Strain-Enhanced Hydrogen Evolution, Electrical, Optical, and Thermoelectric Properties of the Multifunctional 2D CrSi2N4 Monolayer

TL;DR

This study uses first-principles DFT calculations to explore the multifunctional properties of monolayer CrSi2N4, revealing its stability, tunable electronic and optical features, and potential for thermoelectric and electrocatalytic applications.

Contribution

The paper provides a comprehensive first-principles analysis of CrSi2N4 monolayer, highlighting its stability and tunable properties for energy and optoelectronic applications.

Findings

CrSi2N4 exhibits dynamic, thermal, and mechanical stability.

Applying +5% biaxial strain reduces HER free energy from 1.05 eV to 0.46 eV.

The monolayer shows high dielectric constant and strong optical absorption.

Abstract

First-principles density functional theory (DFT) is employed to evaluate the structural, electronic, optical, thermoelectric, and electrocatalytic properties of monolayer CrSi2N4. Its symmetric N-Si-N-Cr-N-Si-N septuple-layer structure exhibits dynamic, thermal (300 K), and mechanical stability, supported by a -8.76 eV/atom cohesive energy. PBE and HSE06 functionals reveal an indirect bandgap of 0.58 eV and 2.16 eV, respectively, driven by localized Cr-3d and N-2p states. The monolayer features 15.57 static dielectric constant and maximum absorption coefficients of 0.9 X 10^6 cm-1 (visible) and 1.4 X 10^6 cm-1 (deep-UV). Semiclassical Boltzmann calculations predict an outstanding room-temperature n-type thermoelectric power factor of 3.5 x mW/mK2. For hydrogen evolution (HER), the basal plane yields a baseline hydrogen adsorption free energy ({\Delta}GH) of 1.05 eV at the N-site. Applying +5% expansive biaxial strain improves HER kinetics, reducing {\Delta}GH to 0.46 eV. Thus, CrSi2N4 is a resilient, tuneable candidate for waste-heat recovery, photodetectors, and sustainable electrocatalysis.