Latest ArticlesUnderstanding the luminescence mechanisms and regulating the emission centers of carbon dots (CDs) are important for advancing their related applications. In this work, we systematically investigate the formation processes of multi-emission centers in CDs synthesized through a bottom-up approach by controlling the solvothermal reaction temperature. CDs synthesized at a lower temperature (140 ℃, 140-CDs) exhibit smaller particle sizes (3–4 nm) with dominant green–yellow emission, while CDs synthesized at a higher temperature (180 ℃, 180-CDs) exhibit larger particle sizes (8–9 nm) with enhanced red emission and emerging near-infrared (NIR) emission. The green–yellow emission and red emission originate from the core state and the surface-related state, respectively, and the emissions could be regulated by temperature-controlled dehydration and carbonization processes. The clear NIR emission center in 180-CDs is attributable to the increased content of radical defects in the cores during the increased dehydration and carbonization processes during higher-temperature solvothermal treatment.
Catalysts can significantly promote the reaction dynamics and are therefore considered crucial components for achieving high electrochemical energy conversion efficiency. However, the active sites of the catalysts, particularly for nano-level and atomic-level catalysts commonly undergo reconstruction under practical applications. Therefore, obtaining an in-depth and systematic understanding on the real active sites through in situ/operando characterization techniques is a prerequisite for establishing the structure-performance relationship and guiding the future design of more efficient electrocatalysts. Herein, we summarize the recent progress of in situ/operando characterization techniques for identifying the nature of active sites of electrocatalysts when used in electrocatalytic energy conversion reaction. Specifically, our focus lies in the fundamental principles of various in situ/operando characterization techniques, with particular emphasis on their applications for electrocatalytic reactions. Beyond that, the challenges and perspective insights are also added in the final section to highlight the future direction of this important field.
Compared to organic thin films, organic single crystals offer significant potential in organic phototransistors (OPTs) due to their enhanced charge transport, large surface area, and defect-free nature. However, the development of n-type semiconductors has lagged behind p-type semiconductors. To enhance semiconductor device performance, a doping process can be employed, which typically involves the introduction of charged impurities into the crystalline semiconducting material. Its aim is to reduce the Ohmic losses, increase carrier density, improve transport capabilities, and facilitate effective carrier injection, ultimately enhancing the electrical properties of the material. Traditional doping processes, however, often pose a risk of damaging the structure of single crystals. In this study, we have synthesized novel cyano-substituted chiral perylene diimides, which self-assemble into two-dimensional single crystals that can be used for n-type semiconductor devices. We have employed a surface doping strategy using diethylamine vapor without disrupting the crystal structure. The fabricated devices exhibit significantly higher charge transport properties after doping, achieving a maximum electron mobility of 0.14 cm2 V−1 s−1, representing an improvement of over threefold. Furthermore, the optoelectronic performance of the doped devices has significantly improved, with the external quantum efficiency increased by over 9 times and the significantly improved response time. These results suggest that our surface doping technology is a promising way for enhancing the performance of 2D organic single-crystal OPTs.
Tryptophan (Trp) is an essential amino acid that plays a critical role in human physiology. The increasing demand for Trp has created a highly promising market, underscoring the urgent necessity for the development of efficient strategies for the simultaneous detection and uptake of tryptophan. Herein, we report an expanded "Texas-sized" molecular box (An-TxSB), which incorporates luminescent anthracene bridging subunits and molecular recognition motifs. This luminescent molecular box demonstrates exceptional sensitivity to Trp in water, permitting its precise quantification with a notably low limit of detection (LOD) of 0.42 µmol/L. Moreover, An-TxSB facilitates the proficient uptake of Trp from simulated water samples, thereby revealing an impressive Trp adsorption capacity of up to 226.0 µmol/g.
