Complete solar-driven dual-photoelectrode fuel cell for water purification and power generation in the presence of peroxymonosulfate

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.