Nanocomposites have the elite features of polymers and nanofillers. Hybrid nanofillers with a high dielectric constant (high-k) have attracted broad attention in energy storage applications. Besides high-k, hybrid nanofillers must have a low dielectric loss, high breakdown strength (Eb), easy fabrication process, green or eco-friendly nanomaterials, low cost, lightweight, and highly competent for different energy applications. Polymers with good chemical stability, high Eb, good processability, and low dielectric loss are good choices for use as polymer-based energy storage material. Although most polymers suffer from low dielectric constant, by introducing significant high-k fillers into polymer matrixes, this problem could be solved. Unfortunately, achieving high-k often requires a high loading nanofillers, leading to a decrease in the Eb of the composites. In this chapter, the use of a hybrid nanofiller strategy is reviewed to overcome this issue. The reviewed data show by incorporation of hybrid filler, not only Eb, dielectric constant, and energy density would be improved, but also lower energy loss would be achieved. 

Solar fuel generation based on first-row transition metal catalysts

https://www.sciencedirect.com/science/article/abs/pii/B9780323954945000070

The demand for energy from renewable sources is soaring so that emissions can be minimized as soon as possible. We present the recent progress in the photoelectrochemical techniques for solar fuel generation using first-row transition metal catalysts based on iron (Fe) and manganese (Mn). In the photoelectrochemical systems, semiconductor materials are explored to fabricate both photoanode and photocathode such as Fe2O3/Fe2TiO5, TiO2-FeMnP, and Zn0.85Mn0.15O. Moreover, the investigation of natural photosynthesis for CO2 reduction opens new windows to prepare new molecular catalysts to produce green energy. Subsequently, we summarized the molecular water oxidation catalysts for H2 production based on Mn and Fe, which are inspired by nature. Further, an insightful overview of the photoelectrochemical CO2 conversion by sunlight using different photocathode and molecular catalysts is also presented.