Photochemical Acceleration of Ammonia Production by Pt1-Ptn-TiN Reduction and N2 Activation.

Stable metal nitrides (MN) are promising materials to fit the future "green" ammonia-hydrogen nexus. Either through catalysis or chemical looping, the reductive hydrogenation of MN to MN1-x is a necessary step to generate ammonia. However, encumbered by the formation of kinetically stable M-NH1─3 surface species, this reduction step remains challenging under mild conditions. Herein, we discovered that deleterious Ti-NH1─3 accumulation on TiN can be circumvented photochemically with supported single atoms and clusters of platinum (Pt1-Ptn) under N2-H2 conditions. The photochemistry of TiN selectively promoted Ti-NH formation, while Pt1-Ptn effectively transformed any formed Ti-NH into free ammonia. The generated ammonia was found to originate mainly from TiN reduction with a minor contribution from N2 activation. The knowledge accrued from this fundamental study could serve as a springboard for the development of MN materials for more efficient ammonia production to potentially disrupt the century-old fossil-powered Haber-Bosch process.

Solar Hydrocarbons: Single-Step, Atmospheric-Pressure Synthesis of C2 -C4 Alkanes and Alkenes from CO2.

Cobalt ferrite (CoFe2 O4 ) spinel has been found to produce C2 -C4 hydrocarbons in a single-step, ambient-pressure, photocatalytic hydrogenation of CO2 with a rate of 1.1 mmol g-1 h-1 , selectivity of 29.8 % and conversion yield of 12.9 %. On stream the CoFe2 O4 reconstructs to a CoFe-CoFe2 O4 alloy-spinel nanocomposite which facilitates the light-assisted transformation of CO2 to CO and hydrogenation of the CO to C2 -C4 hydrocarbons. Promising results obtained from a laboratory demonstrator bode well for the development of a solar hydrocarbon pilot refinery.

Solution-Processed Anatase Titania Nanowires: From Hyperbranched Design to Optoelectronic Applications.

The utilization of solar energy and the development of its related optoelectronic devices have become more important than ever. Solar cells or photoelectrochemical (PEC) cells that require the design of light harvesting assemblies for efficiently converting solar light into electricity or solar fuels are of particular interest. Semiconductor TiO2, serving as the photoelectrode for photovoltaic devices (e.g., dye- or quantum dot-sensitized solar cells (DSSCs/QDSSCs) or perovskite solar cells (PSCs)) and PEC cells, has aroused intense research interest owing to its inherent characteristics of wide band gap and promising optical and electrical properties. TiO2 nanowires (TNWs) have been widely used in optoelectronic devices due to their unique 1D geometry and salient optical and electrical properties. However, the insufficient surface area resulting from the relatively large diameter of NWs and considerable free space between adjacent NWs restricts their optoelectronic performance. Hence, it is desirable to explore every feasible aspect of TNWs in terms of structural design and optical management, aiming to further improve the performance of optoelectronic devices. In this Account, we present a brief survey of strategies for designing branched or hyperbranched TNW-based photoelectrodes and their applications in solar cells and PEC cells. The general strategies (e.g., alkaline/acid hydrothermal method, lift-off transfer, and self-assembly approach) are discussed to address the challenges associated with fabricating TNWs on transparent conducting oxide (TCO) substrates. A series of strategies to fabricate judiciously designed 3D branched array architectures, including length tuning and sequential surface branched or hyperbranched modification, are proposed. The versatile implantation of the TNWs onto other backbones (nanosheets, nanotubes, hollow spheres, or multilayered electrodes) and substrates (fiber-shaped metal wire or mesh, flexible metal foil, or plastic sheet) is demonstrated to construct a new class of the TNW-embedded composite electrode materials with desired morphological characteristics and optoelectronic properties, for example, favorable energy level alignment for cascade charge transfer and rational homogeneous/heterogeneous interfacial engineering. The functionalities of TNW-based electrodes include enlarged surface area and superior light scattering for maximized light harvesting, as well as facilitated charge transport and suppressed charge recombination for enhanced charge collection, which are promising in optoelectronic fields such as solar cells, photocatalysis, and PEC cells. Beyond TNWs, one can also integrate other types of semiconductor (e.g., Fe2O3 or WO3) NWs into rationally designed structures for preparing novel photocatalytic materials with panchromatic absorption, efficient charge transfer, and excellent catalytic properties. Finally, an insightful perspective for rational design of advanced NW-based materials is provided.

