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Previously, theoretical studies for 2,6-lutidine/BR 3 (R = F, Me, C 6 F 5 ) (J. Phys. Chem. A, 2010) and PR 3 /B(C 6 F 5 ) 3 (R = Me, Ph, tBu, C 6 F 5 ) (Chem. Phys. Lett., 2012) pairs have been carried out by us to fully understand the reactivity differences between classical Lewis adducts and frustrated Lewis pairs (FLPs). Fukui function, as a conceptual DFT-based reactivity descriptor, was calculated and shown to explain well the observed reactivity of these Lewis pairs. The initially promising results encouraged us to focus on the reactivity for a huge number of published FLPs by using other conceptual DFT-based reactivity descriptors. In this work, various descriptors were used to understand the intermolecular and intramolecular Lewis centers’ reactivities of FLPs. The calculated results shown that, although there are a few exceptions, the adducts and “frustrated complex” of nonreactive pairs and reactive pairs are characterized by the opposite reactivity descriptors. The reactivity of Lewis pairs evaluated by reactivity descriptors also achieves some thermodynamic support from the Gibbs free energies of H 2 activation. [ABSTRACT FROM AUTHOR]

ZnS is widely used in the photocatalytic decomposition of water to produce hydrogen due to its fast electron-hole pair generation and high negative potential. However, its absorption in the visible region is poor due to its wide band gap, and it has serious photogenerated carrier recombination problems. Herein, a shallow impurity energy level was introduced by doping the ZnS lattice with Cd. Due to its presence, electrons trying to return to the valence band are trapped and excited twice, suppressing the recombination of photogenerated carriers and greatly improving electron utilization. The Cd1.5-ZnS possesses a hydrogen production rate as high as 85722.20 μmol/g, which is 17 times higher than pure ZnS. Meanwhile, Cd1.5-ZnS has a narrower forbidden band and superior visible light absorption, and the serious photocorrosion problem of ZnS has been suppressed. This study provides a viable approach for the synthesis of photocatalysts with adjustable band gaps and enhanced hydrogen precipitation efficiency. The band gap of ZnS is narrowed by doping Cd2+ into the lattice structure of ZnS. Additionally, a shallow impurity energy level is created in close proximity to the bottom of the conduction band. This level has the capacity to trap electrons returning to the valence band from the conduction band and to excite them. thereby greatly increasing the utilization of electrons and reducing the formation of electron-hole complexes. Consequently, the Cd1.5-ZnS exhibits superior photocatalytic hydrogen production performance. [Display omitted] • Shallow impurity energy levels are introduced by Cd2+ doping to give the samples the ability to capture electrons secondarily. • The samples with the optimal Zn/Cd molar ratios exhibited photocatalytic hydrogen production rates up to 85722.20 μmol/g. • The issue of the wide bandgap of ZnS has been effectively improved. [ABSTRACT FROM AUTHOR]

Four D−π−A dyads based on various imidazole derivatives donor and o -carborane acceptor moiety have been designed and synthesized for efficient tunable solid-state fluorescence and low-temperature phosphorescence. The results showed that four dyads are all AIEgens with dual emission properties in solution, highly solid-state emission, and low-temperature phosphorescence. The dual emissions were attributed to the locally excited (LE) and twisted intramolecular charge transfer (TICT) emission. The crystallographic measurements and theoretical calculations demonstrated that the strong phosphorescence with a long lifetime up to 2.18 s at low temperature may be attributed to the C–H⋅⋅⋅N, C–H⋅⋅⋅π interactions, strong TICT effect and the reduced vibration coupling by attaching a bulky carborane moiety to the chromophore. Four o -carborane-imidazole derivatives have been successfully synthesized with AIE and ultra-long lifetime low-temperature phosphorescence properties up to 2.18 s. Image 1 • Four D−π−A dyads based on various imidazole derivatives and o -carborane moiety have been designed and synthesized. • Four dyads are all AIEgens with dual emission properties in solution, highly solid-state emission, and ultra-long lifetime low-temperature phosphorescence. • The strong phosphorescence with a long lifetime up to 2.18 s at low temperature may be attributed to the C–H⋅⋅⋅N, C–H⋅⋅⋅π interactions and strong TICT. [ABSTRACT FROM AUTHOR]

