Latest ArticlesIn order to boost power conversion efficiency (PCE) and operation stability of organic solar cells (OSCs), we propose a new idea of phase junction materials (PJMs) used as a photoactive layer component to improve device performance and stability. For this purpose, a novel PJM of H-TRC8 based on rhodanine unit was designed with a conjugated AH-D-A framework. Here, AH is a hydrogen-donating electron acceptor unit, D-A is an electron donor-acceptor unit. It is found that H-TRC8 has a good carriertransporting ability, as well as definite hydrogen-bond and D-A interaction with donor/acceptor materials. While H-TRC8 is added into the PBDB-T/PC60BM blend film with 1.0 vol% DIO (1, 8-diiodooctane), the resulting blend film exhibited an enhanced absorption and improved morphology. The intermolecular hydrogen bond between H-TRC8 and PBDB-T plays an important role for them, which is confirmed via FT-IR spectra and 2D 1H NMR. As a result, the PBDB-T/PC60BM-based devices with 1.25 wt% H-TRC8 and 1.0 vol% DIO exhibit a significantly improved PCE of 8.06%, which is increased by 20.6% in comparison to that in the binary devices with 1.0 vol% DIO only (PCE = 6.68%). Furthermore, the device stability is significantly enhanced with only 43% PCE roll-off at 150 ℃ for 120 h. This work indicates that AH-D-A-type PJMs are promising photovoltaic materials used as photoactive-layer components to achieve high-performance fullerene OSCs with high device stability.
In this article, three novel and simple molecular structure with donor-acceptor (D-A) type copolymers via only head-to-head alkoxy (OR) and/or alkylthio (SR) side chains onto the bithiophene (BT) as donor units and fluorinated benzotriazole (FBTA) as acceptor unit, namely, PBTOR-FBTA, PBTOSR-FBTA and PBTSRFBTA, were successfully designed and synthesized. The impacts of sulfur-oxygen (S⋯O) or sulfur-sulfur (S⋯S) noncovalent interactions on their physicochemical properties, molecular stacking, carrier mobility, morphologies of blend films, as well as their photovoltaic performance were deeply and systematically studied. The introduction of SR side-chains suddenly lowered the highest occupied molecular orbital (HOMO) energy levels, blue-shifted absorption, enhanced π-π stacking, as well as improved morphology of the photoactive layer blends in comparison with the reference polymer without SR side-chain. Polymer solar cells (PSCs) were fabricated to estimate their photovoltaic performance of the polymers. Under an optimized blend ratio of PBTSR-FBTA:PC71BM (1:0.8, w/w), the PBTSR-FBTAbased device exhibits a higher power conversion efficiency (PCE) of 6.25%, which is about 3.34 and 1.87 folds than that of the PBTOR-FBTA and PBTOSR-FBTA-based devices, respectively. Our research results demonstrate that the modification of the simple and low-cost SR side chains is an effective strategy to improve the photovoltaic performance of the polymers.
The first HFIP-promoted catalyst-free cascade reactions for the synthesis of biologically relevant 3, 3-di (indolyl)indolin-2-ones (27 examples, up to 98% yield) from readily available indoles and isatin derivatives are described. This protocol shows well tolerance of different functional groups and features mild reaction conditions such as short reaction time (~1 h), no usage of catalyst, easy operation and product isolation. Of particular interest is the formation of two C—C bonds and one all-carbon quaternary center. This protocol could serve as an alternative strategy to synthesize biologically important 3, 3-di (indolyl)indolin-2-ones for biological testing.
The development of efficient and cost-effective electrocatalysts toward anodic oxygen evolution reaction (OER) is crucial for the commercial application of electrochemical water splitting. As the most promising electrocatalysts, the OER performances of nickel-iron-based materials can be further improved by introducing metalloid elements to modify their electron structures. Herein, we developed an efficient hybrid electrocatalyst with nickel-iron boride (NiFeB) as core and amorphous nickel-iron borate (NiFeBi) as shell (NiFeB@NiFeBi) via a simple aqueous reduction. The obtained NiFeB@NiFeBi exhibits a small overpotential of 237 mV at 10 mA/cm2 and Tafel slope of 57.65 mV/dec in 1.0 mol/L KOH, outperforming most of the documented precious-metal-free based electrocatalysts. Benefiting from the in situ formed amorphous NiFeBi layer, it shows excellent stability toward the oxygen evolution reaction (OER). These findings might provide a new way to design advanced precious-metal-free electrocatalysts for OER and the application of electrochemical water splitting.
Discrimination of different types of sulfur-containing species not only helps us to deeply understand how sulfur affects cellular signaling, but also contribute to the early diagnosis of diseases. However, the current investigation about sulfur-containing species discrimination is mainly concentrated in biothiols, which is relatively limited for practical application. Toward circumventing this limitation, herein, a convenient sensor array consisting of three kinds of Au NCs-Cu2+ for simultaneous and rapid identification of different types of sulfur-containing species is reported. Based on the fingerprint-like fluorescence responses generated by competitive binding between Au NCs-Cu2+ and different sulfur-containing species, not only ten different types of sulfur-containing species separately but also their binary or ternary randomly selected mixtures can be well discriminated even in human urine and serum samples. It is worth noting that it only takes 2 min to obtain the best response signals for sulfur-containing species discrimination. Most importantly, serums from cancer patients (such as liver cancer and breast cancer) and healthy people as well as sulfur-oxidizing bacteria (SOB) and sulfur-free bacteria can be both effectively and rapidly identified within 2 min, respectively, making it a promising approach for point-of-care disease diagnostic.
