One-Pot Synthesisof a Novel Visible Light-ActiveMetal-Free Polymer within the Graphitic Carbon Nitride Family withEnhanced Photoelectrochemical Performance

Hydrogen fuel is a promising renewable energy source for a sustainable future. To produce green hydrogen gas from ecofriendly energy sources, a photoelectrochemical (PEC) water-splitting reaction can be explored. Metal-free polymer within the graphitic carbon nitride (g-C₃N₄) family is a feasible photocatalyst due to its low cost and proper light absorption characteristics. Here, we propose a novel visible light-active metal-free polymer fabricated by a one-pot synthesis process. The newly fabricated polymer exhibited a modified structure at the molecular level in cross-polarization-magic angle spinning-nuclear magnetic resonance (CP-MAS NMR) analysis, and the narrowed band gap energy was confirmed from X-ray photoelectron spectroscopy and density functional theory (DFT) simulations. We showed that CN-500 has enhanced photoreactivity for the hydrogen evolution reaction with higher electrical conductivity than g-C₃N₄. These findings provide a feasible approach to the production of green hydrogen (H₂) through a PEC water-splitting reaction with a cost-effective metal-free polymer from a one-pot synthesis procedure.