Study of Enhanced Photocatalytic Efficiency by Field Confinement in Plasmonic Nanostructures for Their Potential Application for Detection of Pathogenic Bacteria

Abstract

The interaction of transverse magnetic (TM) plane waves with 1D metallic bowtie gratings on glass substrate has been used for surface plasmon polaritons (SPPs) excitation. Silver (Ag) bowtie metallic grating has been modelled in COMSOL Multiphysics 5.6 Licensed version, for different gap widths (GWs) and film thickness by keeping the periodicity constant. The 0th order transmission spectra for this grating with various geometrical parameters at normal incidence has been extracted and studied by far-field analysis. To check the photocatalytic enhancement, the method of enhanced field confinement is used by exciting SPPs at TiO2/air interface. The enhancement factor is examined by changing gap width (50nm-450nm) with fixed thickness and periodicity. The photocatalytic efficiency is also calculated and degradation of three dyes (Methyl Red (MR), Methyl Orange (MO) and Phenol (Ph)) by calculating their concentrations and photodegradation rate constant ‘k’ are studied as well. Far and near-field analysis are employed to study the optimum structure for effective absorption of light. The results of far-field are supported by applying near-field analysis at resonance wavelength. A brief comparison of enhancement factor and photocatalytic degradation with literature is also presented. This research provides a pathway to real-time applications which are helpful in fabrication of efficient plasmonic based photocatalytic devices for highest degradation efficiency. Such grating devices with optimized parameters can also be used in the field of medical such as biosensor - detection and inhibition of the Pathogenic Bacteria etc.