Morphology Dynamics of Single-Layered Ni(OH)2/NiOOH Nanosheets and Subsequent Fe Incorporation Studied by in Situ Electrochemical Atomic Force Microscopy.

Nickel (oxy)hydroxide-based (NiOxHy) materials are widely used for energy storage and conversion devices. Understanding dynamic processes at the solid-liquid interface of nickel (oxy)hydroxide is important to improve reaction kinetics and efficiencies. In this study, in situ electrochemical atomic force microscopy (EC-AFM) was used to directly investigate dynamic changes of single-layered Ni(OH)2 nanosheets during electrochemistry measurements. Reconstruction of Ni(OH)2 nanosheets, along with insertion of ions from the electrolyte, results in an increase of the volume by 56% and redox capacity by 300%. We also directly observe Fe cations adsorb and integrate heterogeneously into or onto the nanosheets as a function of applied potential, further increasing apparent volume. Our findings are important for the fundamental understanding of NiOxHy-based supercapacitors and oxygen-evolution catalysts, illustrating the dynamic nature of Ni-based nanostructures under electrochemical conditions.

[1]  S. Hwang,et al.  Free-Standing Holey Ni(OH)2 Nanosheets with Enhanced Activity for Water Oxidation. , 2017, Small.

[2]  Chunzeng Li,et al.  Atomic force microscopy with nanoelectrode tips for high resolution electrochemical, nanoadhesion and nanoelectrical imaging , 2017, Nanotechnology.

[3]  Shannon W. Boettcher,et al.  Measurement Techniques for the Study of Thin Film Heterogeneous Water Oxidation Electrocatalysts , 2017 .

[4]  P. Strasser,et al.  NiFe‐Based (Oxy)hydroxide Catalysts for Oxygen Evolution Reaction in Non‐Acidic Electrolytes , 2016 .

[5]  Bryan M. Hunter,et al.  Effect of interlayer anions on [NiFe]-LDH nanosheet water oxidation activity , 2016 .

[6]  Benjamin Paul,et al.  Oxygen Evolution Reaction Dynamics, Faradaic Charge Efficiency, and the Active Metal Redox States of Ni-Fe Oxide Water Splitting Electrocatalysts. , 2016, Journal of the American Chemical Society.

[7]  Fuding Lin,et al.  Semiconductor-Electrocatalyst Interfaces: Theory, Experiment, and Applications in Photoelectrochemical Water Splitting. , 2016, Accounts of chemical research.

[8]  Hanfeng Liang,et al.  Operando Analysis of NiFe and Fe Oxyhydroxide Electrocatalysts for Water Oxidation: Detection of Fe⁴⁺ by Mössbauer Spectroscopy. , 2015, Journal of the American Chemical Society.

[9]  Zhoucheng Wang,et al.  Porous Two-Dimensional Nanosheets Converted from Layered Double Hydroxides and Their Applications in Electrocatalytic Water Splitting , 2015 .

[10]  D. J. Lockwood,et al.  Nickel hydroxides and related materials: a review of their structures, synthesis and properties , 2015, Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences.

[11]  Jens K Nørskov,et al.  Identification of highly active Fe sites in (Ni,Fe)OOH for electrocatalytic water splitting. , 2015, Journal of the American Chemical Society.

[12]  Ziyu Wu,et al.  Ultrathin Nickel Hydroxide and Oxide Nanosheets: Synthesis, Characterizations and Excellent Supercapacitor Performances , 2014, Scientific Reports.

[13]  Nan Li,et al.  Amorphous Ni(OH)2 @ three-dimensional Ni core–shell nanostructures for high capacitance pseudocapacitors and asymmetric supercapacitors , 2014 .

[14]  Fang Song,et al.  Exfoliation of layered double hydroxides for enhanced oxygen evolution catalysis , 2014, Nature Communications.

[15]  Yushan Yan,et al.  Efficient water oxidation using nanostructured α-nickel-hydroxide as an electrocatalyst. , 2014, Journal of the American Chemical Society.

[16]  Anna Fischer,et al.  Water oxidation by amorphous cobalt-based oxides: volume activity and proton transfer to electrolyte bases. , 2014, ChemSusChem.

[17]  S. Boettcher,et al.  Nickel-iron oxyhydroxide oxygen-evolution electrocatalysts: the role of intentional and incidental iron incorporation. , 2014, Journal of the American Chemical Society.

[18]  A. Bell,et al.  An investigation of thin-film Ni-Fe oxide catalysts for the electrochemical evolution of oxygen. , 2013, Journal of the American Chemical Society.

[19]  Yang Li,et al.  Nanoporous Ni(OH)2 thin film on 3D Ultrathin-graphite foam for asymmetric supercapacitor. , 2013, ACS nano.

[20]  M. Qu,et al.  Improved performances of β-Ni(OH)2@reduced-graphene-oxide in Ni-MH and Li-ion batteries. , 2011, Chemical communications.

[21]  H. Dai,et al.  Ni(OH)2 nanoplates grown on graphene as advanced electrochemical pseudocapacitor materials. , 2010, Journal of the American Chemical Society.

[22]  Jun Chen,et al.  Combination of lightweight elements and nanostructured materials for batteries. , 2009, Accounts of chemical research.

[23]  S. Ida,et al.  Synthesis of hexagonal nickel hydroxide nanosheets by exfoliation of layered nickel hydroxide intercalated with dodecyl sulfate ions. , 2008, Journal of the American Chemical Society.

[24]  P. Notten,et al.  Electrochemical Quartz Microbalance characterization of Ni(OH)2-based thin film electrodes , 2006 .

[25]  B. Hwang,et al.  In Situ Raman Studies on Cathodically Deposited Nickel Hydroxide Films and Electroless Ni−P Electrodes in 1 M KOH Solution , 1998 .

[26]  N. Munichandraiah,et al.  Stabilized α ‐ Ni ( OH ) 2 as Electrode Material for Alkaline Secondary Cells , 1994 .

[27]  D. Corrigan.  The Catalysis of the Oxygen Evolution Reaction by Iron Impurities in Thin Film Nickel Oxide Electrodes , 1987 .