This work demonstrates the chiral-induced spin selectivity effect for inorganic copper oxide films and exploits it to enhance the chemical selectivity in electrocatalytic water splitting. Chiral CuO films are electrodeposited on a polycrystalline Au substrate, and their spin filtering effect on electrons is demonstrated using Mott polarimetry analysis of photoelectrons. CuO is known to act as an electrocatalyst for the oxygen evolution reaction; however, it also generates side products such as H2O2. We show that chiral CuO is selective for O2; H2O2 generation is strongly suppressed on chiral CuO but is present with achiral CuO. The selectivity is rationalized in terms of the electron spin-filtering properties of the chiral CuO and the spin constraints for the generation of triplet oxygen. These findings represent an important step toward the development of all-inorganic chiral materials for electron spin filtering and the creation of efficient, spin-selective (photo)electrocatalysts for water splitting.
The fabrication, by an all electrochemical process, of porous Si/ZnO nanostructures with engineered structural defects, leading to strong and broadband deep level emission from ZnO, is presented. Such nanostructures are fabricated by a combination of metal-assisted chemical etching of Si and direct current electrodeposition of ZnO. It makes the whole fabrication process low-cost, compatible with Complementary Metal-Oxide Semiconductor technology, scalable and easily industrialised. The photoluminescence spectra of the porous Si/ZnO nanostructures reveal a correlation between the lineshape, as well as the strength of the emission, with the morphology of the underlying porous Si, that control the induced defects in the ZnO. Appropriate fabrication conditions of the porous Si lead to exceptionally bright Gaussian-type emission that covers almost the entire visible spectrum, indicating that porous Si/ZnO nanostructures could be a cornerstone material towards white-light-emitting devices.
In this article, we describe an advance approach for the fabrication of chiral metal-oxide nanofilms. Our approach is based on the atomic layer deposition of titania and alumina nanofilms onto cellulose microfibers, used as chiral templates, leading to the formation of chiral nanofilms with a spatial fibrous structure. The chiral nanofilms were extensively characterized by X-ray photoelectron spectroscopy and high-resolution electron microscopy. The chiral property of the produced titania nanofilms was studied by enantioselective adsorption experiments using circular-dichroism spectroscopy and chiral high-performance liquid chromatography. We demonstrate the application of the titania chiral nanofilms for enantioselective crystallization. Overall, the basic principle for the preparation of chiral nanofilms by atomic layer deposition is demonstrated, as well as their uses for several enantioselective applications.
bio-mimic interfaces with enantioselective properties remains challenging for chemists and materials scientists. For many research areas, such as medicine, biology, and chemistry, achieving enantioselective control is essential because it is a key parameter in molecular recognition. [5][6][7] Hence, the development of advanced methods to synthesize, separate, and detect chiral compounds is of particular importance.Chirality also plays a useful role in many nanosystems, [8] such as chiroptical molecular switches, [9][10][11] molecular motors, chiral surfaces, [12,13] chiral nanoparticles, [14][15][16][17][18][19] and chiral polymeric nanoparticles. [20][21][22] Overall, the areas of chiral nanoscience and nanotechnology hold exceptionally strong promise for further developments in areas such as catalysis, biorecognition, and chiral separation. Chiral mesoporous materials, for example, chiral mesoporous carbon, [23,24] chiral mesoporous silica, [25][26][27] and silica imprinted with different chiral functionalities, [28][29][30][31] are examples of promising nanosystems and have proved to play an important role in many fields of chemistry.One of the most promising chiral nanoscale systems is based on the use of chiral surfaces. Overall, there are three types of chiral surfaces, including surfaces from chiral bulk structures, such as quartz, and some high Miller-index surfaces of achiral crystals. [14] Chiral surfaces can also be produced by templating using chiral ligands and by the adsorption of chiral molecules to form chiral self-assembled monolayers (SAMs). [32][33][34][35] A potentially promising method to produce chiral surfaces is molecular layer deposition (MLD), used in combination with atomic layer deposition (ALD). [36] The A/MLD (atomic/molecular layer deposition) method is based on bifunctional compounds that vaporize, chemisorb, and react with a suitably functionalized surface. Both ALD and MLD allow the temporal separation of any number of precursors, each of which undergoes a self-limiting adsorption/ reaction on the surface so that the typical uptake is limited to approximately one monolayer of any given precursor. The ALD and MLD system is the same. However, the difference between these two is by replacing the small oxidizing precursor (e.g., water, O 3 ) used for ALD with oxidizing organic molecule as the reactant. Therefore, it will grow molecular layer instead of growing atomic layer. This leads to a growth controlled at the Atomic and molecular layer deposition (ALD and MLD) are techniques based on surface-directed self-limiting reactions that afford deposition of films controlled at the monolayer level and with extreme conformality, even on ultra-high-aspect-ratio and porous substrates. These methodologies are typically used to deposit thin films with desirable physical properties and functionality. Here, the MLD process is harnessed to demonstrate the growth of molecularly thin chiral films that inherit a desirable chemical property directly from the source precursor: using this innovative t...
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