Composites of anodized α-Fe2O3 nanotube arrays (FNA) and graphitic carbon nitride (g-C3N4) nanoparticles were synthesized to enhance photocatalytic hydrogen evolution. FNA was fabricated via two-step anodization of iron foil and subsequent oxygen annealing, followed by conformal low-vacuum physical vapor deposition of g-C3N4 nanoparticles from pre-synthesized g-C3N4 powders. Transmission electron microscopy with elemental mapping confirmed uniformly dispersed deposition of g-C3N4 on nanotube sidewalls as well as larger particles at nanotube openings. The optimized FNA/g-C3N4 composite showed obvious hydrogen evolution from 80:20 water/methanol mixtures under one-sun irradiation, whereas bare FNA showed almost no hydrogen production. Band structure analysis and electron spin resonance spectroscopy suggested the formation of an S-scheme heterojunction at the interface. This heterojunction enables efficient charge separation while preserving strong redox potentials. Overall, this approach offers a versatile design platform for combining g-C3N4 with complex nanostructures for solar-to-hydrogen conversion.
