Effect of boron and phosphorus codoping on the electronic and optical properties of graphitic carbon nitride monolayers: First-principle simulations

TL;DR

This study uses first-principles simulations to show that boron and phosphorus co-doping significantly reduces the band gap of graphitic carbon nitride monolayers, enhancing visible light absorption and potential for solar water splitting.

Contribution

It demonstrates that B/P co-doping alters the electronic structure of g-C3N4, improving optical properties and charge transitions, which was not previously explored.

Findings

Band gap reduced from 3.1 eV to 1.9 eV due to co-doping

Enhanced visible light absorption and electronic transitions observed

Charge redistribution confirmed by electron density and Mulliken analysis

Abstract

We study the effect of boron (B) and Phosphorous (P) co-doping on electronic and optical properties of graphitic carbon nitride (g-C$_3$N$_4$ or GCN) monolayer using density functional simulations. The energy band structure indicates that the incorporation of B and P into a hexagonal lattice of GCN reduces the energy band gap from $3.1$ for pristine GCN to $1.9$ eV, thus extending light absorption toward the visible region. Moreover, on the basis of calculating absorption spectra and dielectric function, the co-doped system exhibits an improved absorption intensity in the visible region and more electronic transitions, which named $\pi^*$ electronic transitions that occurred and were prohibited in the pristine GCN. These transitions can be attributed to charge redistribution upon doping, caused by distorted configurable B/P co-doped GCN confirmed by both electron density and Mulliken charge population. Therefore, B/P co-doped GCN is expected to be an auspicious candidate to be used as a promising photoelectrode in Photoelectrochemical water splitting reactions leading to efficient solar H$_2$ production.