This study reports the development of complete solar-driven dual-photoelectrode fuel cell (PFC) based on WO 3 photoanode and Cu 2 O photocathode with peroxymonosulfate (PMS) serving as cathodic electron acceptor . As indicated by photoelectrochemical measurements, the PMS was able to improve thermodynamic properties of photocathode, achieving an increased open circuit potential from 0.42 V to 0.65 V vs standard hydrogen electrode (SHE). Under simulated sunlight irradiation (~100 mW cm −2 ), the maximum power density of 0.12 mW cm −2 could be obtained at current density of 0.34 mA cm −2 , which was 8.57 times of that produced by PFC without PMS (0.014 mW cm −2 ). Correspondingly, adding PMS (1.0 mM) increased overall removal efficiency of 4-chlorophenol (4-CP) from 39.8% to 96.8%, accounting for the first-order kinetic constant ( k =0.056 min −1 ) being 6.67 times of that in the absence of PMS ( k =0.0084 min −1 ). Radical quenching and electron spin-resonance (ESR) results suggested the contribution of free radicals (•OH and SO 4 •- ) and non-radical pathway associated with direct activation of PMS by Cu 2 O photocathode. Fourier transformed infrared (FTIR) analysis confirmed the strong non-radical interaction between Cu 2 O photocathode and PMS, resulting in 4-CP removal via activation of PMS by surface complex on Cu 2 O. The proof-in-concept complete solar-driven dual-photoelectrode fuel cell may offer an effective manner to realize water purification and power generation, making wastewater treatment more economical and more sustainable.
Wang Yongqiang,Bai Yibo,Han Che,Li Zaimei,Lun Xiaowen,Zhang Conglu
Graphite-like carbon nitride (g-C 3 N 4 ) is favored for its excellent physicochemical properties. However, the high complexation rate of photogenerated carriers greatly limits its practical applications. Based on this, a novel CQDs-doped carbon nitride nanosheets composite (CNS/CQDs) was prepared and applied to the visible light–induced activation of peroxymonosulfate (PMS) for meloxicam (Mel) and tetracycline (TC) degradation. The photocatalytic degradation of Mel and TC were remarkably promoted in the CNS/CQDs+PMS+vis system. Mel photodegradation of 99.90% was achieved over 30 min with 20 mg CNS/CQDs and 20 mg PMS at pH11. And TC photodegradation of 95.97% was achieved over 45 min with 20 mg CNS/CQDs and 20 mg PMS at nature pH6.5. The TOC mineralization rates of Mel and TC were 75.49% and 52.00%, respectively. The transient photocurrent response and electrochemical impedance measurements (EIS) results indicated that the doping of CQDs could improve the charge transfer efficiency of pure g-C 3 N 4 , and CNS/CQDs had a low charge transfer resistance. Capture experiments and EPR tests explored the effective actives in the CNS/CQDs+PMS+vis system. Possible degradation pathways of Mel were also analyzed. This study provides valid residual drugs degradation under the dual conditions of visible light catalytic oxidation and persulfate oxidation, which will be a novel perspective for advanced oxidation technology to effectively remove organic pollutants from water.
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