It has been anticipated that learning from nature photosynthesis is a rational and effective way to develop artificial photosynthesis system, but it is still a great challenge. Here, we assembled a photoelectrocatalytic system by mimicking the functions of photosystem II (PSII) with BiVO semiconductor as a light harvester protected by a layered double hydroxide (NiFeLDH) as a hole storage layer, a partially oxidized graphene (pGO) as biomimetic tyrosine for charge transfer, and molecular Co cubane as oxygen evolution complex. The integrated system exhibited an unprecedentedly low onset potential (0.17 V) and a high photocurrent (4.45 mA cm), with a 2.0% solar to hydrogen efficiency. Spectroscopic studies revealed that this photoelectrocatalytic system exhibited superiority in charge separation and transfer by benefiting from mimicking the key functions of PSII. The success of the biomimetic strategy opened up new ways for the rational design and assembly of artificial photosynthesis systems for efficient solar-to-fuel conversion.

Greek oregano is commonly used as a spice and in traditional medicine in Eurasia. The plant is rich in secondary metabolites, such as volatile organic compounds (VOC) and polyphenols. Chitosan oligosaccharides (COS) are used as a plant elicitor. The objectives of this study were to determine the effects of COS on the growth and content of secondary metabolites in Greek oregano. Four COS treatments (50, 200, 500, and 1000 ppm) were used in a field experiment. The 200 and 500 ppm COS treatments promoted plant height growth, whereas 50 and 200 ppm COS upregulated the content of polyphenols significantly (38 and 29%, respectively). The COS treatments induced H 2 O 2 generation in Greek oregano leaves; thus, the effect of H 2 O 2 treatment was studied to investigate the possible role of H 2 O 2 in growth and polyphenol production. A low concentration of H 2 O 2 also promoted plant height growth, but only tendencies to higher polyphenol content were seen.

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