Blue Long Afterglow and Ultra Broadband Vis-NIR Emission from All-Inorganic Copper-Doped Silver Halide Single Crystals.

All-inorganic metal halides with afterglow emission have attracted increasing attention due to their significantly longer afterglow duration and higher stability compared to their organic-inorganic hybrid counterparts. However, their afterglow colors have not yet reached the blue spectral region. Here, we report all-inorganic copper-doped Rb2AgBr3 single crystals with ultralong blue afterglow (>300 s) by modulating defect states through doping engineering. The introduction of copper(I) ions into Rb2AgBr3 facilitates the formation of bromine vacancies, thus increasing the density of trap states available for charge storage and enabling bright, persistent emission after ceasing the excitation. Moreover, cascade energy transfer between distinct emissive centers in the crystals results in ultra-broadband photoluminescence, not only covering the whole white light with near-unity quantum yield but also extending into the near-infrared region. This 'cocktail' of exotic light-emission properties, in conjunction with the excellent stability of copper-doped Rb2AgBr3 crystals, allowed us to demonstrate their implementation to solid-state lighting, night vision, and intelligent anti-counterfeiting.

Photocatalytic 2-Iodoethanol Coupling to Produce 1,4-Butanediol Mediated by TiO2 and a Catalytic Nickel Complex.

Photocatalytic 2-iodoethanol (IEO) coupling provides 1,4-butanediol (BDO) of particular interest to produce degradable polyesters. However, the reduction potential of IEO is too negative (-1.9 vs NHE) to be satisfied by most of the semiconductors, and the kinetics of transferring one electron for IEO coupling is slow. Here we design a catalytic Ni complex, which works synergistically with TiO2 , realizing reductive coupling of IEO powered by photo-energy. Coordinating by terpyridine stabilizes Ni2+ from being photo-deposited to TiO2 , thereby retaining the steric configuration beneficial for IEO coupling. The Ni complex can rapidly extract electrons from TiO2 , generating a low-valent Ni capable of reducing IEO. The photocatalytic IEO coupling thus provides BDO in 72 % selectivity. By a stepwise procedure, BDO is obtained with 70 % selectivity from ethylene glycol. This work put forward a strategy for the photocatalytic reduction of molecules requiring strong negative potential.

Modulating Oxygen Vacancies in Lead Chromate for Photoelectrocatalytic Water Splitting.

Although modulating oxygen vacancies in semiconductors has attracted broad interest in photocatalysis and photoelectrocatalysis, identifying the intrinsic roles of oxygen vacancies on photoelectrocatalytic properties is often elusive. In this work, the oxygen vacancies in a typical semiconductor lead chromate (PbCrO4 ) are regulated via controlling the oxygen chemical potentials of O-poor and O-rich post-annealing atmospheres. Oxygen vacancies identified in PbCrO4 can introduce electronically shallow energy levels and deep energy levels owing to the symmetry difference of oxygen atoms in the structure. A higher population of deep energy levels created under O-poor atmosphere induces the formation of more surface trapped states, resulting in a higher photovoltage for charge separation. Meanwhile, the existence of surface trapped states can significantly improve the charge injection efficiency of the PbCrO4 photoanode and enhance the water oxidation activity. By modulating oxygen vacancies in the PbCrO4 photoanode, a photocurrent density of 3.43 mA cm-2 at 1.23 V vs reversible hydrogen electrode (RHE) under simulated AM1.5G is acheived. Further passivation of surface trapped states and introducing the water oxidation cocatalyst CoPi lead to a record applied bias photon-to-current efficiency (ABPE) of 1.12%. This work provides a guide to understand the mechanism of oxygen vacancies in oxide-based semiconductor photocatalysis and photoelectrocatalysis.

Deciphering the effects of electrolyte concentration on the performance of lithium batteries by correlative surface characterization.

