Supported bimetallic nanocomposites are promising in photocatalysis due to the multi-component interaction between metals and between metals and carriers. By an in situ reduction method, a series of monometallic (Au@CeO2 and Cu@CeO2) and bimetallic catalysts (Au8Cu2@CeO2, Au5Cu5@CeO2 and Au1Cu9@CeO2) are obtained, with a metallic core and a CeO2 shell structure. The in situ reduction method developed in this work is a one-step strategy to obtain supported multi-component nanomaterials with a core–shell structure. Photo-assisted oxidation of benzyl alcohol to benzaldehyde was performed over the above samples, and the reactivity presented a parabolic plot with the increase of Cu content, reaching the summit for Au1Cu9@CeO2. Inpouring of Cu enlarged the specific surface area and generated more oxygen vacancies, which are significant for improving the photocatalytic performance. The intimate correlation between the reactivity and the concentration of the oxygen vacancies provides that the surface of the CeO2 support with a large number of oxygen vacancies serves as the active site for aerobic oxidation. Accordingly, a mechanism is proposed for the photocatalytic efficiency enhancement as the function of the Cu concentration. Particularly, the catalyst Au1Cu9@CeO2 containing quite a low amount of Au species demonstrated the best catalytic activity and high selectivity and stability, which is strongly desired for cost-effective catalysts.

•H2-evolution is markedly promoted with doping minute quantity of π-conjugate PDI molecules to the Zn0.5Cd0.5S semiconductor.•Mechanism is proposed that PDI functions as an electron collector and transporter to inhibit the charge recombination.•The charge separation and the H2-evolution efficiency depend heavily on the modulated molecular structure of PDIs.On account of the steps of water splitting reaction, suppression of the electron–hole recombination is one key factor to improve the photocatalytic activity. Composites with π-conjugated molecules are promising to inhibit the recombination process by delocalization of the photo-generated electron. In this study, we synthesized perylenetetracarboxylic diimide (PDI) decorated Zn0.5Cd0.5S hybrid photocatalysts to reveal the function of the PDI in promoting the charge separation by electron transfer process. To understand the mechanisms that govern the carrier separation, transport, extraction and their recombination within this inorganic/organic nanocomposite, three PDIs, namely PDI-1, PDI-2 and PDI-3 with different molecular structure were loaded in the Zn0.5Cd0.5S, respectively, and were investigated comparatively. It is demonstrated that PDIs play great roles in increasing the specific surface area and stabilizing the photogenerated electron–hole pairs, resulting in enhancement of the overall hydrogen production rate. The highest rate of 1.32 mmol h−1 g−1 was achieved on the Zn0.5Cd0.5S-PDI-1 composite, which is 6 times higher than the pristine Zn0.5Cd0.5S, owning to the effective photo-driven electron transport between the Zn0.5Cd0.5S and the PDI-1. The results of the current work are relevant in understanding the nature of charge-transfer pathways in photoinduced catalysis.Perylenetetracarboxylic diimide functions as an electron collector and transporter from the Zn0.5Cd0.5S semiconductor to greatly promote the catalyzed H2-evlution under visible light illumination by inhibiting the charge recombination.

In situ morphological transition and turn-on fluorescence of self-assembled NDI derivatives driven by hydrazine hydrate are realized through H-bonding and charging of aromatic building blocks, demonstrating a stimuli-responsive supramolecular system useful for visual detection of hydrazine hydrate.

Supercoils self-assembled from two achiral molecular components have been synthesized in order to better understand the structure and functionality of this chiral supramolecular association. The two-component synthon is a complementary hydrogen-bond pair having one melamine core and three photoaddressable azobenzene units, which self-assembled into long and helical fibers with intrinsic conformational chirality. Hierarchical self-assembly was presented where one-dimensional helixes bundled into a higher order optically active supercoil structure, leading to spontaneous chiral symmetry breaking and amplification of chirality. Circular dichroism (CD) spectroscopy, transmission electron microscopy (TEM) and atomic force microscopy (AFM), as well as X-ray diffraction (XRD) techniques reveal the chiral nature of the assembly. Accordingly, a plausible mechanism of a hierarchical self-assembly process has been proposed, which presents a valid approach for constructing supramolecular chirality from achiral molecular building blocks through non-covalent interactions. The morphology and chirality of the supercoils demonstrate photoresponsivity, which is induced from the photoisomerization of the azobenzene components within the self-assembled nanostructures. Furthermore, the supercoil is a highly proton-conductive material because of its highly ordered structure and the proton transfer between the H-bonded melamine and azobenzene units within this two-component association.

