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This manuscript investigated the catalytic performance of toluene over Ce-Mn-O x catalysts synthesized by four different routes. Ce-Mn-O x prepared by HT method showed superior catalytic activity of toluene due to its more structural defects, oxygen vacancies, surface adsorption oxygen and other active species. Ce-Mn-O x catalysts were synthesized by impregnation (CM-IM), co-precipitation (CM-CP), citrate sol-gel (CM-SG) and hydrothermal (CM-HT) methods. The synthesis methods exhibited a great impact on the physicochemical properties of catalysts, resulting in different catalytic activity. The catalytic oxidation activity of toluene followed the sequence: CM-HT (T 50 : 234 °C; T 90 : 246 °C) > CM-SG (T 50 : 242 °C; T 90 : 249 °C) > CM-CP (T 50 : 243 °C; T 90 : 259 °C) > CM-IM (T 50 : 251 °C; T 90 : 261 °C), which was consistent with the sequence of surface relative percentage of C ov , Ce3+, Mn3+, O α and r values. Among them, CM-HT showed the best catalytic oxidation performance of toluene due to more structural defects, oxygen vacancies, surface adsorption oxygen, normalized conversion rate and other active species. In addition, CM-HT catalysts showed reliable water resistance and good durability, implying the potential industrial application. [ABSTRACT FROM AUTHOR]

Graphical abstract Hierarchically porous ZnO/g-C 3 N 4 microspheres with type-II heterojunction exhibit an enhanced photocatalytic degradation on rhodamine B and phenol. Abstract Graphitic carbon nitride (g-C 3 N 4) is a visible light active semiconductor. However, low conductivity and high recombination rate of photogenerated electrons and holes limit its application in photocatalysis. In this work, we design and synthesize hierarchically porous zinc oxide/graphitic carbon nitride (ZnO/g-C 3 N 4) microspheres with type-II heterojunction to effectively degrade rhodamine B (RhB) via increasing the charge-separation efficiency. The ultraviolet-visible (UV–Vis) absorption spectra, Mott-Schottky plots and valence band X-ray photoelectron spectroscope confirm the formation of type-II heterojunction between ZnO nanocrystals and g-C 3 N 4 nanosheets. As a result, the 1.5-ZnO/g-C 3 N 4 composite (the mass ratio of zinc acetate dihydrate to g-C 3 N 4 is 1.5) exhibits the highest photocatalytic activity with good stability and higher photocatalytic degradation rate comparing to pure g-C 3 N 4 and pure ZnO. In addition, our results confirm that O 2 − and h+ are the main active species for ZnO/g-C 3 N 4 in degradation of RhB. [ABSTRACT FROM AUTHOR]