A hierarchically porous carbon monolith with a density of 0.059 g cm?3 (97 % porosity) was generated through the carbonization of an emulsion-templated monolith formed from a deep-eutectic polymer based on the polycondensation of 2,5-dihydroxy-1,4-benzoquinone with excess urea. The mechanical integrity and thermal stability of the monolith were successfully enhanced through a chain extension reaction with terephthaloyl chloride (TCL) that occurred during/following the formation of a high internal phase emulsion (HIPE). The bimodal, open-cell macroporous structure of the monolith consisted of many smaller voids with an average diameter of 15 [small micro]m and some larger voids with an average diameter of 49 [small micro]m. Carbonization of the monolith introduced microporosity and meso/macro-porosity, yielding a high specific surface area (812 m2 g?1, largely from micropores), a micropore volume of 0.266 cm3 g?1 (an average diameter of 0.67 nm), and a meso/macro-pore volume of 0.238 cm3 g?1 (an average diameter of 8.1 nm). The elemental composition of the chain-extended polymeric monolith was similar to that predicted from the HIPE components except for a relatively low nitrogen content which may indicate the loss of some urea groups during the chain extension reaction with TCL. The nitrogen-carbon bonds in the carbon monolith from the chain-extended polymer were around 47% pyridinic, 20% pyrrolic, and 33% graphitic. While chain-extension reduced the nitrogen content, the mechanical integrity and thermal stability were enhanced, which was key to generating a highly microporous carbon monolith with a hierarchical porous structure. The carbon monolith exhibited promising results for aqueous solution sorption applications, in both batch and flow modes, owing to its advantageous combination of properties
Significance
Biominerals are extraordinarily intricate and possess superior mechanical properties compared with their synthetic counterparts. In this study, we show that the presence of high-Mg calcite nanoparticles within a low-Mg calcite matrix is a widespread phenomenon among marine organisms whose skeletons are composed of high-Mg calcite. It seems most likely that formation of such a complex structure is possible because of the phase separation that occurs as a result of spinodal decomposition of an amorphous Mg–calcium carbonate precursor and is followed by crystallization. We demonstrate that the basis of such phase separation stems from chemical composition rather than from biological similarities. The presence of high-Mg calcite nanoparticles increases the skeletons’ toughness and hardness.
Dislocations in metals affect their properties on the macro- and the microscales. For example, they increase a metal’s hardness and strength. Dislocation outcrops exist on the surfaces of such metals, and atoms in the proximity of these outcrops are more loosely bonded, facilitating local chemical corrosion and reactivity. In this study, we present a unique autocatalytic mechanism by which a system of inorganic semiconducting gold(I) cyanide nanowires forms within preexisting dislocation lines in a plastically deformed Au-Ag alloy. The formation occurs during the classical selective dealloying process that forms nanoporous Au. Nucleation of the nanowire originates at the surfaces of the catalytic dislocation outcrops. The nanowires are single crystals that spontaneously undergo layer-by-layer one-dimensional growth. The continuous growth of nanowires is achieved when the dislocation density exceeds a critical value evaluated on the basis of a kinetic model that we developed.
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