| In this thesis,the interfacial behaviors of two-dimensional nanomaterials including graphene oxide nanosheets and graphene membrane at the liquid/liquid interface was investigated by electrochemical methods.The main work focuses on the adsorption behavior of graphene oxide nanosheets and its effect on ion transfer reactions.In addition,the effect of the modification of liquid/liquid interface by graphene membrane on the ion transfer reactions was preliminarily investigated.On one hand,graphene oxide(GO)has been viewed as an amphiphilic molecule or a soft colloidal particle.So far,most extant works concerning the adsorption behaviors of GO at the liquid/liquid interface(L/L interface)have been limited to the non-polarized L/L interface.However,the adsorption mechanism of GO at the L/L interface under the external electric field and its impacts on some reactions occurring at the L/L interface remain unclear.In this thesis,the adsorption of GO at an interface between two immiscible electrolyte solutions under external polarization was studied by employing cyclic voltammetry(CV)and alternating current voltammetry(ACV).Capacitance measurements by ACV show that the interfacial capacitance increases greatly in the presence of GO nanosheets inside aqueous phase,which can be attributed to the increases of charge density and roughness induced by the parallel adsorption and assembly of GO at the L/L interface.In addition,it is found that the application of an interfacial potential difference by the external polarization can promote the adsorption of GO at the L/L interface.Moreover,the ion-transfer(IT)voltammetric results further demonstrate that the GO layers formed at the interface can hinder the IT reactions due to the interfacial steric hindrance and charge repulsion effect.This work helps to further understand the adsorption behavior of GO at the L/L interface more comprehensively,and also helps to study the interface adsorption and the drug ions release process of the graphene oxide nano drug delivery platform on the nano-biological interface.On the other hand,a multilayer graphene membrane was used to modify the water/1,2-dichloroethane(W/DCE)interface for the first time,and the IT behaviors at the W/DCE interface modified by graphene membrane was preliminarilyinvestigated by employing cyclic voltammetry(CV)and differential pulse voltammetry(DPV).It was found that the W/DCE interface modified by graphene membrane presents a remarkable extension of the polarization window,which is larger than the value(800-1500 m V)obtained at the bare W/DCE interface.In addition,it is found that ion-transfer voltammetric responses can be observed within the electrochemical window obtained at the W/DCE interface modified by graphene membrane.Based on the recent reports on the membrane-modified liquid/liquid interface electrochemistry and the graphene membrane-based molecule or ion nanofiltration,the remarkable extension of the polarization window as observed at the W/DCE interface modified by graphene membrane could be attributed to the the sieving effect of graphene membrane on the supporting electrolyte ions,and the ion-transfer voltammetric responses within the potential window should be closely related to the cation-? interaction between the cation and the aromatic ring in the graphene membrane.This work cannot only enrich the studies of membrane-modified liquid/liquid interface electrochemistry,but also help to understand the ion transport process within the multilayer graphene membrane.In conclusion,the adsorption behavior of graphene oxide nanosheets at the liquid/liquid interface and the effect of the modification of liquid/liquid interface by multilayer graphene membrane on the ion transfer reactions have been investigated in this thesis,which is expected to not only enrich the research of nanomaterial-modified liquid/liquid interface electrochemistry,but also help to further extend the applications of liquid/liquid interface electrochemistry in the nanomaterials. |
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