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Oxygen evolution reaction (OER) supported by electrocatalyst is very important reaction in electrochemical system e.g. air-battery based energy storage devices, water splitting, and photo electrochemical cells. Therefore developing inexpensive, non-hazardous, noble metal free, transition metal oxide based electrocatalyst is necessary for energy application and environmental sustainability. MCo2(III)O4 based oxides in combination of various metal ions (Mn2+, Cu2+, Co2+, Zn2+, Fe2+, Mg2+) are studied as OER electrocatalyst in both acidic and basic medium. When deposited on a glassy carbon current collector the comparative LSV polarization plots revealed that in acidic medium FeCo2O4 is the best OER performing electrocatalyst, showing onset potential +1.62 V vs RHE with current 1.66 mA/cm2, while in basic medium it is MnCo2O4 that preforms the best, showing an onset potential +1.53 V vs RHE with OER current density 2.06 mA/cm2. When nickel foam was used as the current collector, Co3O4 shows the best OER performance, with an onset potential 1.508 V vs RHE and OER current 159 mA/cm2 in acidic medium. However in the basic medium the substrate nickel foam outperforms all the oxides combinations with different metal ions due to partially oxidized NiO at nickel foam, showing onset OER potential +1.58 V vs RHE and OER current density 13mA/cm2. No correlation was found between the rates of OER and the bond dissociation energies of the respective metal-oxygen bonds nor the metal-hydroxide bond strength.

Ordered, closely packed, and vertically oriented titania nanotube arrays with lengths exceeding 10 µm were fabricated by anodization of titanium foils. The effects of anodization voltage and time on the microstructural morphology and the photovoltaic performance of dye sensitized solar cells based on the titania nanotube arrays were investigated. On increasing the anodization voltage or time, the increase in active surface area leads to enhanced photovoltaic currents and thereby an overall higher performance of the dye sensitized solar cells. The efficiency enhancement with rising anodization voltage exceeds the increase in the outer surface area of the nanotubes, indicating that the active surface area is further enlarged by a more accessible inner surface of the nanotube arrays grown with a higher anodization voltage. A promising efficiency of 3.67% for dye sensitized solar cells based on anodized titania nanotube arrays was achieved under AM1.5, 100 mW cm(-2) illumination.

We have performed structural studies of mixed mobile ion phosphate glasses AgxNa1-xPO3 using diffraction experiments and reverse Monte Carlo simulations. This glass system is particularly interesting as a model system for investigations of the mixed mobile ion effect, due to its anomalously low magnitude in the system. As for previously studied mixed alkali phosphate glasses, with a much more pronounced mixed mobile ion effect, we find no substantial structural alterations of the phosphorous-oxygen network and the local coordination of the mobile cations. Furthermore, the mobile Ag+ and Na+ ions are randomly mixed with no detectable preference for either similar or dissimilar pairs of cations. However, in contrast to mixed mobile ion systems with a very pronounced mixed mobile ion effect, the two types of mobile ions have, in this case, very similar local environments. For all the studied glass compositions the average Ag-O and Na-O distances in the first coordination shell are determined to be 2.5 ± 0.1 and 2.5 ± 0.1 A, and the corresponding average coordination numbers are approximately 3.2 and 3.7, respectively. The similar local coordinations of the two types of mobile ions suggests that the energy mismatch for a Na+ ion to occupy a site that previously has been occupied by a Ag+ ion (and vice versa) is low, and that this low energy mismatch is responsible for the anomalously weak mixed mobile ion effect.