Facile Preparation of High‐Surface‐Area Three‐Dimensional Macroporous LaCoO ₃ From Silica Colloidal Crystal Template Approach for the Catalytic Combustion of Soot

ABSTRACT

Given the inherent particle size characteristics of soot particles, the introduction of three‐dimensionally ordered macroporous (3DOM) structures into perovskite oxides is an effective strategy for boosting the catalytic performance of soot combustion. Nevertheless, the synthesis of 3DOM perovskite oxides is greatly limited by the inferior thermal stability of traditional organic templates, especially for Co‐based perovskites that require high‐temperature calcination. In this work, high‐surface‐area 3DOM LaCoO ₃ was successfully synthesized via a novel silica templating route. The physicochemical properties of the as‐prepared catalysts were systematically characterized. In situ TG‐DSC and SEM were employed to track the detailed preparation process and elucidate the underlying formation mechanism. Benefiting from the excellent thermal resistance of the silica template, the ordered macroporous framework can be well preserved even at elevated temperatures, endowing 3DOM LaCoO ₃ with smaller crystallite sizes and a well‐defined 3DOM architecture. Moreover, alkali treatment effectively enriches surface Co ³⁺ species and in situ generates La(OH) ₃ , thereby strengthening NO adsorption and oxidation over the catalyst. Owing to improved catalyst‐soot contact and enhanced intrinsic catalytic activity, the silica‐templated 3DOM LaCoO ₃ catalyst exhibits catalytic performance comparable to that of noble metal Pt catalysts under loose contact conditions.