The electrochemical oxidation of 5-hydroxymethylfurfural (HMF) to valuable chemicals is an efficient way to upgrade biomass molecules and replace traditional catalytic synthesis. It is crucial to develop efficient and low-cost earth-abundant electrocatalysts to enhance catalytic performance of HMF oxidation. Herein, a new type of two-dimensional (2D) hybrid arrays consisting of NiFe layered double hydroxides (LDH) nanosheets and bimetallic sulfide (NiFeS) is constructed via interface engineering for efficient electrocatalytic oxidation of HMF to 2, 5-furandicarboxylic acid (FDCA). The preparation process of 2D NiFe LDH/NiFeS with ultrathin heterostructure involves in anchoring a Co-based metal-organic framework (Co MOF) as template onto the carbon cloth (CC) via in-situ growth, formation of NiFe LDH on the surface of Co MOF and subsequent partial sulfidation. The electrocatalyst of NiFe LDH/NiFeS exhibits outstanding performance towards HMF oxidation, about 98.5% yield for FDCA and 97.2% Faraday efficiency (FE) in the alkaline electrolyte with 10 mmol/L HMF, as well as excellent stability retaining 90.1% FE for FDCA after six cycles test. Moreover, even at an HMF concentration of 100 mmol/L, the yield and FE for FDCA remain high at 83.6% and 93.6%, respectively. These findings highlight that 2D heterostructure containing abundant interfaces between NiFe LDH nanosheets and NiFeS can enhance the intrinsic activity of LDH and thus promote the oxidation reaction kinetics. Additionally, the synergistic effect of the bimetallic NiFe compounds also improved the selectivity of HMF conversion to FDCA. Our present work demonstrates that constructing 2D ultrathin heterostructure of NiFe LDH/NiFeS is a facile strategy via interface engineering to enhance the intrinsic activity of LDH electrocatalysts, which would open new avenues toward low-cost and advanced 2D nanocatalysts for sustainable energy conversion and electrochemical valorization of biomass derivatives.
A rhodium(Ⅲ)-catalyzed hydrosilylation/cyclization reaction of cyclohexadienone-tethered α, β-unsaturated aldehydes (1, 6-dienes) with triethylsilane is described, providing a series of cis-hydrobenzofurans, cis-hydroindoles, and cis-hydroindenes bearing silyl enol ether in good to excellent yields and excellent stereoselectivities. Additionally, the versatility of this method was demonstrated through a gram-scale experiment and various downstream transformations, highlighting its utility.
In this study, a series of arylene-bridged bis(benzimidazolium)triflates 1–62+·2[OTf–] were synthesized by grafting different π-linkers with benzimidazolium scaffolds. Among them, compound 12+·2[OTf–] with anthracene as the linker exhibited remarkable electron transfer capabilities across four distinct redox states. The inclusion of an anthracene unit as the π-linker contributes to its exceptional redox and optoelectronic characteristics. Consequently, 12+·2[OTf–] was successfully utilized as both an electrochromic molecule in an ECD under applied voltage for the first time, and a highly efficient photocatalyst for the formation of carbon–phosphorus bonds via visible-light-induced cross-dehydrogenative coupling reactions.
Environmental endocrine disruptors, represented by bisphenol A (BPA), have been widely detected in the environment, bringing potential health risks to human beings. Nitrogen-containing biocarbon catalyst can activate peroxymonosulfate (PMS) to degrade BPA in water, but its active sites remain opaque. Herein, in this work, nitrogen-containing biochar, i.e., CNedge, enriched with graphitic-N defects at the edges was prepared by one-pot co-pyrolysis of chitosan and potassium carbonate. The results showed that the CNedge/PMS system can effectively degrade 98% of BPA (50 mg/L). The electron transfer based non-radical oxidation mechanism was responsible for BPA degradation. Edge graphitic-N doping endows biochar with strong electron transfer ability. The catalyst had good recovery and reuse performance. This catalytic oxidation was also feasible for other refractory pollutants removal and worked well for treating practical wastewater. This work may provide valuable information in unraveling the N doping configuration-activity relationship during activating PMS by biochar.
In this work, we established an exceptionally facile method for the preparation of Ni-CeO2 nanorods in a kind of deep eutectic solvents (DESs) composed of L-proline and Ce(NO3)3·6H2O. First, Ni-CeO2 nanorods were successfully prepared by adding Ni(NO3)3·6H2O to DESs. Then, we found that Ni-CeO2 nanorods prepared in DESs have more prominent oxidase-like activity than pure CeO2. The outstanding catalytic activity of Ni-CeO2 could be ascribed to its high Ce3+/Ce4+ ratio. As a proof-of-concept application, the Ni-CeO2 nanorods were successfully acted as a colorimetric platform for the sensitive determination of ascorbic acid and α-glucosidase activity, which displays excellent analytical performance. Moreover, this sensing platform was applied for screening natural α-glucosidase inhibitors, such as terpenoids from natural products. The results indicated that ursolic acid and oleanolic acid had good inhibitory rates. This strategy not only provides a new way to construct more kinds of nanomaterials from DESs, but also offers a facile and effective tool to screen the α-glucosidase natural inhibitors as potential anti-diabetic drugs.
We describe a versatile electrophile addition/SPR sequence of readily available cyclopropyl carbinols that affords multi-substituted carbonylated cyclopropanes with high stereo-fidelity. This approach tolerates various heteroatom electrophiles, migration of carbon moiety of all possible hybridization states, facile ring reorganization and natural compound valorization. The examples represent an unprecedented version of SPR wherein migration to a non-benzylic bulky tertiary carbo-cation is realized with promising enantiocontrol.
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