One-pot electrochemical preparation of BiOCl/BiPO₄ double-layer heterojunction film with efficient photocatalytic performance

Highlights: • A novel BiOCl/BiPO₄ heterojunction film has been synthesized by one-pot electrochemical method. • The as-prepared BiOCl/BiPO₄ heterojunction film exhibited high photocatalytic activity and stability. • The plausible formation process of BiOCl/BiPO₄ heterojunction film has been proposed and demonstrated. • The photocatalytic mechanism of phenol degradation presented by BiOCl/BiPO₄ heterojunction film was investigated and analyzed. - Abstract: A BiOCl/BiPO₄ double-layer heterojunction film on metal Bi plate with reduced recombination of photo-induced carriers has been successfully prepared by one-step electrochemical anodization process. The morphology characterizations displayed that the double-layer film consisted of BiPO₄ rods array at the bottom and BiOCl nanosheets on the top. Meanwhile, the control experiments indicated that the BiPO₄ rods array was transformed by BiOCl rather than Bi³⁺ reacting with PO₄³⁻ directly. In addition, the resulting BiOCl/BiPO₄ heterojunction film exhibited excellent photocatalytic activity and stability on the degradation of phenol comparing with pure BiOCl film. Transient photocurrent measurements and PL spectra proved that the enhanced photocatalytic performance of BiOCl/BiPO₄ heterojunction film was attributed to the effective separation of photo-generated electron-hole pairs excited on BiOCl. Moreover, ·O₂⁻ and ·OH played a crucial role in the photodegradation process of phenol. Based on these analytical results, a plausible photocatalytic mechanism has been proposed.