Preparation And Application Of Copper Based Complexes And Transition Metal Oxides With Localized Surface Plasmon Resonances

In recent years,nanomaterials with LSPR properties had attracted extensive attention.The purpose of our work was to study the synthesis of high quality copper based metal and metal chalcogenides and transition metal oxide semiconductor with LSPR properties,then achieved the morphology and size control,explored the related mechanism,and finally expanded the application in photothermal and photocatalysis.The main research contents were as follows:In chapter two,a high-efficiency top-down approach was used to fabricate colloidal nanocrystals of orthorhombic Mo O_3-x(α-Mo O_3-x),in which oleic acid（OA）and oleylamine（OAm）were used as surface-capping agents.The oxygen defect generation processes of these nanocrystals were thoroughly investigated.Mo-O bond could be broken to form oxygen defects through the synergic effect of OA and OAm,in which OA providing H⁺ions and OAm contributing free electrons.Theα-Mo O_3-xnanocrystals showed prominent photothermal conversion effects owing to the strong plasmonic absorption in NIR.Recently ultrathin two-dimensional semiconducting materials have attracted wide attention due to their unique properties.However,the preparation of these nanosheets still remains to be a great challenge.In chapter three,a general one-step colloidal method was used to fabricate ultrathin MO_3-x（M=Mo or W）nanosheets by using H₂Mo O₄ or H₂WO₄ as the raw material with the assistance of oleic acid（OA）and oleylamine（OAm）.They not only displayed intense plasmonic absorptions but also possessed relatively high specific surface areas.The specific surface areas of as-prepared Mo O_3-x and WO_3-x nanosheets were 13.97 and 11.82 m² g^-1,which were4.4 and 4.5 times higher than those of pristine H₂Mo O₄ and H₂WO₄,respectively.Besides,these MO_3-x nanosheets also had superior photocatalytic H₂ evolution performance through the dehydrogenation of ammonia borane under visible light irradiation.The construction of the 2D/2D heterostructured photocatalysts had proven to be an useful means to promote the charge separation for enhancing the photocatalytic efficiencies.In chapter four,the 2D/2D Cu₇S₄/Cd S Janus-type nanoplatelet was designed and prepared by one-pot colloidal method.The prepared 2D-2D nanoplatelet could provide rich active sites for catalytic reaction and had a great deal of low-coordinated atoms,which was in favor of solar light absorption.Based on these outstanding properties,the 2D/2D Cu₇S₄/Cd S Janus-type nanoplatelet displayed dramatically improved photocatalytic hydrogen evolution rates of up to 5885.9μmol g^-1 h^-1 under visible light irradiation（λ>420 nm）,which was 9 times higher than pure Cd S.The photocurrent response results manifested that the improved H₂ evolution activity was mainly attributed to enhanced charge separation efficiency.The fast oxidation of plasmonic Cu nanomaterials caused by surface absorbed oxygen has been a serious problem and hindered their applications in many aspects.In chapter five,a lollipop-shaped Cu@Cu2O/Zn O heterojunction with a core-shell head and a rod-like stem was successfully prepared by colloidal chemical method,exhibiting ultra-long term stability against air oxidation in hexane.The enhanced stability of Cu@Cu₂O/Zn O was due to the presence of zinc acetate,which resulted in the crystal face reconstruction of Cu@Cu₂O and the formation of a thin surface carboxylate coordination layer on the partial surface of Cu@Cu₂O.The passivation layer effectively hindered absorption of surface oxygen,thus reducing the oxidation rate of Cu.