2 O rich) side. The former electrode can be called as oxygen electrode or positive electrode (+) and the latter fuel electrode or negative electrode (−), as marked in Fig. 1. Using external electricity, SOEs are able to electrochemically convert steam to hydrogen and carbon dioxide to carbon monoxide at the fuel electrode. At the same time, pure oxygen can be obtained at the oxygen electrode.While high temperature steam electrolysis has got great progress in producing hydrogen, which is a well-known green alternative energy carrier, 7-12 CO 2 electrolysis using the SOEs for CO 2 capture and storage as well as utilization has also attracted increasing research interests due to the great concern of global climate changes caused by the greenhouse effect.13-20 CO produced from CO 2 electrolysis at the cathode of an SOE can be used as the fuel of an SOFC for generating electricity or as a feed stock for producing synthetic fuel via Fischer-Tropsch synthesis. 16 Pure oxy...