A luminescence ferroelectric oxide, Na(0.5)Bi(2.5)Nb2O9 (NBN), system with bismuth layer structure introduced by lanthanide ion (Er(3+)) has been demonstrated to exhibit reversible, high-contrast luminescence modulation (95%) and excellent fatigue resistance based on visible-light-driven photochromism (407 nm or sunlight). The coloration and decoloration process can be effectively read out by dual modes, upconversion and downshifting, and reversibly converted between green and dark gray by alternating visible light or sunlight irradiation and thermal stimulus. The luminescence modulation degree upon photochromic reactions is strongly dependent upon irradiation light wavelength and irradiation time. After undergoing several cycles, there are no significant degradations, showing high reversibility. Considering its high-contrast photoswitchable luminescence feature and intrinsic ferroelectricity of NBN host, NBN-based multifunctional materials can be suggested as a promising candidate for new potentials in photonic storage and optoelectronic multifunctional devices.

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In this paper, a series of the functionalized graphenes, such as graphene oxide (GO), reduced graphene oxide (rGO), carboxylated graphene oxide (GOCOOH), reduce carboxylated graphene oxide (rGOCOOH), fluorinated graphene oxide (GOF), and reduce fluorinated graphene oxide (rGOF), were successfully fabricated, and were introduced into the Poly (vinylidene fluoride) (PVDF) matrix to form composites. The effects of these functional groups on dielectric properties of GO/PVDF composites were systematically investigated. The results show that the reduced functional graphene/PVDF composites (rGOCOOH/PVDF, rGOF/PVDF) exhibit more excellent dielectric properties than that of composite samples without undergoing the reduction reaction (GOCOOH/PVDF, GOF/PVDF). The reduced samples not only possess high dielectric constant, but also maintain lower dielectric loss. And, the rGOCOOH/PVDF composite has better dielectric properties ( r = 17.64, tg = 0.031) than others, due to strong interfacial and dipolar interactions between PVDF matrix and fillers. These results could be used as a guide to tune dielectric properties of polymer/ graphene composites for their applications in embedded capacitors.

The reasonable design of metal compound electrocatalysts is proved to be a good way to accelerate the sluggish conversion kinetics of polysulfides for high performance lithium-sulfur (Li-S) batteries. Since metal...

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