Direct and efficient conversion of antibiotic wastewater into electricity by redox flow fuel cell based on photothermal synergistic effect

Antibiotic wastewater has caused serious environmental pollution and is hard to utilize. Thus, it is urgent to develop a green and efficient technology for treating antibiotic wastewater and effective utilization. The reported fuel cell technologies can degrade antibiotics and generate electricity simultaneously, but their cell performance is very bad and difficult application. Herein, we reported a new environment-friendly and low-cost redox flow fuel cell (RFFC) based on the photothermal synergistic effect to convert antibiotic wastewater into electricity directly and efficiently at low temperature. The developed RFFC can output the maximum power density of 98.2 mW cm−2 which is 545 times of the reported microbial fuel cells and 270 times of the reported photocatalytic fuel cells. And the photothermal degradation method is better than the thermal degradation and photo degradation. Furthermore, it can discharge stably >2.5 h at high current density of 2 A cm−2 and successfully power a small electrical fan (1.5 V). The reaction mechanism is studied by the density functional theory (DFT) calculation, and the results show that FeCl3 molecules as photocatalyst and electron carriers of the RFFC can complex with antibiotics to greatly reduce the energy gap between HOMO and LUMO of antibiotics, which make the antibiotic molecules easy to be excited to unstable excited state by visible and UV light (λ < 733 nm) and greatly beneficial for their photothermal degradation. Besides, when using cefuroxime sodium wastewater as the model wastewater, HS-GC–MS results show that cefuroxime sodium can be completely degraded into non-toxic micro molecules after generating electricity. This work shows promising potential application for high-value utilization of antibiotic wastewater and generating clean electricity.