Strong Effect of B-Site Substitution on the Reactivity of Layered Perovskite Oxides Probed via Isopropanol Conversion

Perovskite oxides have exhibited promising catalytic performance in photocatalysis, electrocatalysis, and thermocatalysis, and the performance can be potentially enhanced by tuning their flexible electronic and crystal structure. The B cations play essential roles in altering the inherent electronic structure and catalytic activity of these perovskite and related layered perovskite oxides. In this work, we establish the relationship of composition (electronic structure) and activity/selectivity of layered perovskites for pure and B-site-substituted Sr2Sn1–xRuxO4 (0 ≤ x ≤ 1). The isopropanol decomposition was chosen as the probe reaction because its divergent reaction pathways through either dehydration or dehydrogenation are sensitive to the solid-state properties of the metal oxide surface. Both parent layered perovskite oxides of Sr2SnO4 and Sr2RuO4 exhibited decent conversion (20%–30%) and selectivity (>80%) to acetone through dehydrogenation pathways over a temperature range of 280–320 °C under atmospheric pressure, while the substituted perovskites, even with 10 at. % substitution of Ru at the B-site showed remarkable enhancement for both activity and selectivity toward acetone. By varying the dopant concentration linearly, both activity and selectivity showed a volcano-shaped dependency on the atomic concentration of the substituent. Overall, the Sr2Sn0.3Ru0.7O4 had the best yield of acetone, which may be ascribed to the optimal eg filling state of the B site for appropriate B–O bond strength during oxygenate adsorption. The current research provides a guide to the rational design of perovskite oxide catalysts for efficient chemical transformation.