Enhanced electrocatalytic hydrogen evolution activity of nickel foam by low-temperature-oxidation
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fei Kuanga) College of Chemistry and Chemical Engineering, Hunan University, Changsha 410012, People’s Republic of China
Zhaohui Hou and Minjie Zhoub) School of Chemistry and Chemical Engineering, Hunan Institute of Science and Technology, Yueyang 414006, People’s Republic of China
Xiaobo Chenc),d) Department of Chemistry, University of Missouri—Kansas City, Kansas City, Missouri 64110, USA (Received 8 September 2017; accepted 13 November 2017)
Designing advanced nonprecious metal electrocatalysts to reduce overpotential and accelerate hydrogen evolution reaction (HER) has attracted considerable attention. However, improving the sluggish kinetics for electrocatalytic HER in alkaline media is still a great challenge. Herein, we found that amorphous NiO nanoclusters directly grown on nickel foam (NiO/NF) as a bifunctional HER catalyst demonstrated an ultrahigh electrocatalytic activity in alkaline environment. Such excellent HER performance of NiO/NF might mainly originate from the exposed interfaces of metallic Ni and amorphous NiO. The coordinatively unsaturated amorphous NiO domain is propitious to the adsorption of water molecule and the successive cleavage of HO–H bond, while the neighboring metallic Ni domain is beneficial to the adsorption of resulting Hads intermediate and recombination into hydrogen molecules, thus expediting the HER toward lower overpotential. These findings may open a window to the design and preparation of earth-abundant, low-cost metal oxide/metal electrocatalysts with desirable HER activities. I. INTRODUCTION
The significant concerns of rapid fossil fuel consumption and carbon dioxide increase in the environment have been driving the development of renewable energies and technologies,1 among which the electrochemical water splitting for the hydrogen production is regarded as one of the most important approaches for clean and scalable energy substitutes due to its low energy consumption, short reaction period, high-purity product, and environmentally friendly process.2 The electrocatalytic splitting process of water contains two half-reactions: the hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER) with the following equations 2H1 1 2e
Contributing Editor: Edward M. Sabolsky Address all correspondence to these authors. a) e-mail: [email protected] b) e-mail: [email protected] c) e-mail: [email protected] d) This author was an editor of this journal during the review and decision stage. For the JMR policy on review and publication of manuscripts authored by editors, please refer to http://www.mrs. org/editor-manuscripts/. DOI: 10.1557/jmr.2017.446
! H2 and 2H2O ! 4e 1 4H1 1 O2, separately. Assuming that the electrochemical reaction is ideal and the Faradic efficiency is 100%, the volume of produced oxygen is half as much as the evolution volume of hydrogen, and the total amount of such two gases is in direct proportion to the quantity of the electrical charge provided for the electrolytic reaction. To improve the electrolysis efficiency, seeking a highly active electro
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