University of Macau

About: University of Macau is a education organization based out in Macao, Macau, China. It is known for research contribution in the topics: Computer science & Population. The organization has 6636 authors who have published 18324 publications receiving 327384 citations. The organization is also known as: UM & UMAC.

A Dendritic Nickel Cobalt Sulfide Nanostructure for Alkaline Battery Electrodes

Abstract: A uniform dendritic NiCo 2 S 4 at NiCo 2 S 4 hierarchical nanostructure of width ≈100 nm is successfully designed and synthesized. From kinetic analysis of the electrochemical reactions, those electrodes function in rechargeable alkaline batteries (RABs). The dendritic structure exhibited by the electrodes has a high discharge-specific capacity of 4.43 mAh cm -2 at a high current density of 240 mA cm -2 with a good rate capability of 70.1% after increasing the current densities from 40 to 240 mA cm -2 . At low scan rate of 0.5 mV s -1 in cyclic voltammetry test, the semidiffusion controlled electrochemical reaction contributes ≈92% of the total capacity, this value decreases to ≈43% at a high scan rate of 20 mV s -1 . These results enable a detailed analysis of the reaction mechanism for RABs and suggest design concepts for new electrode materials.

Economic dispatch model with fuzzy wind constraints and attitudes of dispatchers

Abstract: The letter describes a new economic dispatch algorithm for systems with uncertain wind generation prediction, similar to the classical thermal dispatch model with load on a single bus. The optimization is achieved in a compromise between fuzzy constraints in the magnitude of wind penetration and the variation of running costs. The model includes also the attitudes of the dispatcher toward risk (security) and cost.

Metal Dichalcogenides Monolayers: Novel Catalysts for Electrochemical Hydrogen Production

Abstract: Catalyst-driven electrolysis of water is considered as a “cleanest” way for hydrogen production. Finding cheap and abundant catalysts is critical to the large-scale implementation of the technology. Two-dimensional metal dichalcogenides nanostructures have attracted increasing attention because of their catalytic performances in water electrolysis. In this work, we systematically investigate the hydrogen evolution reduction of metal dichalcogenides monolayers based on density-functional-theory calculations. We find that metal disulfide monolayers show better catalytic performance on hydrogen production than other metal dichalcogenides. We show that their hydrogen evolution reduction strongly depends on the hydrogen coverage and the catalytic performance reduces with the increment of coverage because of hydrogenation-induced lower conductivity. We further show that the catalytic performance of vanadium disulfide monolayer is comparable to that of Pt at lower hydrogen coverage and the performance at higher coverage can be improved by hybridizing with conducting nanomaterials to enhance conductivity. These metal disulfide monolayers with lower overpotentials may apply to water electrolysis for hydrogen production.