Suppressing Interfacial Charge Recombination in Electron-Transport-Layer-Free Perovskite Solar Cells to Give an Efficiency Exceeding 21 .

The performances of electron-transport-layer (ETL)-free perovskite solar cells (PSCs) are still inferior to ETL-containing devices. This is mainly due to severe interfacial charge recombination occurring at the transparent conducting oxide (TCO)/perovskite interface, where the photo-injected electrons in the TCO can travel back to recombine with holes in the perovskite layer. Herein, we demonstrate for the first time that a non-annealed, insulating, amorphous metal oxyhydroxide, atomic-scale thin interlayer (ca. 3 nm) between the TCO and perovskite facilitates electron tunneling and suppresses the interfacial charge recombination. This largely reduced the interfacial charge recombination loss and achieved a record efficiency of 21.1 % for n-i-p structured ETL-free PSCs, outperforming their ETL-containing metal oxide counterparts (18.7 %), as well as narrowing the efficiency gap with high-efficiency PSCs employing highly crystalline TiO2 ETLs.

Is the combinational administration of doxorubicin and glutathione a reasonable proposal?

The combinational administration of antioxidants and chemotherapeutic agents during conventional cancer treatment is among one of the most controversial areas in oncology. Although the data on the combinational usage of doxorubicin (DOX) and glutathione (GSH) agents have been explored for over 20 years, the duration, administration route, and authentic rationality have not yet been fully understood yet. In the current study, we systematically investigated the pharmacokinetics (PK) and pharmacodynamics (PD) with both in vivo and in vitro models to elucidate the influence of GSH on the toxicity and efficacy of DOX. We first studied the cardioprotective and hepatoprotective effects of GSH in Balb/c mice, H9c2, and HL7702 cells. We showed that coadministration of exogenous GSH (5, 50, and 500 mg/kg per day, intragastric) significantly attenuated DOX-induced cardiotoxicity and hepatotoxicity by increasing intracellular GSH levels, whereas the elevated GSH concentrations did not affect the exposure of DOX in mouse heart and liver. From PK and PD perspectives, then the influences of GSH on the chemotherapeutic efficacy of DOX were investigated in xenografted nude mice and cancer cell models, including MCF-7, HepG2, and Caco-2 cells, which revealed that administration of exogenous GSH dose-dependently attenuated the anticancer efficacy of DOX in vivo and in vitro, although the elevated GSH levels neither influenced the concentration of DOX in tumors in vivo, nor the uptake of DOX in MCF-7 tumor cells in vitro. Based on the results we suggest that the combined administration of GSH and DOX should be contraindicated during chemotherapy unless DOX has caused serious hepatotoxicity and cardiotoxicity.

Synthesis and Photocatalytic Application of Stable Lead-Free Cs2 AgBiBr6 Perovskite Nanocrystals.

Lead halide perovskite nanocrystals (NCs) have demonstrated great potential as appealing candidates for advanced optoelectronic applications. However, the toxicity of lead and the intrinsic instability toward moisture hinder their mass production and commercialization. Herein, to solve such thorny problems, novel lead-free Cs2 AgBiBr6 double perovskite NCs fabricated via a simple hot-injection method are reported, which exhibit impressive stability in moisture, light, and temperature. Such materials are then applied into photocatalytic CO2 reduction, achieving a total electron consumption of 105 µmol g-1 under AM 1.5G illumination for 6 h. This study offers a reliable avenue for Cs2 AgBiBr6 perovskite nanocrystals preparation, which holds a great potential in the further photochemical applications.

Pharmacokinetic and pharmacodynamic evidence for developing an oral formulation of octreotide against gastric mucosal injury.

