Multiple charge separation has been successfully realized by a proton‐coupled electron transfer reaction in an organic cocrystal. Benefiting from the adjustable electronic energy level of the ...electron donor and acceptor through thermal‐induced proton migration, distinct optical absorption behaviors combined with color changes to blue or green are observed in these charge‐separated states. It is of interest to note that such charge‐separated states exhibit a longer lifetime of over a month as a result of the excellent coplanarity and π‐π interaction of the electron acceptors. Moreover, the enhanced absorption toward longer wavelengths endows the charge‐separated state with near‐infrared (808 nm) photothermal conversion for imaging and bacterial inhibition, whereby the conversion performance can be controlled by the degree of proton migration.
Multiple charge separation with a long lifetime has been realized in an organic cocrystal by a proton‐coupled electron‐transfer reaction under irradiation with light. The enhanced absorption toward longer wavelengths can be applied for near‐infrared imaging and bacterial inhibition.
Three new cadmium coordination polymers, namely Cd(NO₃)₂(DPNDI)(CH₃OH)·CH₃OH (
), Cd(SCN)₂(DPNDI) (
), and Cd(DPNDI)₂(DMF)₂·2ClO₄ (
) (DPNDI =
,
-di(4-pyridyl)-1,4,5,8-naphthalene diimide, DMF =
,
...-dimethylformamide) have been synthesized by reactions of DPNDI with Cd(NO₃)₂, Cd(SCN)₂, and Cd(ClO₄)₂, respectively. Compound
is a one-dimensional coordination polymer with strong lone pair-π interactions between the coordinated NO₃
anions and the imide ring of DPNDI; while
is a two-dimensional network with a (4, 4) net topology. In the case of
, due to the presence of uncoordinated perchlorate counter ions, it exhibits a non-interpenetrated square-grid coordination polymer containing one-dimensional rhomboid channels. The structural diversity in these compounds is attributed to different coordination abilities and geometries of counter anions. Due to the presence of electron-deficient NDI moiety, the photochromic behavior of these compounds was studied. Interestingly, only compounds
and
exhibit color changes under light irradiation. The influence of the anions on the photochromism process of the NDI-based materials has been discussed.
As a signaling molecule, hydrogen sulfide (H
2
S) plays an indispensable role in the modulation of ripening and senescence in fruits and vegetables. To explore the role of H
2
S in regulating ...metabolism of postharvest tomato, ripening-related physiological parameters, activities of antioxidant enzymes and gene expression were analyzed in H
2
S-fumigated tomato fruits. These results show that H
2
S significantly delayed the color transition and softening of tomato fruit, and maintained higher level of flavonoids and lower level of anthocyanin during storage. Besides, H
2
S could maintain higher level of nutritional-related metabolites, such as reducing sugar, ascorbic acid during postharvest storage. Moreover, H
2
S decreased the rate of O
2
−
production, inhibited the production of H
2
O
2
and malondialdehyde (MDA), enhanced the activities of antioxidant enzymes including ascorbate peroxidase (APX), superoxide dismutase (SOD), catalase (CAT) and guaiacol peroxidase (POD) in tomato fruits, while reduced the activities of phenylalanine ammonia lyase (PAL), polyphenol oxidase (PPO) and lipoxygenase (LOX). Besides, the expression of the antioxidant-encoding genes
SlCAT2
,
SlPOD12
was generally upregulated with H
2
S fumigation. Principal component analysis (PCA) suggests that H
2
S induced significant discrepancy mainly to the differences in firmness, anthocyanin, flavonoid and the activity of guaiacol peroxidase (POD), and the correlation analysis further shows that H
2
S affected pigment metabolism and nutritional quality. In conclusion, H
2
S could maintain better appearance and nutritional quality, and prolong the storage period of postharvest tomato fruits through activating the antioxidative system.
The pursuit of single‐assembled molecular cage reactors for complex tandem reactions is a long‐standing target in biomimetic catalysis but still a grand challenge. Herein, nanozyme‐like organic cages ...are reported by engineering air‐stable radicals into the skeleton upon photoinduced electron transfer. The generation of radicals is accompanied by single‐crystal structural transformation and exhibits superior stability over six months in air. Impressively, the radicals throughout the cage skeleton can mimic the peroxidase of natural enzymes to decompose H2O2 into OH· and facilitate oxidation reactions. Furthermore, an integrated catalyst by encapsulating Au clusters (glucose oxidase mimics) into the cage has been developed, in which the dual active sites (Au cluster and radical) are spatially isolated and can work as cascade nanozymes to prominently promote the enzyme‐like tandem reaction via a substrate channeling effect.
A tandem reaction with an enhanced rate is achieved by an air‐stable radical cage reactor, in which the dual active sites (radicals as peroxidase mimics; Au clusters as glucose oxidase mimics) are spatially isolated without mutually quenching each other, and can thus serve as cascade nanozymes to accelerate the reaction via a substrate channeling effect.
Batteries with conversion-type electrodes exhibit higher energy storage density but suffer much severer capacity fading than those with the intercalation-type electrodes. The capacity fading has been ...considered as the result of contact failure between the active material and the current collector, or the breakdown of solid electrolyte interphase layer. Here, using a combination of synchrotron X-ray absorption spectroscopy and in situ transmission electron microscopy, we investigate the capacity fading issue of conversion-type materials by studying phase evolution of iron oxide composited structure during later-stage cycles, which is found completely different from its initial lithiation. The accumulative internal passivation phase and the surface layer over cycling enforce a rate-limiting diffusion barrier for the electron transport, which is responsible for the capacity degradation and poor rate capability. This work directly links the performance with the microscopic phase evolution in cycled electrode materials and provides insights into designing conversion-type electrode materials for applications.
