Electrochemical fabrication of dendritic silver–copper bimetallic nanomaterials in protic ionic liquid for electrocarboxylation

Abstract

Silver (Ag) and silver–copper (Ag–Cu) bimetallic composite electrodes were electrochemically prepared on a glassy carbon (GC) substrate in triethylammonium acetate (TEAA) by electrodeposition to investigate their suitability as cathodes for electrocarboxylation process. Cyclic voltammetric investigations reveal that with increase in Cu content, both the stripping as well as deposition current of Ag (I) ions decrease with a shift of cathodic and anodic peak potential in the positive side, where the onset deposition potential difference between Cu and Ag ions becomes less, favouring effective co-deposition of both ionic species. The morphologies of deposits change significantly from cubic structure to flower-shaped dendrites by the incorporation of more amount of Cu, as noted from scanning electron microscopy (SEM) images. Crystallographic (XRD) analysis confirms the formation of Ag–Cu co-deposits and the compositions of the different deposits were found out using atomic absorption spectroscopy (AAS). The Ag–Cu composite containing 23% of Cu (Ag77–Cu23) shows the highest cathodic potential window in N,N-dimethylformamide/tetrabutylammonium tetrafluoroborate (DMF/TBABF4) medium. Further, Ag77–Cu23 shows higher reductive current on the electroreduction of benzophenone in presence and absence of carbon dioxide than that of other Ag based composite electrodes resulting in an enhancement of the product yield.