Pristine GaFeO3 Photoanodes with Surface Charge Transfer Efficiency of Almost Unity at 1.23 V for Photoelectrochemical Water Splitting.

Oxide-based photoelectrodes commonly generate deep trap states associated with various intrinsic defects such as vacancies, antisites, and dislocations, limiting their photoelectrochemical properties. Herein, it is reported that rhombohedral GaFeO3 (GFO) thin-film photoanodes exhibit defect-inactive features, which manifest themselves by negligible trap-states-associated charge recombination losses during photoelectrochemical water splitting. Unlike conventional defect-tolerant semiconductors, the origin of the defect-inactivity in GFO is the strongly preferred antisite formation, suppressing the generation of other defects that act as deep traps. In addition, defect-inactive GFO films possess really appropriate oxygen vacancy concentration for the oxygen evolution reaction (OER). As a result, the as-prepared GFO films achieve the surface charge transfer efficiency (ηsurface ) of 95.1% for photoelectrochemical water splitting at 1.23 V versus RHE without any further modification, which is the highest ηsurface reported of any pristine inorganic photoanodes. The onset potential toward the OER remarkably coincides with the flat band potential of 0.43 V versus RHE. This work not only demonstrates a new benchmark for the surface charge transfer yields of pristine metal oxides for solar water splitting but also enriches the arguments for defect tolerance and highlights the importance of rational tuning of oxygen vacancies.

Coupling effects of Zn single atom and high curvature supports for improved performance of CO2 reduction.

Single-atom catalysts (SACs) have emerged as one of the most competitive catalysts toward a variety of important electrochemical reactions, thanks to their maximum atom economy, unique electronic and geometric structures. However, the role of SACs supports on the catalytic performance does not receive enough research attentions. Here, we report an efficient route for synthesis of single atom Zn loading on the N-doped carbon nano-onions (ZnN/CNO). ZnN/CNO catalysts show an excellent high selectivity for CO2 electro-reduction to CO with a Faradaic efficiency of CO (FECO) up to 97% at -0.47 V (vs. reversible hydrogen electrode, RHE) and remarkable durability without activity decay. To our knowledge, ZnN/CNO is the best activity for the Zn based catalysts up to now, and superior to single atom Zn loading on the two-dimensional planar and porous structure of graphene substrate, although the graphene with larger surface area. The exact role of such carbon nano-onions (CNO) support is studied systematically by coupling characterizations and electrochemistry with density functional theory (DFT) calculations, which have attributed such good performance to the increased curvature. Such increased curvature modifies the surface charge, which then changes the adsorption energies of key intermediates, and improves the selectivity for CO generation accordingly.

Visible light driven photo-reduction of Cu2+ to Cu2O to Cu in water for photocatalytic hydrogen production.

Metal nanoparticles are synthesized via various methods and have found many applications in areas such as sensing, electronics and catalysis. Light induced formation of noble metal nanoparticles, especially platinum, in solution or loaded on semiconductor surfaces, is an established practice in photocatalysis. Nevertheless, preparation of catalytically-active non-precious metal nanoparticles via photo-reduction still have room to be further explored. Here, we report a visible light driven system that can coordinate photo-reduction of CuSO4 to selectively prepare Cu2O or Cu nanoparticles, while at the same time, mediating efficient hydrogen production with in situ generating Cu catalyst without further need to add any components. The Cu2O and Cu nanoparticles in situ generated are crystalline in nature and can perform as pre-catalyst (Cu2O) or catalyst (Cu) to catalyze hydrogen production when reincorporated into the same photo-reduction system with organic photosensitizers. Our work offers an exploratory pathway to prepare target metal nanoparticles while provides some insight into harnessing solar energy for multi-functional purposes.

Heteroporous MoS2/Ni3S2 towards superior electrocatalytic overall urea splitting.

