Reduced carboxylic graphene/palladium nanoparticles composite modified ultramicroelectrode array and its application in biochemical oxygen demand microsensor

In this paper, reduced carboxylic graphene/palladium nanoparticles (rGN-COOH/PdNPs) modified ultramicroelectrode array (UMEA) was investigated and applied in electrochemical determination of biochemical oxygen demand (BOD). The UMEAs were fabricated by micro electro-mechanical system technique. The sensitive film of rGN-COOH/PdNPs was prepared by self-assembling of carboxylic graphene (GN-COOH), electroreducing the GN-COOH and electrodepositing the palladium nanoparticles on UMEA. This modification method is suitable to UMEA, which can immobilize the sensitive film on the designed sites and maintain the unique characteristics of UMEA. Compared with the sensitive film of GN-COOH, rGN-COOH and PdNPs, the sensitive film of rGN-COOH/PdNPs showed satisfied electroreduction performance to dissolved oxygen (DO). A BOD microsensor was fabricated based on the rGN-COOH/PdNPs modified UMEA. A good linear range from 1 to 30 mg/L for BOD determination was displayed.