Supramolecular Crystal Engineering at the Solid–Liquid Interface from First Principles: Toward Unraveling the Thermodynamics of 2D Self‐Assembly

The formation of highly ordered 2D supramolecular architectures self‐assembled at the solid–solution interfaces is subject to complex interactions between the analytes, the solvent, and the substrate. These forces have to be mastered in order to regard self‐assembly as an effective bottom‐up approach for functional‐device engineering. At such interfaces, prediction of the thermodynamics governing the formation of spatially ordered 2D arrangements is far from being fully understood, even for the physisorption of a single molecular component on the basal plane of a flat surface. Two recent contributions on controlled polymorphism and nanopattern formation render it possible to gain semi‐quantitative insight into the thermodynamics of physisorption at interfaces, paving the way towards 2D supramolecular crystal engineering. Although in these two works different systems have been chosen to tackle such a complex task, authors showed that the chemical design of molecular building blocks is not the only requirement to fulfill when trying to preprogram self‐assembled patterns at the solid–liquid interface.     

A Surface‐Functionalized Ionovoltaic Device for Probing Ion‐Specific Adsorption at the Solid–Liquid Interface

Aqueous ion–solid interfacial interactions at an electric double layer (EDL) are studied in various research fields. However, details of the interactions at the EDL are still not fully understood due to complexity induced from the specific conditions of the solid and liquid parts. Several technical tools for ion–solid interfacial probing are experimentally and practically proposed, but they still show limitations in applicability due to the complicated measurements. Recently, an energy conversion device based on ion dynamics (called ionovoltaic device) was also introduced as another monitoring tool for the EDL, showing applicability as a novel probing method for interfacial interactions. Herein, a monitoring technique for specific ion adsorption (Cu²⁺ and Pb²⁺ in the range of 5 × 10^?6–1000 × 10^?6m ) in the solid–liquid interface based on the ionovoltaic device is newly demonstrated. The specific ion adsorption and the corresponding interfacial potentials profiles are also investigated to elucidate a working mechanism of the device. The results give the insight of molecular‐level ion adsorption through macroscopic water‐motion‐induced electricity generation. The simple and cost‐effective detection of the device provides an innovative route for monitoring specific adsorption and expandability as a monitoring tool for various solid–liquid interfacial phenomena that are unrevealed.     

Mechanically Reinforced Localized Structure Design to Stabilize Solid–Electrolyte Interface of the Composited Electrode of Si Nanoparticles and TiO2 Nanotubes

Silicon anode with extremely high theoretical specific capacity (≈4200 mAh g^?1), experiences huge volume changes during Li‐ion insertion and extraction, causing mechanical fracture of Si particles and the growth of a solid–electrolyte interface (SEI), which results in a rapid capacity fading of Si electrodes. Herein, a mechanically reinforced localized structure is designed for carbon‐coated Si nanoparticles (C@Si) via elongated TiO₂ nanotubes networks toward stabilizing Si electrode via alleviating mechanical strain and stabilizing the SEI layer. Benefited from the rational localized structure design, the carbon‐coated Si nanoparticles/TiO₂ nanotubes composited electrode (C@Si/TiNT) exhibits an ideal electrode thickness swelling, which is lower than 1% after the first cycle and increases to about 6.6% even after 1600 cycles. While for traditional C@Si/carbon nanotube composited electrode, the initial swelling ratio is about 16.7% and reaches ≈190% after 1600 cycles. As a result, the C@Si/TiNT electrode exhibits an outstanding capacity of 1510 mAh g^?1 at 0.1 A g^?1 with high rate capability and long‐time cycling performance with 95% capacity retention after 1600 cycles. The rational design on mechanically reinforced localized structure for silicon electrode will provide a versatile platform to solve the current bottlenecks for other alloyed‐type electrode materials with large volume expansion toward practical applications.     

Layer-by-layer formation of block-copolymer-derived TiO(2) for solid-state dye-sensitized solar cells

Morphology control on the 10 nm length scale in mesoporous TiO(2) films is crucial for the manufacture of high-performance dye-sensitized solar cells. While the combination of block-copolymer self-assembly with sol-gel chemistry yields good results for very thin films, the shrinkage during the film manufacture typically prevents the build-up of sufficiently thick layers to enable optimum solar cell operation. Here, a study on the temporal evolution of block-copolymer-directed mesoporous TiO(2) films during annealing and calcination is presented. The in-situ investigation of the shrinkage process enables the establishment of a simple and fast protocol for the fabrication of thicker films. When used as photoanodes in solid-state dye-sensitized solar cells, the mesoporous networks exhibit significantly enhanced transport and collection rates compared to the state-of-the-art nanoparticle-based devices. As a consequence of the increased film thickness, power conversion efficiencies above 4% are reached.     

