A tri-layer approach to controlling nanopore formation in oxide supports

摘要

A novel tri-layer approach for immobilizing metal nanoparticles in SiO2 supports is presented.In this work,we show that under rapid heating to temperatures of approximately 1,000 ℃,metal nanoparticles less than 15 nm in size will entrench in the SiO2 layer on a silicon wafer to create pores as deep as 250 nm.We studied and characterized this entrenching behavior and subsequent nanopore formation for a wide variety of metal nanoparticles,including Au,Ag,Pt,Pd,and Cu.We also demonstrate that an Al2O3 layer acts as a barrier to such pore formation.Thus,by creating a tri-layer architecture consisting of SiO2 on Al2O3 on silicon wafers,we can control the depth to which nanoparticles entrench between 3-5 nm.This small range allows one to entrench particles for the purpose of immobilization but still present them above the surface.The two advances of moving into the sub-15 nm size regime and of controlled particle immobilization through entrenchment have important implications in studying site-isolated and stabilized metal nanoparticles for applications in sensing,separations,and catalysis.