Dye-sensitized solar cells have attracted intense research attention owing to their ease of fabrication, cost-effectiveness and high efficiency in converting solar energy. Noble platinum is generally used as catalytic counter electrode for redox mediators in electrolyte solution. Unfortunately, platinum is expensive and non-sustainable for long-term applications. Therefore, researchers are facing with the challenge of developing low-cost and earthabundant alternatives. So far, rational screening of non-platinum counter electrodes has been hamstrung by the lack of understanding about the electrocatalytic process of redox mediators on various counter electrodes. Here, using first-principle quantum chemical calculations, we studied the electrocatalytic process of redox mediators and predicted electrocatalytic activity of potential semiconductor counter electrodes. On the basis of theoretical predictions, we successfully used rust (a-Fe 2 O 3 ) as a new counter electrode catalyst, which demonstrates promising electrocatalytic activity towards triiodide reduction at a rate comparable to platinum.

As an important metal oxide, anatase titanium dioxide has been widely investigated because of its many promising properties. The properties of anatase TiO2 crystals are largely determined by exposed external surfaces. Since the breakthrough in synthesizing anatase TiO2 single crystals with a large percentage of highly reactive {001} facets in 2008, many unusual properties and applications of these {001} facets dominant in anatase TiO2 have been explored theoretically and experimentally, showing the industrial importance of this semiconductor material. This Perspective focuses on the theoretical simulations and application explorations of the unusual properties of anatase TiO2 bound by highly reactive facets. Research opportunities as well as the challenges for future research in this emerging frontier are also highlighted.

Photocatalytic water splitting using semiconductor photocatalysts has been considered as a "green" process for converting solar energy into hydrogen. The pioneering work on electrochemical photolysis of water at TiO(2) electrode, reported by Fujishima and Honda in 1972, ushered in the area of solar fuel. As the real ultimate solution for solar fuel-generation, overall water splitting has attracted interest from researchers for some time, and a variety of inorganic photocatalysts have been developed to meet the challenge of this dream reaction. To date, high-efficiency hydrogen production from pure water without the assistance of sacrificial reagents remains an open challenge. In this Focus Review, we aim to provide a whole picture of overall water splitting and give an outlook for future research.

Based on molecular studies, the small Chinese genus Petrocodon (two species and one variety) has been recently enlarged to include the monotypic genera Calcareoboea, Paralagarosolen and Tengia. It is shown here that the (6-7) species of Lagarosolen, the monotypic Dolicholoma, a few species of Didymocarpus, and a number of new species that have recently been published (but not formally described) under Petrocodon and Lagarosolen should be included in this genus. This raises the size of the genus from five to around 20 species. With respect to the floral diversity (corolla form, size, and coloration; with the exception of Tengia, the androecium is always diandrous) and inferred pollination syndromes (different forms of melittophily, ornithophily, psycho-and/or sphingophily), Petrocodon represents one of the most varied genera of Old World Gesneriaceae, comparable to some New World genera.

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We report a facile, template-free and nontoxic one-pot solvothermal route of synthesizing submicrometersized yolk@shell hierarchical spheres, which possess a permeable shell self-assembled by ultrathin anatase TiO 2 Nanosheets (NSs) with nearly 90% of exposed {001} facets and mesoporous inner sphere with a high specific surface area. Compared to the {001} faceted TiO 2 NSs and standard Degussa P25, 10 the anatase TiO 2 yolk@shell hierarchical spheres (TiO 2 YSHSs) were obtained with surface area up to 245.1 m 2 ·g -1 and their submicrometer scale simultaneously promoted light scattering in visible region. A light to electricity conversion efficiency (η) of 6.01% was achieved for the DSSCs with TiO 2 YSHSs as its photoanode, under 100 mW cm -2 illumination, indicating 49.9% and 34.8% increases compared to the DSSCs with TiO 2 NSs (4.01%) and the standard Degussa P25 (4.46%) as photoanodes, respectively. The 15 enhancement can be mainly attributed to the higher dye loading on TiO 2 YSHSs (4.35×10 -5 mol·cm -2 ) than that of TiO 2 NSs(3.14×10 -5 mol·cm -2 ) and P25 (3.32×10 -5 mol·cm -2 ); longer lifetime of the injected electrons in TiO 2 YSHSs film (65.79 ms) than that of in TiO 2 NSs film (57.90 ms); and the good capability of light scattering of TiO 2 YSHSs in visible light region, which are confirmed by UV-vis spectrophotometer and electrochemical impedance spectroscopy (EIS). The growth mechanism of the 20 TiO 2 YSHSs has also been investigated in detail. † Electronic Supplementary Information (ESI) available: SEM and TEM 35 images of TiO2 NSs; SEM images and XRD patterns of the samples obtained after different reaction durations. See

The hygroscopic properties of inorganic salt particles, including (NH 4 ) 2 SO 4 , NaCl, Na 2 SO 4 and NaNO 3 , are investigated using a self-assembled hygroscopic tandem differential mobility analyzer (H-TDMA) system. The iso-GF (growth factor) curves are derived to illustrate the effects of the initial particle size (D 0 ) and relative humidity (RH) on the GFs. For those salt particles of 100 nm, the GFs measured agreed well with their theoretical Köhler curves. In the size range of 20-200 nm, the GFs of (NH 4 ) 2 SO 4 , NaCl and Na 2 SO 4 particles all continuously decrease with D 0 increasing below the deliquescence RH (DRH). However, when RH is higher than the DRH, the GFs of those salts aerosols increase with D 0 throughout the investigated size range. Similar increase trend of GFs with D 0 is also observed for NaNO 3 aerosols though they do not exhibit the abrupt deliquescence behavior. From iso-GF curves, it can be clearly observed that the GFs of (NH 4 ) 2 SO4, NaCl and Na 2 SO 4 particles all increase with the RH while the values decrease with D 0 below DRH. And above DRH, the GFs are more sensitive to D 0 for particles smaller than 60 nm, while the GFs are more sensitive to RH for particles larger than 80 nm. For NaNO 3 aerosols, the iso-GF curves indicate the size-effect becomes more prominent on their hygroscopicity as the RH increases. The iso-GF curves provide a lucid and explicit insight into the hygroscopic growth of salts particles. Through iso-GF curves, we can clearly elucidate the major factor that affects the ultimate particle diameter at ambient atmosphere.

Hydrogen bonding (H-bond) interactions have been regarded as a topic of vital scientific research in areas ranging from inorganic to biological chemistry. However, the application and elucidation of surface H-bond functionalized photocatalysts and the alteration of the character of the photocatalyst itself have not been paid sufficient attention. Here we show the high efficiency of visible-light-driven photocatalytic H 2 production, achieved by using a surface H-bonding network decorated g-C 3 N 4 photocatalyst. The hydrated g-C 3 N 4 was designed and synthesized by a facile surface treatment in a slightly alkaline environment. According to NMR and theoretical modeling, the H-bonding bridge can effectively shorten the distance between water molecules and g-C 3 N 4 , provide multiple channels for the transition between protons and the excited electrons on g-C 3 N 4 , stabilize the anionic intermediate and transition states, and restrain charge recombination. The present result opens new opportunities towards a potential approach to designing a new generation of photocatalyst systems.