Intriguing electronic, optical and photocatalytic performance of BSe, M2CO2 monolayers and BSe-M2CO2 (M = Ti, Zr, Hf) van der Waals heterostructures.

M Munawar,B Amin,Iftikhar Ahmad,H U Din,M Idrees

doi:10.1039/d1ra07569a

Abstract

Using density functional (DFT) theory calculations, we have investigated the electronic band structure, optical and photocatalytic response of BSe, M2CO2 (M = Ti, Zr, Hf) monolayers and their corresponding BSe–M2CO2 (M = Ti, Zr, Hf) van der Waals (vdW) heterostructures. Optimized lattice constant, bond length, band structure and bandgap values, effective mass of electrons and holes, work function and conduction and valence band edge potentials of BSe and M2CO2 (M = Ti, Zr, Hf) monolayers are in agreement with previously available data. Binding energies, interlayer distance and Ab initio molecular dynamic simulations (AIMD) calculations show that BSe–M2CO2 (M = Ti, Zr, Hf) vdW heterostructures are stable with specific stacking and demonstrate that these heterostructures might be synthesized in the laboratory. The electronic band structure shows that all the studied vdW heterostructures have indirect bandgap nature – with the CBM and VBM at the Γ–K and Γ-point of BZ for BSe–Ti2CO2, respectively; while for BSe–Zr2CO2 and BSe–Hf2CO2 vdW heterostructures the CBM and VBM lie at the K-point and Γ-point of BZ, respectively. Type-II band alignment in BSe–M2CO2 (M = Ti, Zr, Hf) vdW heterostructures prevent the recombination of electron–hole pairs, and hence are crucial for light harvesting and detection. Absorption spectra are investigated to understand the optical behavior of BSe–M2CO2 (M = Ti, Zr, Hf) vdW heterostructures, where the lowest energy transitions are dominated by excitons. Furthermore, BSe–M2CO2 (M = Ti, Zr, Hf) vdW heterostructures are found to be potential photocatalysts for water splitting at pH = 0, and exhibit enhanced optical properties in the visible light zones.

Highlights

A er the successful synthesis of graphene,[1,2,3,4] great attention has been paid to other 2D materials, such as hexagonal boron nitrides (h-BN),[5] blue and black phosphorene,[6] transition metal dichalcogenides (TMDCs),[7] silicene,[8] germanene,[9] MXenes,[10] and Janus transition metal dichalcogenides (JTMDCs).[11]
Our results show that BSe–M2CO2 (M 1⁄4 Ti, Zr) van der Waals (vdW) heterostructures are a promising novel material for visible light photocatalysis, electronic and optoelectronic devices
In summery, using rst principles density functional (DFT) calculations, we have investigated the electronic band structure, optical and photocatalytic response of BSe, M2CO2 (M 1⁄4 Ti, Zr, Hf) monolayers and their corresponding BSe–M2CO2 (M 1⁄4 Ti, Zr, Hf) vdW heterostructures

Summary

Introduction

Tuning the properties of 2D materials has led to a new eld that assembles 2D materials (isolated) into hybrid heterostructures in a precisely controlled sequence of layer by layer stacking, called vdW heterostructures.[19]. MXenes-based vdW heterostructures, such as MXenes– MXenes,[38] MXene and nitrogen-doped graphene,[39] MXenes– TMDCs,[40] MXene–blue phosphorene,[41] MXenes and B-doped graphene,[42] have already been fabricated and investigated in detail. Small lattice mismatch and the same hexagonal symmetry of the BSe and M2CO2 (M 1⁄4 Ti, Zr, Hf) monolayer allow the creation of BSe– M2CO2 (M 1⁄4 Ti, Zr, Hf) vdW heterostructures. We have investigated the structural and electronic properties, band alignments, average and planar electrostatic potentials, Bader charge analysis, optical and photocatalytic response of BSe, M2CO2 (M 1⁄4 Ti, Zr and Hf) monolayers and their vdW heterostructure. Our results show that BSe–M2CO2 (M 1⁄4 Ti, Zr) vdW heterostructures are a promising novel material for visible light photocatalysis, electronic and optoelectronic devices

Computational details

Results and discussion

Conclusion