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A topotactic molecular doping strategy is developed via in situ coupling of dechlorinated carbon with ringed heterocyclic molecules under mild conditions. Specifically, pyridine and pyrrole-converted carbons show pyridinic N to pyrrolic N ratios of 1.82 and 0.13, respectively. The Npyri-C shows much-advanced activity and kinetics for oxygen reduction over the Npyrr-C sample. [ABSTRACT FROM AUTHOR]

Piezoelectricity, one of the most desirable properties of non-centrosymmetric crystalline materials, has long been blooming in academic research, industrial manufacturing, and daily applications owing to its unique electromechanical transformation capability. Compared with inorganic piezoelectric ceramics dominating the market, molecule-based piezoelectric materials exhibit advantages of light weight, mechanical flexibility, and environment friendliness and have attracted widespread interest recently. However, investigations on molecular materials with large piezoelectric coefficients are mainly focused on organic–inorganic hybrids, while pure organic homochiral piezoelectrics holding large piezoelectric coefficients remain scarce. Herein, by precise molecular modification on (S)-2-methylpiperazin-1-ium perchlorate ([(S)-MPP][ClO4]) with polar cyanomethyl groups, a homochiral pure organic compound (3S)-3-methyl-1,4-di(cyanomethyl)piperazin-1-ium perchlorate [DCM-(S)-MPP][ClO4] with large d22 of 18 pC/N was achieved, along with changes in the space group from nonpolar to polar, giving rise to second harmonic generation and phase transition behaviors. The modification strategy proposed here will benefit piezoelectricity enhancement in more chiral compounds, promoting their application potential in biological medicine, flexible devices, and green chemistry. [ABSTRACT FROM AUTHOR]

Organic–inorganic metal halides (OIMHs) have attracted immense attention in recent decades due to their diverse physical properties, such as optoelectronic properties, photoluminescence, magnetism, and ferroelectricity. Besides these fascinating physical properties, OIMHs have also received much interest for their phase transitions. Muconic acid has captured extensive interest owing to the presence of cis,cis-form (Z,Z) and trans,trans-form (E,E) isomers. However, there have been no reports on muconic acid derivative OIMHs with phase transitions. In this work, we successfully synthesized the first muconic acid derivative OIMHs (Z,Z)- and (E,E)-[BPHD]ZnCl4 (BPHD = N1,N6-bis(piperidine-1-yl) hexa-2,4-diene diamide). Both of them crystallized in the monoclinic space group P21/c at room temperature. Notably, (Z,Z)-[BPHD]ZnCl4 does not exhibit phase transition behavior, while (E,E)-[BPHD]ZnCl4 has a high-temperature phase transition of up to 449.4 K, which is higher than that of the majority of OIMH phase transition compounds. Furthermore, the high-temperature structural analysis of (E,E)-[BPHD]ZnCl4 discloses that its high-temperature phase transition originates from the order–disorder transition of the piperidine groups of one (E,E)-[BPHD]2+ cation and the swing motion of the piperidine groups of another (E,E)-[BPHD]2+ cation. This work expands the family of OIMHs and provides a new platform for designing high-temperature phase transition OIMHs. [ABSTRACT FROM AUTHOR]

Improving the fast-charging capabilities and energy storage capacity of electric vehicles presents a feasible strategy for mitigating the prevalent concern of range anxiety in the market. Nanostructure electrode materials play a crucial role in this process. However, the current method of preparation is arduous and yields restricted quantities. In view of this, we have devised an innovative approach that provides convenience and efficacy, facilitating the large-scale synthesis of CoS2 nanoparticles, which exhibited exceptional performance. When the current density was 1000 mA g−1, the discharging capacity reached 760 mAh g−1 after 400 cycles. Remarkably, even at an increased current density of 5000 mA g−1, the discharging capacity of CoS2 remained at 685.5 mAh g−1. The ultra-high performance could be attributed to the specific surface area, which minimized the diffusion distance of sodium-ions during the charging and discharging processes and mitigated the extent of structural damage. Our straightforward preparation techniques facilitate the mass production and present a novel approach for the development of cost-effective and high-performing anode materials for sodium-ion batteries. [ABSTRACT FROM AUTHOR]

