One hindrance to the development of fuel cells and electrolyzers are the oxygen electrodes, which suffer from high overpotentials and slow kinetics. Perovskite oxides have been shown to be promising oxygen electrode catalysts because of their low cost, flexibility, and tailorable properties. In order to improve perovskite catalysts for the oxygen reduction (ORR) and oxygen evolution (OER) reactions, a better understanding of their reaction mechanisms is needed. This Perspective aims to inform researchers of the current proposed reaction mechanisms for ORR and OER on perovskites and perovskite/carbon composites in order to guide future catalyst development. Additionally, important experimental practices will be recommended. A recent development for OER is the lattice oxygen evolution reaction, which is a possible addition to the conventional four consecutive proton-coupled electron transfer mechanism. Carbon additives are consistently added to perovskites to enhance conductivity and ORR/OER activity. However, carbon plays an active role in ORR, and there is evidence of a synergistic relationship between perovskite and carbon in perovskite/carbon composites.

The vapor pressure (p sat) of methyl oleate was measured with and without the addition of 0.2 mass % of the antioxidant stabilizer tert-butylhydroquinone (TBHQ). The measurements were made by the gas saturation method with a temperature range of 303.15–343.15 K. In the absence of TBHQ, oxidative decomposition severely compromised the measurements, as evidenced by dramatic decreases in the measured p sat for repeat measurements at 323.15 K. When combined with a room-temperature N2 flush of the apparatus, the addition of 0.2 mass % TBHQ limited the decomposition to insignificant levels and resulted in repeatable measurements of p sat. Simultaneous measurements on the control sample n-eicosane (C20H42) yielded values of p sat that were in excellent agreement with reference correlations.

Using combinatorial thermal oxidation of solid solution W 1-x Ti x precursors combined Graphical abstract: with bulk and surface analysis mapping we investigate the oxide phase formation and surface passivation of tungsten titanium oxide in the entire compositional range from pure WO 3 to TiO 2 .

TiO2 and WO3 are two of the most important, industrially relevant earth-abundant oxides. Although both materials show complementary functionality and are promising candidates for similar types of applications such as catalysis, sensor technology, and energy conversion, their chemical stability in reactive environments differs remarkably. In this study, anodic barrier oxides are grown on solid-solution WxTi1-x alloy precursors covering a wide compositional range (0 x 1) with the goal of creating functional oxides with tailored stability. A strong Ti-cation enrichment in the surface region of the grown WxTi1-xOn layer is observed, which can be controlled by both the anodizing conditions and precursor composition. For Ti concentrations above 50 at. %, a continuous nanometer-thick TiO2 protective coating is achieved on top of a homogeneous WxTi1-xOn film as evidenced by X-ray photoelectron spectroscopy and transmission electron microscopy analyses. A comprehensive electrochemical assessment demonstrates a very stable passivation of the surface in both acidic and alkaline environments. This increase in chemical stability correlates directly with the presence of this protective TiO2 film. The results of this work provide insights into the oxidation behavior of W1-xTix alloys, but more importantly demonstrate how controlled oxidation of self-passivating alloys can lead to oxide alloys with thin, protective surface layers that otherwise would require more sophisticated deposition methods.