Recent progress in black phosphorus nanostructures as environmental photocatalysts

Hazardous chemicals excruciatingly contaminated water, air, and soil for the past few decades. Eco-friendly techniques to clean and or destroy these harmful chemicals is an urgent requirement at this moment. In this direction, a large number of methodologies had been suggested to eliminate the awful chemicals, amongst them photocatalysis is believed to be one of the most reliable approaches. Photocatalytic efficiency can be enhanced while absorbing the full range of solar spectra including ultraviolet, visible and near-infrared. On the other hand, lowering the photo-induced charge pairs recombination is one of the strategies to boost the efficiency of the catalyst. Various methods have been employed to engineer the band gap leading to hinder the photo-induced charge recombination. Nonetheless, the ultimate solution is still an open challenge. The utilization of two-dimensional (2D) materials in photocatalysis is a new concept solving the rapid charge carrier recombination and improving the lower energy photons (NIR) adsorption. The employment of black phosphorus (BP) has ushered in as an intriguing new solution. BP nanostructures naturally provide a unique electronic behavior with tunable band gap. In addition, BP band gap energy can be deployed while adjusting the layer thickness. This review highlights the BP-based nanostructures and their heterojunction nano-hybrids in environmental applications. Further, we discussed the BP photocatalytic reactions with a recent breakthrough mechanism such as classical band structure and/or Coulomb interaction facilitated bounded charge carriers models. Furthermore, engineered pyro-catalytic properties were also found in few layers BP. We have also summarized the overall recent research outcomes on BP applied for photocatalytic environmental remediation. In conclusion, the current challenges, perspectives and outlook of the BP nanostructures applications are discussed