Solid ion transition route to 3D S-N-codoped hollow carbon nanosphere/graphene aerogel as a metal-free handheld nanocatalyst for organic reactions

摘要

A novel metal-free bulk nanocatalyst,S-N-codoped hollow carbon nanosphere/graphene aerogel (SNC-GA-1000),has been successfully fabricated using a facile and clean solid ion transition route.In this method,ZnS is used as the hard template and S source,while polydopamine acts as a reducing agent and carbon source.At a high annealing temperature,Zn metal is reduced and evaporates,leaving only free S vapor to diffuse into the carbon layer.Interestingly,the as-obtained SNC-GA-1000 exhibits much higher catalytic activity in an organic reduction reaction than unloaded bare S-N-codoped carbon nanospheres.Hydrothermal reduction of the graphene oxide sheets loaded with ZnS@polydopamine core-shell nanospheres (ZnS@PDA) affords a three-dimensional bulk graphene aerogel.Although nanosized catalysts exhibit high catalytic activities,their subsequent separation is not always satisfactory,making post-treatment difficult.This approach achieves a trade-off between activity and separability.More importantly,due to the 3D structural nature,such bulk and handheld nanocatalysts can be easily separated and recycled.