Band Structure Engineering, Optical, Transport, and Photocatalytic Properties of Pristine and Doped Nb3O7(OH): A Systematic DFT Study

TL;DR

This systematic DFT study investigates how doping Nb3O7(OH) with Ta or Sb alters its electronic, optical, and transport properties, enhancing its potential for photocatalytic and solar cell applications.

Contribution

It demonstrates the effectiveness of TB-mBJ for modeling doped Nb3O7(OH) and details how doping shifts band edges and improves charge mobility.

Findings

Doping reduces the band gap from 1.7 eV to around 1.2 eV.

Doped systems shift optical absorption to the visible spectrum.

Charge carrier mobility increases with Ta/Sb doping.

Abstract

Nb3O2(OH) has emerged as a highly attractive photocatalyst based on its chemical stability, energetic band positions, and large active lattice sites. Compared to other various photocatalytic semiconductors, it can be synthesized easily. This study presents a systematic analysis of pristine and doped Nb3O7(OH) based on recent developments in related research. The current study summarizes the modeling approach and computationally used techniques for doped Nb3O7(OH) based photocatalysts, focusing on their structural properties, defects engineering, and band structure engineering. This study demonstrates that the Trans-Blaha modified Becke Johnson approximation (TB-mBJ) is an effective approach for optoelectronic properties of pristine and Ta/Sb-doped Nb3O7(OH). The generalized gradient approximation is used for structure optimization of all systems studied. Spin-orbit (SO) coupling is also applied to deal with the Ta f orbital and Sb d orbital in the Ta/Sb-doped systems. Doping shifts the energetic band positions and relocates the Fermi level i.e. both the valence band maximum and the conduction band minimum are relocated, decreasing the band gap from 1.7 eV (pristine), to 1.266 eV (Ta-doped)/1.203 eV (Sb-doped). Moreover, doped systems shift the optical threshold to the visible region. Transport properties like effective mass and electrical conductivity are calculated, reflecting that the mobility of charge carriers increases with the doping of Ta/Sb atoms.The reduction in the band gap and red-shift in the optical properties of the Ta/Sb-doped Nb3O7(OH) to the visible region suggest their promising potential for photocatalytic activity and photoelectrochemical solar cells.