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Room temperature afterglow materials have received widespread attention and application in anti‐counterfeiting, imaging, and other fields, but the many shortcomings of traditional afterglow materials in terms of cost, environment, and synthesis methods have limited their development. In contrast, carbon dot materials have attracted more and more research due to their numerous advantages and great potential for development. However, the preparation of carbon dot materials with phosphorescence and delayed fluorescence afterglow emission capabilities remains a difficult task. In this study, a series of long life afterglow carbon dot composites with single‐mode and dual‐mode afterglow emission were successfully prepared by inserting carbon dots synthesized from glucose and glycine into boric acid matrix through a two‐step hydrothermal method. This series of carbon dot composites has achieved a transformation from single‐mode phosphorescent emission to unique dual‐mode afterglow emission, allowing for efficient environmental response color modulation. The composites display different afterglow emissions dominated by either phosphorescent or delayed fluorescence at different temperatures. Based on their excellent temperature sensitivity, a single‐mode long phosphorescence with a lifetime of 1.62 seconds was achieved at low temperature. In summary, we have discovered a convenient and efficient method to achieve dual‐mode emission by adjusting the matrix proportion. [ABSTRACT FROM AUTHOR]

Herein, vanadium‐doped cobalt carbonate hydroxide, V−CoCH, was synthesized as efficient catalyst for water splitting. Vanadium species were partially dissolved in the early stages of the oxygen‐evolution reaction (OER), inducing self‐etching of the catalyst surface, which is helpful for catalyst surface reconstruction and resulted in a higher number of active sites and oxygen vacancies. The synergy between V‐doping and oxygen vacancies improved the catalytic activity: V−CoCH showed an exceptional OER catalytic performance with an overpotential of 183 mV at 10 mA cm−2. The water‐splitting cell consisting of V−CoCH only required 1.52 V to reach 10 mA cm−2. Theoretical calculations revealed that vanadium in V−CoCH played an important role in electron regulation of active sites. The oxygen vacancies had an important effect on improvement of the OER performance through not only the exposure of more active sites but also through modulation of the electronic structure. This work provides an effective strategy for constructing high‐performance electrocatalysts. [ABSTRACT FROM AUTHOR]

Hole transporting materials (HTMs) are imperative for promoting the development of perovskite solar cells (PSCs). Herein, three isomers of RQ4, RQ5, and RQ6 are constructed by methylthio (‐SMe) group in the para, meta, and adjacent sites of terminal benzene on the side‐chain of carbazole‐arylamine derivatives based HTMs, and investigated by means of the theoretical simulation and experimental characterization. As a result of the theoretical simulation, the isomeric HTMs of RQ4‐RQ6 exhibit appropriate highest occupied molecular orbital /lowest unoccupied molecular orbital energy levels and good optical properties. However, by comparison with RQ4 and RQ5, a better planar configuration and closer molecular stacking for RQ6 may be beneficial to promote the hole coupling, interface interaction, and charge transfer at perovskite/HTMs interface. In order to verify the accuracy of the theoretical model, the designed RQ4‐RQ6 are synthesized to be used to assemble PSCs devices. In comparison to isomers RQ4 (20.07%) and RQ5 (18.18%) based devices, the RQ6 based devices has higher power conversion efficiency of 21.03% because of its high hole mobility, the film formation ability, and large charge transfer at perovskite/HTMs interface. The experimental results confirm the reliability of the theoretical simulation and provide an effective strategy to obtain potential HTMs through isomerization of side‐chain functional groups. [ABSTRACT FROM AUTHOR]