用纤维TiO2作光催化剂降解饮用水中腐殖质

用纤维状ＴｉＯ２作为光催化剂，采用间歇和连续两种操作方式，在Ｏ３／ＴｉＯ２／ＵＶ体系中处理含腐殖质的饮用水，使腐殖质去除率在９７％，纤维ＴｉＯ２可过滤回收，易于实际应用。     

A TiO2‐Binding Protein isolated from Rhodococcus Strain GIN‐1 (NCIMB 40340) – Purification,Properties and Potential Applications

A Rhodocuccus strain (Rh. GIN1, NCIMB 40340), which is capable of adsorption to titanium dioxide (TiO₂) and TiO₂‐containing coal fly ash particles, has been isolated previously in our Lab. Selectivity experiments showed that the bacterium is capable of adsorption to other metal oxides as well (e.g. magnetite and Al₂O₃) but at lower affinities. The bacterium binds tightly both to rutile and anatase TiO₂. In electronmicrograms the formation of “bridge‐like” structures between the bacterium and the oxide is observed. A specific protein fraction, located on the cell wall of the bacterium was isolated from the bacterium. This protein was found to adhere strongly to TiO₂ particles at high salt concentrations, similarly to the binding to TiO₂ of the intact bacteria. TiO₂ (rutile) was found to bind the protein faster, stronger and at a higher capacity than the anatase isoform. The 55 kDa Ti‐Binding Protein (TiBP) was isolated from the bacteria after homogenization by French Press. It was purified by affinity chromatography on TiO₂ particles, hydrophobic chromatography on a Fractogel‐propyl column and gel filtration on a Superdex G‐200 column. The same protein was isolated from the bacteria by treatment with mutanolysin, an enzyme which is commonly used to retrieve cell‐wall proteins from Gram‐positive bacteria, demonstrating the outer cell location of the protein in Rh. GIN1. TiBP exhibits metal oxide binding selectivity similar to that of the intact bacterium, namely TiO₂>ZnO>Al₂O₃ >Fe₂O₃(magnetite). Hydrophobic forces seem to dominate the interactions of the protein with TiO₂ as its binding capability is greatly enhanced in the presence of high concentrations of NaCl and its desorption requires high concentrations of urea and SDS. These features differentiate TiBP from other proteins known to adsorb TiO₂ (such as hemoglobin, cytochrome c and bovine serum albumin), mainly by weak, charge‐based interactions.     

Dendritic TiO2/ln2S3/AgInS2 Trilaminar Core–Shell Branched Nanoarrays and the Enhanced Activity for Photoelectrochemical Water Splitting

Hierarchical TiO₂/ln₂S₃/AgInS₂ trilaminar core–shell branched nanorod arrays (T‐CS BNRs) have been fabricated directly on conducting glass substrates (FTO) via a facile, versatile and low‐cost hydrothermal and successive ionic layer adsorption and reaction (SILAR) for photoelectrochemical (PEC) water splitting. On the basis of optimal thickness of AgInS₂ shell, such TiO₂/ln₂S₃/AgInS₂ T‐CS BNRs exhibit a higher photocatalytic activity, the photocurrent density and efficiency for hydrogen generation are up to 22.13 mA·cm^?2 and 14.83%, which is, to the best of our knowledge, the highest value ever reported for similar nanostructures. The trilaminar architecture is able to suppress carrier recombination and increase electron collection efficiency via (i) increasing the photon absorption through the lager specific surface area of TiO₂ BNRs and a sensitizer layer (AgInS₂), (ii) a buffer layer (ln₂S₃), (iii) a better energy level alignment.     

