Tuning graphitic carbon nitride: A computational study of metal, semiconductor, and Non‐Metal doping effects on electronic and thermodynamic properties

Abstract

Graphitic carbon nitride (g-C₃N₄) is emerging as a promising semiconductor for optoelectronics, photocatalysis, and energy storage. The electronic and thermodynamic properties of g-C₃N₄ are investigated in this study via density functional theory (DFT) calculations (B3LYP/Lanl2dz) and the effects of metal, semiconductor, and non-metal doping on these properties assessed. Doping effectively reduces the HOMO–LUMO gap from 2.64 to 1.09 eV, increases the light absorption up to 720 nm, enhances charge transfer, and extends excited state (ES) lifetimes to 127 ns. Electronic structure analysis shows significant changes in charge distribution, and thermodynamic calculations show increased stability. P-gC₃N₄, Si-gC₃N₄, and Cu-gC₃N₄ have lower band gaps and strong excitation energies, making them ideal for light-emitting diodes. Meanwhile, P-gC₃N₄, Cd-gC₃N₄, and Se-gC₃N₄ optimize light absorption, enhancing solar cell efficiency. Ionization energy is ideal for sensors, while variants doped with Cu-gC₃N₄, Cd-gC₃N₄, or Se-gC₃N₄ enhance photodetectors, offering strong visible absorption and efficient charge transport for improved performance. Moreover, g-C₃N₄ doped with GaN₃-gC₃N₄, Cu-gC₃N₄, and W-gC₃N₄ are all found to possess high thermodynamic stabilities for hydrogen storage. Our findings demonstrate that doping is a powerful strategy to optimize g-C₃N₄ for advanced technological applications.