0D hybrid organic–inorganic metal halides have attracted significant interest due to their unique optoelectronic properties, but attainment of efficient and stable white light emission (WLE) in such compounds remains a challenge. Here, efficient WLE via a molecular design that couples intracompound charge transfer and cluster‐centered excited states in 0D halide hybrids is demonstrated. Two Cu(I) halide hybrids, K(18‐crown‐6)Cu2Br3 and Na4(18‐crown‐6)5In2Cu4Br14·8H2O, are synthesized wherein luminescent [Cu4Br6]2− clusters are isolated from each other and surrounded by 18‐crown‐6 coordinated alkali metal cations. In the case of K(18‐crown‐6)Cu2Br3, [Cu4Br6]2− clusters are only partially isolated, leading to strong orange emission with a photoluminescence quantum yield (PLQY) of 53% under UV excitation. Strikingly, to a larger extent of isolation as that, in Na4(18‐crown‐6)5In2Cu4Br14·8H2O as a result of the incorporation of nonemissive [InBr4]− clusters, intense white light emission with a PLQY of 97% is achieved. The dual cluster‐centered states, coupled with a mixed metal‐to‐ligand and halide‐to‐ligand charge transfer state, are responsible for this bright white luminescence. This work provides new design principles for expanding the materials library for single‐component, solid‐state WLE. [ABSTRACT FROM AUTHOR]

Crystallized Ruthenium (Ru) metal with high hydrogen production activity is extremely unstable. Herein, we report an efficient and durable hydrogen evolution reaction (HER) electrocatalyst Ru‐MC (mesoporous carbon) synthesized by a special method, in which Ru3+ is added after the formation of spherical MC, leading to only a small amount of Ru being embedded and the vast majority being evenly distributed on the MC surface. The dispersed Ru nanoparticles not only prevent them from aggregation to greatly improve their stability (both over 160 hours in acidic and alkaline solutions), but also provide outstanding intrinsic catalytic activity because oxygen regulates the electronic structure of Ru nanoparticles. The as‐synthesized catalyst only needs an overpotential of 27 and 40 mV to deliver 10 mA cm−2 in 1.0 M KOH and 0.5 M H2SO4. The present work provides guidance for the design of efficient and stable Ru‐based HER electrocatalysts used in a wide pH range. [ABSTRACT FROM AUTHOR]

Herein, a transition metal dissolution‐oxygen vacancy strategy, based on dissolution of highly oxidized transition metal species in alkaline electrolyte, was suggested to construct a high‐performance amorphous Co(OH)2/WOx (a‐CoW) catalyst for the oxygen evolution reaction (OER). The surface reconstruction of a‐CoW and its evolution were described by regulating oxygen vacancies. With continuous dissolution of W species, oxygen vacancies on the surface were generated rapidly, the surface reconstruction was promoted, and the OER performance was improved significantly. During the surface reconstruction, W species also played a role in electronic modulation for Co. Due to its rapid surface reconstruction, a‐CoW exhibited excellent OER performance in alkaline electrolyte with an overpotential of 208 mV at 10 mA cm−2 and had long‐term stability for at least 120 h. This work shows that the transition metal dissolution‐oxygen vacancy strategy is effective for preparation of high‐performance catalysts. [ABSTRACT FROM AUTHOR]

Tin(IV)‐based metal halides are promising optoelectronic materials due to their robust structure and eco‐friendly nature, but these materials exhibit poor photoluminescence (PL) properties and the underlying mechanisms are still elusive. Here, a novel air‐stable hybrid Sn4+‐halide material (C8H22N2Cl)2SnCl6 that is resistant to moisture (>70% relative humidity) for >1 year is reported. The inferior PL property of (C8H22N2Cl)2SnCl6 is limited by the lattice defects and robust crystal structure, which however could be effectively improved by introducing Sb3+ ion with stereoactive 5s2 lone pair. As a result, Sb3+‐doped (C8H22N2Cl)2SnCl6 exhibits a superbly stable room‐temperature PL centered at 690 nm with an unprecedented quantum yield (QY) of 41.76% from self‐trapped excitons, which is the highest PLQY of hybrid tin(IV)‐based perovskite materials. The improved PL efficiency is attributed to the defect passivation and remarkable structure distortion induced by Sb3+ dopants. This dopant‐induced defect passivation and exciton self‐trapping approach offers an avenue to improve optoelectronic material performance. [ABSTRACT FROM AUTHOR]

