An anion-exchange strategy for 3D hierarchical (BiO)2CO3/amorphous Bi2S3 heterostructures with increased solar absorption and enhanced visible light photocatalysis

Abstract

Bismuth-based nanostructured materials have attracted great interest in a wide range of applications. In the present work, 3D (BiO)₂CO₃ hierarchical microspheres self-assembled by nanosheets were synthesized by a simple hydrothermal method. By using a facile anion-exchange strategy, (BiO)₂CO₃/amorphous Bi₂S₃ heterostructures were constructed through the controlled chemical reaction between (BiO)₂CO₃ microspheres and Na₂S in an aqueous solution. The as-prepared samples were systematically characterized by XRD, SEM-EDX, TEM, FT-IR, XPS, UV-vis DRS and PL techniques. The heterostructured samples were applied for photocatalytic removal of ppb-level NO in air under visible light irradiation. The pure (BiO)₂CO₃ hierarchical microspheres exhibited decent visible light photocatalytic activity due to the surface reflecting and scattering effect. Amorphous Bi₂S₃ showed no photocatalytic activity due to narrow band gap. By hybridization of (BiO)₂CO₃ microspheres with amorphous Bi₂S₃ on the surface, 3D hierarchical (BiO)₂CO₃/amorphous Bi₂S₃ heterostructures were constructed, which demonstrated increased solar light absorption and highly enhanced visible photocatalytic activity and stability. The enhanced performance can be directly ascribed to the increased visible light utilization, promoted charge separation arising from the well-matched band structure and accelerated reactants transfer resulting from special 3D hierarchical structure. The present work opens a new avenue for modification of wide-band gap semiconductor with amorphous components, which could reduce the further thermal treatment and production cost.