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Photoresponsive self-assembling process of rod-coil amphiphiles with spiropyran units was investigated, and achieved visual recognition of copper ions.

Self-assembled nanomaterials composed of amphiphilic oligomers with functional groups have been applied in the fields of biomimetic chemistry and on-demand delivery systems. Herein, we report the assembly behavior and unique properties of an emergent n-shaped rod-coil molecule containing an azobenzene (AZO) group upon application of an external stimulus (thermal, UV light). The n-shaped amphiphilic molecules comprising an aromatic segment based on anthracene, phenyl linked with azobenzene groups, and hydrophilic oligoether (chiral) segments self-assemble into large strip-like sheets and perforated-nanocage fragments in an aqueous environment, depending on the flexible oligoether chains. Interestingly, the nano-objects formed in aqueous solution undergo a morphological transition from sheets and nanocages to small one-dimensional nanofibers. These molecules exhibit reversible photo- and thermal-responsiveness, accompanied by a change in the supramolecular chirality caused by the conformational transitions of the rod backbone. The architecture of n-shaped amphiphilic molecules with a photosensitive group makes them ideal candidates for intelligent materials for applications in advanced materials science.

We demonstrate humidity-responsive structural colors with ultrafast rise and recovery times of 20 and 36 ms from a random arrangement of amorphous titania microspheres. A large fraction of the amorphous titania microsphere is shown to be nanoporous, permitting significant changes to the effective permittivity upon water uptake and thereby altering its scattering cross section. Individually, the microspheres are indistinguishable by scattered light in dry and humid environments, but collectively display color contrast in both environments as the incoherent scattering from each particle allows the individual scattering cross sections to be summed in the far-field, exposing smoothly varying spectral features unique to the humidity environment. Time-resolved humidity response measurements of the microspheres show ultrafast response times due to the fast diffusion dynamics of water molecules in the titania nanoporous network. Absence of spatial ordering among microspheres for generating color also facilitates the fabrication of a simple binary humidity-responsive display, optimized in speed and signal at only a monolayer coverage of particles. As the sensing relies on changes in the scattering cross-section, signal detection can be performed using a monochromatic light source that demands little power (30 μW in our demonstration). Such results suggest intriguing possibilities for realizing cheap, simple, ultrafast and power-efficient colorimetric humidity sensors using structural colors from disordered systems.

The Ga/Zn oxynitride solid solution [(GaN)1–x(ZnO)x] is one of the promising visible light harvesting photocatalysts for overall water splitting. A series of (GaN)1–x(ZnO)x (0.11 ≤ x ≤ 0.33) compounds are synthesized by calcining the carbonate-type Zn/Ga-LDH precursor with and without sodium carbonate flux at 850 °C for 8–14 h under a NH3 gas flow. The solid solutions without flux are determined to be low in crystallinity, but platelike morphology with preferred orientation could be observed. On the other hand, those with flux turn out to be better in crystallinity, and eventually exhibit significantly higher photocatalytic activity for overall water splitting under visible light irradiation than those without flux. In addition, the band gap energies can also be engineered from 2.57 to 2.72 eV by changing a synthetic parameter such as nitridation time. It is, therefore, suggested that the present new approach can offer new opportunities for designing the next generation of photocatalytic systems.

The nanostructure and morphology of mesoporous carbon obtained from a newly designed porous geopolymer template were characterized by low-voltage high-resolution scanning electron microscopy. The present porous carbon exhibited a large specific surface area and pore volume, resulting in a high CO2 uptake capacity.

A novel efficient and safe methodology to sanitize algae in natural water without secondary pollution is developed by fabricating floating graphene-inorganic hybrid films. Two kinds of floating freestanding hybrid films of layered titanate-graphene with efficient algae-killing functionality are fabricated by vacuum-assisted filtration of mixed colloidal suspensions of reduced graphene oxide (rG-O) nanosheets and exfoliated layered titanate nanosheets. Both the titanate nanosheets with lepidocrocite- and trititanate-type structures form homogeneous colloidal mixtures and hybrid freestanding films with rG-O nanosheets. The incorporation of a layered titanate nanosheet enhances the algae-killing activity of the graphene freestanding film, highlighting the beneficial role of photocatalytically-active titanate nanosheet. In comparison to the trititanate nanosheet, the lepidocrocite-type titanate nanosheet is more effective as a building block for enhancing the algae-killing activity of graphene film and for forming a novel nanoblade structure on the surface of the graphene film. The observed high sterilization functionality of the present layered titanate-graphene hybrid films is attributable to both the formation of the novel sharp nanoblade structure and the photocatalytic activity of layered titanate. The present result underscores that hybridization between graphene and photocatalytically-active inorganic nanosheets can provide a powerful way to explore pollution-free recoverable matrix efficient for removing harmful microorganisms in natural water. Refereed/Peer-reviewed

Correction for ‘Water-floating nanohybrid films of layered titanate–graphene for sanitization of algae without secondary pollution’ by In Young Kim et al., RSC Adv., 2016, 6, 98528–98535.