All‐inorganic bismuth‐halide perovskites are promising alternatives for lead halide perovskites due to their admirable chemical stability and optoelectronic properties; however, these materials deliver inferior photoluminescence (PL) properties, severely hindering their prospects in lighting applications. Here, a novel air‐stable but non‐emissive perovskite Rb3BiCl6 is synthesized, and the material is used as a prototype to uncover origin of the poor optical performance in bismuth‐halide perovskite. It is found that the extremely strong exciton–phonon interactions with a large coupling constant up to 693 meV leads to the seriously nonradiative recombination, which, however, can be effectively suppressed to 347 meV by introducing Sb3+ ions. As a result, Sb3+‐doped Rb3BiCl6 exhibits a stable yellow emission with unprecedented PL quantum yield up to 33.6% from self‐trapped excitons. Systematic spectroscopic characterizations and theoretical calculations are carried out to unveil the intriguing photophysical mechanisms. This work reveals the effect of exciton–phonon interaction, that is often underemphasized, on a material's photophysical properties. [ABSTRACT FROM AUTHOR]

The construction of state‐of‐the‐art charge transporting materials (CTMs) is challenging in modulating molecular configurations for simultaneously achieving high thermal stability and appreciable solution processability. Herein, N,N′‐bis(1‐indanyl)naphthalene‐1,4,5,8‐tetracarboxylic diimide (NDI‐ID) is served as a theoretical model to investigate the influence of molecular structure on the tradeoff between thermal stability and solubility. Compared with the alkyl substituted analog, the thermal stability of NDI‐ID is enhanced by the intramolecular and intermolecular short contacts, indicating the conformational rigidity dictates the morphological stability of the film phase. On the other hand, the dynamic topological transformation of material molecules occurs during the solvation process and, where the intramolecular hydrogen bonds are attenuated by the interactions with the surrounding solvent, leads to the increased solubility. The meta‐stable molecular configuration endows NDI‐ID a favorable union of superior solution processability and higher thermal stability, and this insight is also perfectly exemplified by the newly designed CTMs. Therefore, these results reveal the significant role of structural dynamics on material properties, which can provide a new train of thought to develop CTMs for highly efficient and stable perovskite solar cells. [ABSTRACT FROM AUTHOR]

Abstract: Conjugated carbonyl compounds have become the most promising type of organic electrode materials for rechargeable Li‐ion batteries because only they can achieve simultaneously high energy density, high cycling stability, and high power density. In this work, we have performed first‐principles density functional theory (DFT) calculations to explore the fundamental rules of how the electronic structure and redox properties of a typical conjugated carbonyl compound, phenanthrenequinone (PQ), are modified by adjusting the heteroaromatic building blocks. Such a molecular design strategy allows for the improvement in discharge potential while the specific capacity remains nearly unchanged. The correlation between the electronic structures and redox properties for the designed PQ derivatives is systematically discussed. It is demonstrated that the discharge potential of the PQ derivatives depends strongly on the frontier orbital levels, the electric potential, and the Li‐bonding configurations. The electrostatic potential (ESP) maps show visible displays of molecular electric structures and can be applied to understand how the redox properties of the PQ derivatives are modified by the heteroaromatic building blocks. [ABSTRACT FROM AUTHOR]

Abstract: A series of spiro‐annulated triphenylamine/N‐phenylcarbazole derivatives as ambipolar host molecules have been designed by linking different electron acceptors (i. e., diphenylphosphine, phenylsulfone, triphenylsilane and diphenylborane). To reveal their electronic structures, optoelectronic properties and structure‐property relationships of the host materials, a throughout investigation was implied using density functional theory (DFT) and time‐dependent density functional theory (TDDFT) calculations. Results show that the triplet energy (ET), HOMO and LUMO energy levels, as well as some other properties i. e. ionization potentials (IPs), electron affinities (EAs), reorganization energies (λ) can be tuned by chemical modifications of different electron acceptors. The host‐guest models have also been built to investigate the match of the hosts and the reference guests. Comprehensively considering these indexes, the potential performance of 10‐phenyl‐2′‐(phenylsulfonyl)‐10H‐spiro[acridine‐9, 9′‐fluorene] (SOSTF) is a big leap in comparison with experimental host material diphenyl(10‐phenyl‐10H‐spiro[acridine‐9, 9′‐fluoren]‐2′‐yl)phosphine oxide (POSTF). It has been proved that a spiro‐annulated structure can be modified in constructing high ET host material for blue phosphorescent organic light‐emitting diodes. [ABSTRACT FROM AUTHOR]

