Preparation And Catalytic Performance Of PH-responsive Mesoporous Janus Composite Nanosheets

Responsive mesoporous Janus m Si O₂nanosheet catalysts have attracted considerable research interests in the field of interface catalysis.This dissertation focuses on the controllable preparation and catalytic performance of p H-responsive mesoporous Janus m Si O₂composite nanosheets.The main contents are as follows:?1?Preparation and catalytic performance of NH₂-based Janus mesoporous nanosheets of CSN-Au-MSJN.First,co-precipitation method was used to prepare ZIF-67 nanoparticles.Subsequently,core-shell ZIF-67@m Si O₂with mesoporous silica?m Si O₂?layer deposited on ZIF-67 was prepared by a sol-gel of TEOS under basic conditions.ZIF-67@m Si O₂-NH₂was then crafted by the modification of the outside m Si O₂layer of ZIF-67@m Si O₂with 3-aminopropyl trimethoxysilane?APTMS?.Mesoporous Janus nanosheets?HO-m Si O₂-NH₂?tethered with hydroxyl?-OH?on one side and amino group?-NH₂?on the other side were derived from the etching of ZIF-67 with HCl,which were further converted into amphiphilic mesoporous Janus nanosheets(C₁₈-m Si O₂-NH₂)by reacting with octadecyltrimethoxysilane?ODTMS?.Finally,C₁₈-m Si O₂-NH₂@Au?CSN-Au-MSJN?was obtained owing to the coordination interaction between-NH₂and the precursor of HAu Cl₄.Furthermore,the emulsification performance of CSN-Au-MSJN was studied,and the reduction reaction of nitro compounds was used as a model reaction to investigate the homogeneous and emulsion interface catalytic performance of CSN-Au-MSJN.The results demonstrated that CSN-Au-MSJN exhibited p H-triggered emulsification and de-emulsification performance,and the catalytic performance in homogeneous system and emulsion was related to p H value and oil phase,respectively.In addition,CSN-Au-MSJN showed good recyclability.?2?Preparation and catalytic performance of P4VP-based Janus mesoporous nanosheets of CSP-Au-MSJN.At first,ATRP-reactive ZIF-67@m Si O₂-NH₂was produced by the amidation between-NH₂and 2-bromoisobutyryl bromide?BIBB?,and mesoporous Janus nanosheets?HO-m Si O₂-Br?with a-OH on one side and a bromine?-Br?on the other side was then obtained after removing ZIF-67.Under the catalysis of Cu Br,poly-vinylpyridine?P4VP?was grafted onto the–Br side of HO-m Si O₂-Br,and the-OH side was also converted into hydrophobical C₁₈by ODTMS,yielding amphiphilic mesoporous Janus nanosheets with P4VP on one side and C₁₈on the other side(C₁₈-m Si O₂-P4VP).Finally,C₁₈-m Si O₂-P4VP@Au?CSP-Au-MSJN?was created through the coordination interaction between P4VP and HAu Cl₄.Similarly,the emulsification and catalytic performance of CSP-Au-MSJN was studied.The results showed that CSP-Au-MSJN manifested p H-responsive emulsification-deemulsification and excellent catalytic activity in homogeneous system and at emulsion interface.Its homogeneous catalytic activity was mainly affected by p H,and the catalytic activity at emulsion interface was related to the type of oil phase.CSP-Au-MSJN exhibited better catalytic performance than CSN-Au-MSJN at emulsion interface due to the densely grown Au NPs.