Wireless pulsed nanophotoelectrochemical cell for the ultrafast degradation of organic pollutants
Albert Serrà, Elvira Gómez, Nour al Hoda Al Bast, Yue Zhang, Marcos Duque, M.J. Esplandiu, J. Estéve, J. Nogués, Borja Sepúlveda
Abstract
An urgent demand exists for advanced-technologies to efficiently remove persistent organic pollutants from water, while minimizing energy consumption. Here, we introduce an innovative wireless nanophotoelectrochemical (nPEC) cell using pulsed light for the ultrafast degradation/mineralization of organic pollutants. The nPEC cell comprises a nanostructured Si-pn photodiode that monolithically integrates: (i) a Si-n/Au nanowire-based-photocathode for effective light absorption and photovoltage generation, and (ii) a Si-p/mesoporous-NiPt photoanode serving as catalyst to wirelessly amplify the sulfate radical production by low-intensity light without any bias voltage. The efficacy of the nPEC cell was shown by ultrafast degradation (>99 %) and mineralization (>98 %) of three emerging pollutants (tetracycline, levofloxacin and anatoxin-A). Notably, reaction kinetics were boosted by more than one order of magnitude when exposed to light intensities ca. 5-fold lower than sunlight. Remarkably, pulsed light beams in the 100–500 Hz range provided an additional enhancement in the degradation/mineralization efficiencies, reducing energy-input by half, while enhancing the catalyst's oxidation state and durability.