Dye-sensitized photoelectrochemical cells constructed using metal-free perylene diimide-based oxygen production polymers and calixarene dyes

Abstract

The application of metal-free photosensitizers in dye-sensitized photoelectrochemical cells (DSPECs) has attracted great interest due to their low cost in recent years. However, there is an urgent need to develop novel metal-free water oxidation catalysts (WOCs) for DSPECs. In this work, for the first time, three linear conjugated oxygen-producing polymers (OPPs) are introduced into the DSPEC system with calixarene photosensitizers to achieve visible light-driven total water splitting. The best performance is demonstrated by the FTO|TiO₂|C4EOP + Oxamide-PDI photoanode, giving a photocurrent density of 208 μA cm⁻² after 200 s of chopping irradiation at 0.2 V vs. the reversible hydrogen electrode (RHE). Further, Faraday efficiencies of 86.1% at 0.2 V vs. RHE and 66.3% without a bias voltage for oxygen production are obtained. C4EOP-sensitized electrodes exhibit higher photocurrent densities due to their superior light absorption performance, greater electron–hole recombination impedance, and stronger affinity to hydrophilic polymers. Oxamide-PDI loaded electrodes show better performance due to their higher crystallinity and larger π-conjugation width. This is a pioneering study to incorporate OPPs as WOCs into the calixarene-sensitized DSPEC system, which has significant potential as a low-cost and high-efficiency device for photoelectrochemical water splitting.