Excellent photocatalytic properties in 2D ZnO/SiC van der Waals hetero-bilayers: water-splitting H2-fuel production

Abstract

This research unravels the photocatalytic properties of a 2D ZnO/SiC van der Waals hetero-bilayer for potential water-splitting applications by first-principles calculations. Four unique stacking patterns are considered in studying the electronic and optical properties in the presence and absence of biaxial external strain. For pattern-I and II, large negative binding energy and positive phonon frequencies are observed, denoting chemical and mechanical stabilities. Under the HSE-06 pseudo potential, the calculated bandgap value for pattern-I and II reaches 2.86 eV and 2.74 eV, respectively. 2D ZnO/SiC shows a high absorption coefficient (~105 cm-1). The absorption peak under biaxial strain could reach ~3.5 times the peak observed under unstrained conditions. Under strain, a shift from compressive to tensile biaxial strain (-6% to 6%) results in a bandgap decrease from 3.18 eV to 2.52 eV and 3.09 eV to 2.43 eV, for pattern-I and II, respectively. The observed strain-driven kinetic overpotential for 2D ZnO/SiC pattern-I and II easily engenders photocatalytic redox reactions. The excellent mechanical durability and strain-driven large kinetic overpotential suggest 2D ZnO/SiC heterobilayers as a prospective material for water-splitting H2-fuel production.