Self-Assembled PDI Nanowires Enhanced by Plasmonic Effect of Gold Nanorods for Photocatalytic H₂O₂ Production and Photoelectrochemical Cell Application

Considering the wide visible light absorption of perylene diimide (PDI) molecules, gold nanorods (AuNRs) can be utilized by matching their transversal and longitudinal surface plasmon resonance (SPR) bands with the absorption wavelengths of PDI-based photocatalysts to achieve an efficient enhancement of the catalytic activity. Herein, the composite photocatalyst of AuNRs-decorated self-assembled PDI nanowires (s-PDI/AuNRs) has been successfully prepared and further applied in the self-powered photoelectrochemical cell as the anode to supply H2O2 fuel. The s-PDI/AuNRs-based cell displays a maximum power density of 2.36 mW cm–2 in 0.1 M HCl electrolyte, which has 65.0% and 31.8% enhancement compared to the pristine PDI-based cell (1.43 mW cm–2) and the s-PDI-based cell (1.79 mW cm–2), respectively. Moreover, the photocatalytically produced H2O2 can be stored under light, which is then used as a fuel for cell operation in darkness. The specific capacitance can be achieved as high as 43.1 F cm–2, retaining 52.6% of its initial value after 12 h. It is verified that the enhanced photocatalytic performance of s-PDI nanowires can be ascribed to the specific intermolecular π-π stacking caused by the introduction of terminal carboxyl groups, which results in the deepening of the valence bandwidth and the enhancement of hole oxidation capacity.