The synthesis of aromatic azo compounds from anilines and nitrobenzene usually requires environmentally unfriendly transition metal catalysts. Here, we propose that azobenzene oligomers are formed in surface-enhanced Raman experiments assisted by surface plasmon resonance. The photocatalytic polymerization of p-dinitrobenzene (DNB) and p-phenylenediamine (PDA) to the corresponding azo-like oligomers on silver surfaces is studied by the surface-enhanced Raman spectroscopy and density functional theory. First, the normal Raman and surface Raman spectra of DNB and PDA are simulated and measured. The simulated normal Raman spectra are in good agreement with their solid-state Raman spectra. However, the simulated surface Raman spectra of DNB-Ag10 and PDA-Ag10 complexes are significantly different from the experimental surface-enhanced Raman spectra. We propose that DNBs has a reductive coupling and PDAs undergo an oxidative coupling reaction during SERS experiments. Secondly, the Raman spectra of the possible NN coupling oligomers of DNB and PDA are simulated. They are compared with the SERS spectra of DNB and PDA adsorbed on silver surfaces. Especially, the Raman spectra of p, p′-dinitroazobenzene and p, p′-diaminoazobenzene are in good agreement with the SERS spectra of DNB and PDA adsorbed on silver surface. Finally, two reaction mechanisms are proposed to explain the surface photocatalysis of DNB and PDA. In the solution, the nitro group of DNB can be reduced by the excited hot electrons. DNBs are then converted to p, p′-dinitroazobenzene through multiple proton and electron transfers. In the air and in the presence of O2, O2 is firstly activated through surface plasmon resonance. PDAs are then converted to p, p′-diaminoazobenzene by the generated active oxygen species. Copyright © 2016 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

The Hashmi phenol synthesis reaction (the ω-alkynylfuran cycloisomerization) catalyzed by the M6@Au32 (M=Ag, Cu, Pd, Pt, Ru, and Rh) core-shell nanoclusters was investigated systematically. The 5- exo Friedel-Crafts-type mechanism of the ω-alkynylfuran cycloisomerization on the six core-shell nanoclusters was analyzed in details. The adsorption property and catalytic activity of the Au38 nanocluster could be effectively tuned by the substitution of the core Au atoms. The adsorption properties of alkynes on core-shell and Au38 clusters depended on four factors, including the numbers of unoccupied and occupied d orbitals, orientation of d orbital and d-bonding down-shift. Compared with the Au38 cluster, the core-shell nanoclusters could cause larger changes in the interaction energies between the substrate and cluster fragments, which are beneficial for facilitating the cyclization step and the ring closing of the dienone carbene-gold intermediate. In addition, according to the calculated results, the catalytic activity of Au38 can be tuned by substitution of the core gold atoms. [ABSTRACT FROM AUTHOR]

The detailed reaction mechanism of the ω-alkynylfuran cycloisomerization catalyzed by medium-sized bare Au38 nanoclusters was investigated by means of density functional theory at the Perdew-Burke-Ernzerhof level of theory. Both the charge and size effects of the three-dimensional gold clusters are studied at the same level. The mechanistic studies show that the 5- exo Friedel-Crafts-type mechanism is the most favorable mechanism, and could be selective to form phenol derivatives. Additionally, the solvation effect of acetonitrile apparently lowers the energy barrier of the first and second steps of the reaction. The positive charge on the gold clusters could enhance the catalytic activity of the clusters. Suitable positive charges on the reaction sites are essential for the formation of phenol through the cycloisomerization of ω-alkynylfuran. The subnanometer gold clusters show high catalytic efficiency for the conversion of ω-alkynylfurans to phenol derivatives. [ABSTRACT FROM AUTHOR]

