No abstract

Electrochemical reduction of CO2 in an aqueous electrolyte (Briton Robinson buffer, pH = 5.82) was investigated using an Ir/Ru‐oxide coating deposited on a titanium substrate, as a function of electrode potential and temperature. The results demonstrated that the Ir/Ru‐oxide electrode can efficiently be used for the electrochemical conversion of CO2 into different valuable organic molecules at high faradaic efficiency, 85 % and 96 % at 295 K and 277 K, respectively. Ethanol was found to be the major electrochemical reduction product remained in the liquid phase, with a minor contribution of methanol, acetone and acetaldehyde. The amount of formed products and the corresponding faradaic efficiency were found to be strongly dependent on electrode potential. A maximum in both was obtained at −1.7 V (vs. MSE). At this potential, lowering the reaction temperature from 295 K to 277 K was found to increase the CO2 reduction kinetics only at short electrolysis times, while the corresponding faradaic efficiency increased significantly. The presented work demonstrates that the Ir/Ru‐oxide electrode can be considered as a good electrode candidate for the electrochemical conversion of CO2 into usable organic molecules at atmospheric pressure and in aqueous electrolytes.

Multi‐walled carbon nanotubes (MWCNTs) were grown on a stainless steel mesh and decorated with nickel nanoparticles (Ni NPs). The developed Ni NP‐MWCNT material was then used as a cathode in an electrochemical batch reactor to electrocatalytically convert NAD+ to enzymatically‐active 1,4‐NADH. The regeneration of 1,4‐NADH was studied at various electrode potentials. At electrode potential of −1.6 V, a very high recovery (relative amount of 1,4‐NADH in the product mixture) was obtained, 98 ± 1 %. In comparison, to achieve the same recovery on a non‐decorated MWCNT cathode, a much higher cathodic potential was needed (−2.3 V), establishing the importance of Ni NPs on the electrocatalytic activity in reducing NAD+ to 1,4‐NADH. It was postulated that hydrogen adsorbs on Ni NPs immobilized on MWCNTs to form Ni‐Hads, and this activated hydrogen rapidly reacts with neighbouring NAD‐radicals, preventing the dimerization of the latter species, ultimately yielding 1,4‐NADH.

No abstract

Electrochemical, topographical, and morphological properties of thermally‐prepared Irx‐Ru1‐x‐oxide coatings of various compositions (0 < x ≤ 1), formed on a Ti metal substrate, were investigated for their potential application as supercapacitor (SC) electrodes employing scanning electron microscopy and electrochemical techniques of cyclic voltammetry, galvanostatic charge/discharge cycling, and electrochemical impedance spectroscopy. A current state‐of‐the‐art pure ruthenium oxide (RuO2) coating showed relatively low performance compared to other bimetallic IrxRu1‐x‐oxide coatings operated under the same experimental conditions. An electrochemically‐activated Ir0.4Ru0.6‐oxide coating yielded the highest capacitance value (85 mF cm−2). Prolonged electrochemical cycling of the Ir/Ru‐oxide coatings in a corrosive phosphate‐buffered saline pH = 7.4, performed within an extreme potential window of 5 V, revealed an excellent stability of the coatings. In addition, this cycling procedure enabled a significant increase in capacitance for all coating compositions. It was shown that the areal capacitance (CGA) of these coatings is strongly dependent upon the nature of the components of which the metal oxide is composed. The addition of IrO2 to RuO2 improved the stability and capacitive performance of the thermally‐prepared Ir‐Ru‐oxide coatings.