High-performance nanomaterial catalysts for hydrogen evolution reaction via electrochemical water splitting are significant to the development of hydrogen energy. In this work, we report a robust and highly active catalyst fabricated through direct electrochemical deposition of Pt nanodendrites at the surface of activated carbon (Pt NDs). Owing to the large electrochemically active area and the exposed (111) facet of Pt, Pt NDs exhibits outstanding activity towards hydrogen evolution reaction with a low requiring overpotential of 0.027 V at 10 mA/cm2 and Tafel slope of ≈ 22 mV/dec in acidic media. In addition, the hydrogen yield of Pt NDs is 30%-45% larger than that of commercial Pt/C at the same Pt loadings. Moreover, Pt NDs exhibits excellent long-term durability whose hydrogen production efficiency remains unchanged after six-hour hydrogen production, while the efficiency of commercial Pt/C catalyst decayed 9% under the same circumstance. Considering the superiority of catalytic activity and stability, this Pt NDs present great potentiality towards practical hydrogen production application.
Structural and functional biomimicking of the active site of [NiFe]-hydrogenases can provide helpful hints for designing bioinspired catalysts to replace the expensive noble metal catalysts for H2 generation and uptake. Treatment of dianion [Ni(phma)]2- [H4phma = N, N'-1, 2-phenylenebis(2-mercaptoacetamide)] with [NiCl2(dppp)] (dppp = bis(diphenylphosphino)propane) yielded a dinickel product [Ni(phma)(μ-S, S')Ni(dppp)] (1) as the model complex relevant to the active site of [NiFe]-H2ases. The structure of complex 1 has been characterized by single-crystal X-ray analysis. From cyclic voltammetry and controlled potential electrolysis studies, complex 1 was found to be a moderate electrocatalyst for the H2-evoluting reaction using ClCH2COOH as the proton source.
Electrocatalytic N2 reduction to ammonia is a fascinating alternative to Haber-Bosch process and also considered as an energy storage method. This work, Fe doped MoS2/carbon cloth (CC) has been studied on the electro-catalysis fix nitrogen indicating the doped Fe can indeed enhance the MoS2 material ability. Compared with MoS2/CC, Fe-Mo-S-3/CC not only increases 10 times in the rate of production ammonia, but also 5 times in Faraday efficiency.
In addition to the theoretical research, direct ethanol fuel cells have great potential in practical applications. The performance of direct ethanol fuel cells largely depends on the electrocatalysts. Pt-based electrocatalysts have been promising candidates for advancing direct ethanol fuel cells for its high catalytic activity and great durability. Here, a PtSn catalyst with unique three-dimensional porous nanostructure has been designed and synthesized via a two-step liquid phase reduction reaction. Sn formed a self-supporting framework in PtSn alloy particles (~3.5 nm). In ethanol electro-oxidation reaction, the PtSn catalyst exhibited high mass activity and excellent recycling time compared with that of Pt/C. After the morphology characterization before and after potential cycling, the PtSn alloy-based nano-catalyst showed good stability. The PtSn catalysts effectively avoid structural instability due to the external carriers, and prolong the leaching time of Sn. In addition, the introduction of a certain amount of Sn can also solve the poisoning phenomenon of active sites on Pt surface. The design strategy of porous alloy nano-catalyst sheds light on its applications in direct ethanol fuel cells.
Developing a fast, sensitive and convenient method for the detection of hydroxyl radicals (·OH) in the atmosphere could help us know the precursor levels of atmospheric species and control air pollution. In this work, the carbon fiber paper (CFP) functionalizing with a kind of covalent organic frameworks (COFs), formed from 1, 3, 5-triformylphloroglucinol (Tp) and benzidine (BD) (COF(TpBD)), was firstly used a new platform for ·OH trapping and detection. The COF(TpBD) modified CFP was acted as a filter to impregnate salicylic acid (SA) and a detector to detect 2, 5-dihydroxybenzoic acid (2, 5-DHBA) which was produced from the reaction between the impregnated SA and ·OH in the atmosphere. This method provided a linearity for 2, 5-DHBA from 5.0×10-14 mol/L 1.0×10-9 mol/L with a detection limit of 6.9×10-15 mol/L, which is corresponding to the amount of ·OH from 3.0×107 to 6.0×1011 molecules/cm3 with the detection limit of 4.1×106 molecules/cm3. This COF(TpBD)-CFP platform has been successfully applied for the detection of ·OH concentration under different conditions of Yangzhou when the sampling time was shortened to 30 min. This work has provided a new method for atmospheric ·OH detection with excellent sensitivity, simplicity, and high speed.
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