The particle size of piezoelectric catalyst plays an important role in the improvement of piezoelectric catalyst performance. However, the inherent influence mechanism of the synthetic raw materials on piezoelectric catalyst particle size is still unclear. Herein, a super simple direct precipitation method was used to prepare ZnO nanomaterials with different particle size, and explore the internal influencing mechanism between raw material molecules and photocatalyst particle size at molecular level. The results indicated that the particle size of the obtained ZnO gradually increased with the changes of Zn(NO 3) 2 , ZnCl 2 and ZnSO 4. After investigating the reason, it was surprised to find that the shift of catalyst particle size is related to the hydrating ion radius of the reaction raw material: with the increase of the hydrating ion radius of the reaction raw material, the catalyst particle size will gradually increase. Correspondingly, the piezoelectric properties of the catalyst with the smallest hydrating ion radius is the best. After 25 min of ultrasound, the piezoelectric catalytic degradation efficiency is up to 91 %. In addition, the obtained catalyst exhibits good recycling ability. This work explores the internal influencing mechanism among raw material molecules, photocatalyst particle size and catalytic properties from the molecular level, which can provide a selection basis for the selection of raw materials when synthesizing small-sized and high-performance piezoelectric catalysts. The mechanism of molecular scale effect of raw material on catalyst particle size was investigated, and the piezoelectric catalytic ability could be improved by controlling raw material molecules. [Display omitted] [ABSTRACT FROM AUTHOR]

Abstract: The reactivity of PR3/B(C6F5)3 (R=Me, Ph, tBu, C6F5) Lewis pairs are investigated in detail by quantum chemical calculations. The observed reactivity difference of these pairs is interpreted in terms of the existence of a frustrated complex, the condensed Fukui functions of the Lewis centers, and the thermodynamic properties of dihydrogen cleavage reaction. The calculated results are shown to account well for the observed reactivity of these Lewis pairs. [Copyright &y& Elsevier]

Abstract Sulfide-graphene oxide composites photocatalysts were fabricated through a simple solid-state chemical reaction method under different synthesis conditions. The resulting photocatalysts were characterized by X-ray diffraction, transmission electron microscopy, Nitrogen adsorption-desorption specific surface areas, XPS measurements, UV–vis absorption spectroscopy, Transient photocurrent, and Photoluminescence spectra. The result suggests that ZnS and Bi 2 S 3 nanoparticles well distributed on the graphene oxide nanosheets in the sulfide-graphene oxide composites. Nitrogen adsorption-desorption results indicate that the specific surface areas of the composites increased after the graphene oxide is introduced. XPS measurements suggest that there are interactions between sulfide and graphene oxide. The photocatalytic activities of sulfide-graphene oxide composites were measured by the degradation of methyl orange under UV irradiation. Variation of the synthesis conditions allowed the sulfide-graphene oxide composites possessing different structures and photocatalytic activities as revealed by transmission electron microscopy and photocatalytic measurements. The photocatalytic results indicated that the sulfide-graphene oxide composites exhibited much higher photocatalytic activities than that of pure ZnS and Bi 2 S 3 , and nearly 97% and 90% of methyl orange were degraded over ZnS-graphene oxide and Bi 2 S 3 -graphene oxide after irradiation for 120 min, respectively. The superior photocatalytic activities can be attributed to the high specific surface areas, which is benefical for improving photocatalytic reaction. Futhermore, introducing graphene oxide can effectively reduce the photoinduced electron-hole pair recombination probability, and then improve the photocatalytic activities, which have been proved by the transient photocurrent, photoluminescence spectra, and scavengers measurements. Highlights • Sulfide-GO composites were synthesized by a simple solid-state method. • Effects of GO contents and others on activity of composites were investigated. • The composites exhibited superior activities to pure sulfides. • The superior activity is proved by transient photocurrent, PL and scavengers measurements. [ABSTRACT FROM AUTHOR]

A simple wet chemistry method was employed for the synthesis of graphene oxide-metal sulfide composites. The obtained products were characterized by X-ray diffraction, transmission electron microscopy, X-ray photoelectron spectroscopy, nitrogen absorption–desorption specific surface area and UV–Vis spectroscopy. The study indicates that sulfides nanorods were well dispersed on the graphene oxide nanosheets in the graphene oxide-metal sulfide composites. It was found that the specific surface area of the composites increased with the introduction of graphene oxide. The as-synthesized graphene oxide-metal sulfide composites were used as photocatalysts for the color removal of methyl orange under UV light irradiation. The results indicated that the graphene oxide-metal sulfide composites exhibited improved photocatalytic activity to pure sulfides and commericial sulfides, with nearly 95% and 90% of methyl orange degraded after irradiation for 15 min, respectively. The excellent photocatalytic activity of the composites can be ascribed to the high specific surface area and the reduction of photoinduced electron–hole pair recombination due to the introduction of graphene oxide. With the help of various radical scavengers, O 2 − and h + were proved to be the main reactive species for the color removal of methyl orange. [ABSTRACT FROM AUTHOR]

