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This study assessed the primary impacts of exogenous melatonin (MT) treatment on grape berry metabolism. Exogenous MT treatment increased the endogenous MT content and modified berry ripening. Transcriptomic analysis revealed that the processes of polyphenol metabolism, carbohydrate metabolism and ethylene biosynthesis and signaling were the three most significantly altered biological processes upon MT treatment. Further experiments verified that MT treatment increased the contents of total anthocyanins, phenols, flavonoids and proanthocyanidins in berries. Additionally, the contents of 18 of the 22 detected individual phenolic compounds were enhanced by MT treatment; particularly, the resveratrol content was largely increased concomitantly with the up-regulation of STS gene expression. Meanwhile, MT treatment enhanced the antioxidant capacity of berries. On the other hand, it was indicated that ethylene participated in the regulation of polyphenol metabolism and antioxidant capacity under MT treatment in grape berries. In summary, MT enhances the polyphenol content and antioxidant capacity of grape berries partially via ethylene signaling.

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Photocatalysis provides a sustainable route to convert N 2 to NH 3 with the aid of a photogenerated electron. Beyond the typical issue in the photocatalytic field, NH 3 synthesis requires adsorption, activation, and hydrogenation of N 2 . In this report, Ni-doped TiO 2 (Ni-x-TiO 2 ) photocatalysts were fabricated by a simple sol−gel method to introduce the oxygen defects and Ni site on TiO 2 . The oxygen vacancy (Vo) enhances the adsorption of N 2 on the catalyst surface. The Ni doping induced a defect energy level below the conduction band, which prefers to accept the photogenerated electron. The electron captured by Vo tends to transfer to the adsorbed N 2 and activate N 2 . On the other hand, the Ni site is a typical H 2 production site. It provides enough H 2 for the hydrogenation of N 2 to form NH 3 . To sum up all of these advantages, Ni-doped TiO 2 displays a high NH 3 production rate of 46.80 μmol•g −1 •h −1 which is about 7 times higher than that of pure TiO 2 . This manuscript provides a potential method to design a highly efficient photocatalyst for the NH 3 synthesis.

A novel two-step solution approach is put forward to design a unique three dimensional (3D) porous ZnO-SnS p-n heterojunction under mild conditions. This special 3D structure is induced via flower-like ZnO in which SnS serves as an efficient photosensitizer to improve the light harvesting across the whole visible range. A profound investigation of the mechanism shows that this 3D porous ZnO-SnS material effectively integrates the large surface area and high redox potential of ZnO, and wide visible-light harvesting of SnS, which largely promotes the transfer and separation rate of carriers. The systematic study on the active species generated during the photocatalysis illustrates that it is the photoelectrons, ˙OH and O˙ that play the crucial role in the degradation of dyes. As a result, the noble-metal free photocatalyst degrades nearly 100% of rhodamine B (RhB) within 80 min and methylene blue (MB) in 40 min under visible light. The photocatalytic activity is 10 times higher than that of the pure flower-like ZnO and two times higher than that of the SnS material. Moreover, the photocatalyst is easily separated and reused at least four times without obvious change in efficiency and properties. This work provides an effective strategy for the synthesis of 3D porous p-n heterojunction semiconductor-based photocatalysts with low cost and low toxicity, which present promising applications in the field of solar energy storage and conversion.