Alternate Restacking of 2 D CoNi Hydroxide and Graphene Oxide Nanosheets for Energetic Oxygen Evolution

Abstract

Morphology and composition tuning of layered materials is evaluated to influence their electrochemical performance for energy storage and conversion applications. Layered Co1−xNix hydroxides (x=0, 1/2, 1/3, 1/4, 1) of three different morphologies—nanocones, 2 D nanosheets obtained by the rapid exfoliation of nanoconical counterparts, and 2 D superlattice‐like nanostructures alternately restacked by the oppositely charged hydroxide and graphene oxide (GO) nanosheets—have been systematically investigated for electrocatalytic oxygen oxidation. High activity is obtained with the 2 D Co2/3Ni1/3 hydroxide nanosheets/GO superlattice (Co2/3Ni1/3NS–GO), achieving a current density of 10 mA cm−2 at a low overpotential of 259 mV accompanied by a small Tafel slope of 35.7 mV dec−1, surpassing nanocones and 2 D nanosheets, as well as the congeneric heterostructured Co1−xNix hydroxide nanosheets/GO nanoarchitectures (Co1−xNixNS–GO; x=0, 1/2, 1/4, 1) and the commercial RuO2 electrocatalyst. The outstanding activity of Co2/3Ni1/3NS–GO superlattice uncovers the combined merits of 2 D superlattice‐like structure and composition optimization for electrocatalysis, providing a strategy for developing high‐performance electrochemical materials by rational morphology and composition design.

Monolayer Iron and Iron-Rich Hydroxide Nanosheets Exfoliated from High-Quality Green Rust for Enhanced Electrocatalytic Oxygen Evolution Reaction

“…As shown in Figure a,b, the atomic force microscopy (AFM) image and corresponding height profiles indicate a thickness of about 0.8 ± 0.1 nm and a lateral size of hundreds of nanometers. The thickness is consistent with previous reports on unilamellar LDH nanosheets. − Synchrotron in-plane XRD collected from the as-prepared FeFe LDH NS deposited on a Si substrate provides precise information on a 2D atomic lattice (Figure c). Two diffraction peaks were well indexed to 10 and 11, confirming the single crystalline feature as well as the 2D hexagonal structure of the nanosheets.…”