Latest ArticlesRationally designed novel cost-effective hydrogen evolution reaction (HER) electrocatalysts with controlled surface composition and advanced structural superiority is extremely critical to optimize the HER performance. Polyoxometalates (POMs) with structural diversity and adjustable element compositions represent a promising precursor for rational design and preparation of HER electrocatalysts. Herein, a series of transition metal-doped MoS2 materials with different surface engineered structures (Fe, Cr, V doping and S vacancies) (M-MoS2/CC, M = Fe, Cr and V) were fabricated by a simple hydrothermal-vulcanization strategy using Keplerate polyoxomolybdate nanoball ({Mo72Fe30}, {Mo72Cr30}, {Mo72V30}, {Mo132}) as precursors. The enlarged interlayer spacing as well as the integration of homogeneous transition metal doping and abundant sulfur vacancies endows prepared M-MoS2/CC with superior HER electrocatalytic performance and excellent long-term working stability in both acidic and alkaline media. The optimized Fe-MoS2/CC afford current densities of 10 and 50 mA/cm2 at overpotentials of 188/272 mV and 194/394 mV in 0.5 mol/L H2SO4 and 1.0 mol/L KOH aqueous solution, respectively, outperforming most of reported typical transition metal sulfide-based catalysts. This work represents an important breakthrough for POMs-mediated highly efficient transition metal sulfide-based HER electrocatalysts with wide range pH activity and may provide new options for the rational design of promising HER electrocatalysts and beyond.
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.
Due to the advantages of renewable, low pollution and wide distribution of biomass resources, it is selected as the electrode material for supercapacitors. For carbon-based electrode materials, specific surface area and pore structure have a great influence. Exploring and summarizing the influence of activation on pore structure will greatly broaden this field. Based on the activation mechanism of activator, this paper summarizes the latest progress of biomass activation applied to supercapacitors, including traditional physical and chemical activation methods and non-traditional methods such as biological activation method, self-activation method, template assisted activation method and green activator activation. Finally, the challenges, strategies and prospects for the future development of biomass-derived carbon material activation are pointed out. In summary, this review will help researchers choose appropriate strategies to design biomass-derived carbon electrode materials for supercapacitors, thereby promoting the application of biomass materials.
Diatomic-site catalysts (DASCs) have emerged as a kind of promising heterogeneous candidate catalysts for electrochemical CO2 reduction (ECR), which is considered to retain the advantage of single-atom catalysts (SACs) but also introduce opportunities to exceed the limit of single-atom catalysts. In the past few years, tremendous progress has been achieved in this field. Herein, the recent progress in ECR on DASCs has been summarized. It will start with the classification of DASCs. Then the challenges in the precise fabrication and characterization of DASCs have been emphasized. By introducing the advanced ECR performance on DASCs, superior to that on SACs, the synergistic effects of the dual metal atoms are highlighted, as this origin of the advanced ECR performance on DASCs is comprehensively summarized. Finally, the major challenges and perspectives of DASCs have been proposed to shed light on the development of DASCs for ECR application.
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.
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.
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.
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.
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.
Phomaketals A (1) and B (2), two tropolonic meroterpenoids with the unprecedented pentacyclic skeletons, were isolated from the solid-substrate fermentation cultures of a eupC overexpressed mutant strain of the fungus Phoma sp., together with a biogenetically related secondary metabolite pughiinin B (3), and the known one noreupenifeldin B (4). The structures of 1–3 were elucidated primarily by nuclear magnetic resonance (NMR) experiments. The absolute configurations of 1 and 2 were assigned by electronic circular dichroism calculations and the calculated NMR with DP4+ analysis, while that of 3 was established by single-crystal X-ray diffraction analysis using Cu Kα radiation. Biogenetically, phomaketals A (1) and B (2) could be derived from the hypothetical tropolonic sesquiterpene intermediates neosetophomone B (6) and 9-R-neosetophomone B (6′), respectively, via different reactions cascades. Compound 1 showed antiproliferative effect only against the SUPB15 cells, with an 50% inhibitory concentration (IC50) value of 4.85 µmol/L, while the co-isolated known meroterpenoid 4 displayed potent effects against three tumor cell lines, SUPB15, EL4, and H9, showing IC50 values of 0.36–27.08 µmol/L.
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