The formation of solid electrolyte interphase (SEI) and lithium ion intercalation are two crucial processes in lithium ion batteries. Given the complexity and challenges involved in investigating real batteries, a combination of model batteries comprising well-defined ultrathin graphite electrodes with surface-sensitive techniques can provide valuable information on these processes. Here, a comparative study of the performance of batteries using regular- and high-concentration electrolytes (RCE and HCE) is presented, aided by a myriad of correlative surface science techniques. It is found that the SEI formed in HCE possesses a thinner organic layer and more inorganic substances. Such an effective SEI protects the graphite electrode and facilitates the processes of Li+ intercalation/deintercalation, thereby improving the reversibility and cycling stability of the battery, superior to those with RCE. Moreover, the battery performance can be readily tuned by switching the electrolytes. The good cycling stability of the battery can still be maintained in RCE after the preformation of a robust SEI on the ultrathin graphite electrode in HCE. This work highlights the importance of electrolyte-modulated SEI formation to battery performance and provides powerful platforms to comprehensively study the SEI formation and ion intercalation processes.

Identification of the cell wall proteins associated with the softening of Lycium barbarum L. fruit by using iTRAQ technology.

Excessive softening of Lycium barbarum L. (LBL) fruit can limit the storage and transportation of fresh fruit. To better understand the underlying molecular mechanisms of fruit softening in LBL, changes in the pre-climacteric (S1) and post-climacteric (S2) proteomes were investigated by iTRAQ methods. The 14-fold reduction in S2 fruit firmness compared to S1 was accompanied by increased espiratory intensity and degradation of cell wall components. A total of 258 differentially expressed proteins (DEPs) were identified, which were mainly associated with photosynthesis, carbohydrate, amino acids and fatty acids metabolism. From the functional proteomic analysis, enhanced energy metabolisms, such as glycolysis/gluconeogenesis and citrate cycle (TCA cycle) contributed to cell wall degradation and conversion to substrates for respiratory metabolism, leading to fruit softening. These findings have provided new insights into the molecular pathways associated with fruit softening in LBL and the bioinformatics analyses provided insightful information for further transcriptional studies.

In Situ Visualization of Atmosphere-Dependent Relaxation and Failure in Energy Storage Electrodes.

Ambient atmosphere is critical for the surface/interface chemistry of electrodes that governs the operation and failure in energy storage devices (ESDs). Here, taking an Al/graphite battery as an example, both the relaxation and failure processes in the working graphite electrodes have been dynamically monitored by multiple in situ surface and interface characterization methods within various well-controlled atmospheres. Relaxation effects are manifested by recoverable stage-structure change and electronic relaxation occurring in anhydrous inert atmospheres and O2, which are induced by the anion/cation redistribution within the neighboring graphene layers and have slight influence on the long-term cycling. In contrast, rapid and unrecoverable failure behaviors happen in hydrous atmospheres as shown by the stage-structure degradation and electronic decoupling between guest ions and host graphite, which are caused by the hydrolysis between newly intercalated H2O molecules and intercalants. Consistent with the characterization results, exposure to H2O can cause nearly 100% capacity loss. The methodology and concept adopted in this work to unravel the battery mechanism under ambient conditions are universal and significant to investigate many ESDs.

Structural transformation of h-BN overlayers on Pt(111) in oxidative atmospheres.

Interaction of hexagonal boron nitride (h-BN) with gases is of great importance for its properties and applications. In the present work, the structural changes of h-BN overlayers on Pt(111) in oxidative atmospheres including O2 and NO2 have been investigated by using low energy electron microscopy, Auger electron spectroscopy, X-ray photoelectron spectroscopy (XPS), and near ambient pressure XPS. We find that h-BN islands can be intercalated by oxygen in 10-6 Torr O2 at 200 °C, while oxygen intercalation of full layer h-BN around 200 °C requires near ambient pressure O2 (0.1 Torr) or such a strong oxidant as NO2 (10-6 Torr). h-BN overlayers can be etched away in the gases at much high temperatures, e.g. 800 °C. Upon mild oxidation in O2 or NO2 at temperatures of 400-450 °C, h-BN is transformed to boron oxide (BOx) overlayers, which can be converted back to h-BN by heating in NH3 at 800 °C.

