Bi2O2(OH)(NO3) as a desirable [Bi2O2]2+ layered photocatalyst: strong intrinsic polarity, rational band structure and {001} active facets co-beneficial for robust photooxidation capability

Abstract

Developing high-performance photocatalytic materials is of huge significance and highly desirable for fulfilling the pressing need in environmental remediation. In this work, we demonstrate the use of bismuth nitrate Bi₂O₂(OH)(NO₃) as an absorbing photocatalyst, which integrates multiple superiorities, like a [Bi₂O₂]²⁺ layered configuration, a non-centrosymmetric (NCS) polar structure and highly reactive {001} facets. Bi₂O₂(OH)(NO₃) nanosheets are obtained by a facile one-pot hydrothermal route using Bi(NO₃)₃·5H₂O as the sole raw material. Photocatalysis assessment revealed that Bi₂O₂(OH)(NO₃) holds an unprecedented photooxidation ability in contaminant decomposition, far out-performing the well-known photocatalysts BiPO₄, Bi₂O₂CO₃, BiOCl and P25 (commercial TiO₂). Particularly, it displays a universally powerful catalytic activity against various stubborn industrial contaminants and pharmaceuticals, including phenol, bisphenol A, 2,4-dichlorophenol and tetracycline hydrochloride. In-depth experimental and density functional theory (DFT) investigations co-uncovered that the manifold advantages, such as large polarizability and rational band structure, as well as exposed {001} active facets, induced robust generation of strong oxidating superoxide radicals (˙O₂⁻) in the conduction band and hydroxyl radicals (˙OH) in the valence band, thus enabling Bi₂O₂(OH)(NO₃) to have a powerful and durable photooxidation capability. Bi₂O₂(OH)(NO₃) also presents high photochemical stability. This work not only rendered a highly active and stable photocatalyst for practical applications, but also laid a solid foundation for future initiatives aimed at designing new photoelectronic materials by manipulating multiple advantageous factors.