A simple wet chemical method has been employed to obtain CdS nanorods with the assistance of thioglycollic acid. The as-synthesized samples were characterized by X-ray diffraction (XRD), Transmission electron microscopy (TEM), Brunauer–Emmett–Teller (BET), and UV–vis diffuse reflection spectrum (UV). The photocatalytic activity was evaluated by the photocatalytic degradation of methyl orange in an aqueous solution under UV light irradiation. The effects of thioglycollic acid on the morphology and photocatalytic activity were investigated. The results suggest that thioglycollic acid plays an important role in the formation of CdS nanorods. Moreover, the as-synthesized CdS nanorods assisted by thioglycollic acid displayed an excellent photocatalytic performance with a degradation rate of 93% within 40 min under UV light irradiation, even higher than that of commericial CdS. The excellent photocatalytic ability of CdS nanorods can be attributed to the synergic effects of large surface area and unique nanorods structure. With the help of scavengers, · O 2 − was proved to be the main reactive species for the degradation of methyl orange. [ABSTRACT FROM AUTHOR]

A simple mechanical grinding method was used to adsorb aniline organic molecules on the surface of TiO 2. The reduction capacity of the photocatalyst and the amount of surface charge increase simultaneously. [Display omitted] • At room temperature, simple mechanical grinding was used to successfully adsorb organic aniline molecules on the surface of TiO 2. • After aniline was adsorbed, the photoreduction capacity of TiO 2 and the amount of surface charge increased synchronously. • The preparation method is simple, without precious metal additives, and the raw materials are abundant and easy to obtain. • Improved photocatalytic hydrogen production performance of commercial P25 with the help of a simple molecular adsorption strategy. The work explains the mechanism of photocatalytic performance enhancement and contributes to a better understanding of the process of photolytic hydrogen precipitation from molecularly modified nanomaterials. A higher conduction band position and more photogenerated electrons are distinctly important for the high-efficiency photocatalytic hydrogen evolution performance. However, raising conduction band position will enlarge the band gap and reduce the production of photogenerated electrons. Herein, a super simple and efficient ammonia molecular adsorption strategy was proposed and designed to promote efficient hydrogen production by a simple ammonia molecules adsorption on commercial TiO 2 surface. The experimental and theoretical calculation results indicated that aniline can be successfully adsorbed on TiO 2 surface by a straightforward mechanical grinding method, and the photocatalytic hydrogen production performance of TiO 2 can be improved by more than 9 times after the adsorption of aniline. This is because the adsorbed aniline can provide electrons to the TiO 2 surface and lead to a charge redistribution and accumulation on the surface of TiO 2. Excessive electrons make the conduction band of TiO 2 bend upward, thus improving the photogenerated electron reduction ability and the photocatalytic performance of TiO 2. In addition, the adsorption of aniline enables TiO 2 to show light absorption in the visible region, generating more photogenerated electrons to participate in the photocatalytic water splitting reaction. In this work, the molecular adsorption strategy is not only simple to operate, but also can improve the photoreduction ability and surface charge quantity of materials. It provides a simple and efficient new method for photocatalyst modification in addition to the traditional modification methods such as doping compounds. [ABSTRACT FROM AUTHOR]

A simple solid-state method was employed for the first time to obtain ZnS/graphene nanocomposites. The chemical composition, morphology and properties of the products were characterized by X-ray diffraction, Raman spectroscopy, transmission electron microscopy, nitrogen absorption-desorption and UV–vis spectroscopy. The photocatalytic performances of the products were evaluated by methyl orange. The results indicated that nanocomposites exhibited superior photocatalytic activity to pure ZnS, owing to the reduction of photoinduced electron–hole pair recombination induced by the introduction of graphene. In addition, effects of solid-state synthetic conditions on photoactivity were also investigated. It was found that the nanocomposite obtained by the reduction of NaBH 4 exhibited higher photoactivity than that of got by the direct addition of graphene, which can be attributed to the high specific surface area and the enhanced synergetic effect between ZnS and graphene. With the help of scavengers, ·O 2 - was proved to be the main reactive species during the degradation. [ABSTRACT FROM AUTHOR]