Preparation Of RGO-Mesoporous Silica Nanosheets As Pickering Interfacial Catalysts

A series of reduced graphene oxide-mesporous silica nanoflakes（rGO-MSN）with adjustable surface wettability were developed.Detailed SEM,TEM,XRD,BET,and TGA analyses demonstrated that morphologies,structures,porosities of the obtained composite materials were greatly influenced by rGO content.Moreover,micrographs and conductivity measurements were conducted to investigate the performance of rGO-MSN as emulsifier in stabilizing paraffin/water two-phase system.Furthermore,anchored with–SO₃H,the modified hybrid nanoflakes SO₃H-rGO-MSN-x%were employed as solid emulsifier and catalyst（Pickering Interfacial catalyst）at solvent free oil-oil interface for acetal reaction and showed excellent dodecyl aldehyde conversion more than 90%.（1）Synthesis of rGO-Mesoporous Silica nanosheets（rGO-MSN）:we reported a sol-gel method to prepare reduced graphene oxide-mesoporous silica nanoflakes（rGO-MSN）.By tuning the addition of GO and TEOS（the source of rGO and silica）,we modified the wettability of rGO-MSN.Moreover,the morphologies,structures,porosities of the obtained materials were investigated.It was found that the silica pore channels are vertical to the reduced graphene oxide sheet from both sides.Analyses showed the increasing amount of GO could destroy the long-range ordering,enlarge the pore diameter distribution interval and reduce the BET surface area of the rGO-MSN.With the increasing addition amount of GO,the rGO exposed in hybrid nanosheets enlarged,at the same time,contact angle of rGO-MSN decreased.（2）Preparation of water-rGO-MSN-paraffin Pickering emulsions:The rGO-MSN were employed as emulsifier in paraffin/water emulsions.Furthermore,micrographs and conductivity measurements were conducted to investigate the performance of rGO-MSN as emulsifier.The optical microscope images of the Pickering emulsions with varying amounts of r GO-MSN-10%were recorded and showed a regular change as previously reported.（3）Intensification of acetal reaction:Anchored with–SO₃H,the modified hybrid nanoflakes SO₃H-rGO-MSN were employed as solid emulsifier and catalyst（Pickering Interfacial catalyst）at solvent free oil-oil interface for acetal condensation reaction.The catalytic performance of the prepared materials was investigated.SO₃H-rGO-MSN-10%and SO₃H-rGO-MSN-15%showed high C₁₂-aldehyde conversions and fast reaction rates.