High-efficiency and selective photocatalytic degradation activity of black phosphorus nanosheets via superoxide radical

Among various reactive oxygen species, the formation pathways and proportional contributions of superoxide radicals ( ∙ O 2 − ) play a decisive role in governing the efficiency and selectivity of photocatalytic dye degradation, owing to their moderate oxidizing capability. Herein, the microcosmic correlation between selective dye degradation behavior and ∙ O 2 − radicals is systematically elucidated using black phosphorus nanosheets (BPNS) as photocatalyst and methyl orange (MO), rhodamine B (RhB) and eosin Y (EY) as target pollutants. High-crystallinity few-layer black phosphorus nanosheets (BPNS) are massively fabricated via a chemical vapor transport method combined with mechanical exfoliation. Physical characterization reveals that as-prepared BPNS exhibit broad-spectrum light absorption and rapid charge transfer capability. Meanwhile, their conduction band position well matches the formation potential of ∙ O 2 − . These favorable properties collectively satisfy the essential prerequisites for achieving highly selective photocatalytic degradation of organic dyes. Compared with the degradation efficiency of cationic RhB (55.6%), the removal efficiencies of anionic MO and EY in BPNS photocatalytic system reach 99.1% and 97.2% under identical conditions. The distinct differences in dye degradation performances mainly originate from the abundant production of ∙ O 2 − , as well as the excellent photoelectric intrinsic properties of BPNS photocatalyst.