Among the somatostatin analogues, octreotide (OCT) is the most commonly used in clinic via intravenous or subcutaneous injection to treat various diseases caused by increased secretion of growth hormone, gastrin or insulin. In order to assesse the feasibility of developing oral formulations of OCT, we conducted systematical pharmacokinetic and pharmacodynamic analyses of OCT in several animal models. The pharmacokinetic studies in rats showed that intragastric administration of OCT had extremely low bioavailability (<0.5%), but it could specifically distribute to the gastric mucosa due to the high expression of somatostatin receptor 2 (SSTR2) in the rat stomach. The pharmacodynamic studies revealed that intragastric administration of OCT dose-dependently protected against gastric mucosal injury (GMI) in mice with WIRS-induced mouse gastric ulcers, which were comparable to those achieved by intravenous injection of OCT, and this effect was markedly attenuated by co-administration of CYN-154806, an antagonist of SSTR2. In pyloric ligation-induced ulcer mice, we further demonstrated that OCT significantly reduced the secretion of gastric acid via down-regulating the level of gastrin, which was responsible for the protective effect of OCT against GMI. Overall, we have provided pharmacokinetic and pharmacodynamic evidence for the feasibility of developing an oral formulation of OCT. Most importantly, the influence of SSTR2 on the pharmacokinetics and pharmacodynamics of OCT suggested that an oral formulation of OCT might be applicable for other clinical indications, including neuroendocrine neoplasms and pituitary adenoma due to the overexpression of SSTR2 on these tumor cells.

A CsPbBr3 Perovskite Quantum Dot/Graphene Oxide Composite for Photocatalytic CO2 Reduction.

Halide perovskite quantum dots (QDs), primarily regarded as optoelectronic materials for LED and photovoltaic devices, have not been applied for photochemical conversion (e.g., water splitting or CO2 reduction) applications because of their insufficient stability in the presence of moisture or polar solvents. Herein, we report the use of CsPbBr3 QDs as novel photocatalysts to convert CO2 into solar fuels in nonaqueous media. Under AM 1.5G simulated illumination, the CsPbBr3 QDs steadily generated and injected electrons into CO2, catalyzing CO2 reduction at a rate of 23.7 µmol/g h with a selectivity over 99.3%. Additionally, through the construction of a CsPbBr3 QD/graphene oxide (CsPbBr3 QD/GO) composite, the rate of electron consumption increased 25.5% because of improved electron extraction and transport. This study is anticipated to provide new opportunities to utilize halide perovskite QD materials in photocatalytic applications.

Multistack integration of three-dimensional hyperbranched anatase titania architectures for high-efficiency dye-sensitized solar cells.

An unprecedented attempt was conducted on suitably functionalized integration of three-dimensional hyperbranched titania architectures for efficient multistack photoanode, constructed via layer-by-layer assembly of hyperbranched hierarchical tree-like titania nanowires (underlayer), branched hierarchical rambutan-like titania hollow submicrometer-sized spheres (intermediate layer), and hyperbranched hierarchical urchin-like titania micrometer-sized spheres (top layer). Owing to favorable charge-collection, superior light harvesting efficiency and extended electron lifetime, the multilayered TiO2-based devices showed greater J(sc) and V(oc) than those of a conventional TiO2 nanoparticle (TNP), and an overall power conversion efficiency of 11.01% (J(sc) = 18.53 mA cm(-2); V(oc) = 827 mV and FF = 0.72) was attained, which remarkably outperformed that of a TNP-based reference cell (η = 7.62%) with a similar film thickness. Meanwhile, the facile and operable film-fabricating technique (hydrothermal and drop-casting) provides a promising scheme and great simplicity for high performance/cost ratio photovoltaic device processability in a sustainable way.

Constructing 3D branched nanowire coated macroporous metal oxide electrodes with homogeneous or heterogeneous compositions for efficient solar cells.

