wileyonlinelibrary.comreliability of the lithium titanate render this material one of the most suitable anode materials for the EV application. However, the rate performance of lithium titanate is seriously limited by its low electronic and ionic conductivities. Such poor charge transport characteristic of Li 4 Ti 5 O 12 basically results from its wide bandgap energy related to the empty 3d states of Ti 4+ ions. [ 3f,k ] Various attempts such as cationic and anionic doping, and the hybridization and surface coating with conductive carbon are made to circumvent this drawback of lithium titanate. [ 3 ] Although these strategies are somewhat successful in improving the electrode activity of metal oxide, they might cause other several side effects such as the lowering of thermal stability. In general, the metal sulfi de possesses smaller bandgap energy and higher electrical conductivity than does the corresponding metal oxide, since (metal− sulfur) bond is more covalent than (metal−oxygen) bond. [ 4 ] The composite formation with conductive metal sulfi de can provide new effi cient way to improve the electrode performance of semiconducting metal oxide through the increase of electrical conductivity. However, the formation of metal sulfi de domain in the pristine metal oxide domain cannot be achieved by the use of conventional sulfurization agent such as thiourea, ammonium sulfi de, sodium sulfi de, and elemental sulfur due to their limited diffusivity into the solid lattice. Instead of the formation of metal sulfi de domain, this process leads to the formation of sulfate (SO 4 2− ) species on the surface of metal oxide. [ 5 ] The effective formation of metal sulfi de grains in the solid lattice might be achieved by the use of gaseous agents such as H 2 S. However, the high toxicity of hydrogen sulfi de might cause serious safety problems. [ 6 ] Instead, less toxic CS 2 liquid with Ar carrier gas can be used as a sulfurization agent to provide a safe and scalable synthetic method for metal oxide−metal sulfi de nanocomposites. To the best of our knowledge, there is no report about the in situ incorporation of conductive metal sulfi de domain to improve the electrochemical activity of semiconducting metal oxides.In the present study, a novel effective way to improve the electrode activity of semiconducting metal oxide is developed on the basis of the in situ formation of conductive metal sulfi de (Li x-Ti y S 2 ) domain in the metal oxide (Li 4 Ti 5 O 12 ) matrix using the CS 2 liquid. The experimental setup for this experiment is illustrated A new effective way to improve the electrochemical activity of semiconducting metal oxide is developed by the in situ formation of conductive metal sulfi de domain in the metal oxide matrix. The Li 0.96 Ti 1.08 S 2 −Li 4 Ti 5 O 12 nanocomposites with tunable compositions and electrical properties are synthesized by the reaction of Li 4 Ti 5 O 12 with CS 2 at elevated temperature. The resulting incorporation of conductive Li 0.96 Ti 1.08 S 2 domain in the Li 4 Ti 5 O 12 matrix is...

An effective methodology to stabilize highly dispersed metal nanoparticles is developed by employing the exfoliated 2D metal oxide nanosheets with variable surface structures as substrates. The selection of appropriate crystal structure of titanate nanosheet is very crucial in stabilizing atomically dispersed Pt nanoparticles through the tuning of chemical interaction between Pt and titanate substrate. A theoretical study using density functional theory calculations confirms the significant influence of the crystal structure of layered titanate nanosheet on the crystal growth behavior of immobilized metal nanoparticle. As a consequence of the good dispersion of Pt nanoparticles, the Pt–trititanate nanohybrids with stronger interaction show much higher content of atomically dispersed Pt and better catalyst performances than do the Pt–lepidocrocite titanate ones. The applicability of the present method for other metal species is evidenced by the successful tuning of the crystal size and functionality of Au nanoparticles via immobilization on layered titanate nanosheets. The functionality of Au for surface‐enhanced Raman spectroscopy becomes improved by the anchoring on the lepidocrocite‐type titanate nanosheet. The present study underscores that the use of the metal oxide 2D nanosheets with appropriate surface structure as substrates is effective in tailoring the crystal growth and the functionalities of immobilized metal nanoparticles.

Pseudo-first-order rate constants (kobsd) have been measured for reactions of phenyl Y-substituted-phenyl carbonates with alkali metal ethoxides (EtOM, M = Li, Na, and K). The plot of kobsd vs. [EtOM] curves upward for the reaction of diphenyl carbonate with EtOM but is linear for that with EtOK in the presence of 18-crown-6-ether (18C6), indicating that the reaction is catalyzed by M+ ions and the catalytic effect disappears in the presence of 18C6. The kobsd values for the reactions with EtOK have been dissected into kEtO and kEtOK, i.e., the second-order rate constants for the reactions with dissociated EtO− and ion-paired EtOK, respectively. The Hammett plots correlated with σ− and σ constants exhibit highly scattered points, while the Yukawa–Tsuno plots result in an excellent linear correlation with ρ = 2.11 and r = 0.21 for kEtO -, and ρ = 1.62 and r = 0.26 for kEtOK, implying that the reaction proceeds through a concerted mechanism. The catalytic effect (i.e., the kEtOK/kEtO - ratio) is independent of the electronic nature of the substituent Y. Thus, it has been concluded that K+ ion catalyzes the reaction by increasing the electrophilicity of the reaction center.

On page 4948, I. Y. Kim and co‐workers demonstrate that the in situ formation of metal sulfides using CS2 is effective in synthesizing novel nanocomposites consisting of Li0.96Ti1.08S2 domains embedded in Li4Ti5O12. The metallization of the semiconducting oxide in the composite formation is very efficient for exploring promising composite electrode materials with good rate characteristics.