Influence of gas adsorption on surface potential of porphyrin functionalized boron doped diamond thin films

Abstract

Porphyrins functionalized diamond surfaces are interesting candidates for wide variety of applications due to their remarkable physical and chemical properties. In this work, the properties of 5-(4-carboxyphenyl) triphenyl porphyrins functionalized boron-doped diamond (BDD) surface followed by gas adsorption were studied at room temperature. After structural and morphological characterizations of the bare BDD surface and porphyrins functionalized BDD surface, a scanning Kelvin probe system was used to investigate the surface potential distribution due to the adsorption of volatile organic compounds (VOCs) under visible light illumination conditions. Gas adsorption studies showed poor response in bare BDD surfaces under different gas atmospheres. On the other hand, a significant response with discriminable gas interactions was achieved in porphyrins functionalized BDD surface under visible light illumination. The obtained results suggest that visible light has influenced gas interactions because of porphyrins. The increased response (∼ 2.5 times) of metal-free porphyrin functionalized BDD thin film towards triethylamine (TEA) is accounted to the donor nature of TEA. This study helps in developing a new generation of novel conductive type diamond-based photo enhanced gas sensors at room temperature that can be utilized for fish freshness monitoring.