Light-harvesting and charge collection have attracted increasing attention in the domain of photovoltaic cells, and can be facilitated dramatically by appropriate design of a photonic nanostructure. However, the applicability of current light-harvesting photoanode materials with single component and/or morphology (such as, particles, spheres, wires, sheets) is still limited by drawbacks such as insufficient electron-hole separation and/or light-trapping. Herein, we introduce a universal method to prepare hierarchical assembly of macroporous material-nanowire coated homogenous or heterogeneous metal oxide composite electrodes (TiO2 -TiO2 , SnO2 -TiO2 , and Zn2 SnO4 -TiO2 ; homogenous refers to a material in which the nanowire and the macroporous material have the same composition, i.e. both are TiO2 . Heterogeneous refers to a material in which the nanowires and the macroporous material have different compositions). The dye-sensitized solar cell based on a TiO2 -macroporous material-TiO2 -nanowire homogenous composition electrode shows an impressive conversion efficiency of 9.51 %, which is much higher than that of pure macroporous material-based photoelectrodes to date.

Surface passivated halide perovskite single-crystal for efficient photoelectrochemical synthesis of dimethoxydihydrofuran.

Halide perovskite single-crystals have recently been widely highlighted to possess high light harvesting capability and superior charge transport behaviour, which further enable their attractive performance in photovoltaics. However, their application in photoelectrochemical cells has not yet been reported. Here, a methylammonium lead bromide MAPbBr3 single-crystal thin film is reported as a photoanode with potential application in photoelectrochemical organic synthesis, 2,5-dimethoxy-2,5-dihydrofuran. Depositing an ultrathin Al2O3 layer is found to effectively passivate perovskite surface defects. Thus, the nearly 5-fold increase in photoelectrochemical performance with the saturated current being increased from 1.2 to 5.5 mA cm-2 is mainly attributed to suppressed trap-assisted recombination for MAPbBr3 single-crystal thin film/Al2O3. In addition, Ti3+-species-rich titanium deposition has been introduced not only as a protective film but also as a catalytic layer to further advance performance and stability. As an encouraging result, the photoelectrochemical performance and stability of MAPbBr3 single-crystal thin film/Al2O3/Ti-based photoanode have been significantly improved for 6 h continuous dimethoxydihydrofuran evolution test with a high Faraday efficiency of 93%.

High-performance light-driven heterogeneous CO2 catalysis with near-unity selectivity on metal phosphides.

Akin to single-site homogeneous catalysis, a long sought-after goal is to achieve reaction site precision in heterogeneous catalysis for chemical control over patterns of activity, selectivity and stability. Herein, we report on metal phosphides as a class of material capable of realizing these attributes and unlock their potential in solar-driven CO2 hydrogenation. Selected as an archetype, Ni12P5 affords a structure based upon highly dispersed nickel nanoclusters integrated into a phosphorus lattice that harvest light intensely across the entire solar spectral range. Motivated by its panchromatic absorption and unique linearly bonded nickel-carbonyl-dominated reaction route, Ni12P5 is found to be a photothermal catalyst for the reverse water gas shift reaction, offering a CO production rate of 960 ± 12 mmol gcat-1 h-1, near 100% selectivity and long-term stability. Successful extension of this idea to Co2P analogs implies that metal phosphide materials are poised as a universal platform for high-rate and highly selective photothermal CO2 catalysis.

CsPbBr3 Nanocrystal/MO2 (M = Si, Ti, Sn) Composites: Insight into Charge-Carrier Dynamics and Photoelectrochemical Applications.

Though coating CsPbBr3 nanocrystal (NC) with an outer layer has been regarded as an effective strategy to address its instability issues, deep investigations into the electronic interaction between CsPbBr3 NC and coating layer have yet to be conducted. In this study, the dynamics of hot carrier and charge carrier of CsPbBr3 nanocrystal with various MO2 (M = Si, Ti, Sn) coating layers have been comprehensively studied. Combined transient optical characterizations (time-resolved photoluminescence and ultrafast transient absorption) and photoelectrochemical measurements reveal that coating with insulating SiO2 accelerates the hot carrier relaxation and enhances the radiative recombination by passivating surface traps, whereas efficient charge-carrier separation and extraction are observed after coating with SnO2 and TiO2. The electron injection from CsPbBr3 NC to SnO2 (1.14 × 108 s-1) is 2-fold faster than to TiO2 (5.4 × 107 s-1) owing to the lower conduction band edge and the higher electron mobility of SnO2. Particularly, the first time fabricated CsPbBr3 NC/SnO2 composite exhibits superior stability against UV light and moisture, as well as the best photocurrent response in this study. This work has implied that rational design of the coating layer for perovskite NC can not only improve the stability but also tailor the electronic and optoelectronic properties for various applications.

