The synergetic effect of lanthanide (La and Ce) and N co-doping of ZnO NPs for high-rate photocatalytic phenol degradation.

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.

Modification of photocatalytic property of BaTiO3 perovskite structure by Fe2O3 nanoparticles for CO2 reduction in gas phase.

In this work, perovskite structure of BaTiO3 was coupled with Fe2O3 in different molar ratios achieving the best photocatalytic performance of CO2 reduction in the presence of CH4 as reducing agent; both of them are main greenhouse gases. The photocatalysts were synthesized by facile hydrothermal method. The samples were characterized by XRD, FTIR, FESEM, EDX, UV-Vis DRS, and photoluminescence (PL) analyses. The BaTiO3 synthesized in this research showed a weak PL signal which is due to the intrinsic ferroelectric property as has been observed in previous reports. Compared to the pure BaTiO3 and Fe2O3, the heterojunctions exhibited enhanced photocatalytic activity. The maximum CO2 reduction under visible light irradiation was obtained to be 22% during 60 min process time. The enhanced photocatalytic activity could be attributed to the increased optical absorption, the good separation, and immigration of photogenerated charge carriers that decreased the recombination rate of charge carriers in the n-n heterojunction.