Preparation of water-dispersed monolayer LDH nanosheets by SMA intercalation to hinder the restacking upon redispersion in water.

We present a novel method for preparing water-dispersed monolayer layered double hydroxide (LDH) nanosheets (m-LDH). By intercalating styrene-maleic anhydride copolymer (SMA) into LDH, we obtained m-LDH through a simple aging step that produced stable, translucent colloidal solutions. After drying, the resulting powder can be redispersed in water to recover the m-LDH monolayer structure. To our knowledge, this is the first report of immediate recovery of the m-LDH monolayer structure from dried powder after redispersion in water. Our method may have significant implications for preparing and utilizing m-LDH nanosheets in various applications.

Nanocrystalline Cellulose Cures Constipation via Gut Microbiota Metabolism.

Constipation can seriously affect the quality of life and increase the risk of colorectal cancer. The present strategies for constipation therapy have adverse effects, such as causing irreversible intestinal damage and affecting the absorption of nutrients. Nanocrystalline cellulose (NCC), which is from natural plants, has good biocompatibility and high safety. Herein, we used NCC to treat constipation assessed by the black stool, intestinal tissue sections, and serum biomarkers. We studied the effect of NCC on gut microbiota and discussed the correlation of gut microbiota and metabolites. We evaluated the long-term biosafety of NCC. NCC could effectively treat constipation through gut microbiota metabolism, which required a small dosage and did not affect the organs and intestines. NCC could be used as an alternative to medications and dietary fiber for constipation therapy.

Hydrothermal synthesis of a CoIn2S4/g-C3N4 heterojunctional photocatalyst with enhanced photocatalytic H2 evolution activity under visible light illumination.

CoIn2S4, a black semiconducting material, possesses an outstanding visible light response and is employed to modify g-C3N4. A series of CoIn2S4/g-C3N4 heterojunctional photocatalysts are synthesized via a hydrothermal method, whereby cubic CoIn2S4 nanosheets are in situ immobilized on the surfaces of porous g-C3N4 nanosheets. Compared with the pristine g-C3N4 and CoIn2S4, under visible light (λ > 420 nm) irradiation, the CoIn2S4/g-C3N4 composite samples show markedly enhanced photocatalytic activity in hydrogen evolution. Among all of the samples, the 30% CoIn2S4/g-C3N4 sample shows the maximum H2 evolution rates, 5.2 and 23.9 times higher than those of g-C3N4 and CoIn2S4, respectively. The efficient photocatalytic activity of CoIn2S4/g-C3N4 composite photocatalysts is attributed to the formation of an intimate heterostructure, which not only significantly facilitates charge migration, but also enhances visible light absorption. Moreover, a plausible photocatalytic mechanism for the composite photocatalyst has been elucidated. This research provides a novel hint for fabricating visible-light-responsive heterojunction photocatalysts with high performance for energy production.

An oriented built-in electric field induced by cobalt surface gradient diffused doping in MgIn2S4 for enhanced photocatalytic CH4 evolution.

A gradient cobalt-doped MgIn2S4 (MgIn2S4-Co) homojunction photocatalyst was reported, creating an oriented built-in electric field for efficient extraction of photogenerated carriers from the inside to the surface of the photocatalyst. The MgIn2S4-Co photocatalysts showed remarkably enhanced photocatalytic CO2 reduction activity compared with pristine MgIn2S4.

Fabrication of Heterogeneous-Phase Solid-Solution Promoting Band Structure and Charge Separation for Enhancing Photocatalytic CO2 Reduction: A Case of ZnXCa1-XIn2S4.

Photocatalytic CO2 reduction into solar fuels illustrates huge charm for simultaneously settling energy and environmental issues. The photoreduction ability of a semiconductor is closely correlated to its conduction band (CB) position. A homogeneous-phase solid-solution with the same crystal system always has a monotonously changed CB position, and the high CB level has to be sacrificed to achieve a benign photoabsorption. Herein, we report the fabrication of heterogeneous-phase solid-solution ZnXCa1-XIn2S4 between trigonal ZnIn2S4 and cubic CaIn2S4. The ZnXCa1-XIn2S4 solid solutions with orderly tuned photoresponsive range from 540 to 640 nm present a more negative CB level and highly enhanced charge-separation efficiency. Profiting from these merits, all of these ZnXCa1-XIn2S4 solid solutions exhibit remarkably strengthened photocatalytic CO2 reduction performance under visible light (λ > 420 nm) irradiation. Zn0.4Ca0.6In2S4, bearing the most negative CB position and highest charge-separation efficiency, casts the optimal photocatalytic CH4 and CO evolution rates, which reach 16.7 and 6.8 times higher than that of ZnIn2S4 and 7.2 and 3.9 times higher than that of CaIn2S4, respectively. To verify the crucial role of the heterogeneous-phase solid solution in promoting the band structure and photocatalytic performance, another heterogeneous-phase solid-solution ZnXCd1-XIn2S4 has been synthesized. It also displays an upshifted CB level and promoted charge separation. This work may provide a new perspective into the development of an efficient visible-light driven photocatalyst for CO2 reduction and other photoreduction reactions.

Polypyrrole decorated BiOI nanosheets: Efficient photocatalytic activity for treating diverse contaminants and the critical role of bifunctional polypyrrole.

