Antimony sulphoiodide (SbSI), a narrow band-gap non-oxide ternary semiconductor with efficient photocatalytic activity

In the context of the harvesting of solar photons, one dimensional semiconductors are attractive as they provide uninterrupted transport pathways for charge carriers, along the covalently bonded atomic chain direction. Moreover, the one-dimensional growth leads to a lower proportion of dangling bonds at the surfaces due to preferential growth in a particular direction. We report here a non-metal oxide semiconductor, antimony sulphoiodide (SbSI) which displays high optical absorption and a low and tunable band gap for visible light photocatalytic applications. Highly crystalline 1-D micro-rods of SbSI which eventually self-assemble into 3-D ``urchin''-shaped structures are synthesized by using a simple solution method. The morphology of the SbSI is studied in terms of the dangling bonds at the surface planes. The results conclusively show that the SbSI has a lower proportion of dangling bonds at the surface. The electronic structure of SbSI, studied using density functional theory, displays a large static dielectric constant due to the ns(2) cation (Sb3+) which enhances the separation of electron and hole pairs effectively. The combination of these two features makes SbSI a promising material for visible photocatalytic degradation of organic pollutants in water, in spite of an overall low surface area (approximate to 2.6 m(2) g(-1))

Nickel nanoparticles wrapped in N-doped carbon nanostructures for efficient electrochemical reduction of NO to NH3

Production of ammonia (NH3) from flue gas (i.e., NO) via the electrocatalytic route has been considered a promising approach for rejuvenating the environment over the conventional methods. MOF-derived zero-valent nickel nanoparticles wrapped with nitrogen-doped carbon nanostructures (NiNC) were successfully grown on a carbon fiber (CF). The NiNC@CF catalyst delivered an NH3 yield rate of 94 mu mol h(-1) cm(-2) with significantly high faradaic efficiency (87%) at -0.5 V vs. RHE. Coupling with an OER catalyst in a full cell system produces 88 mu mol h(-1) cm(-2) of NH3 with long-term stability.TRU

Optimizing Photovoltaic Response by Tuning Light-Harvesting Nanocrystal Shape Synthesized Using a Quick Liquid-Gas Phase Reaction

The electron recombination lifetime in a sensitized semiconductor assembly is greatly influenced by the crystal structure and geometric form of the light-harvesting semiconductor nanocrystal. When such light harvesters with varying structural characteristics are configured in a photoanode, its interface with the electrolyte becomes equally important and directly influences the photovoltaic efficiency. We have systematically probed here the influence of nanocrystal crystallographic structure and shape on the electron recombination lifetime and its eventual influence on the light to electricity conversion efficiency of a liquid junction semiconductor sensitized solar cell. The light-harvesting cadmium sulfide (CdS) nanocrystals of distinctly different and controlled shapes are obtained using a novel and simple liquid gas phase synthesis method performed at different temperatures involving very short reaction times. High resolution synchrotron X-ray diffraction and spectroscopic studies respectively exhibit different crystallographic phase content and optical properties. When assembled on a mesoscopic TiO2 film by a linker molecule, they exhibit remarkable variation in electron recombination lifetime by 1 order of magnitude, as determined by ac-impedance spectroscopy. This also drastically affects the photovoltaic efficiency of the differently shaped nanocrystal sensitized solar cells

Electrochemical Reduction of Nitric Oxide with 1.7% Solar-to-Ammonia Efficiency Over Nanostructured Core-Shell Catalyst at Low Overpotentials

Transition metals have been recognized as excellent and efficient catalysts for the electrochemical nitric oxide reduction reaction (NORR) to value-added chemicals. In this work, a class of core-shell electrocatalysts that utilize nickel nanoparticles in the core and nitrogen-doped porous carbon architecture in the shell (Ni@NC) for the efficient electroreduction of NO to ammonia (NH3) is reported. In Ni@NC, the NC prevents the dissolution of Ni nanoparticles and ensures the long-term stability of the catalyst. The Ni nanoparticles involve in the catalytic reduction of NO to NH3 during electrolysis. As a result, the Ni@NC achieves a faradaic efficiency (FE) of 72.3% at 0.16 V-RHE. The full-cell electrolyzer is constructed by coupling Ni@NC as cathode for NORR and RuO2 as an anode for oxygen evolution reaction (OER), which delivers a stable performance over 20 cycles at 1.5 V. While integrating this setup with a PV-electrolyzer cell, and it demonstrates an appreciable FE of >50%. Thus, the results exemplify that the core-shell catalyst based electrolyzer is a promising approach for the stable NO to NH3 electroconversion.TRU

