Electrochemical Study of the Chemiadsorption, Chemical Protection and Desorption of Cysteine in Gold and Copper Electrodes

2019 ◽  
Vol 15 (1) ◽  
pp. 353-363
Author(s):  
Mariana O. González-Mares ◽  
M. G. García-Jiménez ◽  
L. M. De León Rodríguez
2019 ◽  
Vol 25 (28) ◽  
pp. 59-68 ◽  
Author(s):  
Jewel A. Gomes ◽  
Md. Sanoar Rahman ◽  
Kamol Das ◽  
Srikanth Varma ◽  
David Cocke

2020 ◽  
Author(s):  
Jennifer A. Rudd ◽  
Ewa Kazimierska ◽  
Louise B. Hamdy ◽  
Odin Bain ◽  
Sunyhik Ahn ◽  
...  

The utilization of carbon dioxide is a major incentive for the growing field of carbon capture. Carbon dioxide could be an abundant building block to generate higher value products. Herein, we describe the use of porous copper electrodes to catalyze the reduction of carbon dioxide into higher value products such as ethylene, ethanol and, notably, propanol. For <i>n</i>-propanol production, faradaic efficiencies reach 4.93% at -0.83 V <i>vs</i> RHE, with a geometric partial current density of -1.85 mA/cm<sup>2</sup>. We have documented the performance of the catalyst in both pristine and urea-modified foams pre- and post-electrolysis. Before electrolysis, the copper electrode consisted of a mixture of cuboctahedra and dendrites. After 35-minute electrolysis, the cuboctahedra and dendrites have undergone structural rearrangement. Changes in the interaction of urea with the catalyst surface have also been observed. These transformations were characterized <i>ex-situ</i> using scanning electron microscopy, X-ray diffraction, and X-ray photoelectron spectroscopy. We found that alterations in the morphology, crystallinity, and surface composition of the catalyst led to the deactivation of the copper foams.


Author(s):  
Kailun Yang ◽  
Recep Kas ◽  
Wilson A. Smith

<p>This study evaluated the performance of the commonly used strong buffer electrolytes, i.e. phosphate buffers, during CO<sub>2</sub> electroreduction in neutral pH conditions by using in-situ surface enhanced infrared absorption spectroscopy (SEIRAS). Unfortunately, the buffers break down a lot faster than anticipated which has serious implications on many studies in the literature such as selectivity and kinetic analysis of the electrocatalysts. Increasing electrolyte concentration, surprisingly, did not extend the potential window of the phosphate buffers due to dramatic increase in hydrogen evolution reaction. Even high concentration phosphate buffers (1 M) break down within the potentials (-1 V vs RHE) where hydrocarbons are formed on copper electrodes. We have extended the discussion to high surface area electrodes by evaluating electrodes composed of copper nanowires. We would like highlight that it is not possible to cope with high local current densities on these high surface area electrodes by using high buffer capacity solutions and the CO<sub>2</sub> electrocatalysts are needed to be evaluated by casting thin nanoparticle films onto inert substrates as commonly employed in fuel cell reactions and up to now scarcely employed in CO<sub>2</sub> electroreduction. In addition, we underscore that normalization of the electrocatalytic activity to the electrochemical active surface area is not the ultimate solution due to concentration gradient along the catalyst layer.This will “underestimate” the activity of high surface electrocatalyst and the degree of underestimation will depend on the thickness, porosity and morphology of the catalyst layer. </p> <p> </p>


The application of preparations of biological origin in the protection system of soybean grown under conditions of intensive irrigated crop rotations conforms to the modern tendencies of science and production development. The use of them contributes to solving ecological, production and social-economic problems. The study presents the three-year research on the efficiency of systems protecting soybean from pests and diseases based on biological and chemical preparations. The research was conducted in typical soil and climate conditions of the South of Ukraine. Zonal agricultural methods and generally accepted research methodology were used. The purpose of the research was to create a soybean protection system based on preparations of biological origin, ensuring high productivity of high-quality products reducing a negative impact of the crop production on the environment. The study emphasizes that, under irrigated conditions of the South of Ukraine, the application of biological preparations has a positive impact on the indexes of growth, development and formation of the elements of soybean yield structure. There was an increase in the crop biological weight by 13.8 % and 22.1 % and the number of seeds per plant rose by 11.6 and 14.6 % as a consequence of eliminating harmful organisms with the plant protection systems. The larger ground mass was formed by medium-ripe varieties Danai and Svyatogor, on which the increase from protection measures was higher. Weight 1000 pcs. the seeds did not undergo significant changes. It is established that the larger seeds were formed by Danaya and Svyatogor varieties, in which the average weight is 1000 pcs. seeds were 142 and 136 g, respectively, while in the variety Diona this figure was 133 g. There was an increase in the height of the lowest pod when the total plant height rose. For medium-ripe varieties was characterized by a higher attachment of beans, where the highest values of this indicator acquired in the variety Svyatogor. The medium maturing soybean variety Danaia formed the maximum yield of 3.23 and 3.35 t/ha respectively, when biological and chemical protection systems were applied. The research establishes that the application of the bio-fungicide Psevdobakterin 2 (2.0 l/ha) in the crop protection system at the beginning of soybean flowering and the bio-fungicide Baktofit (2.5 l/ha) with the bio-insecticide Lepidotsid-BTU (10.0 l/ha) at the beginning of pod formation does not reduce the productivity of the soybean varieties under study considerably, when compared to the application of chemical preparations. The research determines that the soybean protection system under study ensures a decrease in the coefficient of soybean water uptake by 7.2-13.0 %, increasing the total water intake to an inconsiderable degree. Biologization of the soybean crop protection system leads to a reduction in production costs compared to the chemical protection system. Taking into account the needs for the collection of additional products, costs increase by an average of 1 thousand UAH/ha, while for chemical protection systems by 1.8 thousand UAH/ha. At the same time, the cost is reduced by 220-360 UAH/t and the profitability of growing crops is increased by 3.8-7.8 %. There has been a reduction in the burden of pesticides on the environment and the production of cleaner products. This indicates the prospect of using the biofungicides Pseudobacterin 2 and Bactophyte and the bioinsecticide Lepidocid-BTU on soybeans to protect plants from pests.


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