Vidhika Sharma

Enhanced Photoelectrochemical Activity of 120 MeV Ag9+ Irradiated Nanostructured Thin Films of ZnO for Solar-Hydrogen Generation via Splitting of Water

This paper deals with a study on 120 MeV Ag9+ irradiated thin films of zinc oxide (ZnO), obtained by sol-gel – spin coating onto TCO glass plates. Films irradiated at fluence 5×1011, 3×1012, 5×1012 and 2×1013 ions cm-2, were optically characterized for band gap determination. XRD analysis revealed polytypism as both wurtzite and zincblend phases co-evolved. Scherrer’s calculations indicated grain size in nanodimensions, while SEM analysis indicated smooth surface morphology of films. Flat band potentials and donor densities were evaluated by Mott-schottky calculations. For PEC studies, thin films of ZnO were employed as working electrode in conjunction with Platinum Counter electrode, Saturated Calomel Reference electrode, 13 pH aqueous solution of NaOH as electrolyte and 150W Xenon Arc light source for illumination. A significant gain in photoelectrochemical current was recorded on SHI irradiation. The films irradiated at fluence 3×1012 ions cm-2 yielded maximum increase in photocurrent that was nearly five times compared to unirradiated samples.

Nanostructured ZnO for photoelectrochemical splitting of water to produce hydrogen: swift heavy ion irradiation vis-à-vis dye-sensitisation

Nanostructured ZnO is a promising material for solar light driven photoelectrochemical splitting of water to produce hydrogen. With a band gap around 3.3 eV, it can easily generate required photopotential for electrolysis of water. However, its high band gap does not permit efficient absorption of solar light. To overcome this limitation, several approaches are being tried. A popular approach is its sensitisation with a dye having λ max in the visible region. In an innovative approach, authors irradiated sol-gel derived nanostructured ZnO films by 120 MeV Ag 9+ ions to induce structural defects that might shift absorption threshold in the visible region. This report presents, with regard to PEC splitting of water, a comparison of SHI irradiated vis-a-vis dye-sensitised films of ZnO. Films were subjected to XRD, SEM and Mott-Schottky analysis and optical characterisation. For PEC studies, these were used in conjunction with Pt counter electrode, saturated calomel reference electrode and 150 W Xenon arc light source.