Binary solvent mixtures of alkanethiols and 1,2-ethylenediamine have the ability to readily dissolve metals, metal chalcogenides, and metal oxides under ambient conditions to enable the facile solution processing of semiconductor inks; however, there is little information regarding the chemical identity of the resulting solutes. Herein, we examine the molecular solute formed after dissolution of Sn, SnO, and SnS in a binary solvent mixture comprised of 1,2-ethanedithiol (EDT) and 1,2-ethylenediamine (en). Using a combination of solution (119)Sn NMR and Raman spectroscopies, bis(1,2-ethanedithiolate)tin(II) was identified as the likely molecular solute present after the dissolution of Sn, SnO, and SnS in EDT-en, despite the different bulk material compositions and oxidation states (Sn(0) and Sn(2+)). All three semiconductor inks can be converted to phase-pure, orthorhombic SnS after a mild annealing step (∼350 °C). This highlights the ability of the EDT-en solvent mixture to dissolve and convert a variety of low-cost precursors to SnS semiconductor material.

Because of its useful optoelectronic properties and the relative abundance of its elements, the quaternary semiconductor Cu 2 ZnSnS 4 (CZTS) has garnered considerable interest in recent years. In this work, we dope divalent, high spin transition metal ions (M 2+ = Mn 2+ , Co 2+ , Ni 2+ ) into the tetrahedral Zn 2+ sites of wurtzite CZTS nanorods. The resulting Cu 2 M x Zn 1−x SnS 4 (CMTS) nanocrystals retain the hexagonal crystalline structure, elongated morphology, and broad visible light absorption profile of the undoped CZTS nanorods. Electron paramagnetic resonance (EPR), X-ray photoelectron spectroscopy (XPS), and infrared (IR) spectroscopy help corroborate the composition and local ion environment of the doped nanocrystals. EPR shows that, similarly to Mn x Cd 1−x Se, washing Cu 2 Mn x Zn 1−x SnS 4 nanocrystals with trioctylphosphine oxide (TOPO) is an efficient way to remove excess Mn 2+ ions from the particle surface. XPS and IR of as-isolated and thiol-washed samples show that, in contrast to binary chalcogenides, Cu 2 Mn x Zn 1−x SnS 4 nanocrystals aggregate not through dichalcogenide bonds, but through excess metal ions cross-linking the sulfur-rich surfaces of neighboring particles. Our results may help in expanding the synthetic applicability of CZTS and CMTS materials beyond photovoltaics and into the fields of spintronics and magnetic data storage.

A synthesis method that results in ∼180 nm plate-like crystallites of β-(Co(OH)2 anchored on the surface of zeolite Y particles is reported. These crystals of β-Co(OH)2 are transformed to Co3O4 by thermal treatment without a change in morphology. Characterization of the cobalt phases and the transformation was carried out by powder X-ray diffraction, X-ray photoelectron spectroscopy, Raman spectroscopy, and electron microscopy. These cobalt-based materials provide an opportunity to contrast their photocatalytic activity. Using the Ru(bpy)3 2+−persulfate system, the oxidation of water to oxygen was measured. The most active catalyst was β-(Co(OH)2, and with transformation to Co3O4, the catalytic activity declined, suggesting that β-Co(OH)2 is a better photocatalyst than Co3O4. The photocatalytic activity of the β-(Co(OH)2/zeolite decreased during a second photocatalytic cycle, due to surface transformation to Co3O4, though the bulk of the catalyst still maintains the brucite-like β-Co(OH)2 structure. This is the first report on how catalytic activity is altered in the cobalt oxide system by phase transformation, keeping morphological features unchanged.

Highly dispersed iron-based quantum dots (QDs) onto powdered Vulcan XC-72R substrate were successfully electrodeposited by the rotating disk slurry electrodeposition (RoDSE) technique. Our findings through chemical physics characterization revealed that the continuous electron pathway interaction between the interface metal–carbon is controlled. The rotating ring-disk electrode (RRDE) and the prototype generation unit (PGU) of in-situ H2O2 generation in fuel cell experiments revealed a high activity for the oxygen reduction reaction (ORR) via two-electron pathway. These results establish the Fe/Vulcan catalyst at a competitive level for space and terrestrial new materials carriers, specifically for the in-situ H2O2 production. Transmission electron microscopy (TEM) analysis reveals the well-dispersed Fe-based quantum dots with a particle size of 4 nm. The structural and chemical-physical characterization through induced coupled plasma-optical emission spectroscopy (ICP-OES), transmission scanning electron microscopy (STEM), X-ray diffraction (XRD), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), and X-ray absorption spectroscopy (XAS); reveals that, under atmospheric conditions, our quantum dots system is a Fe2+/3+/Fe3+ combination. The QDs oxidation state tunability was showed by the applied potential. The obtention of H2O2 under the compatibility conditions of the drinking water resources available in the International Space Station (ISS) enhances the applicability of this iron- and carbon-based materials for in-situ H2O2 production in future space scenarios. Terrestrial and space abundance of iron and carbon, combined with its low toxicity and high stability, consolidates this present work to be further extended for the large-scale production of Fe-based nanoparticles for several applications.

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