Doping and Defect-Induced Germanene: A Superior Media for Sensing H2S, SO2, and CO2 gas molecules

TL;DR

This study uses first-principles DFT calculations to explore how defects and doping in germanene nanosheets enhance their ability to detect gases like H2S, SO2, and CO2, showing defect engineering as a promising sensing strategy.

Contribution

It demonstrates that vacancy defects significantly improve germanene's gas-sensing performance, and doping effects are minimal except for CO2 detection on N-doped germanene.

Findings

Vacancy defects increase gas sensitivity of germanene.

Weak adsorption of CO2 on pristine germanene.

N-doping enhances CO2 detection specifically.

Abstract

First-principles calculations based on density functional theory (DFT) have been employed to investigate the structural, electronic, and gas-sensing properties of pure, defected, and doped germanene nanosheets. Our calculations have revealed that while a pristine germanene nanosheet adsorbs CO2 weakly, H2S moderately, and SO2 strongly, the introduction of vacancy defects increases the sensitivity significantly which is promising for future gas-sensing applications.Mulliken population analysis imparts that an appreciable amount of charge transfer occurs between gas molecules and a germanene nanosheet which supports our results for adsorption energies of the systems. The enhancement of the interactions between gas molecules and the germanene nanosheet has been further investigated by density of states.Projected density of states provides detailed insight of the gas molecules contribution in the gas-sensing system.Additionally, the influences of substituted dopant atoms such as B, N, and Al in the germanene nanosheet have also been considered to study the impact on its gas sensing ability. There was no significant improvement found in doped gas sensing capability of germanene over the vacancy defects, except for CO2 upon adsorption on N-doped germanene.