Junyang Xu,Yanjun Jiang,Liya Zhou,Li Ma,Zhihong Huang,Jiafu Shi,Jing Gao,Ying He
Immobilization is an effective method to promote the application of enzyme industry for improving the stability and realizing recovery of enzyme. To some extent, the performance of immobilized enzyme depends on the choice of carrier material. Therefore, the development of new carrier materials has been one of the key issues concerned by enzyme immobilization researchers. In this work, a novel organic–inorganic hybrid material, nickel-carnosine complex (NiCar), was synthesized for the first time by solvothermal method. The obtained NiCar exhibits spherical morphology, hierarchical porosity and abundant unsaturated coordination nickel ions , which provide excellent anchoring sites for the immobilization of proteins. His-tagged organophosphate-degrading enzyme (OpdA) and ω-transaminase (ω-TA) were used as model enzymes to evaluate the performance of NiCar as a carrier. By a simple adsorption process , the enzyme molecules can be fixed on the particles of NiCar, and the stability and reusability are significantly improved. The analysis of protein adsorption on NiCar verified that the affinity adsorption between the imidazole functional group on the protein and the unsaturated coordination nickel ions on NiCar was the main force in the immobilization process, which provided an idea way for the development of new enzyme immobilization carriers.
Zhu Gang,Zhang Chaoling,Li Kaiqian,Xi Xuedong,Zhang Xupeng,Lei Hong
Zeolitic imidazolate frameworks (ZIFs) materials have been extensively studied in various enviornmentally friendly application. However, due to the powdered crystalline state and intrinsic brittleness of ZIFs, their processability and handling remain a significant challenge. Combining ZIFs and wood aerogel (WA) substrates to obtain advanced composites is excepted to further enhance their performance with higher practicability. Herein, a multifunctional ZIF-8@WA composite was successfully fabricated via in-situ growth of ZIF-8 nanoparticles on the wood aerogel obtained by selectively removing lignin and hemicellulose from balsa wood. Owing to the structural characteristics of ZIFs and WA, the resultant ultralight ZIF-8@WA composite exhibit hierarchical porostity, efficient dye adsorption performance and superior flame retardancy. At a 7.5 wt.% ZIF-8 loading, the composite displays high removal efficiency up to 95.0% for methylene blue (MB) and the adsorption capacity can reach 198.33 mg g −1 at 298 K. The MB removal efficiency could maintain 88.87% even after five cycles of repeated usage. Moreover, the incorporation of ZIF-8 has significantly effect on thermal stability at the early stage and char layer formatting of WA substrate. Compared with the pristine WA, the peak of heat release rate of the ZIF-8@WA hybrid materials exhibited a drastic decline by 63.4% from 145.8 to 53.3 W g −1 and the total heat release from 13.8 to 4.4 kJ g −1 .This work offers a new avenues for designing and constructing functionalized MOF@wood-derived advanced composite that may boost their environmental- and green building-related applications.
Developing highly efficient, sustainable carbon cathodes is essential for emerging Zn-ion hybrid supercapacitors (ZICs). Herein, lignin's novel chemical modification (amination) has been developed to produce high quantity pyrrolic-N moieties as active sites. Furthermore, chemically modified amine moieties in lignin are vital as a natural self-activating template to generate hierarchical porosity in the 2D (graphene-like) architecture with exceedingly high surface area (2926.4 m 2 g −1 ). The rationally introduced dominated pyrrolic-N moieties boost the Zn-ion storage capacity and reaction kinetics due to the dual energy storage mechanism and efficient charge transfer between pyrrolic-N and Zn +2 ions. Furthermore, the pyrrolic-N species are energetically favorable for the adsorption of Zn +2 ions by the formation of N -Zn +2 chemical bonds. Besides, the nitrogen oxides reduce the intrinsic resistance and induce a more polarized surface, resulting in high wettability and efficient transfer of electrolytes into the pores of hydrophobic carbon materials . Subsequently, the chemically modified lignin-derived activated carbon material (Chem-ACM) as a cathode in ZICs delivers a high capacity of 161.2 mA h g −1 at 1 A g −1 with the admirable energy density of 106.7 W h kg −1 at 897 W kg −1 and excellent retention capacity (94%) after 10,000 cycles. Mainly, the assembled quasi solid-state ZICs using Chem-ACM retains the remarkable storage capacity (202 mA h g −1 at 0.2 Ag −1 ) even at a high bending angle. Notably, the Chem-ACM has been further employed in symmetric supercapacitors as an electrode, and it displays exceptional specific capacitance of 354 Fg −1 at 0.5 Ag −1 with tremendous energy (43.5 W h kg −1 ) and the power density (0.53 kW kg −1 ). Additionally, the charge storage capability of Chem-ACM is positively dependent on high nitrogen contents, and it is extrapolated that pyrrolic-N moieties are dominant active sites. Hence, the designed amination-assisted biocarbon synthesis provides a new way to prepare high nitrogen-containing biocarbon for ZICs and further understand pyrrolic-N species' impact on Zn-ion storage.
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