Large-Area Synthesis of a Ni2P Honeycomb Electrode for Highly Efficient Water Splitting.

Transition metal phosphides have recently been regarded as robust, inexpensive electrocatalysts for both the hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER). Thus far, tremendous scientific efforts have been applied to improve the catalytic activity of the catalyst, whereas the scale-up fabrication of morphology-controlled catalysts while maintaining their desired performance remains a great challenge. Herein, we present a facile and scalable approach to fabricate the macroporous Ni2P/nickel foam electrode. The obtained electrocatalyst exhibits superior bifunctional catalytic activity and durability, as evidenced by a low overpotential of 205 and 300 mV required to achieve a high current density of 100 mA cm-2 for HER and OER, respectively. Such a spray-based strategy is believed to widely adapt for the preparation of electrodes with uniform macroporous structures over a large area (e.g., 100 cm2), which provides a universal strategy for the mass fabrication of high performance water-splitting electrodes.

3D Cathodes of Cupric Oxide Nanosheets Coated onto Macroporous Antimony-Doped Tin Oxide for Photoelectrochemical Water Splitting.

Cupric oxide (CuO), a narrow-bandgap semiconductor, has a band alignment that makes it an ideal photocathode for the renewable production of solar fuels. However, the photoelectrochemical performance of CuO is limited by its poor conductivity and short electron diffusion lengths. Herein, a three-dimensional (3D) architecture consisting of CuO nanosheets supported onto transparent conducting macroporous antimony-doped tin oxide (mpATO@CuONSs) is designed as an excellent photocathode for promoting the hydrogen evolution reaction (HER). Owing to the 3D structure affording superior light-harvesting characteristics, large contact areas with the electrolyte, and highly conductive pathways for separation and transport of charge carriers, the mpATO@CuONSs photocathode produces an impressively high photocurrent density of -4.6 mA cm-2 at 0 V versus the reversible hydrogen electrode (RHE), which is much higher than that of the CuONSs array onto planar FTO glass (-1.9 mA cm-2 ).

Achieving Highly Efficient Photoelectrochemical Water Oxidation with a TiCl4 Treated 3D Antimony-Doped SnO2 Macropore/Branched α-Fe2O3 Nanorod Heterojunction Photoanode.

Utilizing photoelectrochemical (PEC) cells to directly collecting solar energy into chemical fuels (e.g., H2 via water splitting) is a promising way to tackle the energy challenge. α-Fe2O3 has emerged as a desirable photoanode material in a PEC cell due to its wide spectrum absorption range, chemical stability, and earth abundant component. However, the short excited state lifetime, poor minority charge carrier mobility, and long light penetration depth hamper its application. Recently, the elegantly designed hierarchical macroporous composite nanomaterial has emerged as a strong candidate for photoelectrical applications. Here, a novel 3D antimony-doped SnO2 (ATO) macroporous structure is demonstrated as a transparent conducting scaffold to load 1D hematite nanorod to form a composite material for efficient PEC water splitting. An enormous enhancement in PEC performance is found in the 3D electrode compared to the controlled planar one, due to the outstanding light harvesting and charge transport. A facile and simple TiCl4 treatment further introduces the Ti doping into the hematite while simultaneously forming a passivation layer to eliminate adverse reactions. The results indicate that the structural design and nanoengineering are an effective strategy to boost the PEC performance in order to bring more potential devices into practical use.

Maximizing omnidirectional light harvesting in metal oxide hyperbranched array architectures.

