Electrocatalytic oxidation and flow injection analysis of formaldehyde at binary metal oxides (Co3O4-NiO and CuO-Co3O4) modified pencil graphite electrodes

Abstract

In this work, a highly efficient performance of bimetallic thin films as their oxide forms (Co3O4-NiO and CuO-Co3O4) modified on pencil graphite electrodes (PGEs) was presented for electrocatalytic oxidation of formaldehyde. In addition, a sensitive and selective amperometric determination of formaldehyde in flow injection analysis system have been first performed using binary transition metal oxides modified PGEs. Co3O4-NiO and CuO-Co3O4 films were electrochemically deposited on the PGE surface using cyclic voltammetric procedures. The recorded cyclic voltammograms in the presence of formaldehyde in 0.10 M NaOH containing 0.10 M KCl showed that the prepared binary transition metal oxides modified PGEs exhibited a higher electrocatalytic activity than single metal oxide thin films modified PGEs towards oxidation of formaldehyde. The linear responses based on electrocatalytic oxidation of formaldehyde were determined as 2.5-5000 mu M and 0.25-1000 mu M for Co3O4-NiO/PGE and CuO-Co3O4/PGE, respectively. Moreover, limit of detections and sensitivities were estimated as 0.73 mu M and 81.8 mu A mM(-1) cm(-2) and 0.09 mu M and 166 mu A mM(-1) cm(-2) for Co3O4-NiO/PGE and CuO-Co3O4/PGE, respectively. The results from real sample studies proved that the fabricated FI-amperometric sensors enable high applicability towards determination of formaldehyde in real water samples.