# From Structure to Functional Implications: Investigation of the Melon-Like Framework of Graphitic Carbon Nitride for Li–S Batteries

## TL;DR

This study clarifies the structure of graphitic carbon nitride and shows how its melon-like framework affects its performance in lithium-sulfur batteries.

## Contribution

The first experimental confirmation of the melon-like structure of gCN and its electrochemical implications in Li–S batteries.

## Key findings

- gCN synthesized from urea and melamine consistently adopts a melon-like framework with P21212 symmetry.
- The melon-like structure of gCN shows strong correlations between structural attributes and electrochemical performance.
- Density functional theory supports the experimental findings on gCN's structure and functionality.

## Abstract

Graphitic carbon nitride (gCN) has emerged as a promising
material
for sustainable energy storage applications, photocatalysis, and sensors.
Despite extensive research, its precise crystallographic structure
remains controversial, particularly regarding the distinction between
heptazine-based and melon-like frameworks. In this study, we investigate
the structural characteristics of gCN synthesized using different
precursors, urea and melamine. Comprehensive characterization, including
X-ray diffraction (XRD), confirms that all samples exhibit a melon-like
framework with P21212 symmetry.
This contradicts the widely cited but experimentally unsupported heptazine-based
model. We further explore how precursor selection influences crystallinity,
elemental composition, and electrochemical behavior. Additionally,
density functional theory (DFT) studies are also incorporated to support
the experimental findings. Notably, our study is among the first to
report the electrochemical performance of gCN with a confirmed melon-like
structure, highlighting the strong correlation between structural
attributes and functional properties. These findings provide valuable
insights into the structure–property relationships in gCN and
open new avenues for its rational design and applications in energy
storage and conversion technologies for metal–sulfur batteries.