A series of poly(4,4-vinyltriphenylamine) based non-conjugated polymer as host molecules are designed and studied by density functional theory. The results show that the substituent has a great influence on the properties of polymer. The parent molecule directly linked para-carbazole, β-pyrrole and triphenylamine are favorable to hole injection, and para-carbazole could significantly increase ET of the host molecules. The large changes of structural parameters between the lowest triplet state and ground state can cause the decrease of ET. Moreover, parent molecule directly linked carbazole and triphenylamine units possess strong and low singlet and triplet energy difference (∆ EST). The calculated results also show that all designed host molecules are suitable for green emitter by comparing with the ET. S1 → S1 and T1 → T1 energy transfer mechanism between host and guest is thermodynamically feasible. In addition, host-guest model is built to study the nature, and the results indicate that a good can be achieved between host and guest materials. In the designed host molecules, the N atom of parent molecule linked para-carbazole substituent shows a great potential for the green phosphorescent polymer . Copyright © 2015 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

The structures and electronic properties of furo[3,4-b]pyridine-based alternating donor and acceptor conjugated oligomers, in which furan and pyrrole are used as donors, and their periodic polymers were investigated using density functional theory at the B3LYP/6-31G(d) level. The bond lengths, bond length alternation, bond critical point (BCP) properties, nucleus-independent chemical shift (NICS) and Wiberg bond index (WBI) were analyzed and correlated with conduction properties. The changes of bond length, BCP properties, NICS and WBI all show that the degree of conjugation increases with main chain extension. The changes of NICS also show that the conjugation is stronger in the central section than in the outer section. Hydrogen bonding interactions and nitrogen atom substitution in the acceptors play very important roles in the geometries, electronic structures and energy gaps. The theoretical results suggest that pyrrole-based polymers are good candidates for conducting materials, compared with furan-based polymers. With an increase of nitrogen atom substitution in the acceptors in these polymers, the intermolecular charge transfers along the polymeric axes are enhanced, and the bond length alternations and HOMO-LUMO energy gap for these polymers are decreased. The results suggest that the six polymers studied all have lower energy gaps (in the range 0.81-1.26 eV), which indicate that these proposed polymers are good candidates for n-doping conductive materials, especially poly(7-(furan-2-yl)furo[3,4-e][1,2,4]triazine) and poly(7-(1H-pyrrol-2-yl)furo[3,4-e][1,2,4]triazine). Copyright © 2011 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

The reaction mechanism of the palladium(II)-catalyzed addition of urea to dienes to form 1,2-diamine was studied using the B3LYP density functional theory (DFT) method. The results indicate that the first C&bond;N σ-bond formation is the rate-determining step, and that the covalent bonds are formed favorably by the terminal carbon atoms of dienes and nitrogen atom. The Pd(NCMe)-catalyst may significantly lower the energy barrier of the rate-determining step from the nonligand Pd(II)-catalyst counterpart. The results are in strong support of a recent experiment. Copyright © 2008 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Quantum chemical ab initio computations of the structures and properties of oxazaborolidine-alkoxyborane adduct with a B—N—B—O four-membered ring and succeeding reaction intermediates are carried out in the current work by means of the Hartree–Fock (HF) and the density functional methods. All the structures are optimized completely at the HF/6-31G(d) and Becke's three-parameter exchange functional and the gradient-corrected functional of Lee, Yang, and Paar (B3LYP)/6-31G(d) levels. As shown in the obtained results, the oxazaborolidine-alkoxyborane adduct with a B—N—B—O four-membered ring may be formed during the reduction of the carbonyl bond of the catalyst-borane-keto oxime ether adduct. The breakdown of the B—N—B—O four-membered ring results in the formation of the adduct with a B—N—B—O—C—C—N seven-membered ring and an oxime bond. The reduction of the oxime bond leads to the adduct with a chiral oxime carbon. The B(2)—NC—N bond in the B—N—B—O—C—C—N seven-membered ring of the adduct with a reduced oxime bond is weaker comparatively and thus may be more easily broken down. All the adducts have four stable structures. © 2003 Wiley Periodicals, Inc. Int J Quantum Chem 93: 294–306, 2003 [ABSTRACT FROM AUTHOR]

