Oxygen Reduction Reaction (ORR) catalysts, from waste automobile tyres obtained from Microwave assisted pyrolysis (MAP), were enriched with Co and Cu using the simple treatments sonochemical and electrochemical deposition. Catalytic activity was evaluated through onset potential and number of exchanged electrons measurements. Electrochemical data demonstrate an improvement in catalytic activity of the electrochemical modified char with Co. Char electrodes enriched with Co show a maximum positive shift of 40 mV with respect to raw char electrodes with a number of exchanged electrons per O2 molecule close to 4 (as for Pt) for the best sample. This corresponds to a reduction of the production of unwanted oxygen peroxide from 23% for raw char to 1%. Sample structure evolution before and after electrochemical deposition and electro-catalysis was investigated by scanning transmission electron microscopy and XPS. Such electrochemical treatments open new possibilities of refining waste chars and finding an economic alternative to noble metals-based catalysts for alkaline fuel cells.

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In order to substitute traditional cyanide-based baths and obtain a new eco-compatible route to synthesize via electrodeposition a CZTS (copper-zinc-tin sulfide) absorber films, this paper describes the development of a green electrodeposition bath for Cu–Sn alloys. CZTS, being a p-type semiconducting material could be used in novel and sustainable photovoltaic devices. In this work we analyzed the electrochemical behavior of different methanesulfonic acid-based prototype deposition bath containing tin methanesulfonate as tin precursor, copper sulfate or methanesulfonate as copper precursor, and hydroquinone, nitrilotriacetic acid and 2-picolinic acid as organic additives. Electrodeposition was conducted with different deposition parameters such as deposition potential, current density, potentiostatic or galvanostatic mode. Surface and cross-section morphology as well as composition of the films were characterized using SEM-EDS. The composition of the samples in terms of crystalline phases was analyzed using XRD, highlighting the information obtained by superlattice diffraction peaks based on the crystallography of Cu–Sn intermetallic phases. From prototype bath S4 a uniform composition around Cu:Sn = 2:1 was observed with η ′ phase as the dominant phase, which could possibly facilitate the synthesis of CZTS due to its aligned body-center vacancies that could serve as sulfur diffusion path during sulfurization within each η ′ crystal.

Abstract:The passivation of metal electrodes covered by self-assembled monolayers of long-chain thiols is well known. The disappearance of the voltammetric peak of redox species in solution is a classical test for the formation of full layers of thiols. Similar studies on semiconductors are still very limited. We used silver surfaces covered by an ultrathin layer of CdS as substrate for self-assembling of n-hexadecanethiol (C 16 SH), and we compared the experimental results with those obtained by using the bare silver surface as substrate. The strong insulating effect of C 16 SH deposited on Ag(III) is shown by the inhibition of the voltammetric peak of Ru(NH 3 ) 6 3+/2+ . On the contrary, the voltammogram obtained on CdS-covered Ag(III) is very similar to that obtained on the bare Ag(III) electrode, thus suggesting that the presence of CdS exerts a contrasting effect on the passivation of the silver electrode. A crucial point of our work is to demonstrate the effective formation of C 16 SH monolayers on Ag(III) covered by CdS. The formation of full layers of C 16 SH was strongly suggested by the inhibition of the stripping peak of Cd from the CdS deposit covered by C 16 SH. The presence of C 16 SH was confirmed by electrochemical quartz crystal microbalance (EQCM) measurements as well as by Auger electron spectroscopy (AES) analysis.

This paper explores the conditions for the electrodeposition of Moad (molybdenum adlayer) on Ag(111) from alkaline aqueous solution. Moreover, the first stages of the growth of MoSe2 are also presented, performing the deposition of Sead on the deposited Moad. The deposition of Moad on Sead/Ag(111) was also explored. MoSe2 is of interest due to its peculiar optoelectronic properties, making it suitable for solar energy conversion and nanoelectronics. In this study, electrodeposition techniques were exploited for the synthesis process as more sustainable alternatives to vacuum based techniques. The electrochemical atomic layer deposition (E-ALD) method emerges as a suitable technique to grow inorganic semiconductor thin films thanks to its fulfillment of the green energy predicament and a strict structural and morphological control, and this approach has gathered the attention of the scientific community. Indeed, E-ALD exploits surface limited reactions (SLRs) to alternate the deposition of chemically different atomic layers constituting a compound semiconductor. Thus, E-ALD is one of the most promising electrodeposition techniques for the growth of thin-film of compound semiconductors under a strict structural and morphological control. On this ground, E-ALD can be considered an ideal technique for the growth of 2D materials.