Microwave-Assisted Synthesis of Pt Nanoparticles via Liquid-Phase Polyol Reaction for Catalytic Volatile Organic Compound Elimination

The microwave-assisted synthesis of functional metal nanoparticles (NPs) has gained considerable interest because of the shorter reaction period, significantly reduced energy consumption, and lower environmental impact compared to conventional heating. Herein, we elucidate the microwave-assisted synthesis of Pt NPs via liquid-phase polyol reaction based on a detailed investigation of the reaction dynamics during synthesis and its correlation with NP growth and crystallinity formation. The reduction behavior of Pt precursor under temperature scale is initially clarified, whose results suggest that precursor reduction plays an important role in deciding the crystallinity of Pt NPs core-state, that is polycrystalline Pt NPs with twinned crystal planes in microwave-assisted fast heating, and single crystalline Pt NPs in microwave-assisted slow heating. In addition, through a systematic comparison with oil-bath-induced conventional heating under identically controlled experimental conditions, the effect of microwave irradiation on the synthesis of the Pt NPs is also clarified. We also study the volatile oxidation products generated in polyol processes and derived a reaction mechanism distinct from the existing theory. By loading structurally controlled Pt NPs on hydroxyapatite, we successfully develop a high-performance catalyst for the elimination of VOC. Despite the 100-fold lower loading amount of Pt NPs herein compared with previous studies, the developed catalyst exhibits a superior CO2 selectivity of 100% in the oxidative decomposition of VOC under entire low-temperature regions (200–400 °C). The excellent catalytic activity of Pt NPs originating from the unique surface/interface structure tailored by microwave-assisted fast heating is elucidated. The insights from this work not only provide important information on nanomaterial chemistry, but also offer guidance on the design and development of functional nanoparticle catalyst for environmental cleaning.