Fig. 2

Characterization of CuS:Gd NPs. a TEM images of CuS:Gd NPs. b The longitudinal relaxation rate of the CuS:Gd NPs, Inset: Corresponding MR images. c The degradation performance of CuS:Gd NPs on MB at different time points (1 min, 3 min, 5 min, 10 min, 20 min, 30 min, 60, min, 90 min, 120 min and 240 min) (n = 3, mean ± SD). d The degradation of MB under different pH values (5.4, 6.5 and 7.4), indicating the negligible difference under different pH conditions. e EPR spectra of different groups (CuS:Gd-G only, CuS:Gd-G with H₂O₂ at pH 7.4, CuS:Gd-G with H₂O₂ at pH 6.5 and CuS:Gd-G with H₂O₂ at pH 5.4) with the 5,5-dimethyl-l-pyrroline N-oxide (DMPO) as the spin trap to detect the ·OH generation during the reaction