Novel BiOI/LaOXI〈IX〉 heterojunction with enhanced visible-light driven photocatalytic performance: unveiling the mechanism of interlayer electron transition

Abstract

Improving visible light absorption plays an important role in the utilization of solar power for photocatalysis. Using first-principles calculations within the HSE06 functional, we propose that the semiconductor heterojunction BiOI/LaOXI〈IX〉 extends the optical absorption to the near-infrared range, boosts the absorption coefficient from 1.28 × 10⁵ cm⁻¹ to above 2.20 × 10⁵ cm⁻¹ in the visible light range, and increases the conversion efficiency of solar power up to 9.48%. The enhanced optical absorption derives from the significant interlayer transition and excitonic effect which benefit from polarized LaOXI with a flat band in the highest valence band (VB). In BiOI/LaOClI〈ICl 〉, the electrostatic potential difference (ΔΦ) modifies the band edge positions to meet the requirements for photocatalytic overall water splitting, while the polarized electric field (E_p) accelerates the separation of photogenerated carriers and regulates the overpotentials of photogenerated carriers following a direct Z-scheme strategy. In addition, BiOI/LaOXI〈IX〉 is dynamically and thermodynamically stable. Furthermore, only a low external potential is needed to drive the redox reaction. Our theoretical results suggest that BiOI/LaOXI〈IX〉 could be a potential photocatalyst for overall water splitting with enhanced visible light absorption.