Fig. 1. Schematic illustration of the synthesis process of 2D C and 2D C/Cu.

Fig. 2. (a1-d3) SEM and TEM images; (e) Schematic illustration; (f) XRD patterns and (g) Raman spectra of 2D C, 2D C/Cu1, 2D C/Cu2, and 2D C/Cu3. The values of scale bars in a1, b1 and c1 are the same as that in d1. Similarly, the values of scale bars in a2, b2, and c2 are the same as that in d2, and the values in a3, b3, and c3 are the same as that in d3.

Fig. 3. Photothermal performance. (a) Vis-NIR absorbance spectra (400-1000 nm) of aqueous suspensions of dispersed 2D C at varied concentrations (25, 50,100, 200 and 400 p.p.m.); (b) Photothermal heating curves of aqueous suspensions of dispersed 2D C (100 p.p.m.) under 808 nm laser irradiation at varied power densities (0.5, 1.0 and 1.5 W cm-2); (c) Photothermal heating curves of aqueous suspensions of dispersed 2D C under 808 nm laser irradiation (1.0 W cm-2) at varied concentrations (50, 100 and 200 p.p.m.); (d) Recycling heating profiles of 100 p.p.m. of 2D C under 808 nm laser irradiation (1.0 W cm-2) for three on/off cycles; (e) Calculation of the photothermal-conversion efficiency (η) of 2D C at 808 nm. Black line: photothermal effect for certain periods, and then the laser is turned off. Red line: time constant (τs) from the cooling period by using the linear time data.

Fig. 4. (a-c) Calculation of the photothermal-conversion efficiency (η) of 2D C/Cu1, 2D C/Cu2, and 2D C/Cu3 at 808 nm. Black line: photothermal effect for certain periods, and then the laser is turned off. Red line: time constant (τs) from the cooling period by using the linear time data; (d) Photothermal conversion efficiency (η) of various carbon-based photothermal agents in the literatures.

Fig. 5. Ions release behavior. Cumulative Cu2+ release curves of 2D C/Cu1, 2D C/Cu2, and 2D C/Cu3 (200 p.p.m.) at 37 °C in PBS for (a) short-term release (1 day) and (b) long-term release (4 weeks). Error bars indicate means ± standard deviations (n = 2 independent samples). Source data are provided as a Source Data file.

Fig. 6. Antibacterial activity in vitro. (a) E. coli and S. aureus bacteria treated with 2D C, 2D C/Cu1, 2D C/Cu2, and 2D C/Cu3 (200 p.p.m.), respectively, then kept in the dark for 12 h, spread onto LB agar plates and incubated at 37 °C for 24 h; (b, c) statistical results of the corresponding antibacterial activity (b: E. coli, and c: S. aureus). Error bars indicate means ± standard deviations (n = 3 biologically independent samples): *P < 0.05, **P < 0.01, and ***P < 0.001 (t-test).

Fig. 7. Antibacterial activity in vitro. (a) E. coli, S. Aureus, and MRSA bacteria treated with 2D C/Cu2 (200 p.p.m.) through different treatment, including Light and Light + Dark, then spread onto LB agar plates and incubated at 37 °C for 24 h; (b) Corresponding amounts of Cu2+ releases after light for 10 min under 808 nm laser irradiation; (c-e) statistical results of the corresponding antibacterial activity (c: E. coli, d: S. aureus, and e: MRSA). Error bars indicate means ± standard deviations (n = 3 biologically independent samples): *P < 0.05, **P < 0.01, and ***P < 0.001 (t-test).

Fig. 8. Antibacterial mechanism. TEM images of ultrathin section and corresponding EDS of MRSA treated with 2D C/Cu2 for Dark and Light + Dark group (scale bars = 200 nm).

Fig. 9. Cellular morphology and viability. (a) Fluorescent images of NIH-3T3 cells after co-cultured with 2DC, 2D C/Cu1, 2D C/Cu2, and 2D C/Cu3, and followed by incubation for 24 h at 37 °C; F-actin stained with TRITC Phalloidin (red) and nucleus stained with DAPI (blue). (b) Cell viability of NIH-3T3 cells cultured with 2D C, 2D C/Cu1, 2D C/Cu2, and 2D C/Cu3 (50, 100 and 200 p.p.m.) for 1, 3, and 7 days. Error bars indicate means ± standard deviations (n = 3 biologically independent samples): *P < 0.05, **P < 0.01, ***P < 0.001 (t-test).