Sb‐Doped SnO2 Nanorods Underlayer Effect to the α‐Fe2O3 Nanorods Sheathed with TiO2 for Enhanced Photoelectrochemical Water Splitting

Here, a Sb‐doped SnO₂ (ATO) nanorod underneath an α‐Fe₂O₃ nanorod sheathed with TiO₂ for photoelectrochemical (PEC) water splitting is reported. The experimental results, corroborated with theoretical analysis, demonstrate that the ATO nanorod underlayer effect on the α‐Fe₂O₃ nanorod sheathed with TiO₂ enhances the PEC water splitting performance. The growth of the well‐defined ATO nanorods is reported as a conductive underlayer to improve α‐Fe₂O₃ PEC water oxidation performance. The α‐Fe₂O₃ nanorods grown on the ATO nanorods exhibit improved performance for PEC water oxidation compared to α‐Fe₂O₃ grown on flat fluorine‐doped tin oxide glass. Furthermore, a simple and facile TiCl₄ chemical treatment further introduces TiO₂ passivation layer formation on the α‐Fe₂O₃ to reduce surface recombination. As a result, these unique nanostructures show dramatically improved photocurrent density (139% higher than that of the pure hematite nanorods).     

TiO2 and Co Nanoparticle‐Decorated Carbon Polyhedra as Efficient Sulfur Host for High‐Performance Lithium–Sulfur Batteries

Metal organic frameworks (MOFs)‐derived porous carbon is proposed as a promising candidate to develop novel, tailorable structures as polysulfides immobilizers for lithium–sulfur batteries because of their high‐efficiency electron conductive networks, open ion channels, and abundant central ions that can store a large amount of sulfur and trap the easily soluble polysulfides. However, most central ions in MOFs‐derived carbon framework are encapsulated in the carbon matrix so that their exposures as active sites to adsorb polysulfides are limited. To resolve this issue, highly dispersed TiO₂ nanoparticles are anchored into the cobalt‐containing carbon polyhedras that are converted from ZIF‐67. Such a type of TiO₂ and Co nanoparticles‐decorated carbon polyhedras (C? Co/TiO₂) provide more exposed active sites and much stronger chemical trapping for polysulfides, hence improving the sulfur utilization and enhancing reaction kinetics of sulfur‐containing cathode simultaneously. The sulfur‐containing carbon polyhedras decorated with TiO₂ nanoparticles (S@C? Co/TiO₂) show a significantly improved cycling stability and rate capability, and deliver a discharge capacity of 32.9% higher than that of TiO₂‐free S@C? Co cathode at 837.5 mA g^?1 after 200 cycles.     

Extension of the Stöber Method to Construct Mesoporous SiO2 and TiO2 Shells for Uniform Multifunctional Core–Shell Structures

Core–shell nanoparticles (CSNs) have attracted considerable attention because of their promising applications in a wide range of fields. Recently, substantial efforts have been focused on the development of facile and versatile methods for preparing CSNs with mesoporous SiO₂ or TiO₂ shells because of their fascinating properties, such as high surface area, large pore channels and high pore volume. This Research News reviews the recent progress in facile, versatile and reproducible approaches which are simply extended from the well‐known Stöber method to construct mesoporous SiO₂ and TiO₂ shells for uniform multifunctional core–shell nanostructures. Several strategies, including the surfactant‐templating process, the long‐chain organosilane‐assisted approach, the phase transfer assisted surfactant‐templating process, and the kinetics‐controlled coating approach, are discussed. In addition, new trends in this field for the creation of multifunctional CSNs and novel nanostructures are highlighted.     

Suppressed Jahn–Teller Distortion in MnCo2O4@Ni2P Heterostructures to Promote the Overall Water Splitting

Jahn–Teller distortion in cobalt based spinel electrocatalysts causes poor activity and stability in potentially promising catalysts for water splitting. Here, a novel strategy to resolve this problem by interface engineering is reported, in which, Jahn–Teller distortion in MnCo₂O₄ is significantly suppressed by in situ growth Ni₂P nanosheets onto the MnCo₂O₄. The significance of interface engineering in suppressing Jahn–Teller distortion of Mn³⁺ is further investigated by X‐ray photoelectron spectroscopy, the resulting increased catalytic activity and the effects of suppressed distortion demonstrated by density functional theory calculations. The resulting MnCo₂O₄@Ni₂P heterostructures exhibit superior electrocatalytic activity for the both oxygen evolution reaction and hydrogen evolution reaction with small overpotentials of 240 and 57 mV at 10 mA cm^‐2, respectively. Furthermore, the heterogeneous composite electrode demonstrates a superior current density of 10 mA cm^‐2 at a voltage of 1.63 V with excellent durability in a water splitting cell.