Core–shell (CS) nanoparticles (NPs) have many applications in areas such as catalysis and sensing. The utilization of hollow nanostructured materials as the supports, such as nanotubes (NT), is a growing interest to anchor NPs. Generally, several steps are necessary to prepare CS NP–NT nanocomposites, including: (i) the synthesis of CS NPs; (ii) the preparation of NTs; and (iii) the combination of CS NPs and NTs. Moreover, surface modifications with organic ligands are often involved during the synthesis of CS NPs and/or the step combining CS NPs and supports. Here we report a facile method for in situ growth of Au@CeO2 CS NPs and CeO2 NTs by mixing HAuCl4 and Ce(OH)CO3 nanorods under mild conditions. The formation of Au–CeO2 nanocomposite is due to the interfacial oxidation–reduction reaction between HAuCl4 and Ce(OH)CO3, where Au(III) in HAuCl4 is reduced to Au(0) by Ce(III) in Ce(OH)CO3, while Ce(III) is oxidized into Ce(IV), followed by hydrolysis to generate CeO2. The slow hydrolysis rate of Ce(IV) leads to the coverage of CeO2 on the Au NPs, and on the residual Ce(OH)CO3 surface, developing into Au@CeO2 and Ce(OH)CO3@CeO2 CS structures. Further depletion/dissolution of Ce(OH)CO3 results in Au@CeO2 CS NP–CeO2 NT nanocomposite eventually. The advantages of our synthetic strategy are independent of foreign reducing agents and additional surface modification. And, such CS NP–NT nanocomposite can be obtained in one step, simplifying the synthesis procedures greatly. This method based on interfacial oxidation–reduction may be employed as a unique entry to other nanocomposites.

Supramolecular chirality has generally been fabricated by an aggregation process of chiral building blocks. Herein, we report the fabrication of the soft chiral nanotubes by chiral self-assembly, exclusively from a novel designed achiral carboxylic-substituted bolaamphiphilic azobenzene. Based on the studies with UV-vis absorption, circular dichroism (CD), transmission electron microscopy (TEM), and X-ray diffraction (XRD) spectra, a plausible mechanism by which a chirally helical shape emerges from the nonsymmetric packing of an achiral molecule has been proposed. Our results demonstrate a valid approach for correlating the molecular structure to the macroscopic properties, in which, by ingenious molecular design, supramolecular chirality can be achieved from achiral molecular building blocks. It was further revealed that the morphology and chirality of the self-assembled nanostructures change in response to external stimuli such as light and heat. This should open an avenue for a good understanding of the ways in which structural variation affects self-assembled structures at the molecular level. We should also find potential applications as smart carriers for the controlled release and site-specific targeting of the loading, modulated by environmental stimuli.

Ceria hollow nanocrystals with single-crystalline-like structure were prepared facilely by solvothermal synthesis free from templates, in which CeCl3 was proposed to hydrolyze with the assistance of poly(vinylpyrrolidone) (PVP) in the water–ethanol mixed solvent. TEM and SEM analyses demonstrated the formation of CeO2 hollow nanocrystals ascribed to a dissolution–recrystallization mechanism. It was found that both the counter ions of the cerium sources (e.g.CeCl3, Ce(NO3)3 or (NH4)2Ce(NO3)6) and the composition of the solvent mixture were critical factors in determining the final morphology of CeO2. The as-prepared CeO2 hollow nanocrystals with high crystallinity exhibited a higher catalytic activity and thermal stability towards CO oxidation.

A bisthienylethene-functionalized perylene diimide (BTE-PDI) photochromic dyad was synthesized for self-assembly into 1-D nanotubes by a reprecipitation method. SEM and TEM observations showed that the nanotubes were formed from their 0-D precursors of hollow nanospheres. HR-TEM images revealed that both the nanospheres and the nanotubes have highly ordered lamellar structure, indicating the hierarchical process during assembly. The IR and XRD results revealed that DAE-PDI molecules were connected through intermolecular hydrogen bonds to form building blocks that self-assembled into nanostructures. Electronic absorption and fluorescence spectroscopic results indicated the H-aggregate nature of the self-assembled nanostructures. Competition and cooperation between the dipole−dipole interaction, intermolecular π−π stacking, and hydrophilic/hydrophobic interaction are suggested to result in nanostructures. Reconstruction was found to happen during the morphology transition progress from the 0-D nanospheres to the 1-D nanotubes, which was driven by donor−acceptor dipole−dipole interactions. Green emission at 520 nm originating from the DAE subunit was observed for the aggregates of vesicles and nanotubes, which could be regulated by photoirradiation with 365 nm light, suggesting the nanoaggregates to be photochromic switches.

