Dielectric material is an important material for film capacitors. However, the progress of this material is either impeded by its low dielectric constant, high loss tangent, or insufficient flexibility. In this work, PVA/GO film with alternating layer structure was fabricated by Spin-Coating-Assembly (SCA) method. This alternating layer structure not only benefits forming numerous microscale capacitors which improve ε value a lot, but also helps eliminate perpendicular contact of GO and prevents the formation of conductive pathways. Thus, compared with pure PVA, significantly increased dielectric permittivity and a low loss tangent were simultaneously observed for the PVA/GO film. The ratio of dielectric permittivity to loss tangent increased from 68 to 165. These films might be potential flexible dielectric materials for advanced electrical devices such as embedded capacitors.
Min Wang,Haitao Zhao,Limin Zhao,Jianmin Dou,Xingliang Yin
CdS, as a visible-light responsible photocatalyst , has gained considerable attentions for its relatively narrow bandgap and negative conduction band edge. However, its photocatalytic activity is hindered by challenges such as severe charge recombination, insufficient active sites and poor stability. In this work, a robust strategy is proposed to optimize the transfer channel for charge carriers and enhance the active sites by heterojunction and cocatalyst engineering. The well-designed GO/CdS/MoS 2 shows remarkable durability (20 h without significant loss of H 2 production rate) with a high photocatalytic H 2 production rate of 1.45 mmol h −1 g −1 (about 6.6-fold enhancement compared with CdS) at GO content of 0.1 wt% and MoS 2 loading amount of 5.0 wt%. The bolstered H 2 production rate is attributed to the augmented transfer channels of mass owing to the holey structure of GO , the enhanced active sites since the introduction of MoS 2 , and the unidirectional transfer of electrons from CdS to MoS 2 , which is ascribed to the built-in electric field in the CdS/MoS 2 interface. Thanks to the directional transfer of holes from CdS to GO in the GO/CdS interface, the assemblage of holes in CdS is prevented, thus contributing to the amplified stability GO/CdS/MoS 2 . Our findings offer insights for the enhanced photocatalytic activity of CdS based photocatalysts, which may inspire the development of the heterostructure photocatalysts for solar-to-fuel conversion.
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