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Dye-sensitized solar cells (DSSCs) are regarded as prospective solar cells for the next generation of photovoltaic technologies and have become research hotspots in the PV field. The counter electrode, as a crucial component of DSSCs, collects electrons from the external circuit and catalyzes the redox reduction in the electrolyte, which has a significant influence on the photovoltaic performance, long-term stability and cost of the devices. Solar cells, dye-sensitized solar cells, as well as the structure, principle, preparation and characterization of counter electrodes are mentioned in the introduction section. The next six sections discuss the counter electrodes based on transparency and flexibility, metals and alloys, carbon materials, conductive polymers, transition metal compounds, and hybrids, respectively. The special features and performance, advantages and disadvantages, preparation, characterization, mechanisms, important events and development histories of various counter electrodes are presented. In the eighth section, the development of counter electrodes is summarized with an outlook. This article panoramically reviews the counter electrodes in DSSCs, which is of great significance for enhancing the development levels of DSSCs and other photoelectrochemical devices.

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In this work, we demonstrated the EG-assisted solvothermal synthesis of 3-D microspherical BiOBr architectures assembled by nanosheets. The morphology and compositional characteristics of the 3-D architectures were investigated by various microscopy techniques. The possible formation mechanism for the architectures was discussed. The band gap of the obtained BiOBr materials was estimated to be 2.54 eV by UV-vis. The specific surface area and porosity of the BiOBr 3-D architectures also were investigated by using nitrogen adsorption and desorption isotherms. Because of the narrow bandgap and the novel 3-D micro-/nanostructure, the BiOBr architectures show a more excellent photocatalytic activity under visible light irradiation than the BiOBr bulk plates. Several possible reasons for the higher photocatalytic activity have been taken into consideration. In addition, the photocatalyst is stable during the reaction and can be used repeatedly.

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Since the prototype of a dye-sensitized solar cell (DSSC) was reported in 1991 by O'Regan and Grätzel, [1] it has aroused intensive interest over the past decade due to its low cost and simple preparation procedure. [1,2] Based on liquid electrolytes, a photoelectric conversion efficiency of 11 % for DSSC has been achieved. [3,4] However, the potential problems caused by the liquid electrolytes, such as the leakage and volatilization of liquid, is considered as some of the critical factors limiting the long-term performance and practical use of the DSSCs. Thus, solid-state and quasi-solid-state electrolytes, such as polymer gel electrolytes, organic hole conductors and inorganic p-type semiconductors, [5][6][7][8][9][10][11][12][13][14][15][16][17] were attempted to replace the liquid electrolytes. However, due to low ionic conductivity, imperfect soakage of porous TiO 2 film and poor contact with counter electrode, the photoelectric conversion efficiency of DSSCs based on the solid-state electrolytes were less than 5 %. If an electrolyte can avoid the leakage and volatilization of liquid electrolyte and keep a high ionic conductivity and good interface contact with porous TiO 2 film and counter electrode, it is possible to accelerate the practical application of DSSCs. Gel electrolyte is one kind of electrolyte according with the above prerequisites, especially these thermo-irreversible (Thermosetting) gel electrolytes, which show high ionic conductivity, perfect interface contact, excellent chemical stability and temperature tolerance. [6,8,[18][19][20][21] Here, we report a novel thermosetting gel electrolyte (TSGE) based on poly (acrylic acid)-(ethylene glycol) (PAA-PEG) hybrid absorbing liquid electrolyte. It is known that poly (acrylic acid) (PAA) is a superabsorbent with 3D networks structure and hydrophilic groups, it can absorb large amount of liquid and the absorbed liquid is hard to be released even under some pressure. [22,23] However, pure PAA is not a good absorbent for conventional organic solvents used in liquid electrolytes. By modifying with amphiphilic poly (ethylene glycol) (PEG), the PAA-PEG hybrid shows a high absorbent ability for liquid electrolytes and the absorbed liquid electrolytes are hard to be leaked and volatilized for a long time. On the other hand, due to large amount of liquid is contained in the PAA-PEG hybrid, the ionic conductivity and interface soakage ability of the PAA-PEG hybrid is superior to that of solid-state electrolyte or other polymer gel electrolyte. The absorbed liquid electrolyte is kept in the networks of the hybrid due to hydrogen bonding between carboxylic groups and ether groups in the hybrid. Moreover, through reaction between Lewis basic organic solvents and the polyacid hybrid (PAA-PAG), a part of solvents is hanging on the polymer chains. Consequently, an electrolyte with thermosetting character and good stability, and with advantages for both liquid electrolyte and solid state electrolyte can be expected. Based on the TSGE, the DSSC shows a high photoel...

Ferromagnetic metal‐based materials display interesting properties for microwave applications. Here the authors report obtaining ferromagnetic monodisperse particles in the nanometer size range by the polyol process. By accurate control of the particle size the influence of the particle upon the microwave permeability could be studied. Three different behaviors are detected in a size range varying by over two orders of magnitude, in which the change from a polydomain to a monodomain configuration occurs.

We report on the synthesis of high-quality microporous/mesoporous BN material via a facile two-step approach. An extremely high surface area of 1687 m(2) g(-1) and a large pore volume of 0.99 cm(3) g(-1) have been observed in the synthesized BN porous whiskers. The formation of the porous structure was attributed to the group elimination of organic species in a BN precursor, melamine diborate molecular crystal. This elimination method maintained the ordered pore structure and numerous structural defects. The features including high surface area, pore volume and structural defects make the BN whiskers highly suitable for hydrogen storage and wastewater treatment applications. We demonstrate excellent hydrogen uptake capacity of the BN whiskers with high weight adsorption up to 5.6% at room temperature and at the relatively low pressure of 3 MPa. Furthermore, the BN whiskers also exhibit excellent adsorption capacity of methyl orange and copper ions, with the maximum removal capacity of 298.3 and 373 mg g(-1) at 298 K, respectively.