Electronic and Optical Properties of the Recently Synthesized 2D Vivianites (Vivianenes): Insights from First-Principles Calculations

TL;DR

This study uses first-principles calculations to explore the structural, electronic, and optical properties of the newly synthesized 2D Vivianene, revealing its stability and potential for optoelectronic applications.

Contribution

It provides the first comprehensive theoretical analysis of Vivianene's properties, including stability, band structure, and optical response, highlighting its technological potential.

Findings

Vivianene is thermodynamically stable at room temperature.

It has an indirect bandgap of 3.03 eV, slightly lower than bulk Vivianite.

Optical properties show high UV absorption and potential for optoelectronic use.

Abstract

Vivianite (Fe$_3$(PO$_4$)$_2$8H$_2$O) is a naturally occurring layered material with significant environmental and technological relevance. This work presents a comprehensive theoretical investigation of its two-dimensional (2D) counterpart, Vivianene, focusing on its structural, electronic, and optical properties. Using density functional theory (DFT) calculations and ab initio molecular dynamics (AIMD) simulations, we evaluate its thermodynamic stability, band structure, density of states, and optical response. Our results confirm that Vivianene retains the main structural features of bulk Vivianite while exhibiting enhanced thermodynamic stability at room temperature. The electronic structure analysis reveals an indirect bandgap of 3.03 eV for Vivianene, which is slightly lower than the 3.21 eV observed for bulk Vivianite, deviating from the expected quantum confinement trend in 2D materials. The projected density of states (PDOS) analysis indicates that Fe d orbitals predominantly contribute to the valence and conduction bands. Optical calculations demonstrate that Vivianene exhibits a higher optical band gap (3.6 eV) than bulk Vivianite (3.2 eV), with significant absorption in the ultraviolet region. The refractive index and reflectivity analyses suggest that most of the incident light is absorbed rather than reflected, reinforcing its potential for optoelectronic applications. These findings provide valuable insights into the fundamental properties of Vivianene and highlight its potential for advanced applications in sensing, optoelectronics, and energy-related technologies.