Simultaneously lanthanide and N modified ZnO NPs were synthesized and applied for the photocatalytic phenol degradation under LED irradiation. Among La and Ce, Ce doped ZnO exhibited more efficiently photocatalytic activity. XRD analysis confirmed that most of Ce3+ was oxidized to Ce2O3/CeO2 over the photocatalyst surface as a secondary phase. This is due to the larger ionic radius of Ce3+ relative to that of Zn2+. Ce and N co-doping of ZnO led to narrowing the band gap and suppressing charge recombination rate. The effect of key variables, dopant type, dopant concentration, catalyst loading, initial dye concentration, light source power, solution pH and H2O2 content on the photocatalytic degradation of phenol was systematically investigated. The utmost conversion of phenol, 100%, was observed by ZnO-Ce5-N0.33 sample under optimum conditions. Kinetics investigation revealed that under the optimum conditions, photodegradation of phenol follows a pseudo first-order kinetics model with rate constant of 0.0631 min-1. Given the fact that the ZnO-Ce5-N0.33 is a heterostructure composed of Zn1-xCexO1-yNy and Ce2O3 and CeO2, a double Z-scheme pattern is suggested as a plausible charge transfer mechanism.
