PtNi nanoparticles embedded in porous silica microspheres as highly active catalysts for p -nitrophenol hydrogenation to p -aminophenol

Supported Pt-based alloy nanoparticles have attracted greater attention in catalysis due to their high activity, reduced cost, and easy recycling in chemical reactions. In this work, mesoporous SiO 2 microspheres were employed as support to immobilize PtNi alloy nanocatalysts with different mass ratios of Pt and Ni (1:0, 3:1, 1:1, 1:3 and 0:1) by a facile in situ one-step reduction in the absence of any capping agent. SEM, EDS, TEM, FTIR, XRD, ICP-AES, XPS and nitrogen adsorption/desorption analysis were employed to systematically investigate the morphology and structure of the obtained SiO 2 microspheres and SiO 2 /PtNi nanocatalysts. Results show that uniform PtNi nanoparticles can be homogeneously and firmly embedded into the surface of SiO 2 microspheres. When the as-prepared SiO 2 /PtNi nanocatalysts were used in the reduction process of p -nitrophenol to p -aminophenol, the nanocatalyst with Pt and Ni mass ratio of 1:3 showed the highest catalytic activity (TOF of 5.35 × 10 18 molecules⋅ g −1 ⋅ s −1 ) and could transform p -nitrophenol to p -aminophenol completely within 5 min. The SiO 2 /PtNi nanocatalyst can also maintain high catalytic activity in the fourth cycle, implying its excellent stability during catalysis. Graphical Abstract PtNi was embedded into mesoporous SiO 2 surface to avoid its aggregation and loss in catalysis. SiO 2 /PtNi(1:3) catalyst can be used/reused as efficient catalyst with high activity and stability.