Hydrogen storage may be the bottle neck in hydrogen economy, where hydrogen spillover is in dispute as an effective mechanism. In this context, activated carbon (AC) was doped with nitrogen by using ammonia gas, and was further decorated with platinum, palladium, nickel, rhodium, iridium and ruthenium, via an ultrasound-assisted impregnation method, with average particle sizes of around 74, 60, 78, 61, 67 and 38 nm, respectively. The hydrogen storage was compared, before and after modification at both ambient and cryogenic temperatures, for exploring the spillover effect, induced by the decorating transition metals. Ammonia treatment improved hydrogen storage at both 298 K and 77 K, for the samples, where this enhancement was more remarkable at 298 K. Nevertheless, metal decoration reduced the hydrogen uptake of AC for all of the decorated samples other than palladium at cryogenic temperature, but improved it remarkably, especially for iridium and palladium, at room temperature. This observation suggested that metal decoration’s counter effect overcomes hydrogen spillover at cryogenic temperatures, while the opposite takes place at ambient temperature.

Activated carbon (AC) was treated with ammonia for nitrogen doping and then was further anchored with platinum nanoparticles through ultrasound-assisted impregnation method. Methane (CH₄) and carbon dioxide (CO₂) storage of the pristine and modified activated carbon were determined at ambient temperature. All the samples showed high storage capacities with preference towards carbon dioxide storage, which would be favorable for both energy and environmental applications. Ammonia treatment slightly improved the storage of both CH₄ and CO₂ for all the samples, which could be attributed to the little improvement in the micropore properties upon nitrogen doping. Platinum decoration had an opposite influence on both CH₄ and CO₂ storage, which might be due to the absence of metal encouraging storage mechanism such as gas dissociation or reconstruction on platinum’s surface in addition to the harmful effect of metal pore-blocking and higher density of metal particles.

The effects of post-annealing treatment temperature and ambient gas on the properties of ZnO thin films were investigated. The results showed that the properties of the ZnO thin film depended on the crystal quality, the type and density of the intrinsic defects. Treating the ZnO thin films at 300°C, regardless of the ambient gas, affected only on the crystal quality of the thin films. When the samples were treated at 500°C and 600°C, the structural properties were significantly improved, accompanied by changes in the optical and electrical properties. The extent of improvements varied with the treatment ambient. These variations in the optical and electrical properties of the thin films were attributed to the different reaction mechanisms when ZnO was treated under different ambient conditions. The thin films, treated at 600°C under N2O ambient, exhibited the best structural, optical, and electrical properties for metal-semiconductor-metal photodetector (MSM-PD) applications.

The active layer material quality and doping profile effects on the ZnO-based thin film metal-semiconductor-metal photodiode’s (MSM-PD) performance are studied using a two-dimensional numerical simulation. The results of the simulation reveal that the temporal response advantages of increasing the doping concentration of the PD’s active layer are only appreciable at low bias. Whereas, using the downgraded material the temporal response advantages are maintained for all applied biases but at the expense of a very low responsivity. The paper discusses the possibility of improving the temporal response while maintaining excellent responsivity. It is shown that the composed structure, made of a good material heavily doped top layer, and a bottom layer lightly doped made of downgrade material, exhibits the desired temporal response advantages while maintaining an excellent responsivity.