Hierarchically porous BiOCl@NiCo2O4 nanoplates as low-cost and highly efficient catalysts for the discoloration of organic contaminants in aqueous media

Abstract

The construction of noble metal-free materials with remarkable activity and high stability via a simple, green, efficient, and low-cost method remains a crucial task for addressing the problem of water contamination. Herein, ultrathin NiCo₂O₄ nanosheets were in situ assembled on the surface of BiOCl single-crystal nanosheets with a vertical orientation to form a well-defined hierarchically porous structure. Notably, the obtained BiOCl@NiCo₂O₄ nanoplates displayed outstanding catalytic activity in the reductive conversion of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP). On account of their special morphology, plentiful porosity, and good stability, the as-prepared composite could finish the reduction reaction within 280 s with a large rate constant (k_app) of 7.18 × 10⁻³ s⁻¹. The BiOCl@NiCo₂O₄ nanoplates possessed excellent recyclability, and the original activity could be maintained even after seven consecutive cycles. Furthermore, the resultant BiOCl@NiCo₂O₄ could also act as a hyperactive catalyst for the reductive discoloration of organic dyes (rhodamine B, rhodamine 6G, Congo red, and methyl orange). Our strategy, therefore, promotes the development of low-cost and high-performance noble metal-free catalysts to treat water pollution.