Mixing Thermodynamics and Photocatalytic Properties of GaP-ZnS solid solutions: A Multi-Configurational Supercell Approach

Joel Shenoy, Judy Hart, Ricardo Grau-Crespo, Neil Allan, Claudio Cazorla

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Abstract

Preparation of solid solutions represents an effective means to improve the
photocatalytic properties of semiconductor-based materials. Nevertheless, the
effects of site-occupancy disorder on the functional properties of materials are
difficult to predict and consequently many experimental trials may be required
before achieving enhanced photocatalytic activity. Here, first-principles
methods are employed to estimate the mixing free energy and the structural
and electronic properties of (GaP)x(ZnS)1−x solid solutions. The method
relies on a multi-configurational supercell approach that takes into account
the configurational and vibrational contributions to the free energy. Phase
competition among the zinc-blende and wurtzite polymorphs is also
considered. Overall excellent agreement with the available experimental data
is demonstrated, namely: 1) zinc-blende is energetically most favorable, 2) the
solid solution energy band gap lies within the 2–3 eV range, and 3) the energy
band gap of the solid solution is direct for compositions x ≤ 75%. It is found
that at ambient conditions, (GaP)x(ZnS)1−x solid solutions with x ≈ 25%,
50% and 75% render promising hydrogen evolution photocatalysts for water
splitting under visible light, owing to their favorable energy band gaps and
band levels relative to vacuum
Original languageEnglish
Article number1800146
Number of pages9
JournalAdvanced Theory and Simulations
Volume2
Early online date10 Jan 2019
DOIs
Publication statusPublished - Mar 2019

Bibliographical note

Special Issue: Computational Materials Design

Keywords

  • density functional theory calculations
  • multiconfigurational supercell approach
  • photocatalytic materials
  • semiconductor solid solutions

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