A simple carbazole based sensitizer attached to a Nafion-coated-TiO2 photocatalyst: the impact of controlling parameters towards visible light driven H2 production

Abstract

Here we report a new composite material consisting of a simple and cost effective carbazole based photosensitizer attached onto a Nafion/Pt/TiO₂ (NPT) hybrid as a high-performance photocatalyst for H₂ evolution under visible light. The engineered composite of dye with NPT is shown to render improvement in its photocatalytic activity. We have spectroscopically observed that the spacer free simple carbazole based dye was perfectly attached onto TiO₂ surfaces, which also remained unaffected in alkaline medium. The development of the photocatalyst was confirmed by different morphological characterization procedures. Under optimum conditions (pH 10, 1.0 × 10⁻⁴ mol/10 mg AM dye, 0.5 wt% Pt), the maximal apparent quantum yield (AQY%) of D1@PT and D1@NPT for hydrogen evolution increases up to 16.5% and 19.16% under ∼2-sun-intensity of visible light irradiation with triethanolamine (TEOA) as a sacrificial agent. The combined effects of several factors may contribute to the remarkably enhanced photocatalytic activity for the D1@NPT sample including dye concentration, pH and catalyst amount variation, and the spacer effect of the sensitizers (with and without oligothiophene moieties).