Well‐dispersed PtNi nanoparticles (NPs) grown on carbon nanodots (CNDs) derived from a metal–organic framework (ZIF‐8) are synthesized by a simple reduction of metal precursors in the presence of ...CNDs, wherein the CNDs prove to be a powerful dispersion agent and distinct support for the PtNi NPs. The resultant PtNi‐CND catalyst exerts almost 100 % H2 selectivity and a high activity for the decomposition of hydrous hydrazine at room temperature. This excellent catalytic performance might be a result of the synergistic effect of the CND support and the PtNi NPs. The utilization of CNDs as a support to anchor the active component NPs and thus to facilitate the electron transfer and mass transport kinetics during the catalytic reaction process opens up new avenues to design high‐performance catalysts.
Dot dot dot: Highly dispersed bimetallic PtNi nanoparticles with different PtNi compositions have been immobilized on ZIF‐8‐derived carbon nanodots (CNDs). These materials show high catalytic activity and durability for hydrogen generation from the decomposition of hydrazine in aqueous solution at room temperature.
Assessing biochar's ability to resist oxidation is fundamental to understanding its potential to sequester carbon. Chemical oxidation exhibits good performance in estimating the oxidation resistance ...of biochar. Herein, oxidation resistance of 14 types of biochars produced from four feedstocks at different pyrolysis conditions (hydrothermal versus thermal carbonization) was investigated via hydrogen peroxide oxidation with varying concentrations. The oxidation resistance of organic carbon (C) of hydrochars was relatively higher than that of 250°C pyrochars (P250) but was comparable to that of 450°C pyrochars (P450). Both hydrochars and P450 from ash-rich feedstocks contained at least three different C pools (5.9–18.3% labile, 43.2–56.5% semi-labile and 26.9–45.9% stable C). Part (<33%) of aromatic C within 600°C pyrochars (P600) was easily oxidizable, which consisted of amorphous C. The influence of pyrolysis temperature upon oxidation resistance of biochars depended on the feedstock. For ash-rich feedstock (rice straw, swine manure and poultry litter), the oxidation resistance of biochars was determined by both aromaticity and mineral components, and mineral protection was regulated by pyrolysis conditions. The amorphous silicon within hydrochars and P450 could interact with C, preventing C from being oxidized, to some extent. Nevertheless, this type of protection did not occur for P250 and P600.
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•Oxidation resistance of biochar was studied using H2O2 with varying concentrations.•Hydrochar showed higher oxidation resistance than low temperature pyrochar.•Impact of temperature upon oxidation resistance of pyrochar depended on feedstock.•Oxidation resistance of ash-poor biochar was mainly regulated by aromaticity.•Oxidation resistance of ash-rich biochar was also affected by mineral encapsulation.
Photodegradation and biodegradation of pyrogenic dissolved organic matter (pyDOM) play crucial roles in regulating greenhouse gas emissions and stabilizing organic matter. In this study, we conducted ...a 56-day microbial laboratory incubation to investigate the biodegradation patterns of pristine and photobleached pyDOM leached from a thermal series of chars (300, 450, and 600 °C) based on FT-ICR-MS, gas analysis, N speciation, and 16S rDNA sequencing. As the pyrolysis temperature increased, the among of biomineralized carbon of pyDOM decreased, while the molecular diversity and aromaticity increased. Photobleaching increased the among of biomineralized carbon of pyDOM from 40%–70% to 60%–80%, but decreased the molecular diversity, molecular weight, and aromaticity, with a major removal of lignin-like compounds. Microbial incubation lowered the molecular diversity but increased the molecular weight and aromaticity of both pristine and photobleached samples. Tannin-like structures, carbohydrates, and aliphatic/protein were preferentially biodegraded, while lipid, lignin-like structures, unsaturated hydrocarbons, and condensed aromatics were more likely to be preserved or newly produced. The photobio-resistant components were mainly comprised of lignin-like and tannin-like structures. Photobleached pyDOM samples released more CO2 but less N2O, as they may possess high denitrification rate due to their high carbon reactivity. The bacterial richness and diversity in pyDOM were lower than the original inoculum. In addition, distinct differences were noted between the bacterial community structure of the original inoculum and that of pristine and photobleached pyDOM samples following various incubation times. Specifically, proteobacteria was increased and remained the predominant phylum in all pyDOM solutions compared to the original inoculum, while Actinobacteriota, Bdellovibrionota, Firmicutes, or Nitrospirota phyla were increased in several samples either after 7 or 56 days of incubation. In particular, photobleached pyDOM pyrolyzed at 600 °C exhibited the strongest filtration effects on the bacterial microflora. These results help to elucidate the biogeochemical cycling and turnover of pyDOM in sunlit and dark aquatic environments such as fluvial and groundwater networks, lakes, and the ocean.
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•Photobleached pyDOM of lower pyrolysis temperature had higher biodegradability.•Incubation lowered the molecular diversity but increased the aromaticity of pyDOM.•Photobio-resistant components mainly comprised lignin- and tannin-like structures.•Photobleached pyDOM released more CO2 but less N2O than pristine pyDOM.•PyDOM sources and incubation time regulated bacterial succession.
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