Lysosome-targetable brightly green fluorescence carbon dots for real-time monitoring in cell and highly efficient removal in environment of hypochlorite

•The brightly green C-dots can sensitively and quickly detect ClO- in real samples.•The C-dots can selectively localize in the lysosome.•The C-dots can real-time monitor and image of ClO- in lysosome.•The C-dots@Fe3O4 MNCs can highly efficiently remove ClO- in real samples.•Our work is beneficial to investigate biological functions of ClO- at organelle levels.