The scrupulous design of nanoarchitectures and smart hybridization of specific active materials are closely related to the overall photovoltaic performance of an anode electrode. Here we present a solution-based strategy for the fabrication of well-aligned metal oxide-based nanowire-nanosheet-nanorod hyperbranched arrays on transparent conducting oxide substrates. For these hyperbranched arrays, we observe a twofold increment in dye adsorption and enhanced light trapping and scattering capability compared with the pristine titanium dioxide nanowires, and thus a power conversion efficiency of 9.09% is achieved. Our growth approach presents a strategy to broaden the photoresponse and maximize the light-harvesting efficiency of arrays architectures, and may lead to applications for energy conversion and storage, catalysis, water splitting and gas sensing.

A double layered TiO2 photoanode consisting of hierarchical flowers and nanoparticles for high-efficiency dye-sensitized solar cells.

We report the innovative development of a double layered photoanode made of hierarchical TiO2 flowers (HTFs) as the overlayer and TiO2 nanoparticles (TNPs) as the underlayer, for dye-sensitized solar cells (DSSCs). They were prepared via a mild and simple one-step hydrothermal reaction of TiO2 nanoparticles/FTO glass substrate in an alkaline solution. The underlayer made of TNPs with a small size (20 nm in diameter) serves as a transparent photoanode for efficient dye adsorption. The overlayer consisting of HTFs (3-5 µm in diameter) embedded by TiO2 nanosheets plays multiple roles in enhancing light-scattering and fast electron transport. DSSCs based on this novel double layered photoanode (5 µm TNPs + 5 µm HTFs) exhibit greater than 7.4% power conversion efficiency (PCE), which is higher than that of single layer TNP based photoanodes (6.59%) with similar thickness (∼10 µm), and this is mainly attributed to the superior light scattering ability and fast electron transport of the former. Meanwhile, the thickness of the TNP underlayer has been optimized to further improve the PCE and an excellent PCE of over 9% has been achieved based on a 15 µm TNP + a 5 µm HTF double layered photoanode, accompanied by a short-circuit photocurrent density of 17.85 mA cm(-2), an open-circuit voltage of 763 mV and a fill factor of 0.67.

Hydrothermal fabrication of hierarchically anatase TiO2 nanowire arrays on FTO glass for dye-sensitized solar cells.

Hierarchical anatase TiO(2) nano-architecture arrays consisting of long TiO(2) nanowire trunk and numerous short TiO(2) nanorod branches on transparent conductive fluorine-doped tin oxide glass are successfully synthesized for the first time through a facile one-step hydrothermal route without any surfactant and template. Dye-sensitized solar cells based on the hierarchical anatase TiO(2) nano-architecture array photoelectrode of 18 µm in length shows a power conversion efficiency of 7.34% because of its higher specific surface area for adsorbing more dye molecules and superior light scattering capacity for boosting the light-harvesting efficiency. The present photovoltaic performance is the highest value for the reported TiO(2) nanowires array photoelectrode.

Macroporous SnO2 synthesized via a template-assisted reflux process for efficient dye-sensitized solar cells.

Macroporous SnO2 composed of small SnO2 nanoparticles with diameters around 10 nm is prepared via a reflux process. This novel structure is designed as the photoanode in dye-sensitized solar cells (DSSCs), intending to improve the light utilization efficiency with its excellent light scattering ability. Though the dye adsorption of macroporous SnO2 (14.00 × 10(-8) mol cm(-2)) is lower than that of SnO2 nanoparticles (19.24 × 10(-8) mol cm(-2)), the photovoltaic performance of the DSSCs based on the former is 4.87% compared to 4.41% for SnO2 nanoparticles, showing over 10% increment than the latter. This improvement is mainly due to the enhanced light scattering ability and charge collection efficiency of the macroporous structure, both of which contribute to a higher short current density and hence for the better power conversion efficiency. Furthermore, a double-layer structure composed of SnO2 nanoparticles (active layer) and macroporous SnO2 (scattering layer) possess both large dye adsorption (22.82 × 10(-8) mol cm(-2)) and scattering property, thus leads to a significant overall conversion efficiency of 5.78%.