Novel Supramolecular Photocatalyst Based on Conjugation of Cucurbit[7]uril to Non-Metallated Porphyrin for Electrophotocatalytic Hydrogen Generation from Water Splitting

Visible-light triggerable, stable, organic material-based photocatalysts that can function in alkaline media without the necessity of sacrificial agent for hydrogen production are highly sought after. Here, we report a novel supramolecular photocatalyst that confers the aforementioned features. This supramolecular photocatalyst (TPP-4CB7) is synthesized through the conjugation of monohydroxylated cucurbit(7)uril (CB7) hosts to a suitably substituted tetraphenyl porphyrin. Although TPP-4CB7 by its own preforms as an efficient visible light triggered photocatalyst, the hydrogen production efficiency is significantly enhanced upon mixing with TiO2. The resulting nanocomposite (TPP-CB-TiO2@Pt) is observed to exhibit remarkable electrophotocatalytic activity under visible light and produces hydrogen (onset potential -10 mV, turn over frequency (TOF) 0.202 s(-1), 24.5 mmol h(-1) g(-1)) from water splitting without any significant degradation during four runs (5 h each) in alkaline media and in the absence of sacrificial agent.