Planar Heterojunction Solar Cell Employing a Single-Source Precursor Solution-Processed Sb2S3 Thin Film as the Light Absorber

We discuss here a solution-processed thin film of antimony trisulphide (Sb2S3; band gap approximate to 1.7 eV; electronic configuration: ns(2)np(0)) for applications in planar heterojunction (PHJ) solar cells. An alternative solution processing method involving a single-metal organic precursor, viz., metal-butyldithiocarbamic acid complex, is used to grow the thin films of Sb2S3. Because of excess sulphide in the metal complex, the formation of any oxide is nearly retarded. Sb2S3 additionally displays structural anisotropy with a ribbon-like structure along the 001] direction. These ribbon-like structures, if optimally oriented with respect to the electron transport layer (ETL)/glass substrate, can be beneficial for light-harvesting and charge-transport properties. A PHJ solar cell is fabricated comprising Sb2S3 as the light absorber and CdS as an ETL coated on to FTO. With varying film sintering temperature and thickness, the typical ribbon-like structures predominantly with planes hkl: l = 0 stacked horizontally along with respect to CdS/FTO are obtained. The morphology of the films is observed to be a function of the sintering temperature, with higher sintering temperatures yielding compact and smooth films with large-sized grains. Maximum photon to electricity efficiency of 2.38 is obtained for PHJ solar cells comprising 480 nm thick films of Sb2S3 sintered at 350 degrees C having a grain size of few micrometers (>5 mu m). The study convincingly shows that improper grain orientation, which may lead to nonoptimal alignments of the intrinsic structure with regard to the ETL/glass substrate, is not the sole parameter for determining photovoltaics performance. Other solution-processing parameters can still be suitably chosen to generate films with optimum morphology, leading to high photon to electricity efficiency

Nrf2 deficiency promotes apoptosis and impairs PAX7/MyoD expression in aging skeletal muscle cells

Skeletal muscle redox homoeostasis is transcriptionally regulated by nuclear erythroid-2-p45-related factor-2 (Nrf2). We recently demonstrated that age-associated stress impairs Nrf2-ARE (antioxidant response element) transcriptional signaling. Here, we hypothesize that age-dependent decline or genetic ablation of Nrf2 leads to accelerated apoptosis and skeletal muscle degeneration. Under basal-physiological conditions, disruption of Nrf2 significantly down regulates antioxidants and causes oxidative stress. Surprisingly, Nrf2-null mice had enhanced antioxidant capacity identical to wild-type (WT) upon acute endurance exercise stress (AEES), suggesting activation of Nrf2-independent mechanisms (i.e. PGC1α) against oxidative stress. Analysis of pro-survival pathways under the basal state reveals decreased Akt levels, while pp53, a repressor of Akt, was increased in Nrf2-null versus WT mice. Upon AEES, Akt and p-Akt levels were significantly (p<0.001) increased (>10 fold) along with profound down regulation of pp53 (p<0.01) in Nrf2-null versus WT skeletal muscle, indicating the onset of pro-survival mechanisms to compensate the loss of Nrf2 signaling. However, we found a decreased stem cell population (Pax7) and MyoD expression (differentiation) along with profound activation of ubiquitin and apoptotic pathways in Nrf2- null versus WT mice upon AEES, suggesting that compensatory pro-survival mechanisms failed to overcome the programed cell death and degeneration in skeletal muscle. Further, the impaired regeneration was sustained in Nrf2-null vs. WT mice after 1 week of post-AEES recovery. In an age-associated oxidative stress condition, ablation of Nrf2 results in induction of apoptosis and impaired muscle regeneration