Cyclic reaction network modeling for the kinetics of photoelectrocatalytic degradation

Among various advanced oxidation processes (AOPs) employed for the destruction of pollutants, photocatalysis has witnessed a tremendous development over the past two decades. Studies have reported the recombination of valence band holes and conduction band electron as a barrier in achieving higher degradation rate. To avoid recombination, an external bias can be applied to keep the charge carriers i.e. holes and electron separated. The present work investigates the synergistic effect of photocatalysis and electrocatalysis. A reaction network model is also developed for obtaining better insights of underlying complex processes. To validate the model, experiments were carried out for the anionic dyes with combustion synthesized TiO2 as catalyst. The model has shown good agreement with the experimental findings. Loop coefficients were calculated in each case to have an estimate of hydroxyl radicals formed. Synergy, which is defined on the basis of first order rate constants, was observed in all cases of photoelectrocatalysis and increased with applied bias.