The heteroporous MoS2/Ni3S2 catalyst exhibits excellent electrocatalytic activity for the overall urea splitting with only a cell voltage of 1.45 V at 20 mA cm-2 in 1 M KOH with 0.33 M urea. This value is the best of all the bifunctional urea splitting electrocatalysts, including Pt, reported to date.

Cu(OH)2 supported on Fe(OH)3 as a synergistic and highly efficient system for the dehydrogenation of ammonia-borane.

Herein, we first describe the physical mixture of Cu(OH)2/Fe(OH)3 as a composite catalyst precursor for the dehydrogenation of ammonia borane (AB) in methanol. During the initial period of catalytic reaction, Cu nanoparticles were formed in-situ. The catalytic activity of Cu nanoparticles can be significantly enhanced with the assistance of Fe species and OH-. A maximum turnover frequency (TOF) of 50.3 molH2 moltotal metal-1 min-1 (135.6 molH2 molCu-1 min-1) was achieved at ambient temperature, which is superior to those of previously reported Fe or Cu based systems.

Preparation of Ce- and La-Doped Li4Ti5O12 Nanosheets and Their Electrochemical Performance in Li Half Cell and Li4Ti5O12/LiFePO4 Full Cell Batteries.

This work reports on the synthesis of rare earth-doped Li4Ti5O12 nanosheets with high electrochemical performance as anode material both in Li half and Li4Ti5O12/LiFePO4 full cell batteries. Through the combination of decreasing the particle size and doping by rare earth atoms (Ce and La), Ce and La doped Li4Ti5O12 nanosheets show the excellent electrochemical performance in terms of high specific capacity, good cycling stability and excellent rate performance in half cells. Notably, the Ce-doped Li4Ti5O12 shows good electrochemical performance as anode in a full cell which LiFePO4 was used as cathode. The superior electrochemical performance can be attributed to doping as well as the nanosized particle, which facilitates transportation of the lithium ion and electron transportation. This research shows that the rare earth doped Li4Ti5O12 nanosheets can be suitable as a high rate performance anode material in lithium-ion batteries.

Rapid synthesis of ultralong Fe(OH)3:Cu(OH)2 core-shell nanowires self-supported on copper foam as a highly efficient 3D electrode for water oxidation.

One-dimensional core-shell nanowire materials have recently received great attention as durable catalysts for water splitting. Herein we report the facile and rapid synthesis of ultralong Fe(OH)3:Cu(OH)2 core-shell nanowires grown in situ on an open 3D electrode to function as a highly efficient electrocatalyst for water oxidation. It only requires an overpotential of ∼365 mV to reach a 10 mA cm-2 current density in 1.0 M KOH. As far as we know, this shows the best result amongst Cu-based heterogeneous OER systems reported to date.

A ratiometric fluorescence RRE RNA-targeted assay for a new fluorescence ligand.

The Rev protein regulates HIV-1 gene expression. Small ligands that bind to the Rev response element (RRE) RNA would inhibit Rev function and suppress HIV-1 replication. A novel ratiometric fluorescence assay was applied in the present study to monitor ligand-RNA interactions by using red-emitting CdTe quantum dots (QDs) coated with silica as a reference. A small fluorescence ligand, ICR 191, was found to interact with RRE at the Rev binding site and compete with the Rev peptide. After adding red-emitting QDs to the interaction system, it was observed that ICR 191 did not fluoresce upon the addition of RRE, and fluorescence recovered when ICR 191 was displaced by a Rev model peptide, whereas the fluorescence of QDs remained constant. Furthermore, variations in the fluorescence ratios between ICR 191 and QDs were exploited to characterize the interactions of Rev with two known antagonists, neomycin B and tobramycin, by using RRE RNA with ICR 191 as a fluorescence indicator. Together, our results demonstrated that ratiometric fluorescence-based nanotechnology applications can be used for ligand-RNA interaction assays. This ICR 191-RRE RNA interaction assay can potentially be developed to build a screening model for assessing antagonists of the Rev binding element in RRE.

