Hydrogen Evolution on Nano-StructuredCuO/Pd Electrode: Raman Scattering Study

In this study, the processes taking place on the surfaces of nanostructured Cu/CuO and Cu/CuO/Pd electrodes at different potential, E, values in the solutions of 0.1 M KOH in H 2 O and D 2 O (heavy water) were probed by surface enhanced Raman spectroscopy (SERS), and the analysis of electrochemical reactions occurring under experimental conditions is presented. The bands of the SERS spectra of the Cu/CuO/Pd electrode observed in the range of E values from +0.3 V to 0 V (standard hydrogen electrode (SHE)) at 1328–1569 cm − 1 are consistent with the existence of species that are adsorbed or weakly bound to the surface with the energy of interaction close to 15–21 kJ mol − 1 . These bands can be attributed to the ad(ab)sorbed (H 3 O + ) ad , (H 2 + ) ab , and (H 2 + ) ad ions as intermediates in reversible hydrogen evolution and oxidation reactions (HER/HOR) taking place on the Cu/CuO/Pd electrode. There was no isotopic effect observed; this is consistent with the dipole nature of the electron-ion pair formation of adsorbed (H 3 O + ) ad and (H 2 + ) ad or (D 3 O + ) ad and (D 2 + ) ad . In accordance with the literature data, SERS bands at 125–146 cm − 1 and ∼520–565 cm − 1 were assigned to Cu(I) and Cu(II) oxygen species. These findings corroborate the quantitative stepwise mechanism of water reduction

Engineering of conformal electrode coatings by atomic layer deposition for aqueous Na-Ion battery electrodes

The application of atomic layer deposition on active material particles or as conformal layers directly on electrodes is an effective and viable approach for protecting the battery materials from degradation. Al2O3, TiO2, and HfO2 coatings are applied on NaTi2(PO4)3, which is among the most studied negative electrode materials for aqueous Na-ion batteries. The coated electrodes are characterized in terms of electrochemical kinetics, charge capacity retention, and electrochemical impedance spectra. Al2O3, a widely used protective coating in non-aqueous batteries, is shown to be insufficient to suppress parasitic processes and is eventually dissolved by reaction with hydroxide during extended cycling in aqueous Na2SO4. However, this process provides a local buffering effect making the protective action of this coating mainly of chemical nature. TiO2 is found to be very resistant to increase in pH and remains almost intact during electrochemical cycling. However, we provide strong evidence that TiO2 itself is electrochemically active in aqueous electrolytes at negative potentials. The protonation of TiO2 leads to an additional increase in local pH which is detrimental to NaTi2(PO4)3 and results in even faster capacity loss than in uncoated electrodes. Only HfO2 is found to be sufficiently stable and electrochemically inert ALD coating for negative NaTi2(PO4)3 electrodes operating in aqueous electrolytes

Selectivity of tungsten oxide synthesized by Sol-Gel method towards some volatile organic compounds and gaseous materials in a broad range of temperatures

In this research, the investigation of sensing properties of non-stoichiometric WO3 (WO3−x) film towards some volatile organic compounds (VOC) (namely: Methanol, ethanol, isopropanol, acetone) and ammonia gas are reported. Sensors were tested at several temperatures within the interval ranging from a relatively low temperature of 60 up to 270 ◦C. Significant variation of selectivity, which depended on the operational temperature of sensor, was observed. Here, the reported WO3/WO3–x-based sensing material opens an avenue for the design of sensors with temperature-dependent sensitivity, which can be applied in the design of new gas- and/or VOC-sensing systems that are dedicated for the determination of particular gas- and/or VOC-based analyte concentration in the mixture of different gases and/or VOCs, using multivariate analysis of variance (MANOVA)

Black-Si as a Photoelectrode

The fabrication and characterization of photoanodes based on black-Si (b-Si) are presented using a photoelectrochemical cell in NaOH solution. B-Si was fabricated by maskless dry plasma etching and was conformally coated by tens-of-nm of TiO2 using atomic layer deposition (ALD) with a top layer of CoO x cocatalyst deposited by pulsed laser deposition (PLD). Low reflectivity R < 5 % of b-Si over the entire visible and near-IR ( λ < 2   μ m) spectral range was favorable for the better absorption of light, while an increased surface area facilitated larger current densities. The photoelectrochemical performance of the heterostructured b-Si photoanode is discussed in terms of the n-n junction between b-Si and TiO2