ε-Polylysine organic ultra-long room-temperature phosphorescent materials based on phosphorescent molecule doping.

Achieving long-lived room-temperature phosphorescence from pure organic amorphous polymers is attractive, and afterglow materials with colour-tunable and multiple-stimuli-responsive afterglow are particularly important, but only few materials with these characteristics have been reported so far. Herein, a facile and general method is reported to construct a series of ε-polylysine (ε-PL)-based afterglow materials with tunable colour (from blue to red) and long life. By doping guest molecules into ε-PL to obtain composite materials, the polymer matrix provides a rigid environment for luminescent groups, resulting in amorphous polymers with different RTPs. In this system, the materials even have impressive humidity-stimulated responses, and the phosphorescence emission exhibits excitation-dependent and time-dependent properties. The humidity-responsive afterglow is caused by the destruction of hydrogen bonds and quenching of triplet excitons. The time-dependent afterglow should stem from the formation of diversified RTP emissive species with comparable but different lifetimes. 9,10-diaminophene has Ex-De properties in the film doping state. With the change of excitation wavelength (254 nm to 365 nm), the emission wavelength shifts from 461 nm to 530 nm, accompanied by the change of emission colour from blue to green. In addition, the phosphorescence life of the film is the longest, up to 2504.7 ms, and the afterglow lasts up to 15 s, which is conducive to its applications in anti-counterfeiting and information encryption.

Modified photoanode by in situ growth of covalent organic frameworks on BiVO4 for oxygen evolution reaction.

The development of efficient oxygen evolution reaction (OER) catalysts is of great significance because the water oxidation reaction at the photoanode is the rate-determining step in photoelectrocatalytic (PEC) water splitting. Herein, two hybrid photoanodes named BiVO4/COF-Azo and BiVO4/COF-Ben were prepared by in situ solvothermal growth on a modified BiVO4 photoanode. Characterization results revealed that the Azo and Ben COFs could match with BiVO4 well to form heterojunctions, which could effectively enhance the separation efficiency of photogenerated carriers. Also, the smaller impedance of the composite photoanodes and faster kinetics of the water oxidation reaction promoted the charge transmission and enhanced the reaction efficiency of the surface-reaching holes, respectively. As a result, the composite photoanodes exhibited a larger photocurrent and more negative onset potential compared to the pristine BiVO4. This work not only provides a new strategy to construct efficient hybrid photoanodes, but also expands the applications of COFs.