Efecto electrocatalítico de nanopartículas bimetálicas de Ag y Cd hacia la reducción de iones nitrato y/o nitrito

RUBÉN E. AMBRUSI; MIGUEL D. SANCHEZ; SILVANA G. GARCÍA

REVISTA MATéRIA

UNIV FED RIO DE JANEIRO

Año: 2018

1517-7076

Theelectrocatalytic effect of Cd-Ag bimetallic nanoparticles supported on highlyoriented pyrolytic graphite (HOPG) and vitreous carbon (VC) substrates wasevaluated for the nitrate and/or nitrite ions reduction reaction. For this, ina first stage, the metallic and bimetallic deposits were obtained on thecarbonaceous substrates (CS) using the electrochemical technique of the singlepotentiostatic pulse. In the case of the bimetallic pair, the amount of Cd wasselectively deposited on the Ag nanoparticles previously supported on HOPG orCV, due to the strong interaction between the two metals, using differentpolarization times. Potentiodynamic studies of the system Cd-Ag/(CS) indicatedthat, for relatively large polarization times, it is feasible the formation ofa surface alloy between Ag and Cd atoms, due to an interdiffusion processbetween them, which may affect its catalytic activity. The generated particleson HOPG, were characterized by ex­situ AFM and XPS analysis, corroborating thelatter the formation of a Cd-Ag alloy. Subsequently, the electrodes modifiedwith metallic and bimetallic nanoparticles, and also the substrates free ofdeposits, were analysed by cyclic voltammetry in solutions containing nitrateions. It was found that the reduction of nitrate and/or nitrite ions processesbegin at more positive potential values in the case of bimetallic deposits,corresponding to a more pronounced catalytic effect by the presence of Cd andAg, which could be alloyed in the surface, producing a synergistic effect forthe reduction of the anions. Even, a change in the catalytic performance byusing longer polarization times for the deposition of Cd on supported Agnanoparticles was verified, that could be related with that alloyed phase. Thereaction products were analyzed by colorimetry and ion exchange chromatographyfor determining nitrate, nitrite and ammonium amounts in solution.