title: Hydrothermal continuous flow synthesis and exfoliation of NiCo layered double hydroxide nanosheets for enhanced oxygen evolution catalysis.
abstract: We report the controlled synthesis of NiCo layered double hydroxide (LDH) nanoplates using a newly developed high temperature high pressure hydrothermal continuous flow reactor (HCFR), which enables direct growth onto conductive substrates in high yield and, most importantly, better control of the precursor supersaturation and, thus, nanostructure morphology and size. The solution coordination chemistry of metal-ammonia complexes was utilized to synthesize well-defined NiCo LDH nanoplates directly in a single step without topochemical oxidation. The as-grown NiCo LDH nanoplates exhibit a high catalytic activity toward the oxygen evolution reaction (OER). By chemically exfoliating LDH nanoplates to thinner nanosheets, the catalytic activity can be further enhanced to yield an electrocatalytic current density of 10 mA cm(-2) at an overpotential of 367 mV and a Tafel slope of 40 mV dec(-1). Such enhancement could be due to the increased surface area and more exposed active sites. X-ray photoelectron spectroscopy (XPS) suggests the exfoliation also caused some changes in electronic structure. This work presents general strategies to controllably grow nanostructures of LDH and ternary oxide/hydroxides in general and to enhance the electrocatalytic performance of layered nanostructures by exfoliation.
authors: Department of Chemistry, University of Wisconsin-Madison , 1101 University Ave., Madison, Wisconsin 53706, United States.
authors: Hanfeng
authors: H
authors: Liang
authors: Fei
authors: F
authors: Meng
authors: Miguel
authors: M
authors: Cabán-Acevedo
authors: Linsen
authors: L
authors: Li
authors: Audrey
authors: A
authors: Forticaux
authors: Lichen
authors: L
authors: Xiu
authors: Zhoucheng
authors: Z
authors: Wang
authors: Song
authors: S
authors: Jin
keywords: Layered double hydroxide (LDH); exfoliation; hydrothermal continuous flow synthesis; nanoplates; nanosheets; oxygen evolution reaction (OER)