The development of novel metal organic framework (MOF) friction power generation materials with high stability is important. This paper reports the first example of a double-helix metal chain organic framework with a network structure (ZUT-8). ZUT-8 shows high chemical stability, functional adjustability, and excellent output performance of friction power generation, which is superior to traditional coordination polymer materials. The cathodic protection system with ZUT-8 can prevent metal corrosion significantly. The output performance can be improved effectively by enhancing the conjugate effect of the linker. The theoretical calculation results showed that an increase in the degree of conjugation could significantly reduce the band gap, thereby affecting the friction power output signal. This study opens the door to constructing MOF materials with a double-helix metal chain and will promote their potential applications in self-powered electrochemical cathodic protection.
Metal–organic frameworks (MOFs)
as friction nanopower generation
materials have attracted more and more research and attention because
of the inherent three-dimensional framework structure and large aperture.
In this work, the ZUT-75(Mn) with a one-dimensional pore structure
was synthesized by using electron-rich benzimidazole carboxylic acid
ligands, and isomorphic offspring MOF materials were obtained by single
crystal–single crystal solvent-assisted metal-ion exchange.
The exchange process was monitored by liquid UV–vis spectroscopy,
atomic absorption spectrometry, and energy-dispersive X-ray spectroscopy.
The metal–oxygen coordination energy, X-ray photoelectron spectroscopy
binding energy, and hard–soft acid–base principle verified
the spontaneity of the central-metal-exchange reaction. The four materials
were applied to a triboelectric nanogenerator (TENG), and the output
performance law of ZUT-75 was Co-MT > Zn-MT > Cu-MT > Mn-MT.
Among
them, the charge and power densities of Co-MT were up to 127.05 μC
m–2 and 3280.50 mW m–2. When the
density functional theory calculation and variable-temperature magnetic
susceptibility test results were combined, it was concluded that low
metal-ion-coupling degree promoted the formation and transfer of contact
electrifications, which greatly improved the output performance of
the TENG. This work provided a new idea for improving the output performance
of the TENG.
The Fe3O4@Au core–shell nanocomposites, as the multifunctional magnetic surface enhanced Raman scattering (SERS) substrates, were fabricated successfully by the seeds growth method based on the Fe3O4–Au core-satellite nanocomposites. The SERS properties of the Fe3O4–Au core-satellite nanocomposites and the Fe3O4@Au core–shell nanocomposites were compared using 4-aminothiophenol (4-ATP) as the probe molecule. It was found that Fe3O4@Au core–shell nanocomposites showed better SERS performance than Fe3O4–Au core-satellite nanocomposites. The Au shell provided an effectively large surface area for forming sufficient plasmonic hot spots and capturing target molecules. The integration of magnetic core and plasmonic Au nanocrystals endowed the Fe3O4@Au core–shell nanocomposites with highly efficient magnetic separation and enrichment ability and abundant interparticle hot spots. The Fe3O4@Au core–shell nanocomposites could be easily recycled because of the intrinsic magnetism of the Fe3O4 cores and had good reproducibility of the SERS signals. For practical application, the Fe3O4@Au core–shell nanocomposites were also used to detect thiram. There was a good linear relationship between the SERS signal intensity and the concentration of thiram from 1 × 10−3 to 1 × 10−8 M and the limit of detection was 7.69 × 10−9 M. Moreover, residual thiram on apple peel was extracted and detected with a recovery rate range of 99.3%. The resulting substrate with high SERS activity, stability and strong magnetic responsivity makes the Fe3O4@Au core–shell nanocomposites a perfect choice for practical SERS detection applications.
This study aims to examine the nudging effect of the sports facility construction on physical exercise (PE) participation with consideration of the moderating role of mental health in China. Multiple linear regression models are used in this study. The subjects are 4634 from the 2014 China Family Panel Studies (CFPS) data, which is a nationally representative longitudinal survey of Chinese individuals. We find that the construction of sports facilities nudges people to participate in PE, and gender, age, and education significantly influence people’s participation in PE. Young, female, and better-educated people compose the “neo-vulnerable” population, who participate less in PE in China and need more interventions. Mental health status has no significant effect on people’s PE participation, while it negatively moderates the nudging effect of the construction of sports facilities on PE. The results of this study suggest that only building sporting facilities is insufficient to encourage PE participation. Policies and interventions should be given to mentally disturbed individuals to guarantee and magnify the nudging effect of sports facilities on PE.
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