One-step redox precipitation engineering Pt–Mn solid solutions in hollow MnO2 for ultralow-temperature CH4 oxidation

A HRP (hydrolysis-driven redox precipitation) strategy is developed to synthesize Pt-MnOx hollow-sphere/nanorod composites with tunable Mn/Pt ratios (2–13), enabling one-step construction of Pt–Mn solid solutions while circumventing phase separation in conventional co-precipitation. The optimized HRP-4Mn1Pt catalyst (Mn/Pt = 5) delivers an ultrahigh specific surface area (276.2 m2/g) and exceptional low-temperature methane oxidation activity (T50 = 325 °C, T90 = 334 °C at 30 000 ml g−1 h−1), representing a 15%–20% improvement in catalytic efficiency over conventional Pt/MnO2 catalysts [Li et al., Colloids Surf. A 665, 131248 (2023) and Liang et al., Mol. Catal. 547, 113380 (2023)], maintaining stability for 48 h. Our investigation into the reaction mechanism shows that adding Pt2+ distorts the MnO2 crystal structure. This distortion creates more gaps for oxygen (oxygen vacancies) and makes the catalyst easier to reduce, as shown by a peak at 228 °C in our H2-TPR measurements. This enhanced ability to transport oxygen is key to the catalyst’s high performance.