The tantalizing prospect of harnessing the unique properties of graphene crumpled nanostructures continues to fuel tremendous interest in energy storage and harvesting applications. However, the paper ball-like, hard texture, and closed-sphere morphology of current 3D graphitic nanostructure production not only constricts the conductive pathways but also limits the accessible surface area. Here, we report new insights into electrohydrodynamically-generated droplets as colloidal nanoreactors in that the stimuli-responsive nature of reduced graphene oxide can lead to the formation of crumpled nanostructures with a combination of open structures and doubly curved, saddle-shaped edges. In particular, the crumpled nanostructures dynamically adapt to non-spherical, polyhedral shapes under continuous deposition, ultimately assembling into foam-like microstructures with a highly accessible surface area and spatially interconnected transport pathways. The implementation of such crumpled nanostructures as three-dimensional rear contacts for solar conversion applications realize benefits of a high aspect ratio, electrically addressable and energetically favorable interfaces, and substantial enhancement of both short-circuit currents and fill-factors compared to those made of planar graphene counterparts. Further, the 3D crumpled nanostructures may shed lights onto the development of effective electrocatalytic electrodes due to their open structure that simultaneously allows for efficient water flow and hydrogen escape.
Bibliographical noteFunding Information:
The authors gratefully acknowledge the research award from the Doctoral New Investigator Award from ACS Petroleum Fund (ACS PRF 54717-DNI10, V.T.), Ministry of Science and Technology of Taiwan (NSC 101-2112-M-009-021-MY3, Y.C.C.) and the Center for Interdisciplinary Science under the MOE-ATU project for NCTU (Y.C.C.). Characterization and fabrication of ultracapacitor in this work were performed as a user project (#3192 and #3715) at the Molecular Foundry, Lawrence Berkeley National Lab, supported by the Office of Basic Energy Sciences, of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231. Y.C would like to acknowledge the fellowship from NASA MIRO Center under Contract No. NNX15AQ01A.
© The Author(s) 2016.
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