A general synthesis strategy of multi-metallic nanoparticles within mesoporous titania via in situ photo-deposition†
The design and preparation of efficient, stable and economical supported multi-metallic nanoparticles (MMNPs) has been a major direction in many applications especially in the catalysis area. The conventional methods for MMNP synthesis are generally complex and lack tight control over the composition. Herein, we report a simple and general method for the synthesis of MMNPs within extra-large three-dimensional mesoporous titania (EP-TiO2), based on a one-step, versatile in situ photo-deposition process. The successful simultaneous photo-deposition of multi-metallic precursors allows us to synthesize a series of supported MMNPs (AuPt/AuPd/PtPd/AuPtPd). The composition of MMNPs can be easily controlled by changing the initial molar ratio of metal precursors. Furthermore, the metal alloying process is carried out under low-temperature annealing in air, which benefits from the extra-large mesoporous networks of EP-TiO2 with significantly reduced particle-migration probability. For AuPt/EP-TiO2, a homogeneous alloy structure is obtained after annealing at 350 °C, with Au50Pt50 showing optimum activity in the catalytic combustion of n-hexane. It is expected that the one-step in situ photosynthesis of MMNPs within mesoporous materials has profound implications toward the design of better catalytic nano-architectures.