Journal Article 27YLU75U4W Phosphorus black phosphorus nanosheets Janus nanostructures Review antioxidants asymmetric growth blood-brain barrier carbon dioxide reduction reaction chemotherapy composite sites drug discovery facets heterogeneous catalysis nanoparticles neurodegenerative disorder photodynamic therapy photothermal therapy single atoms single-atom catalysts synergistic effect synergistic therapy, drug delivery tandem catalysis