Various bifunctional metal-oxide composites have recently been proposed as advanced hydrogen oxidation reaction (HOR) electrocatalysts for anion-exchange membrane fuel cells (AEMFCs). It is postulated that metal and oxide are active sites for the adsorption of hydrogen/proton and hydroxide ions, respectively. Of particular interest are the so-called buried interfaces. To investigate processes governing activity and stability at such interfaces, we prepare model Pd and Pt electrocatalysts which are fully covered by thin CeO x films. We investigate how oxide thickness influences HOR activity and dissolution stability of the electrocatalysts. It is found that materials behave very differently and that only Pd exhibits an enhanced HOR activity, while both oxide-protected metals are more stable toward dissolution. A 10-fold decrease in dissolution and 15-fold increase in HOR exchange current density are demonstrated for the optimized Pd/CeO x composites in comparison to pure Pd. We assess the mechanism of the electrocatalytic improvement as well as the role of the protective oxide films in such systems through advanced electrochemical and physical analysis. It is highlighted that a uniform, semipermeable oxide layer with a maximized electrocatalyst− oxide interface is crucial to form HOR catalysts with improved activity and stability.

The interaction of In and Pd in bimetallic particles causes dramatic changes in the CO₂ reduction behavior.

We report a cathode material based on plasma‐treated single‐walled carbon nanotubes decorated by RuOx nanoparticles using atomic layer deposition. We have examined cathode performance towards hydrogen evolution reaction by tailoring material wettability, conductivity yielded by plasma treatment, and the catalyst loading. We discuss that nucleation of particles is facilitated by the appearance of carboxylic and hydroxyl groups triggered by oxygen plasma action. The best performance is associated with samples containing RuOx particles of 4–5 nm, which show hydrogen evolution onset potential to be about −5 mV (vs. RHE) in 0.5 M H2SO4 measured at a current density of −1 mA cm−2 and Tafel slope of 47.5 mV/dec. The material possesses stable performance at −10 mA cm−2 with a potential of about −160 mV.

This paper consists of multiple approaches to develop a new model to determine the porosity, permeability, and rate of desorption of 1.5-in. shale samples. Permeability measurements of very tight rocks is difficult and uncertain, and no clear industry standard has yet been agreed upon. Therefore, this technique will investigate a new way to determine the porosity and permeability in shales. The raw NMR signal of the sample is measured before methane injection and is used as a base signal. During the injection of methane, the raw NMR signal increases. The base signal is subtracted from the response during the methane injection. This difference is inverted in multiple exponential distributions to only obtain the T 2 distributions and T 1 −T 2 correlations related to the injected methane in the shales. T 2 distribution holds information on the pore size distribution. Using cutoff values to separate the signal, different zones can be extracted. During injection and production of fluids, the rate and the total fluid filled porosity are used to calculate the permeability related to the individual pore size distributions. In the majority of shale gas formations, two types of pore systems are present; kerogen-hosted organic pores (OP) and inorganic pores (IP). By fully saturating 1.5-in. shale cores and by continuously measuring the NMR signal, it is possible to determine the individual porosity and permeabilities of the pore system. T 1 −T 2 measurements are made to confirm the individual zones and the mobility of the fluid in the zones. A single exponential decay formula is defined to calculate the permeability. This formula is tested with a reservoir simulation (using Eclipse) to validate the calculated value. Eventually a multiexponential model is used to distinguish the high and low permeability components in shales. This high permeability component is interpreted to represent the inorganic pores and microfractures, while the low permeability component is interpreted to represent the organic pores and the desorption from the pore surface. The Posidonia core samples show better production potential than the Qusaiba samples. Understanding the shale porosities for different storage mechanisms as well as the corresponding permeabilities is essential for developing shale reservoirs and target zone selection.

No abstract