Synthesis of Cd-Cu nanoparticles supported on HOPG for use as electrocatalytic material for nitrate reduction

Abstract

Bimetallic nanoparticles application has attracted great attention in the field of electrocatalysis because they canenhance the catalytic properties toward certain reactions of technological interest, such as nitrate reduction. Forthis purpose, Cd-Cu bimetallic nanoparticles were prepared on highly oriented pyrolytic graphite substrates bysequential electrodeposition of both metals. The process was studied by conventional electrochemical techniques,and the generated deposits were characterized by scanning electron microscopy energy dispersive Xrayspectroscopy analysis. Initially, Cu nanoparticles were prepared by a simple potentiostatic pulse applied tothe carbonaceous substrate. Scanning electron microscopy images showed high density of mainly hemisphericalshapedCu crystals distributed preferably on step edges and surface defects of the highly oriented pyrolyticgraphite electrode. Subsequently, Cd particles were prepared in the same way by immersing the Cu nanoparticles/ highly oriented pyrolytic graphite modified substrate in an electrolyte solution containing Cd2+ ions, exploitingthe phenomenon of underpotential deposition. It was evidenced that the existing crystals grew in size, most ofthem showing the typical shapes of those for Cd nanoparticles. The application of the Cd-Cu nanoparticles /highly oriented pyrolytic graphite electrode as a feasible electrocatalyst material for nitrate reduction wasinvestigated by cyclic voltammetry for different nitrate concentrations, also considering the possibility of usingthis procedure as a method for the anion detection.