Hybrid Carbon Nitride/Cobalt Phthalocyanine Nanocomposites for Efficient Photocatalytic Hydrogen Generation

Abstract

The photocatalytic production of hydrogen stands out as a promising strategy to convert and store solar energy as chemical energy, in the form of a sustainable energy carrier. In the present study, a hybrid photocatalyst based on cobalt phthalocyanine (CoPc) coupled with polymeric carbon nitride (CN), is synthesised with a simple, cost-effective and upscalable method. Both components are held together in the hybrid nanocomposite via π-π interactions, as showed by a detailed structural and optical characterization. The synergistic interaction between both components, CN, a metal-free semiconductor, valued for its stability and tuneable electronic properties and CoPc, known for its excellent light absorption and electronic properties is evidenced in a proof-of-concept photocatalytic reaction: the photo-oxidation of benzyl alcohol (BzOH) to benzaldehyde (BzO). Chemical trapping reagents were employed to elucidate the reaction mechanism, showing favourable recombination dynamics of the hybrid photocatalyst (CoPc/CN), compared to the individual components. Furthermore, the photocatalytic hydrogen production was conducted in an aqueous solution, using triethanolamine (TEOA) as an electron donor, with the optimized CoPc/CN nanocomposite producing 1136.5 μmol h-1 gcat–1 of H2, achieving a 50% higher hydrogen yield, compared to pristine CN. These results contribute to the design of high-performance photocatalytic materials for promising Solar-to-X transformations.