This work reports the construction of a miniaturized Ag/AgCl nanoelectrode on a nanopipette, which is capable of dual-functions of single-cell drug infusion and chloride detection and is envisioned to promote the study of chloride-correlated therapeutic effects. [ABSTRACT FROM AUTHOR]

Bismuth chalcogenide and its derivatives have been attracting attention in various fields as semiconductors or topological insulators. Inspired by the high piezoelectric properties of Janus Bi2TeSeS monolayer and the excellent optical absorption properties of the Bi2X3 (X = Te, Se, S) monolayers, we theoretically predicted four new-type two-dimensional (2D) monolayers Janus Bi2X2Y (X = Te, Se; Y = Te, Se, S) using the first principles combined with density functional theory (DFT). The thermal, dynamic, and mechanical stabilities of Janus Bi2X2Y monolayers were confirmed based on ab initio molecular dynamics (AIMD) simulations, phonon dispersion, and elastic constants calculations. Their elastic properties, band structures, piezoelectric, and optical properties were systematically investigated. It was found that Janus Bi2X2Y monolayers have a typical Mexican hat-shaped valence band edge structure and, therefore, have a ring-shaped flat band edge, which results in their indirect band gaps. The results show that Janus Bi2X2Y monolayers are semiconductors with moderate band gaps (0.62–0.98 eV at the HSE + SOC level). After considering the electron–phonon renormalization (EPR), the band gaps are reduced by less than 5% at 0 K under the zero-point renormalization (ZPR) and further reduced by approximately 10% at 300 K. Besides, Janus Bi2X2Y monolayers also exhibit excellent optical absorption properties in the blue-UV light region, with the peak values at the order of 8 × 105 cm−1. Particularly, the Janus Bi2Te2S monolayer was found to exhibit a piezoelectric strain coefficient d11 of up to 20.30 pm V−1, which is higher than that of most of the 2D materials. Our results indicate that Janus Bi2X2Y monolayers could be promising candidates in solar cells, optical absorption, and optoelectronic devices; especially, a Janus Bi2Te2S monolayer can also be an excellent piezoelectric material with great prospects in the fields of mechanical and electrical energy conversion. [ABSTRACT FROM AUTHOR]

The chemistry underlying bone mineral formation in vertebrates is the reaction of calcium phosphate precipitation. In a near-neutral solution, an amorphous phase and hydroxyapatite nanoparticles appear successively, and the reaction system containing either of the two kinds of precipitates is in a non-equilibrium state. Here, we propose a pseudo-equilibrium approach to the solution chemistry of the precipitation reactions. We employed two series of reaction systems, collected samples at various stages, and analyzed the solution chemistry data on the basis of a simplified model of reaction. We derived two types of pseudo-equilibrium equations from the two series, respectively. These equations reveal the existence of multiple structural units in a precipitate particle and correlate the ionic product with the surface proportion per structural unit (m). The surface proportion, in turn, is related to the whole particle through a particle-surface equation. Notably, the two types of pseudo-equilibrium constants have the common expression of "Kd = ionic product" if the number of the structural units (u) is large enough. Together, these findings have revealed some aspects of the non-equilibrium thermodynamics of precipitation reactions, indicating the solution chemistry route to the equilibrium state. The concept of the multi-unit particle may shed new light on the study of precipitation reactions of other slightly soluble electrolytes. And the relationship between the ionic product and the surface proportion of a structural unit is not only fundamental in chemistry, but may also apply to non-equilibrium systems in nature and biology, such as marine sedimentation, human vascular calcification, and bone mineral metabolism. [ABSTRACT FROM AUTHOR]