“…However, at low concentration levels, iron oxide could decrease the recombination rate thanks to charge separation [27,29,30] . For both FeOOH and Fe 2 O 3 , the delocalisation pathway of electron-hole pairs with zinc oxide is still in debate [14,15,19,22,[27][28][29][30][31][32] . We hypothesize the most favourable pathway is the delocalisation of the electrons from ZnO CB to iron oxide CB, leading to a decrease in the recombination rate and an increase in hydroxyl radical production.…”