Selective detection of 2,4,6-trinitrophenol based on a fluorescent nanoscale bis(8-hydroxyquinoline) metal complex.

The reliable and accurate detection of explosives such as 2,4,6-trinitrophenol (TNP) and 2,4,6-trinitrotoluene (TNT) is in high demand for homeland security and public safety. Although extremely high sensitivity towards TNT has been demonstrated, detection of TNP remains a challenge. In this work, a fluorescent nanoscale complex composed of bis(8-hydroxyquinoline) and Al(3+) ions has been prepared, characterized and applied in detection of TNP. This complex exhibits the ability to sense the nitro explosive TNP via a fluorescence quenching mechanism with high selectivity. A simple paper test system for the rapid monitoring of TNP was also investigated. The results show that Bhq-Al is a quite ideal sensing material for trace-level detection of TNP.

Robustly photogenerating H2 in water using FeP/CdS catalyst under solar irradiation.

Photosplitting water for H2 production is a promising, sustainable approach for solar-to-chemical energy conversion. However, developing low-cost, high efficient and stable photocatalysts remains the major challenge. Here we report a composite photocatalyst consisting of FeP nanoparticles and CdS nanocrystals (FeP/CdS) for photogenerating H2 in aqueous lactic acid solution under visible light irradiation. Experimental results demonstrate that the photocatalyst is highly active with a H2-evolution rate of 202000 µmol h(-1) g(-1) for the first 5 h (106000 µmol h(-1) g(-1) under natural solar irradiation), which is the best H2 evolution activity, even 3-fold higher than the control in situ photo-deposited Pt/CdS system, and the corresponding to an apparent quantum efficiency of over 35% at 520 nm. More important, we found that the system exhibited excellent stability and remained effective after more than 100 h in optimal conditions under visible light irradiation. A wide-ranging analysis verified that FeP effectively separates the photoexcited charge from CdS and showed that the dual active sites in FeP enhance the activity of FeP/CdS photocatalysts.

A sensitive aptasensor for colorimetric detection of adenosine triphosphate based on the protective effect of ATP-aptamer complexes on unmodified gold nanoparticles.

Adenosine triphosphate (ATP) is the most direct source of energy in organisms. This study is the first to demonstrate that ATP-aptamer complexes provide greater protection for unmodified gold nanoparticles (AuNPs) against salt-induced aggregation than either aptamer or ATP alone. This protective effect was confirmed using transmission electron microscopy, dynamic light scattering, Zeta potential measurement, and fluorescence polarization techniques. Utilizing controlled particle aggregation/dispersion as a gauge, a sensitive and selective aptasensor for colorimetric detection of ATP was developed using ATP-binding aptamers as the identification element and unmodified AuNPs as the probe. This aptasensor exhibited a good linear relationship between the absorbance and the logarithm concentration of ATP within a 50-1000 nM range. ATP analogs such as guanosine triphosphate, uridine triphosphate and cytidine triphosphate resulted in little or no interference in the determination of ATP.

Spectacular photocatalytic hydrogen evolution using metal-phosphide/CdS hybrid catalysts under sunlight irradiation.

A highly efficient and robust heterogeneous photocatalytic hydrogen evolution system was established for the first time by using the CoP/CdS hybrid catalyst in water under solar irradiation. The H2-production rate can reach up to 254,000 µmol h(-1) g(-1) during 4.5 h of sunlight irradiation, which is one of the highest values ever reported on CdS photocatalytic systems in the literature.

Electrochemical water oxidation by in situ-generated copper oxide film from [Cu(TEOA)(H2O)2][SO4] complex.

Although many noble-metal oxide catalysts show high activities and low overpotentials for water oxidation, there remain challenges in the sustainable developments of more inexpensive, efficient, and robust catalysts. Here, we report a heterogeneous copper oxide film toward water oxidation formed upon the oxidative polarization of an acetate electrolyte containing Earth-abundant Cu(II) salts in combination with commercially available triethanolamine (TEOA) as the catalyst precursor. A 1:1 molar ratio of TEOA coordinates to Cu(II) is favored in aqueous solution and the single crystal of the complex was obtained. The film has a modest overpotential of 550 mV and the catalytic performance of the material is demonstrated by long-term electrolysis at 1.3 V vs normal hydrogen electrode, a stable current density persists for at least 3 h, and a Faradaic efficiency of almost 100% is obtained.