A conducting polymer polypyrrole (Ppy) was first employed to decorate BiOI for fabricating an organic-inorganic hybridized Ppy-BiOI nanocomposite photocatalyst via a facile in situ precipitation strategy at room temperature. The composite and intimate interface was confirmed by FTIR, XPS, SEM, HRTEM and TEM-mapping. In comparison with pristine BiOI, the Ppy-BiOI hybrids present significantly enhanced photocatalytic activity for degradation of Rhodamine B (RhB) under visible light (λ>420nm). Particularly, the Ppy-BiOI composite exhibits an universal photocatalytic performance for removing diverse industrial pollutants and antibiotics, including bisphenol A, 2,4-dichlorophenol, tetracycline hydrochloride and chlortetracycline hydrochloride. The enhanced photocatalytic activity of Ppy-BiOI composite is found attributable to the bifunctional role that Ppy takes. Ppy-BiOI composite has an enhanced specific surface area, which benefits adsorption and generation of more active sites. Notably, high separation and transfer of the photogenerated charge carriers was achieved on the interface between Ppy and BiOI, and the photogenerated hole transfer action of Ppy is demonstrated. Therefore, synergistic effect of adsorption-enrichment and photocatalytic degradation is realized. Our work may offer a guideline to manipulate high-performance Bi-based composite photocatalyst by coupling conducting polymers.

Fuzzy, copper-based multi-functional composite particles serving simultaneous catalytic and signal-enhancing roles.

Multifunctional plasmonic particles serving simultaneously as catalysts and label-free reporting agents are highly pursued due to their great potential in enhancing reaction operational efficiencies. Copper is an abundant and economic resource, and it possesses practical applicability in industries, but no dual-functional copper-based catalytic and self-reporting particles have been reported so far. This study proposes a facile strategy to prepare high-performance dual-functional copper-based composite particles that catalyze reactions and simultaneously serve as a SERS (surface enhanced Raman spectra) active, label-free reporting agent. Polyelectrolyte-modified reduced graphene oxide particles are used as the reactive precursors in the fabrication method. Upon adding Cu(NO3)2 solutions into the precursor dispersions, composite particles comprised by copper/copper oxide core and polyelectrolyte-graphene shell were facilely obtained under sonication. The as-prepared composite particles efficiently catalyzed the conversion of 4-nitrophenol to 4-aminophenol and simultaneously acted as the SERS-active substrate to give enhanced Raman spectra of the produced 4-aminophenol. Taking advantage of the assembling capabilities of polyelectrolyte shells, the composite particles could be further assembled onto a planar substrate to catalyze organic reactions, facilitating their application in various conditions. We expect this report to promote the fabrication and application of copper-based multifunctional particles.

PAH/DAS covalently cross-linked layer-by-layer multilayers: a "nano-net" superstratum immobilizes nanoparticles and remains permeable to small molecules.

A "nano-net" superstratum strategy is developed to stabilize layer-by-layer (LbL) films that incorporate nanoparticles. The superstratum immobilizes silica, gold, or magnetic nanoparticles and at the same time is permeable to small molecules. Unlike most strategies to stabilize LbL multilayers reported in the literature, our strategy does not directly cross-link the nanoparticles and polymers in the adjacent layer, thus circumventing the tedious processes of (surface) modification of the nanoparticles or polymers. The unique advantage of our strategy is further employed in the preparation of a model functional device, where mesoporous silica nanoparticles are held in the composite multilayers with enhanced stabilities. A model drug, methylene blue, is then loaded in large amounts due to the porous structure of the silica particles, and could be released in a delayed manner up to 55 h.

Synthesis of starch-g-lactic acid copolymer with high grafting degree catalyzed by ammonia water.

The study of starch-g-lactic acid copolymer has gained much attention for its completely degradable property, but its intricate synthetic procedure and low graft degree inhibited its further application. In this work, the synthesis of starch-g-lactic acid copolymer was attempted via the catalysis of ammonia water by one-step process, and the structure of starch-g-lactic acid copolymer was characterized by means of IR, (13)C NMR and HMBC. The synthetic conditions were optimized as follows, the starch was activated for 2h at 80°C at first, starch and lactic acid with weight ratios of 1:4 reacted for 4h at 90°C in vacuum. The starch-g-lactic acid copolymer can be finally obtained with graft degree of starch 58.9%.

Preparation and properties of Starch-g-PLA/poly(vinyl alcohol) composite film.

Starch/lactic acid graft copolymer (Starch-g-PLA) was prepared by the in situ copolymerization of starch grafted with lactic acid catalyzed with sodium hydroxide, and then mixed with poly(vinyl alcohol) (PVA) to get composite films. The structures of the graft copolymer and composite films were characterized by Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD) and scanning electron microscopy (SEM). The mechanical properties, water resistance, and thermal stability were also investigated. It was found that the compatibility of Starch-g-PLA and PVA was better than that of starch and PVA in the composite films. The tensile strength and elongation at break of the Starch-g-PLA/PVA composite film increased by 69.15% and 84.22%, respectively, while the water absorption decreased by 50.39%, which overcame the shortcomings of hydrophilicity and poor mechanical properties of Starch/PVA film. Thermogravimetric analysis (TGA) also showed that the thermal stability of Starch-g-PLA/PVA film was improved compared with Starch/PVA film.