Photocatalytic Solar Hydrogen Generation by SWCNT-Supported Nickel Oxide Nanoparticles Wrapped by Polypyrrole

High-performance and noble metal-free green hydrogen generation from water by photocatalysis is a reliable and sustainable approach to solving energy and environmental problems. We report a study on a hybrid nanocomposite photocatalyst of polypyrrole (PPy), nickel [nickel oxide (NiO)], and single-walled carbon nanotubes (SWCNTs) that was produced cost-effectively. The optimal design of the catalyst with the incorporation of 4 wt % of SWCNTs is sensitive to the crystallite size and lattice strain, which tune the optical energy gap for solar irradiation activity. Also, NiO acts as a conducting channel between the PPy-coated SWCNTs, facilitating high charge transportability. The photoexcited charge separation efficiency is accelerated in the presence of SWCNTs. Finally, cooperative agreement on the energy levels of the individual component promotes remarkable hydrogen (H-2) generation, harnessing the full band spectrum of simulated sunlight in the presence of only 1 vol % methanol as a photosensitizer. The solar H-2 evolution rate is improved by factors of 22.4 and 5.6 compared to that of the pristine PPy and PPy-NiO (PNC0) hybrid. This work delivers a facile and simple approach to developing a highly efficient noble metal-free carbon-based organic-inorganic composite system for solar photocatalytic H-2 generation.