Insight into the Electrochemical Processes of the Titanate Electrode with in Situ Ni Exsolution for Solid Oxide Cells

Abstract

Perovskite-type titanate with in situ exsolution is one promising electrode material for solid oxide cells because of its distinct properties to resist redox operation, carbon deposition, and sulfur contamination. However, lacking a mechanistic understanding of the electrochemical processes significantly hinders further optimization of the exsolved titanate electrode for its practical application. In this study, the in situ growth of Ni nanoparticles and its effect on the electrode processes was investigated on the Ni-doped Sr0.94Ti0.9Nb0.1O3‑δ electrode for solid oxide cells. Four individual electrode processes were distinguished and determined by equivalent circuit modeling and distribution of relaxation times analysis of the electrochemical impedance data. Correlated with in situ and ex situ characterizations, it is revealed that the electrochemical processes were dominated by the surface reaction process, which was substantially activated by the exsolution of Ni nanoparticles by providing catalytically active sites and accelerating the rate of H2/H2O dissociative adsorption.

Rational Design of Two-Layer Fe-Doped PrBa0.8Ca0.2Co2O6−δ Double Perovskite Oxides for High-Performance Fuel Cell Cathodes

“…The polarization resistance (R pol ) was determined from the intercepts of the high-and low-frequency arcs with the real axis of the Nyquist plot and modeled using ECs. 34 Under the same conditions (400 sccm air), the R pol values of the PBCCFe5 and PBCCFe40 electrodes were 0.017 and 0.038 Ω cm −2 at 700 °C, respectively, and 0.225 and 0.394 Ω cm −2 at 550 °C, respectively (Supporting Information, Figure S2 and Table S2). The DRT method was employed to further clarify the electrode reaction processes of the enhancement in R pol .…”

Progress of Exsolved Metal Nanoparticles on Oxides as High Performance (Electro)Catalysts for the Conversion of Small Molecules

“…Similar to the previous section, materials with exsolved single metal nanoparticles were widely investigated as catalysts for water electrolysis. The exsolved metal species include Ni, [ 54,56,83,123–128 ] Cu, [ 83,142,143 ] and Fe. [ 54,93,132–134 ] Besides the exsolution of single metal nanoparticles, the exsolution of alloy nanoparticles, such as Fe–Ni [ 147,148 ] and Co–Fe, [ 154,157 ] was also reported to enhance the activity of the catalysts for high temperature steam electrolysis.…”

New Insight into the Doped Strontium Titanate Cathode with In Situ Exsolved Nickel Nanoparticles for Electrolysis of Carbon Dioxide

“…[ 4 ] To facilitate this process, cathodes containing metal catalyst such as nickel are generally needed. [ 5 ]…”

“…On the contrary, some perovskites with ABO 3 structure could be used as cathodes for SOE without protective gases, but their performance must be improved by proper doping. [ 3a,6c,8 ] About one decade ago, doped SrTiO 3 was used in solid oxide fuel cells as anode material, [ 5,9 ] then La doped SrTiO 3 (LST) was reported to be used as cathode material for SOE application. [ 10 ] Other elements, such as Al, Ga, Fe, Mg, Mn, Sc, Ni, and Cr, had also been doped into SrTiO 3 for application in SOE.…”

“…It is of value to do more research on the questions about structure alternation after exsolution, the diffusion distance of metal ions in lattice, and the effect on the rate of oxygen ion diffusion and how it influences the electrochemical processes during CO 2 electrolysis. [ 5 ]…”