Efficient water oxidation catalyzed by mononuclear ruthenium(II) complexes incorporating Schiff base ligands.

Four new charge-neutral ruthenium(II) complexes containing dianionic Schiff base and isoquinoline or 4-picoline ligands were synthesized and characterized by NMR and ESI-MS spectroscopies, elemental analysis, and X-ray diffraction. The complexes exhibited excellent chemical water oxidation activity and high stability under acidic conditions (pH 1.0) using (NH4)2Ce(NO3)6 as a sacrificial electron acceptor. The high catalytic activities of these complexes for water oxidation were sustained for more than 10 h at low concentrations. High turnover numbers of up to 3200 were achieved. A water nucleophilic attack mechanism was proposed. A Ru(V)=O intermediate was detected during the catalytic cycle by high-resolution mass spectrometry.

Aggregation-induced photoluminescent changes of naphthyridine-BF2 complexes.

Luminous boron: new 1,8-naphthyridine-BF(2) complexes with strong emissions both in solution and in the solid state have been developed. Aggregation-induced blueshifts of emissions in DMSO/water mixtures and solvent-influenced luminescence in crystalline states have been observed and are discussed.

Large Stokes shift induced by intramolcular charge transfer in N,O-chelated naphthyridine-BF2 complexes.

Novel N,O-chelated naphthyridine-BF(2) complexes with push-pull structures have been synthesized and characterized. Spectral investigations on these complexes reveal that photoinduced intramolecular charge transfer occurs and results in a large Stokes shift, which is further supported by density functional theory based theoretical calculations.

Photophysical and electrochemical properties of platinum(II) complexes bearing a chromophore-acceptor dyad and their photocatalytic hydrogen evolution.

A series of platinum(II) complexes bearing a chromophore-acceptor dyad obtained by reacting 4-(p-bromomethylphenyl)-6-phenyl-2,2'-bipyridine or 4'-(p-bromomethylphenyl)-2,2':6',2''-terpyridine with pyridine, 4-phenylpyridine, 4,4'-bipyridine, 1-methyl-4-(pyridin-4'-yl)pyridinium hexafluorophosphate respectively, were synthesized. Their photophysical properties, emission quenching studies by Pt nanoparticles and methyl viologen, electrochemical properties and photoinduced electron-transfer reactions in a photocatalytic hydrogen-generating system containing triethanolamine and colloidal Pt without an extra electron relay, were investigated. A comparison of the rates of hydrogen production for the two photocatalytic systems, one containing a metal-organic dyad and the other comprising a 1:1 mixture of the parental platinum(II) complexes and the corresponding electron relay, showed that intramolecular electron transfer improves the photocatalytic efficiency. Compared with cyclometalated platinum(II) complexes, the related platinum(II) terpyridyl complexes exhibited poor performance for photocatalytic hydrogen evolution. An investigation into the amount of hydrogen generated by three platinum(II) complexes containing cyclometalated ligands with methyl groups located on different phenyl rings revealed that the efficiency of hydrogen evolution was affected by a subtle change of functional group on ligand, and the hydrogen-generating efficiency in the presence or absence of methyl viologen is comparable, indicating electron transfer from the excited [Pt(C^N^N)] chromophore to colloidal Pt. (1)H NMR spectroscopy of the metal-organic dyads in an aqueous solution in the presence of excess triethanolamine revealed that the dyad with a viologen unit was unstable, and a chemical reaction in the compound occurred prior to irradiation by visible light under basic conditions.

Synthesis, characterization, photoinduced isomerization, and spectroscopic properties of vinyl-1,8-naphthyridine derivatives and their copper(I) complexes.

