Figures (4)  Tables (0)

    • Figure 1. 

      The biofilms formed in Fe2O3–B. megaterium systems showed photovoltaic effects. (a)–(d) The surface morphologies of the biofilm on Fe2O3 displaying a lamellar structure. (e) This Fe2O3-B. megaterium system showed electro-charging and discharging processes under alternating light and dark conditions (p < 0.001). (f) The summarized ∑σ values of the co-culturing system in light were significantly higher than those released in dark. (g) This biofilm exhibited a photovoltaic effect in dark-light cycles. The interaction between FeOOH and B. megaterium followed a similar pattern as presented in Supplementary Figs S5−S7.

    • Figure 2. 

      Prolonging the illumination duration of the iron mineral/B. megaterium co-culturing systems enhances both the rate and extent of antibiotics degradation. When TCH or CPL was introduced to the systems after being illuminated for 0, 20, and 60 min, (a) the Fe2O3/B. megaterium, and (b) FeOOH/B. megaterium co-culturing systems promoted pollutant degradation of TCH or CPL in a dark environment. Notably, the degradation of antibiotics by the biofilm formed through biofilm was independent of free radicals (Supplementary Text 1).

    • Figure 3. 

      B. megaterium reduces the Fe(III) in Fe2O3 to Fe3(PO4)2, along with the altered elemental composition and electronic structure of the mineral. The content of Fe(II) increased with the increase of (a) bacteria proportion, (b) crystal type, and (c) Raman intensity also changed after B. megaterium and Fe2O3 co-culturing.

    • Figure 4. 

      The Fe2O3/B. megaterium biofilm is conducive to electron transfer. (a) Time constant τ values of the composites were significantly lower than that of Fe2O3 or B. megaterium under light. (b) The interface double-layer capacitance Q1 of the composite system increased by 5 to 9 times compared to the individual system, and a new pseudo-capacitance Q2 was formed. (c) The Rct of Fe2O3/B. megaterium composites decreased by approximately three orders of magnitude compared to that of Fe2O3 or B. megaterium alone. (d) The exchange current density j of biofilm surpasses that of Fe2O3. The results of FeOOH and B. megaterium are presented in Supplementary Table S2.