Accelerating the Oxygen Reduction Reaction and Oxygen Evolution Reaction Activities of N and P Co-Doped Porous Activated Carbon for Li-O2 Batteries

Rechargeable lithium–oxygen (Li-O2) batteries represent state-of-the-art electrochemical energy storage devices that provide high energy densities. However, their commercialization is challenging owing to their low charging/discharging efficiencies, short battery lives, high overpotentials, and high cathode manufacturing costs. In this study, we prepared a metal-free, N,P co-doped, porous activated carbon (N,P-PAC) electrode via KOH activation and P doping for application as a Li-O2 battery cathode. When used in a rechargeable Li-O2 battery, the N,P-PAC cathode showed a high specific discharge capacity (3724 mA h g−1 at 100 mA g−1), an excellent cycling stability (25 cycles with a limit capacity of 1000 mA h g−1), and a low charge/discharge voltage gap (1.22 V at 1000 mA h g−1). The N,P-PAC electrode showed a low overpotential (EOER-ORR) of 1.54 V. The excellent electrochemical performance of the N,P-PAC electrode can mainly be attributed to its large active area and oxygen-containing functional groups generated via KOH activation and P-doping processes. Therefore, the N,P-PAC prepared in this study was found to be a promising eco-friendly and sustainable metal-free cathode material for Li-O2 batteries.

Numerical Simulation of Heat Transfer Using Cooling Roof Panels

Roof cooling can be used in coffered roofs, acoustic panels, as active cooling plasterboard attached to a standard metal structure designed for lowered roofs, or as a system of cooling register under the plaster. The roof cooling system works on the principle of heat transfer through a large active area and there is no unpleasant air flow than with conventional air conditioning. For technological reasons, very often pipes with a heat transfer medium are attached to a sheet metal of various materials, the thermokinetic properties of which significantly influence the intensity of the heat flux dissipated by the cooling system. The paper presents a numerical analysis of heat transport using stainless steel and aluminium sheets as the supporting sheet, as well as the influence of different ways of installing large panels under the roof.

Facile Fabrication of Hierarchical rGO/PANI@PtNi Nanocomposite via Microwave-Assisted Treatment for Non-Enzymatic Detection of Hydrogen Peroxide

A hierarchical composite based on the modified reduced graphene oxide with platinum-nickel decorated polyaniline nano-spheres (rGO/PANI@PtNi) was facilely prepared via microwave-assisted self-reduction for an application in nonenzymatic hydrogen peroxide (H2O2) detection. Compared to the pristine rGO, the composite exhibited a much tougher surface due to the stacking of conductive PANI nano-spheres on rGO sheets, leading to good dispersion of PtNi nanoparticles and a large active area. Furthermore, the multi-valance Ni2+/3+ in the PtNi particles effectively promoted the catalytic property of Pt sites and facilitated a superior electrochemical performance of PtNi alloy than that of neat Pt. Owing to the synergistic effect of the improved electrical conductivity and the promoted electrocatalytical property, the modified glassy carbon electrode (GCE) with rGO/PANI@PtNi nanocomposite displayed an outstanding electrochemical sensitivity towards H2O2 with a fast response time (<2 s), a wide linear range (0.1–126.4 mM), a low detection limit (0.5 µM), as well as a long-life stability for one week without obvious degradation. This novel strategy opens a novel and promising approach to design high performance sensors for H2O2 detection.