Mixed Conducting Perovskite Materials as Superior Catalysts for Fast Aqueous-Phase Advanced Oxidation: A Mechanistic Study

Abstract

A mixed ionic−electronic conducting (MIEC) double perovskite, PrBaCo 2 O 5+δ (PBC), was synthesized and evaluated as the heterogeneous catalyst to generate radicals from peroxymonosulfate (PMS) for the oxidative degradation of organic wastes in aqueous solution. A superior catalytic activity was obtained for PBC, which was much higher than that of the most popular Co 3 O 4 nanocatalyst. More importantly, a detailed mechanism of PMS activation on the MIEC perovskite was proposed. Electron paramagnetic resonance (EPR) and radical competitive reactions suggested that both sulfate radicals (SO 4 •−) and hydroxyl radicals ( • OH) participated in and played important roles in the catalytic oxidation processes. Oxygen temperature-programmed desorption (O 2 -TPD) demonstrated that the PBC perovskite oxide is capable of facilitating an easier valence-state change of the B-site cation (cobalt ions) to mediate a redox process. Additionally, the oxygen vacancies could facilitate the bonding with PMS molecules and promote the reactivity of cobalt ions for PMS activation. Electrochemical impedance spectroscopy (EIS) was also performed to evidence charge transfer and surface reaction rates of the PBC catalyst that are much faster than those of Co 3 O 4 . Additionally, suppressed cobalt leaching was also achieved through tailoring the pH value of the reaction solution. This study provides insight into MIEC perovskites in catalytic reactions and applications.

Effect of Two‐Dimensional Crystal Orbitals on Fermi Surfaces and Electron Transport in Three‐Dimensional Perovskite Oxides

“…Perovskite oxides span numerous compositions and are heavily studied as materials for catalytic, fuel cell, thermoelectric, and oxide electronics applications . SrTiO 3 is a particularly promising candidate for electronics, because it supports two‐dimensional electron gases at its surfaces and interfaces, which may lead to new device applications .…”

Effect of Two‐Dimensional Crystal Orbitals on Fermi Surfaces and Electron Transport in Three‐Dimensional Perovskite Oxides

“…Perovskite oxides span numerous compositions and are heavily studied as materials for catalytic, [1][2][3][4] fuel cell, [5][6][7][8] thermoelectric, [9][10][11][12] and oxide electronics applications. [13][14][15][16] SrTiO 3 is ap articularly promising candidate for electronics, because it supports two-dimensional electron gases at its surfaces and interfaces, [17][18][19] which may lead to new device applications.…”

Fine‐Tuning Surface Properties of Perovskites via Nanocompositing with Inert Oxide toward Developing Superior Catalysts for Advanced Oxidation

“…In addition, L 1+ x FO ( x > 0) catalysts with higher zeta potentials and positively charged surfaces (Figure a) were conducive for MO and H 2 O 2 adsorption hence reinforcing the catalytic oxidation. Moreover, the charge‐transfer ability may have a great influence on H 2 O 2 activation . The electrochemical impendence spectroscopy (EIS) evaluation in Figure d was conducted to probe the charge transport capacity at the interfaces between L 1+ x FO with H 2 O 2 .…”