2 research outputs found
A Comparison of Research Methods to Determine the Sustainability of Mineral Resources in Henan Province Based on Cloud Analysis
In order to improve the fuzzy comprehensive evaluation model of mineral resource sustainability and enhance its scientific and objective nature, in this paper, a cloud model-based risk assessment method is introduced to determine the sustainability of mineral resources in a comprehensive comparison, while using a combination of subjective and objective weighting method combining improved hierarchical analysis and the entropy weighting method. Compared with the previous single-assignment evaluation method, the method used in this paper has the advantages of more reasonable determination of weights, more accurate results and better visualization. On this basis, the combined weight method, cloud model method and hierarchical fuzzy evaluation method are organically combined to conduct a comprehensive evaluation of the sustainability of mineral resources in Henan Province. The case analysis shows that the comprehensive evaluation results of the sustainability of mineral resources obtained according to the method are scientifically reasonable and have important reference value and promotion significance for quantitative research in related fields
Graphene-Directed Formation of a Nitrogen-Doped Porous Carbon Sheet with High Catalytic Performance for the Oxygen Reduction Reaction
A nitrogen
(N)-doped porous carbon sheet is prepared by in situ
polymerization of pyrrole on both sides of graphene oxide, following
which the polypyrrole layers are then transformed to the N-doped porous
carbon layers during the following carbonization, and a sandwich structure
is formed. Such a sheet-like structure possesses a high specific surface
area and, more importantly, guarantees the sufficient utilization
of the N-doping active porous sites. The internal graphene layer acts
as an excellent electron pathway, and meanwhile, the external thin
and porous carbon layer helps to decrease the ion diffusion resistance
during electrochemical reactions. As a result, this sandwich structure
exhibits prominent catalytic activity toward the oxygen reduction
reaction in alkaline media, as evidenced by a more positive onset
potential, a larger diffusion-limited current, better durability and
poison-tolerance than commercial Pt/C. This study shows a novel method
of using graphene to template the traditional porous carbon into a
two-dimensional, thin, and porous carbon sheet, which greatly increases
the specific surface area and boosts the utilization of inner active
sites with suppressed mass diffusion resistance