Catalytic Properties of Double Substituted Lanthanum Cobaltite Nanostructured Coatings Prepared by Reactive Magnetron Sputtering

Abstract

Lanthanum perovskites are promising candidates to replace platinum group metal (PGM), especially regarding catalytic oxidation reactions. We have prepared thin catalytic coatings of Sr and Ag doped lanthanum perovskite by using the cathodic co-sputtering magnetron method in reactive condition. Such development of catalytic films may optimize the surface/bulk ratio to save raw materials, since a porous coating can combine a large exchange surface with the gas phase with an extremely low loading. The sputtering deposition process was optimized to generate crystallized and thin perovskites films on alumina substrates. We found that high Ag contents has a strong impact on the morphology of the coatings. High Ag loadings favor the growth of covering films with a porous wire-like morphology showing a good catalytic activity for CO oxidation. The most active composition displays similar catalytic performances than those of a Pt film. In addition, this porous coating is also efficient for CO and NO oxidation in a simulated Diesel exhaust gas mixture, demonstrating the promising catalytic properties of such nanostructured thin sputtered perovskite films.

Unusual Phase Formation in Reactively Sputter‐Deposited La—Co—O Thin‐Film Libraries

“…Moreover, in general, there are only a few reports on combinatorial approaches for the sputter fabrication and characterization of La‐based perovskite forming systems like La x Ta 1− x O y N z , [ 26 ] LaFeO 3 , and LaFeO 3− x N x [ 27 ] exist. Most studies focused on the fabrication of discrete perovskite compositions or sputtering from a perovskite‐composition target, like reported for LaCoO 3 , [ 28,29 ] La—Cu—O, [ 30 ] La—Ni—O, [ 31,32 ] LaMnO 3 , [ 33 ] La—Pb—Mn—O, [ 34 ] LaVO 3 , [ 35 ] La—Ti—O, [ 36 ] or LaCrO 3 . [ 37 ] Since none of the studies investigated a larger compositional range of the described La—M—O (M = transition metal) systems, no unusual film growth or phase formation behavior such as reported in this work, was observed.…”

Sputter‐Deposited La–Co–Mn–O Nanocolumns as Stable Electrocatalyst for the Oxygen Evolution Reaction

“…A comparable structure formation was observed during hot sputter deposition of La-Co-O, [33] whereas nanostructure formation was observed for a Sr-and Ag-substituted La-Co-O system. [34,35] The SEM image in Figure 2b shows the columns in a pristine, as-grown state in top view. The SEM image in Figure 2c is taken from a region where the columns were intentionally broken on the substrate, and Figure 2d shows a TEM image of the columnar structures in cross-section.…”

Emissions Control Catalysis

“…On the other hand, a major part of contributions (9/21) concerns original research on nitrogen oxides reduction processes [20][21][22][23][24][25][26][27][28], reflecting the fact that this topic still remains hot among the targets of environmental catalysis. Five out of 21 studies concern CO and hydrocarbons oxidation processes [29][30][31][32][33] while the remained 4/21 concern CO 2 capture/recycling processes under the view of cyclic economy [34][35][36][37].…”

“…Briois and co-workers [30] in an attempt to provide means of replacing expensive platinum group metals with cost-effective perovskite type materials for catalytic oxidation reactions, prepared thin catalytic coatings of Sr and Ag doped lanthanum perovskites, La 1−x−y Sr x Ag y CoO 3−α (x = 0.13-0.28, and y = 0.14-0.48), on alumina substrates by using the cathodic co-sputtering magnetron method in reactive condition. Such thin porous catalytic film arrangements can optimize the surface/bulk ratio by combining a large gas exposure surface area with an extremely low loading, thus saving raw materials.…”