Spatial separation of electrons and holes is critical for improving their photocatalytic performance, which is ascribed to the suppressed photoinduced carriers’ recombination among facets. In this work, the ZnO–Au–MnO x heterogeneous nanostructure photocatalyst was prepared by photodepositing Au and MnO x on the ZnO polar {0001} and {101̅0} crystal facets, respectively. The photocatalytic performance of ZnO–Au–MnO x was higher than ZnO and ZnO–Au for the degradation of rhodamine B dye under UV light irradiation. Due to the potential difference between different crystal planes of zinc oxide, electrons and holes will migrate to different crystal planes of zinc oxide. This will lead to the deposition of Au and MnO x on different crystal facets of zinc oxide. The efficient photoinduced carrier separation of ZnO–Au–MnO x resulted in the high photocatalytic activity, which is well supported by photoelectrochemical and photoluminescence analyses. The intermediated species formed during the reaction were investigated by high performance liquid chromatography. The reaction mechanism was investigated by radical trapping experiments and electron spin resonance analysis. The special structure of selective deposition of redox cocatalysts on the different facets should be promising and intriguing for designing highly efficient photocatalysts.

Coordination–photocatalysis synergism progress upon pyridine denitrification of MTi.

No abstract

The objective of this study was to investigate the spatial variation of volatile organic compounds and antioxidant activity of turmeric essential oils (TEOs) harvested from four provinces of China. The major chemical components of these TEOs were analyzed using headspace solid-phase micro-extraction gas chromatography-mass spectrometry. More than forty volatile organic compounds in TEOs were identified, which accounted for 82.09–93.64% of the oil components. The relative abundances of the main volatile organic compounds in TEOs at the genus level were visualized by a heat map. The antioxidant activity of the TEOs of five different origins was characterized by the DPPH free radical scavenging activity, in which the antioxidant activity of the TEOs from Guangxi was superior to those of other sources. Furthermore, the IC 50 values of the antioxidants TEOs collected from Guangxi, Sichuan, Yunnan, Changting, and Liancheng were 33.30, 42.5, 35.22, 63.27, and 39.96 mg/mL, respectively, which indicated the excellent free radical scavenging activity of those TEOs. Therefore, the TEOs might be considered as a natural antioxidant with potential applications in food and pharmaceutical industries.