The indiscreet use of fossil fuels has led to environmental pollution. To mitigate this, it is expected that the hydrogen evolution reaction (HER) can be performed at the cathode of electrolytic cells in energy conversion devices and eco-friendly renewable energy sources. Owing to the sluggish kinetics of the HER, the design and development of cost-effective, long term, highly stable, and efficient alternative electrocatalysts are crucial for their practical application. Herein, ruthenium (Ru) particles loaded titanium carbide (Ru/TiC) are successfully prepared through a simple reduction method. We employ experimental approaches to investigate the stability and electrocatalytic activity of Ru as a transition metal atom on a TiC support. The as-synthesized catalyst is characterized by X-ray powder diffraction, scanning electron microscopy, transmission electron microscopy, and X-ray photoelectron spectroscopy. Ru/TiC electrocatalyst exhibits HER activity with low overpotentials, fast reaction kinetics and high stability in alkaline and acidic medium. The remarkable electrocatalytic activity of Ru/TiC will promote interest in the futuristic development of cost-effective nanomaterials for energy and environmental applications.

Defect engineering can effectively modulate the band structure of a thermoelectric (TE) material, thereby enhancing its power factor S-2 sigma. Furthermore, residual stress engineering influences the film performance, especially in the planar technologies. For the TE Mg-doped CuCrO2-based materials, the limitations in achieving an outstanding figure of merit, ZT, arise from their characteristically low charge carrier mobility and high thermal conductivity. Herein, we propose a combination of defect engineering and stress engineering via heavy doping CuCr1-xMgxO2 with x = 0.15 at different deposition temperatures to overcome the aforementioned limitations. Combining the compressive residual stress with multiscale defects (point defects, grain boundaries, and nano-inclusions) significantly reduces the thermal conductivity (kappa) to 0.44 W/mK. The sigma of the films shows a remarkable enhancement because of point defects introduced via heavy doping. Notably, the compressive-stressed films exhibit higher ZT values, compared to the tensile-stressed films. As a result, an outstanding approximated ZT of 0.66 is observed in the compressive-stressed CuCr0.85Mg0.15O2 films, overcoming the limitations of its ZT value observed for the past two decades.

In this work, role of phase composition and interstitial oxygen on the thermoelectric properties of CuCr0.85Mg0.15O2 materials prepared at different sintering temperatures (1273-1673 K) for short time (3 h) are reported. Interestingly, the samples sintered at 1273 K and 1673 K had the same Seebeck coefficient, despite the 1273 K sample having significantly lower conductivity, which are discussed via phase compo-sition and interstitial oxygen induced during the CuCrO2 phase formation and its related defect (V-Cu, V-Cr,...). Besides, high conductivity of the 1673 K sample originated from the low percentage of CuO phase and the appearance of Cu2O phase. Since the 1273 K and 1673 K sintered samples have almost the same percentage of delafossite and spinel phases so the 1673 K sample still remain its high Seebeck coefficient. We suggest some reaction chemical equations for elucidating the roles of interstitial oxygen on the phase composition and thermoelectric properties CuCr0.85Mg0.15O2 delafossite material. (C) 2021 Elsevier B.V. All rights reserved.

The thermoelectric performance of CuCr1-xMgxO2 materials in terms of multi-scale defects induced at various Mg dopant concentrations (x = 0-0.3) was thoroughly studied in this paper. At 748 K and for x = 0.05, 0.15, and 0.30, we report the following power factors and thermal conductivities: 175, 213, and 2.3 mu W/m K-2 and 7.85, 5.60, and 3.82 W/m K, respectively. In the low doping regime (x < 0.15), the thermoelectric performance is mainly dependent on hole carriers originated from point defects via Mg substitution on Cr sites, whereas the thermoelectric properties reduce significantly for x >= 0.15 due to nanoscale secondary phases (MgCr2O4, Cu2O and CuO) and mesoscale grain boundaries. At 748 K, our CuCr0.85Mg0.15O2 samples exhibit a high figure of merit ZT = 0.028, which is better than those of other CuCr1-xMgxO2 and related delafossite materials. The correlations between the structural and thermoelectric properties of CuCr1-xMgxO2 materials are also discussed in detail. (c) 2020 Elsevier B.V. All rights reserved.

A lot of people were trapped in elevators without power supply when BLACK-OUT situation occurred in 2011. The telephone network of control room connected to the elevators had problem operating poorly. In this paper we propose an ICT based elevator emergency call device prototype system and evaluate the performance of the system. The proposed system quickly responds in emergency situation to guarantee passenger safety. For the goal, firstly the system tries to connect to a control room. If it fails the system attempts to call numbers for emergency contact and a rescue team sequentially. The system is designed to quickly support emergency contact as well. Finally, the information of elevator failure is rapidly transferred to the failure process device by the proposed system.