Hematite photoanode with complex nanoarchitecture providing tunable gradient doping and remarkable low onset potential for advanced PEC water splitting

Over the past years, αFe2O3 (hematite) has reemerged as a promising photoanode material in photoelectrochemical (PEC) water splitting. In spite of considerable success in obtaining relatively high solar conversion efficiency, the main drawbacks hindering practical application at hematite are related to an intrinsically hampered charge transport and a sluggish kinetics of the oxygen evolution reaction on the photoelectrode surface. In the present work, we report a strategy on how to synergistically address both these critical limitations. Our approach is based on three key features that are applied simultaneously, specifically i) a careful nanostrcuturing of hematite photoanode in the form of nanorods, ii) doping of hematite by Sn4+ ions by a controlled gradient, and iii) surface decoration of hematite by a new class of double hydroxide layered (LDH) OER cocatalysts based on ZnCo LDH. All three interconnected forms of functionalization result in an extraordinary cathodic shift of the photocurrent onset potential by more than 300 mV and a PEC performance that reaches a photocurrent density of 2.00 mA/cm2 at 1.50 VRHE

Lithium Phenolates Solvated By Tetrahydrofuran And 1,2Dimethoxyethane: Structure Determination Using The Method Of Continuous Variation

The role of O-Lithiated species has a very strong precedence in literature ranging from well-known reactions like Aldol, Wittig, Brook etc. in academia to their immense uses in pharmaceutical industry. According to recent study by Pfizer, over two decades, 68% of all C-C bond-forming reactions are carbanion based and 44% of them involve enolates, the most common O-Lithiated species. However, despite their prevalence, very little is known about their structure-reactivity relationships due to a lack of understanding stemming from difficulty in characterizing aggregation states in solution. Highly symmetric aggregates coupled with a spectroscopically opaque Li-O bond make this characterization really tough. The method of continuous variation in conjunction with 6Li NMR spectroscopy has been used to characterize lithium phenolates solvated by tetrahydrofuran (THF) and 1,2-dimethoxyethane (DME) with the intention of providing a general solution to this problem. The strategy relies on the formation of ensembles of homo- and heteroaggregated phenolates and plotting them against the mole-fraction of a particular species. In this case, its worth mentioning that phenolates stand on their merits because of their stability, availability, substrate flexibility and aggregate diversity and both the solvents THF and DME offer to examine the influence of mono- and bifunctional ligands on lithium phenolate aggregation. With the help of this method, a very broad range of structurally (both electronically and sterically) different phenolates has been characterized both in THF and DME. While, THF affords tetrameric, dimeric, and monomeric lithium phenolates depending on solvent and substrate concentrations and on the aryl substituents, DME offers five aggregation states ranging from monomer to pentamer, a unique diversity that presumably stems in part from its capacity to serve as either a monodentate or bidentate (chelating) ligand. The occurrence of cyclic trimers and pentameric ladders uniquely in DME suggests that chelation is mandatory. The stabilization by chelation is also supported by DFT computational studies. Not only the aggregation states, the solvation number of a particular aggregation state can also be obtained by fitting the solvent dependent equilibrium of different aggregates to free solvent concentration and this technique has been used to assign solvation numbers of different aggregates in both THF and DME

Efficient Noble Metal-Free (Electro)Catalysis of Water and Alcohol Oxidations by Zinc–Cobalt Layered Double Hydroxide

Replacing rare and expensive noble metal catalysts with inexpensive and earth-abundant ones for various renewable energy-related chemical processes as well as for production of high value chemicals is one of the major goals of sustainable chemistry. Herein we show that a bimetallic Zn–Co layered double hydroxide (Zn–Co–LDH) can serve as an efficient electrocatalyst and catalyst for water and alcohol oxidation, respectively. In the electrochemical water oxidation, the material exhibits a lower overpotential, by ∼100 mV, than monometallic Co-based solid-state materials (e.g., Co­(OH)2 and Co3O4)-catalytic systems that were recently reported to be effective for this reaction. Moreover, the material’s turnover frequency (TOF) per Co atoms is >10 times as high as those of the latter at the same applied potentials. The Zn–Co–LDH also catalyzes oxidation of alcohols to the corresponding aldehydes or ketones at relatively low temperature, with moderate to high conversion and excellent selectivity

Glutathione-triggered release of model drug molecules from mesoporous silica nanoparticles via a non-redox process

Model drug-loaded mesoporous silica nanoparticles (MSNs) that are responsive to the pH rather than the redox changes related to glutathione (GSH) are prepared using surfactant-free MSNs as a precursor.</p