A series of 1,8-naphthyridine derivatives containing vinyl, 2-(2-acetylamino-pyridine-6-ethylene)-4-methyl-7-acetylamino-1,8-naphthyridine (L(1)), 2-(2-acetylamino-pyridine-6-ethylene)-1,8-naphthyridine (L(2)), 2-(2-acetylamino-pyridinyl-6-ethylene)-4-methyl-7-hydroxyl-1,8-naphthyridine (L(3)), 2-(2-diacetylamino-pyridinyl-3-ethylene)-7-diacetylamino-1,8-naphthyridine (L(4)), and 7-(2-diacetylamino-pyridinyl-3-ethylene)-4'-acetyl-pyrrolo[1',5'-a]-1,8-naphthyridine (L(5)), as well as complexes [CuL(1)(PCy(3))](BF(4))(2) (1) (PCy(3) = tricyclohexylphosphine), [Cu(2)L(1)(PPh(3))(4)](BF(4))(2) (2) (PPh(3) = triphenylphosphine), [Cu(2)L(1)(dppm)](BF(4))(2) (3) (dppm = bis(diphenylphosphino)methane), and [Cu(2)(L(1))(dcpm)][BF(4)](2) (4) (dcpm = bis(dicyclohexylphosphino)methane, were synthesized. All these compounds, except for L(1) and L(2), were characterized by single crystal X-ray diffraction analysis, and a comprehensive study of their spectroscopic properties involving experimental theoretical studies is presented. We found an intramolecular 1,3-hydrogen transfer during the formation of L(3) and L(4), which in the case of the latter plays an important role in the 1,5-dipolar cyclization of L(5). The spectral changes that originate from an intramolecular charge transfer (ICT) in the form of a pi(py)-->pi*(napy) transition can be tuned through acid/base-controlled switching for L(1)-L(3). A photoinduced isomerization for L(1)-L(3), 1, and 2 having flexible structures was observed under 365 nm light irradiation. Quantum chemical calculations revealed that the dinuclear complexes with structural asymmetry exhibit different metal-to-ligand charge-transfer transitions.

COX-2 expression in gastric cancer and its relationship with angiogenesis using tissue microarray.

AIM: To explore the expression and clinicopathological significance of cyclooxygenase-2 (COX-2) and microvessel density (MVD) in gastric carcinogenesis, and to investigate their roles in the invasion and the relationship between biological behaviors and prognosis of gastric cancer. METHODS: Using Envision immunohistochemistry, COX-2 and CD34 expressions in gastric cancer tissue array were examined. MVD was counted and the relationship between the biological behaviors and prognosis was analyzed. RESULTS: The expression of COX-2 in gastric cancer tissue was significantly higher than that in normal mucosa (c2 = 12.191, P < 0.05). The over-expression of COX-2 in gastric cancer was obviously related to metastasis and depth of invasion (c2 = 6.315, P < 0.05), but not related to the histological type and Borrmann type (c2 = 5.391 and c2 = 2.228, respectively). Moreover, MVD in gastric cancer tissues was significantly higher than that in the normal mucosa (65.49 +/- 20.64 vs 36.21 +/- 18.47, t/F = 7.53, P < 0. 05). MVD was related to the histologic type and metastasis (t/F = 3.68 and t/F = 4.214, respectively, P < 0. 05), but not related to the depth of invasion and Borrmann type (t/F = 0.583 and t/F = 0.459, respectively). MVD in COX-2-positive tissues was markedly higher compared to COX-2-negative tissues, indicating a positive correlation between COX-2 expression and MVD (t = 13.12, P < 0. 05). CONCLUSION: Tissue microarray (TMA) is a powerful tool for rapid identification of the molecular alterations in gastric cancer. COX-2 expression, via inducing angiogenesis, may play an important role in gastric carcinogenesis. It could be served as a determinant factor for clinical prognosis and curative effect.