A novel approach of photo-charging and dark-discharging mechanisms by using V2O5 / g-C3N4 photocatalysts for ciprofloxacin degradation

Day and night photocatalysis offers a novel approach by integrating the electron storage principle to ensure effectiveness even in the absence of light. A groundbreaking vanadium pentoxide / graphitic carbon nitride (V2O5 / g-C3N4) composite photocatalyst functioned as g-C3N4 absorbs and utilizes visible light, while V2O5 transfers and stores more photo-generated electrons. The composite with a 2 % loading ratio showed the highest CIP removal efficiency: 91 % during daytime and 75 % at night. Successful nighttime degradation was due to stored electrons in V5+/ V4+ pairs, confirmed by XPS analysis of the reduction of V5+ to V4+. The study proposes detailed mechanisms for charge generation, reactive species action, and reactions during both day and night photocatalysis. This has significance for water treatment in real environmental settings with lower energy requirements, overcoming light-related limitations.