Magnetron Sputter-Coated Nanoparticle MoS2 Supported on Nanocarbon: A Highly Efficient Electrocatalyst toward the Hydrogen Evolution Reaction.

From Europe PMC via Jisc Publications RouterHistory: ppub 2018-07-01, epub 2018-07-03Publication status: PublishedThe design and fabrication of inexpensive highly efficient electrocatalysts for the production of hydrogen via the hydrogen evolution reaction (HER) underpin a plethora of emerging clean energy technologies. Herein, we report the fabrication of highly efficient electrocatalysts for the HER based on magnetron-sputtered MoS2 onto a nanocarbon support, termed MoS2/C. Magnetron sputtering time is explored as a function of its physiochemical composition and HER performance; increased sputtering times give rise to materials with differing compositions, i.e., Mo4+ to Mo6+ and associated S anions (sulfide, elemental, and sulfate), and improved HER outputs. An optimized sputtering time of 45 min was used to fabricate the MoS2/C material. This gave rise to an optimal HER performance with regard to its HER onset potential, achievable current, and Tafel value, which were -0.44 (vs saturated calomel electrode (SCE)), -1.45 mV s-1, and 43 mV dec-1, respectively, which has the highest composition of Mo4+ and sulfide (MoS2). Electrochemical testing toward the HER via drop casting MoS2/C upon screen-printed electrodes (SPEs) to electrically wire the nanomaterial is found to be mass coverage dependent, where the current density increases up to a critical mass (ca. 50 μg cm-2), after which a plateau is observed. To allow for a translation of the bespoke fabricated MoS2/C from laboratory to new industrial applications, MoS2/C was incorporated into the bulk ink utilized in the fabrication of SPEs (denoted as MoS2/C-SPE), thus allowing for improved electrical wiring to the MoS2/C and resulting in the production of scalable and reproducible electrocatalytic platforms. The MoS2/C-SPEs displayed far greater HER catalysis with a 450 mV reduction in the HER onset potential and a 1.70 mA cm-2 increase in the achievable current density (recorded at -0.75 V (vs SCE)), compared to a bare/unmodified graphitic SPE. The approach of using magnetron sputtering to modify carbon with MoS2 facilitates the production of mass-producible, stable, and effective electrode materials for possible use in electrolyzers, which are cost competitive to Pt and mitigate the need to use time-consuming and low-yield exfoliation techniques typically used to fabricate pristine MoS2

Feeding propolis or essential oils (cashew and castor) to bulls: performance, digestibility, and blood cell counts

Background: in cattle production systems, antibiotics are commonly fed to cattle to prevent diseases, metabolic disorders, and to improve feed efficiency. Considerable effort has been devoted towards developing alternatives to the use of antibiotics. Objective: to evaluate the effect of propolis or cashew and castor oils on animal performance, feed intake, digestibility, and blood cell counts of young bulls. Methods: bulls were kept in a feedlot for 49 days. Starting on the 40th day, feces were sampled for five days to estimate digestibility using indigestible dry matter (DM) as a marker. Bulls were fed a control diet (CON) with sorghum silage (41% DM) and cracked corn, soybean meal, glycerine, limestone, and mineral salt. The propolis-supplemented group (PRO) received 3 g/animal/d in the concentrate. The essential oils-supplemented group (OIL) received 3 g/animal/d (1.5 g cashew oil + 1.5 g castor oil) added to the concentrate. Results: final body weight, average daily gain and feed efficiency were better for bulls fed the OIL diet. Propolis or essential oils had no effect on feed intake and digestibility. There was no effect of propolis or essential oils on blood cell counts. Red blood cell concentration was greater in the last day of the experiment, while the number of white blood cells was lower. Conclusions: dietary addition of propolis did not affect bull performance or feed efficiency. The addition of essential oils improved performance. Feed intake, digestibility, and blood cell counts were similar in all treatments