Latest ArticlesDeveloping low-loading single-atom catalysts with superior catalytic activity and selectivity in formaldehyde (HCHO) oxidation at room temperature remains challenging. Herein, ZrO2 nanoparticles coupled low-loading Ir single atoms in N-doped carbon (Ir1-N-C/ZrO2) was prepared. The optimal Ir1-N-C/ZrO2 with 0.25 wt% Ir loading delivers the high HCHO removal and conversion efficiency (> 95%) at 20 ℃, which is higher than that over Ir1-N-C with the same Ir loading. The specific rate can reach 1285.6 mmol gIr−1 h−1, surpassing the Ir based catalysts reported to date. Density functional theory calculation results and electron spin resonance spectra indicate that the introduction of ZrO2 nanoparticles modulate the electronic structure of the Ir single atoms, promoting O2 activation to •O2–. Moreover, the Ir-C-Zr channel is favorable for the dissociation of •O2– to active oxygen atom (*O), and further accelerates the transformation of HCHO and intermediates (dioxymethylene and formates) to CO2 and H2O. This work provides a facile strategy to design low-loading single-atom catalysts with high catalytic activity toward HCHO oxidation.
Recently electrochemical synthesis of H2O2 through oxygen reduction reaction (ORR) via 2e− pathway is considered as a green and on-site route. However, it still remains a big challenge for fabricating novel metal-free catalysts under acidic solutions, since it suffers from high overpotential due to the intrinsically week *OOH adsorption. Herein, a co-doped carbon nanosheet (O/NC) catalyst toward regulating O and N content was synthesized for improving the selectivity and activity of H2O2 electrosynthesis process. The O/NC exhibits outstanding 2e− ORR performance with low onset potential of 0.4 V (vs. RHE) and a selectivity of 92.4% in 0.1 mol/L HClO4 solutions. The in situ electrochemical impedance spectroscopy (EIS) tests reveals that the N incorporation contributes to the fast ORR kinetics. The density functional theory (DFT) calculations demonstrate that the binding strength of *OOH was optimized by the co-doping of oxygen and nitrogen at certain content, and the O/NCCOOH site exhibits a lower theoretical overpotential for H2O2 formation than OCCOOH site. Furthermore, the promoted kinetics for typical organic dye degradation in simultaneous electron-Fenton process on O/NC catalyst was demonstrated particularly for broadening its environmental application.
The severe interfacial charge recombination as well as the stability issues brought by the Li-TFSI still hinder the commercialization of high-performance perovskite solar cells (PSCs). Here, a polyoxometalates (POMs)-based complex, POM@ ionic liquid (IL), is synthesized and applied as an effective additive that simultaneously enhances the performance and stability of PSCs. The interactions between POM@IL complex and Li-TFSI inhibit the aggregation of Li-TFSI. The synergistic oxidation of POM@IL complex and Li-TFSI towards 2, 2′, 7, 7′-tetrakis[N, N-di(4-methoxyphenyl)amino]-9, 9'-spirobifluorene (Spiro-OMeTAD) effectively enhances the electrical properties of hole transport layer film and the photovoltaic performances of PSCs. The champion device modified with the POM@IL complex yields an excellent power conversion efficiency (PCE) of 22.73%. Moreover, the incorporation of POM@IL improves the humidity stability of PSCs. After storing under high humidity conditions (25 ℃, 60% RH) for 1200 h, the POM@IL modified device retained a remarkable 81.2% of its initial PCE. This work provides new insight into constructing POMs-based materials for high-performance photovoltaic devices.
Three-dimentional (3D) transition metal selenides with sufficient channels could produce significant superiority on enhancing reaction kinetics for sodium-ion batteries. However, the thorough exploration of 3D architecture with a facile strategy is still challenging. Here we report that a polycrystalline Cu2-xSe film was epitaxial grown on (220) facets-exposed Cu by direct selenization of a nanoporous Cu skeleton, which is obtained by dealloying rolled CuMn@Cu alloy foil. Density functional theory calculation result shows strong adsorption energy for Se atoms on Cu (220) planes during selenization reaction, rendering a low energy consumption. By virtue of this core-shell 3D nanoporous architecture to offer abundant active sites and endow fast electron/ion transportation, the nanoporous Cu2-xSe@Cu-0.15 composite electrode exhibits remarkable sodium-ion storage properties with high reversible capacity of 950.6 µAh/cm2 at 50 µA/cm2, suprior rate capability of 457.6 µAh/cm2 at 500 µA/cm2, as well as an ultra-long stability at a high current density. Mechanism investigation reveals that the electrochemical reaction is a typical conversion-type reaction with different intermediates. This novel electrode synthetic strategy provides useful instructions to design the high-performance anode material for sodium-ion batteries.
Due to their superior fluorescence, phosphorescence, and catalytic capabilities, carbon dots (CDs), an emerging class of fluorescent carbon nanomaterials, have a wide range of potential applications. The properties of CDs have recently been controlled extensively by heteroatom doping. Boron atoms have been effectively doped into the structure of CDs due to their similar size to carbon atoms and excellent electron-absorbing ability to further improve the performance of CDs. In this review, we summarize the research progress of boron-doped CDs in recent years from the aspects of doping strategies, effects of boron doping on different performances of CDs and applications. Starting from the two aspects of single boron doping and boron and other atom co-doping, from different precursor materials to different synthesis methods, the doping strategies of boron-doped CDs are reviewed in detail. Then, the effects of boron doping on the fluorescence, phosphorescence and catalytic performance of CDs and applications of boron-doped CDs in optical sensors, information encryption and anti-counterfeiting are discussed. Finally, we further provide a prospect towards the future development of boron-doped CDs.