Wrinkle-Free Single-Crystal Graphene Wafer Grown on Strain-Engineered Substrates.

Wrinkles are ubiquitous for graphene films grown on various substrates by chemical vapor deposition at high temperature due to the strain induced by thermal mismatch between the graphene and substrates, which greatly degrades the extraordinary properties of graphene. Here we show that the wrinkle formation of graphene grown on Cu substrates is strongly dependent on the crystallographic orientations. Wrinkle-free single-crystal graphene was grown on a wafer-scale twin-boundary-free single-crystal Cu(111) thin film fabricated on sapphire substrate through strain engineering. The wrinkle-free feature of graphene originated from the relatively small thermal expansion of the Cu(111) thin film substrate and the relatively strong interfacial coupling between Cu(111) and graphene, based on the strain analyses as well as molecular dynamics simulations. Moreover, we demonstrated the transfer of an ultraflat graphene film onto target substrates from the reusable single-crystal Cu(111)/sapphire growth substrate. The wrinkle-free graphene shows enhanced electrical mobility compared to graphene with wrinkles.

Unique Transformation from Graphene to Carbide on Re(0001) Induced by Strong Carbon-Metal Interaction.

During graphene growth on various transition metals in the periodic table, metal carbides always emerge to behave as complex intermediates. On VIII metals, metastable carbides usually evolve and then transform into graphene along the phase interfaces, and even no metal carbides can form on IB-IIB metals. In contrast, during graphene growth on group IVB-VIB metals, carbides are usually generated even before the evolution of graphene and stably exist throughout the whole growth process. However, for the remaining transition metals, e.g., group VIIB, located in between IVB-VIB and VIII, the interplay between graphene and carbide is still vague. Herein, on Re(0001) (VIIB), we have revealed a novel transition from graphene to metal carbide (reverse to that on VIII metals) for the first time. This transition experienced graphene decomposition, dissolution, and carbon segregation processes, as evidenced by scanning tunneling microscopy (STM) and on-site, variable-temperature low electron energy diffraction (LEED) characterizations. This work thus completes the picture about the interplay between graphene and carbide on/in transition metals in the periodic table, as well as discloses a new territory for the growth of carbon-related materials, especially the metal carbide.

3-Carboxy-pyrazino[2,3-f][1,10]phenanthrolin-9-ium-2-carboxyl-ate.

In the title zwitterionic compound, C(16)H(8)N(4)O(4), the dihedral angle between the carboxyl and carboxyl-ate groups is 72.14 (2)°. In the crystal, mol-ecules are linked by strong inter-molecular O-H⋯O(-) and N(+)-H⋯O(-) hydrogen bonds into double chains extended along [001]. These chains are additionally stabilized by π-π stacking inter-actions between the pyridine and benzene rings [centroid-centroid distance = 3.5542 (8) Å].

Aqua-(2,2'-bipyridine-κN,N')[2-(3-thien-yl)malonato-κO,O']zinc(II) dihydrate.

In the crystal structure of the title compound, [Zn(C(7)H(4)O(4)S)(C(10)H(8)N(2))(H(2)O)]·2H(2)O, the Zn(II) ion assumes a trigonal-bipyramidal coordination geometry completed by two N atoms from a 2,2'-bipyridine ligand, two O atoms from a 2-(3-thien-yl)malonate anion and a water mol-ecule. The S atom of the 2-(3-thien-yl)malonate ligand is disordered over two sites with an occupancy ratio of 0.701 (5):0.299 (5). Inter-molecular O-H⋯O hydrogen bonding is present in the crystal structure.