Organic bipolar electrodes can undergo both n‐type and p‐type reactions for energy storage due to numerous active sites, which can usually deliver a high theoretical specific capacity. Herein, a new bipolar polymer cathode material PQPZ is designed and synthesized. The electron‐donating phenazine group undergoes a two‐electron redox reaction which can store anions, the electron‐withdrawing phenanthraquinone can store sodium‐ions through a two‐electron redox reaction. Notably, as a bipolar cathode material for sodium‐ion batteries, PQPZ exhibits a reversible specific capacity of up to 270 mAh g−1 in the voltage range of 1.0–4.0 V (vs. Na+/Na) and achieves a high energy density of 696 Wh kg−1 in a half‐cell. A capacity retention rate of 90% is obtained after 300 cycles at a current density of 0.5C. More excitingly, even after being cycled for 10000 cycles at 10C, the PQPZ electrode shows an average decay rate as low as 0.0036% per cycle, manifesting a very stable cycling performance. In addition, PQPZ also shows excellent performances when tested at −10 °C, making it promising in practical applications. Considering the bipolar character of PQPZ, symmetric batteries are also successfully constructed, fulfilling the “ready‐to‐charge” property without a pre‐activation process. The results reveal the potential application of PQPZ in practical use. [ABSTRACT FROM AUTHOR]

A computational study with the M06/B3LYP density functional is carried out to explore the effects of additives C5H5NO vs. PhNO on the gold‐catalyzed dehydrogenative heterocyclization of 2‐(1‐alkynyl)‐2‐alken‐1‐ones to form 2,3‐furan‐fused carbocycles. The following three conclusions are obtained based on our theoretical calculations. (a) The Au(I) catalyst plays a crucial role on the intramolecular cyclization reaction. (b) Both additives C5H5NO and PhNO as the proton shuttle can assist proton‐transfer through a two‐step proton‐transfer mechanism including the protonation of additive and the deprotonation of additive‐H+, whereas the catalytic capability of PhNO is weaker than that of C5H5NO (energy barrier: 90.6 vs. 33.2 kJ/mol). (c) C5H5NO‐H+ has stronger stability comparing with PhNO‐H+ because the basicity of C5H5NO is stronger than that of PhNO, which cause that the energy barrier of ts3 + PhNO‐H+ (131.5 kJ/mol) is higher than that of ts3 + C5H5NO‐H+ (60.5 kJ/mol) in the intermolecular addition. Therefore, the base strength is the primary factor that controls the catalytic capability of additives C5H5NO vs. PhNO. These studies are expected to improve our understanding of Au(I)‐catalyzed reactions involving additive as the cocatalyst and to provide guidance for the future design of new catalysts and new reactions. [ABSTRACT FROM AUTHOR]

The direct utilization of biomass waste to design catalysts with high stability and excellent electrochemical activity is still the key challenge in the development of fuel cells. Herein, the structural modification of precursors obtained by the carbonization of walnut shells is carried out and several highly N‐doped carbon catalysts with porous structures and excellent graphitization degrees are achieved. These catalysts have a high content of pyridinic‐N species and high specific surface area. Herein, it is shown that one of these catalysts, WS350Z900@Fe, has a higher stability than the Pt/C catalyst and excellent oxygen reduction reaction (ORR) performance with an onset potential of 0.98 V and a half‐wave potential of 0.86 V through a four‐electron reaction mechanism. Furthermore, density functional theory calculation indicates that the rate‐determining step of the ORR of these catalysts is the protonation of *O2. Also, the pyridinic‐N structure is conductive to reduce the reaction barrier. Herein, a significant means for designing inexpensive and high‐efficient ORR catalysts utilizing biowaste materials is offered. [ABSTRACT FROM AUTHOR]