Covalent bioactive compounds are successfully used in clinic and attracted intense research efforts in the fundamental study as well as drug development. The advantageous effects of covalent compounds compared with non-covalent ones are highly dependent on electrophilic warheads. Hence, electrophilic warheads with tunable reactivity and selectivity are highly demanded in fields of medicinal chemistry and chemical biology. Herein, we report a novel electrophilic warhead, chloromethyl group activated by thiol-substituted 1,2,4-triazole. Interestingly, a pair of regioisomers could be simultaneously occurred in the step of alkylation during the synthesis of this unique motif. This is a rare example that the alkylation could simultaneously generate these two separable regioisomers of 1,2,4-triazole at the nitrogen or sulfur atom. The covalent-working mechanism of this new warhead is confirmed by various chemoproteomics experiments including target identification and binding site mapping. Importantly, the reactivity and selectivity of this new electrophilic warhead could be efficiently tuned by virtue of stereo effect. Interestingly, one pair of regioisomers (19S and 19X) induced distinct modes of cell death. Isomer 19S could induce apoptosis of colon cancer cells while 19X could induce both apoptosis and ferroptosis. Together, this study provides pairs of novel electrophilic warheads that could be useful not only in supporting the design of covalent compounds for drug discovery but also in providing chemical probes for the fundamental biological study.
Strand displacement reaction enables the construction of enzyme-free DNA reaction networks, thus has been widely applied to DNA circuit and nanotechnology. It has the characteristics of high efficiency, universality and regulatability. However, the existing regulation tools cannot enable effective control of the reaction sequence, which undoubtedly limits the construction of complex nucleic acid circuits. Herein, we developed a regulation tool, toehold lock, and achieved strict control of reaction sequence without loss of the main reaction signal output. Furthermore, we applied the tool to scenarios such as seesaw circuits, AND/OR logic gates, and entropy-driven circuits, and respectively demonstrated its significant superiority compared to the original method. We believe that the proposed toehold lock has greatly optimized the efficiency of DNA strand displacement-based networks, and we anticipate that the tool will be widely used in multiple fields.
In recent years, rechargeable zinc-ion batteries (ZIBs) are considered to be a promising alternative to lithium-ion batteries owing to their high safety and theoretical capacity with low cost. Nevertheless, the in-depth development of rechargeable zinc-ion batteries is restricted by a sequence of issues, such as the dissolution and structure collapse of cathode materials, the formation of by-products, severe anode corrosion, passivation, and the growth of zinc dendrites. The covalent organic frameworks (COFs) can solve the above problems to a certain extent owing to their ideal characteristics, such as rigid structure, insolubility, high porosity, and abundant active sites. COFs, as advanced materials for ZIBs, have attracted researchers' attention. In this review, we systematically summarized the synthesis methods of COFs and discussed the application of several advanced characterization technologies in COFs, which would provide a reference for the in-depth research of COFs. In addition, we elucidated the use of COFs as cathode materials and anode protective layers in rechargeable ZIBs. Finally, we discussed the challenges and solutions in the development of COF materials, which would provide constructive insights into the future direction of COFs.
Na+ batteries (SIBs) have been emerging as the most promising candidate for the next generation of secondary batteries. However, the development of high-performance and cost-effective anode materials is urgently needed for the large-scale applications of SIBs. In this study, carbon dots confined bimetallic sulfide (NiCo2S4) architecture (NiCo2S4@CDs) was proposed and synthesized from assembling nanosheets into cross-stacked superstructure and the subsequent confinement of carbon dots. This novel decussated structure assembly from nanosheets is greatly beneficial to the structure stability of electrode material during the successive charge/discharge processes. Besides, the CDs based carbon conductive network can enhance the electrical conductivity for facilitating the easy transport of electron/Na+. Benefitting from these advantages, NiCo2S4@CDs exhibits high-rate performance and an ultralong cycling life in SIBs. Specifically, the specific capacity of NiCo2S4@CDs can reach the discharge specific capacity as high as 568.9 mAh/g at 0.5 A/g, which can also maintain 302.7 mAh/g after 750 cycles at 5.0 A/g. Additionally, ex-situ characterization techniques such as ex-situ XRD and ex-situ XPS were employed to further explore the sodium storage mechanism of the NiCo2S4@CDs anode.
Size is one of the most important characteristics of nanoparticles to influence their biodistribution and antitumoral efficacy. Particles with large sizes have difficulty in deep tumor penetration, while small particles are easily removed from tumor tissues due to the high tumor interstitial fluid pressure. To address these issues, an intelligent core-crosslinked polyion complex micelle (cPCM) with a reversibly size-switchable feature was engineered in this study. The micelles are consisting of methoxy poly(ethylene glycol)-poly(D,L-lactide) copolymer (mPEG-PLA), mPEG-PLA-(HE)6CC, and mPEG-PLA-(RG)6CC at an optimal mass ratio of 6:1:1 with an antiangiogenic compound, dabigatran etexilate (DE), encapsulated. The net charge inside the micelles is switchable when exposed to different pH conditions, thereby leading to revisable size-change of micelles. DE-loaded micelles (DE@cPCM) can swell and release drugs at the tumor sites with a mildly acidic pH, while they shrink and protect the cargo from leaking into the blood circulation with a neutral pH. Results indicated that DE@cPCM can inhibit tumor angiogenesis in vitro and in vivo, thereby efficiently restraining tumor growth in a 4T1-bearing mouse model. Collectively, the size-switchable cPCM is a promising nanoplatform for targeting delivery of anticarcinogens into the matrix of tumor tissues.
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