8-Hydroxylquinoline (OQ) is demonstrated for the first time as a strong alternative anchoring group porphyrin dyes to improve the long-term stability of solar cells.

A new organic dye (BET) was synthesized and coadsorbed on TiO 2 nanoparticles to make mixed BET/ porphyrin-sensitized solar cells (DSCs). The BET is a boron dipyrromethene compound with one benzoic acid group attached to the meso position for its binding to the TiO 2 nanoparticles and two ethyl groups in the 3 and 3′ positions of pyrrolic units to broaden its absorption. Two ethyl groups are in the cis position, as revealed by its single-crystal X-ray diffraction analysis. The BET exhibits strong absorption in the green light region with an absorption maximum at 528 nm in CH 2 Cl 2 , which is complementary to the absorption spectrum of porphyrin dyes. When the BET coadsorbs on the TiO 2 nanoparticles with porphyrin dyes (TMPZn and LD12), the power conversion efficiencies increase from 1.09% to 2.90% for TMPZn-sensitized solar cells and from 6.65% to 7.60% for LD12-sensitized solar cells, respectively. The IPCE of the devices in the green light region increases dramatically due to the cosensitizing effect of BET. The fluorescence of BET in solution is partially quenched and that of porphyrin is enhanced in the presence of BET dye, indicating an intermolecular energy transfer from BET to the porphyrin dyes. The direct electron injection from BET to the TiO 2 conduction band was rather poor; only negligible photocurrent was observed. Comparative studies of absorption spectra on the TiO 2 nanoparticle films and electrochemical impedance at the dye/TiO 2 interface also indicate that the BET is an excellent coadsorber to prevent the aggregation of porphyrin dyes. An intermolecular energy transfer model is proposed to account for the observed photovoltaic enhancement of the cosensitization system.

Covalent organic frameworks (COFs) have been proven to be an efficient host material for trapping sulfur in lithium–sulfur batteries. However, the potential application as the coating layer of the separator has not been well-addressed yet. Here, we synthesized an imine-based COF, DMTA-COF, which exhibited an AB-stacking mode and had a pore size of 0.56 nm. For the first time, we applied this nanoporous COF as the coating layer of the ceramic separator; the corresponding cell gave an initial discharge capacity up to 1415 mA h/g, and 1000 mA h/g remained after 100 cycles at 0.5 C. The performance is much better than that of the pristine ceramic separator and the super-P coated ceramic separator, demonstrating that the nanopores in the composite separator can effectively block the polysulfide across the separator, thus reducing the “shuttle” effect and the loss of active materials. This study provides a new design strategy for separators in lithium–sulfur batteries.

Lithium-sulfur (Li-S) battery is regarded as one of the most promising next-generation efficient energy storage systems because of its ultrahigh theoretical capacity of 1675 mAh/g and energy density of 2600 Wh/kg accompanied by the environmental benignity and abundance from natural sulfur. However, the insulating nature of sulfur and the dissolution of the polysulfides LiS (4 ≤ n ≤ 8) seriously restrict its practical application. The metastable small sulfur molecules (S) stored in microporous carbon (pore size of <0.6 nm) as the active materials can avoid the production of the soluble polysulfide and solve the shuttle effect thoroughly. In addition, the conductivity of sulfur can be also improved. However, the preparation of microporous carbon materials with reasonable pore size and unique morphology for efficiently encapsulating S is still challenging. Herein, three flowerlike microporous nitrogen-doped carbon nanosheets with the pore size of <0.6 nm (namely, FMNCN-800, -900, and -1000) as the cathode materials in Li-S batteries were obtained from temperature-dependent carbonization of the metal-organic framework (MOF), Zn-TDPAT, which was from the simply reflux reaction of N-rich ligand HTDPAT with Zn(II) salt. Our study showed that the FMNCN-900 from carbonization of Zn-TDPAT at 900 °C has suitable pore volume and nitrogen content, accommodating small S molecules in its micropores with the mass uptake of about 45%. Meanwhile, the appropriate amount of the nitrogen doping and the unique nanostructure of the flowerlike carbon nanosheet in the FMNCN-900 can effectively support its fast electronic transmission and lithium-ion conduction. The resulting S@FMNCN-900 composite cathode material presents the excellent electrochemical property in the Li-S battery (here the carbonate as electrolytes) with a reversible capacity of about 1220 mAh/g at 0.1C after 200 cycles and even 727 mAh/g at 2C after the long-term cycle of 1000 with only around 0.02% capacity loss per cycle. Obviously, the results indicate that the delicate construction of MOF-derived nitrogen-doped microporous carbon nanosheet is a promising strategy to develop novel electrode material for high-performing Li-S batteries.

A robust primitive diamond-type topology 3-D metal-organic framework (MOF) of {[Cd(hbhdpy)(bdc)(DMA)]·(HO)} (1, DMA = N,N-dimethylacetamide) was constructed from the planar secondary building units of the dinuclear cadmium clusters, Cd(μ-O), and two linear organic linkers of the new multidentate Schiff base of 4-(2-hydroxy-3-methoxy-benzyli-denehydrazino-carbonyl)-N-pyridin-4-yl-benzamide (Hhbhdpy) through the solvothermal reaction. 1 presents a 2-fold interpenetrating network along with confined narrow channels and rich acylamide groups as well as potential metal open sites for excellent selective CO uptake over CH/N and high luminescent response for 2,4,6-trinitrophenol (TNP) in DMA solution under ambient conditions. With 2-amino-1,4-dicarboxy-benzene (Hbdc-NH) replacing Hbdc, an amine-functionalized MOF of {[Cd(hbhdpy)(bdc-NH) (DMA)]·(HO)} (1-NH) as an isomorphism of 1, was synthesized under the same reaction conditions. Compared with 1, the corresponding bifunctional features of 1-NH is more obvious. To the best of our knowledge, it is the first reported interpenetrating Cd-MOFs with highly sensitive luminescence response for TNP molecules combined with excellent selectivity for CO/N and CO/CH.