Core–shell (CS) nanoparticles (NPs) have many applications in areas such as catalysis and sensing. The utilization of hollow nanostructured materials as the supports, such as nanotubes (NT), is a growing interest to anchor NPs. Generally, several steps are necessary to prepare CS NP–NT nanocomposites, including: (i) the synthesis of CS NPs; (ii) the preparation of NTs; and (iii) the combination of CS NPs and NTs. Moreover, surface modifications with organic ligands are often involved during the synthesis of CS NPs and/or the step combining CS NPs and supports. Here we report a facile method for in situ growth of Au@CeO2 CS NPs and CeO2 NTs by mixing HAuCl4 and Ce(OH)CO3 nanorods under mild conditions. The formation of Au–CeO2 nanocomposite is due to the interfacial oxidation–reduction reaction between HAuCl4 and Ce(OH)CO3, where Au(III) in HAuCl4 is reduced to Au(0) by Ce(III) in Ce(OH)CO3, while Ce(III) is oxidized into Ce(IV), followed by hydrolysis to generate CeO2. The slow hydrolysis rate of Ce(IV) leads to the coverage of CeO2 on the Au NPs, and on the residual Ce(OH)CO3 surface, developing into Au@CeO2 and Ce(OH)CO3@CeO2 CS structures. Further depletion/dissolution of Ce(OH)CO3 results in Au@CeO2 CS NP–CeO2 NT nanocomposite eventually. The advantages of our synthetic strategy are independent of foreign reducing agents and additional surface modification. And, such CS NP–NT nanocomposite can be obtained in one step, simplifying the synthesis procedures greatly. This method based on interfacial oxidation–reduction may be employed as a unique entry to other nanocomposites.

Supported bimetallic nanocomposites are promising in photocatalysis due to the multi-component interaction between metals and between metals and carriers. By an in situ reduction method, a series of monometallic (Au@CeO2 and Cu@CeO2) and bimetallic catalysts (Au8Cu2@CeO2, Au5Cu5@CeO2 and Au1Cu9@CeO2) are obtained, with a metallic core and a CeO2 shell structure. The in situ reduction method developed in this work is a one-step strategy to obtain supported multi-component nanomaterials with a core–shell structure. Photo-assisted oxidation of benzyl alcohol to benzaldehyde was performed over the above samples, and the reactivity presented a parabolic plot with the increase of Cu content, reaching the summit for Au1Cu9@CeO2. Inpouring of Cu enlarged the specific surface area and generated more oxygen vacancies, which are significant for improving the photocatalytic performance. The intimate correlation between the reactivity and the concentration of the oxygen vacancies provides that the surface of the CeO2 support with a large number of oxygen vacancies serves as the active site for aerobic oxidation. Accordingly, a mechanism is proposed for the photocatalytic efficiency enhancement as the function of the Cu concentration. Particularly, the catalyst Au1Cu9@CeO2 containing quite a low amount of Au species demonstrated the best catalytic activity and high selectivity and stability, which is strongly desired for cost-effective catalysts.

In situ morphological transition and turn-on fluorescence of self-assembled NDI derivatives driven by hydrazine hydrate are realized through H-bonding and charging of aromatic building blocks, demonstrating a stimuli-responsive supramolecular system useful for visual detection of hydrazine hydrate.

Supercoils self-assembled from two achiral molecular components have been synthesized in order to better understand the structure and functionality of this chiral supramolecular association. The two-component synthon is a complementary hydrogen-bond pair having one melamine core and three photoaddressable azobenzene units, which self-assembled into long and helical fibers with intrinsic conformational chirality. Hierarchical self-assembly was presented where one-dimensional helixes bundled into a higher order optically active supercoil structure, leading to spontaneous chiral symmetry breaking and amplification of chirality. Circular dichroism (CD) spectroscopy, transmission electron microscopy (TEM) and atomic force microscopy (AFM), as well as X-ray diffraction (XRD) techniques reveal the chiral nature of the assembly. Accordingly, a plausible mechanism of a hierarchical self-assembly process has been proposed, which presents a valid approach for constructing supramolecular chirality from achiral molecular building blocks through non-covalent interactions. The morphology and chirality of the supercoils demonstrate photoresponsivity, which is induced from the photoisomerization of the azobenzene components within the self-assembled nanostructures. Furthermore, the supercoil is a highly proton-conductive material because of its highly ordered structure and the proton transfer between the H-bonded melamine and azobenzene units within this two-component association.