Stabilizing effect in nano-titania functionalized CdS photoanode for sustained hydrogen generation

摘要

Efficient and stable photoanode has been fabricated by the surface functionalization of the nanostructured film. For this, the surface of spray deposited CdS thin film was modified through bi-functional molecule mediated chemisorption of TiO_2 nanoparticles (NP). Consequently, a systematic control over efficiency and photoanode stability against corrosion has been investigated. An in-depth quantitative analysis of the photocorrosion of these photoanodes is further studied using chronoamperometry, X-ray photoelectron spectroscopy and induced coupled plasma spectroscopy. TiO_2 NP modified photoanodes show an enhanced efficiency and a stability. For photoelectrochemical (PEC) systems, the stability factor (Σ) has been defined for the first time based on the time dependent chronoamperometry, which clearly demonstrates that Σ_(modified) Σ_(bare). The modified photoanode shows an improved Incident Photon to Current Efficiency of 22% than the bare CdS (～8%) electrode. It gives an enhanced solar-to-hydrogen conversion efficiency of STH ～ 0.7% w.r.t bare CdS (0.2%) under AM 1.5G solar simulator, at 0.2 V/SCE. Improved stability of more than nine hours and enhanced efficiency is attributed to the controlled passivation of CdS surface through TiO_2 NP (5 nm), and inhibition of the charge recombination. Superior and stable performance of modified photoelectrode has been validated by higher and stable hydrogen evolution over modified electrode.