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Mechanosynthesis of graphene nanoribbons from waste zinc–carbon batteries
Martínez-González J.,Reyes-Contreras D.,Vigueras-Santiago Enrique,Patiño-Carachure C.,Reyes-Esqueda J. A.,Castrejón-Sánchez V. H.,García-Orozco I. 한국탄소학회 2022 Carbon Letters Vol.32 No.2
The mechanosynthesis route is a physical top–down strategy to produce different nanomaterials. Here, we report the formation of graphene nanoribbons (GNRs) through this route using carbon bars recovered from discarded alkaline batteries as raw material. The mechanosynthesis time (milling time) is shown to have an influence on different features of the GNRs such as their width and edges features. TEM revealed the presence of GNRs with widths of 15.26, 8.8, and 23.55 nm for the milling times of 6, 12, and 18 h, respectively. Additionally, the carbon bars evolved from poorly shaped GNRs for the shortest milling time (6 h) to well-shaped GNRs of oriented sheets forming for the longest milling time. Besides GNRs, graphene sheets (GNS) of different sizes were also observed. The Raman analysis of the 2D bands identified the GNS signal and confirmed the GNRs nature. ID/IG values of 0.21, 0.32, and 0.40 revealed the degree of disorder for each sample. The in-plane sp2 crystallite sizes (La) of graphite decreased to 91, 60, and 48 nm with increasing peeling time. The RBLM band at 288 cm−1 confirmed the formation of the GNRs. Mechanosynthesis is a complex process and the formation of the GNRs is discussed in terms of a mechanical exfoliation, formation of graphene sheets and its fragmentation to reach GNR-like shapes. It is shown that the synthesis of GNRs through the mechanosynthesis route, besides the use of recycled materials, is an alternative for obtaining self-sustaining materials.
Goda Thomas,Sánchez González Santiago 한국국제경제학회 2024 International Economic Journal Vol.38 No.1
Literature contends that the manufacturing sector is crucial for economic development, and it is conventional wisdom that exports drive manufacturing growth. However, it has yet to be established empirically whether the market size of export destinations is an essential factor in explaining diverging regional and sectoral manufacturing growth patterns. This article argues that accessing a few large external markets reduces entry costs, increases expectations of economies of scale, and fosters capital formation. To test this hypothesis, we construct a novel Relative Export Market Size (REMS) index that measures whether the share of sectoral exports destined to large economies in one region is higher than in other regions. Using a PVAR model with fixed effects, we verify the impact of the REMS index on value added, employment, and capital accumulation of 129 manufacturing sectors in 23 regions in Colombia from 1992 to 2017. The obtained results show that exporting to larger markets positively impacts employment, capital formation, and value added per capita of manufacturing sectors at a regional level. This finding indicates that exporting to the world’s largest market helps develop competitive manufacturing sectors.