Efficiency of different methods and forms of microelements application in function of n fertilizer in apple trees

In order to achieve a high yield and quality of apple fruit, more effective ways of fertilization are required in the modern, high density apple orchards. The objective of this research was to determine the efficiency (partial nutrient balance, PNB) of different methods (foliar and fertrigation) and forms (chelates and salts) of microelements application in relation to the levels of N fertilization in apple orchard cultivar (‘Golden Delicious’). The combined effects of these fertilizers on the number of apple fruits per tree and on the yield per tree were also studied. Foliar application of Mn, Zn and Fe had significantly higher partial nutrient balance values compared to the soil application in both years of the experiment. However, most of the PNB values were below 10% indicating relatively low efficiency of the applied fertilizers with microelements

Photoelectrochemical properties of nanocrystalline ZnS discrete versus continuous coating of ZnO nanorods prepared by electrodeposition

International audienceWe developed nanostructured photoanodes for photoelectrochemical (PEC) water splitting and hydrogen generation. They are based on ZnO nanorods electrodeposited on conductive ITO glass on which ZnO@ZnS heterojunctions were formed using two different approaches. In the first case, the ZnO nanorods were sulfided by a prolonged contact with Na2S aqueous solution, while in the second one, they were immersed in an alcoholic solution of 2 nm sized polyol-made ZnS quantum dots (QDs). Transmission electron microscopy showed that a continuous thin layer of ZnS is formed around ZnO leading to a core@shell structure in the first case, while discrete QD aggregates were grafted at the surface of these rods leading to a kind of tologyin, in the second case. PEC properties of both composite films were measured, using a home-made electrochemical cell and illuminating the anodes with a Xenon lamp. A net enhancement of the photocurrent was observed when the ZnS coating was processed, suggesting a low carrier recombination rate, a higher efficiency toward water oxidation, and then electron transfer to the used cathode (Pt wire) for H+ reduction and H2 generation. Interestingly, the performances of the two composite films were found to be comparable, suggesting that a discrete coating of the ZnO nanorods by a small amount of preformed ZnS QDs is enough to improve their properties for the desired application

The structural and the photoelectrochemical properties of ZnO–ZnS/ITO 1D hetero-junctions prepared by tandem electrodeposition and surface sulfidation: on the material processing limits

International audienceZnO–ZnS 1D hetero-nanostructures were prepared by an easy and scalable processing route. It consists of ZnO nanorod electrodeposition on ITO substrate and surface sulfidation by ion exchange in an aqueous Na 2 S solution. Increasing the treatment contact time (t c) from 8 to 48 h involves different ZnS growth mechanisms leading to different structural and microstructural rod characteristics, even if the overall size does not change significantly. Grazing X-ray diffraction, high-resolution microscopy, energy-dispersive spectrometry and X-ray photoelectron spectroscopy describe the outer surface layer as a poly-and nanocrystalline ZnS blende shell whose thickness and roughness increase with t c. The ZnO wurtzite–ZnS blende interface goes from continuous and dense, at short t c , to discontinuous and porous at long t c , indicating that ZnS formation proceeds in a more complex way than a simple S 2À /O 2À ion exchange over the treatment time. This feature has significant consequences for the photoelectrochemical performance of these materials when they are used as photoanodes in a typical light-assisted water splitting experiment. A photocurrent (J p) fluctuation of 45% for less than 5 min of operation is observed for the sample prepared with a long sulfidation time while it does not exceed 15% for that obtained with a short one, underlining the importance of the material processing conditions on the preparation of valuable photoanodes