A coupled faradaic/electrostatic boosting strategy for decolorization of a refractory dye inside a dually-biased photoelectrochemical reactor: Time and energy saving

Abstract

A green sustainable strategy for environmental remediation and treatment of dye-polluted water is the application/development of effective photoelectrochemical (PEC) reactors. Despite some recent progress in PEC systems, achieving a complete decolorization is still a challenging issue and often requires a long period of reactor operation. Herein, the authors address this interesting time/energy-related problem, demonstrating how without consuming extra electricity/chemicals, fabricating complex photoelectrodes, or changing the pH of medium, one can effortlessly promote the activity of a PEC reactor just by its coupling to a non-faradaic bias source. By applying this novel dually biased (faradaic/electrostatic) boosting strategy, we reveal that decolorization of methyl orange (a refractory dye pollutant) is significantly improved and the decolorization time (thereby energy consumption) is reduced by almost half in comparison to that of a conventional PEC reactor–operating under a single-bias (faradaic) condition. The reactor activity and its photoelectrochemical response are finally discussed in detail in terms of applied potential biases, semiconductor's band bending, open-circuit-potential displacement, electrostatic interaction and electrosorption of dye pollutant.