For the first time, organic semiconducting polymer dots (Pdots) based on poly[(9,9'-dioctylfluorenyl-2,7-diyl)-co-(1,4-benzo-{2,1',3} thiadiazole)] (PFBT) and polystyrene grafting with carboxyl-group-functionalized ethylene oxide (PS-PEG-COOH) are introduced as a photocatalyst towards visible-light-driven hydrogen generation in a completely organic solvent-free system. With these organic Pdots as the photocatalyst, an impressive initial rate constant of 8.3 mmol h(-1)  g(-1) was obtained for visible-light-driven hydrogen production, which is 5-orders of magnitude higher than that of pristine PFBT polymer under the same catalytic conditions. Detailed kinetics studies suggest that the productive electron transfer quench of the excited state of Pdots by an electron donor is about 40 %. More importantly, we also found that the Pdots can tolerate oxygen during catalysis, which is crucial for further application of this material for light-driven water splitting.

Visible-light-driven chemical transformations via photocatalysis have witnessed an explosive growth in the past decade, accompanying the enormous development of the photocatalyst design. Among the intensely investigated systems, molecular photocatalysts as transition-metal complexes and conjugated organic dyes have been established as efficient homogeneous photocatalytic systems for organic photoredox reactions. Nonetheless, heterogeneous photocatalysts possess considerable advantages such as being highly stable, easily separable, and reusable. Especially, the organic, macromolecular heterogeneous photocatalysts have emerged as a nontoxic and potentially more environmentally friendly alternative to the traditional catalytic systems. Among them, poly(benzothiadiazoles) and their derivatives have demonstrated the ability to catalyze various organic photoredox reactions under visible-light irradiation. In this Review, the recent development of metal-free and heterogeneous photocatalytic systems based on poly(benzothiadiazoles) and their derivatives is summarized. An overview of organic photoredox reactions mediated via radicals obtained from the photogenerated electron and hole of the photocatalysts is given, and the underlying mechanisms of photochemical transformations are illuminated. The structural design principles of poly(benzothiadiazoles) for targeted photoredox reactions are also discussed.

Tough and self-recoverable hydrogel membranes with micrometer-scale thickness are promising for biomedical applications, which, however, rarely be realized due to the intrinsic brittleness of hydrogels. In this work, for the first time, by combing noncovalent DN strategy and spin-coating method, we successfully fabricated thin (thickness: 5-100 µm), yet tough (work of extension at fracture: 10 5 -10 7 J m −3 ) and 100% self-recoverable hydrogel membranes with high water content (62-97 wt%) in large size (≈100 cm 2 ). Amphiphilic triblock copolymers, which form physical gels by self-assembly, were used for the first network. Linear polymers that physically associate with the hydrophilic midblocks of the first network, were chosen for the second network. The internetwork associations serve as reversible sacrificial bonds that impart toughness and self-recovery properties on the hydrogel membranes. The excellent mechanical properties of these obtained tough and thin gel membranes are comparable, or even superior to many biological membranes. The in vitro and in vivo tests show that these hydrogel membranes are biocompatible, and postoperative nonadhesive to neighboring organs. The excellent mechanical and biocompatible properties make these thin hydrogel membranes potentially suitable for use as biological or postoperative antiadhesive membranes.

Cerium oxide (CeO(2)) nanoparticles display excellent antioxidant properties by scavenging free radicals. However, some studies have indicated that they can cause an adverse response by generating reactive oxygen species (ROS). Hence, it is important to clarify the factors that affect the oxidant/antioxidant activities of CeO(2) nanoparticles. In this work, we report the effects of different buffer anions on the antioxidant activity of CeO(2) nanoparticles. Considering the main anions present in the body, Tris-HCl, sulfate, and phosphate buffer solutions have been used to evaluate the antioxidant activity of CeO(2) nanoparticles by studying their DNA protective effect. The results show that CeO(2) nanoparticles can protect DNA from damage in Tris-HCl and sulfate systems, but not in phosphate buffer solution (PBS) systems. The mechanism of action has been explored: cerium phosphate is formed on the surface of the nanoparticles, which interferes with the redox cycling between Ce(3+) and Ce(4+). As a result, the antioxidant activity of CeO(2) nanoparticles is greatly affected by the external environment, especially the anions. These results may provide guidance for the further practical application of CeO(2) nanoparticles.

A dependence of oxygen reduction reaction activity and generation of OH radicals upon the composition of Pt-Co alloy electrocatalyst supported on graphene was found in alkaline solutions.