Stepwise Preparation of Uniform-Size Ultrafine Pt Nanoparticles for High-Performance Catalysis of Methanol Oxidation and Nitrophenol Reduction

Ultrafine Pt nanoparticles (Pt UPs) were prepared using a stepwise modulation approach, ensuring consistent reaction kinetics throughout each step to achieve uniform size and high dispersion of Pt UPs. The morphology of the Pt nanoparticle was precisely controlled by managing the reaction conditions at each step, thereby enhancing the catalytic activity of the Pt metals. In order to form photoinduced hydrolysis products with different dispersions and particle sizes, two steps were conducted. First, homogeneously dispersed photoinduced hydrolysis products were adsorbed on nitrogen-doped multiwalled carbon nanotubes using ice photochemistry under stabilizer-free conditions. Second, these products were photoinduced by using different wavelengths of light. Subsequent in situ reduction with various reducing agents influenced the composition, particle size, and dispersion degree of the Pt UPs. Furthermore, the subtle charge transfer between the supporter and Pt was adjusted by employing low- and high-temperature nitrogen doping methods, resulting in Pt UPs with electron-deficient and electron-rich charge structures on the surface. This study offers insights into the precise modulation of the Pt nanoscale morphology and reveals the subtle adjustments in charge transfer between the supporter and the metal through nitrogen doping. Additionally, the origin of the catalytic activity of Pt in various reactions was explored.