Flame Spray Pyrolysis Synthesis of Ultra‐Small High‐Entropy Alloy‐Supported Oxide Nanoparticles for CO2 Hydrogenation Catalysts

Abstract The synthesis of high‐entropy alloys (HEAs) with ultra‐small particle sizes has long been a challenging task. The complex and time‐consuming synthesis process hinders their practical application and widespread adoption. This study presents the novel synthesis of TiO 2 nanoparticles loaded with a quinary high‐entropy alloy through flame spray pyrolysis (FSP) for the first time. The extremely fast heating rate of flame combustion makes the precursor fast pyrolysis gasification, high temperature in the flame field promotes the metal vapor mixing uniformly, and the fast quenching process can reduce the particle aggregation sintering, the ultra‐small particle size of HEA firmly attached to the TiO 2 surface. The catalysts prepared via this gas‐to‐particle pathway exhibit excellent performance in CO 2 hydrogenation, achieving a conversion rate of 62% at 450 °C, and maintaining their activity for over 220 h without significant particle agglomeration. This finding provides valuable insights for the future design of catalytically active materials with enhanced activity and long‐term stability.