Unconventional dual-vacancies in nickel diselenide-graphene nanocomposite for high-efficiency oxygen evolution catalysis
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n Key Laboratory of Environmental Remediation and Pollution Control, College of Environmental Science and Engineering, Nankai University, Tianjin 300350, China 2 Department of Civil and Environmental Engineering, Rice University, Houston, Texas 77005, USA 3 Center for Aircraft Fire and Emergency, Economics and Management College, Civil Aviation University of China, Tianjin 300300, China 4 Division of Nanomaterials & Chemistry, Hefei National Laboratory for Physical Sciences at the Microscale, CAS Center for Excellence in Nanoscience, Hefei Science Center of CAS, Collaborative Innovation Center of Suzhou Nano Science and Technology, Department of Chemistry, University of Science and Technology of China, Hefei 230026, China © Tsinghua University Press and Springer-Verlag GmbH Germany, part of Springer Nature 2020 Received: 14 June 2020 / Revised: 19 July 2020 / Accepted: 22 July 2020
ABSTRACT Although nickel-based catalysts display good catalytic capability and excellent corrosion resistance under alkaline electrolytes for water splitting, it is still imperative to enhance their activity for real device applications. Herein, we decorated Ni0.85Se hollow nanospheres onto reduced graphene oxide (RGO) through a hydrothermal route, then annealed this composite at different temperatures (400 °C, NiSe2-400 and 450 °C, NiSe2-450) under argon atmosphere, yielding a kind of NiSe2/RGO composite catalysts. Positron annihilation spectra revealed two types of vacancies formed in this composite catalyst. We found that the NiSe2-400 catalyst with dual Ni-Se vacancies is able to catalyze the oxygen evolution reaction (OER) efficiently, needing a mere 241 mV overpotential at 10 mA·cm−2. In addition, this catalyst exhibits outstanding stability. Computational studies show favorable energy barrier on NiSe2-400, enabling moderate OH− adsorption and O2 desorption, which leads to the enhanced energetics for OER.
KEYWORDS hollow nanospheres, NiSe2, oxygen evolution reaction, dual-vacancies
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Introduction
With the increase of energy source crisis, electrocatalytic water splitting to produce hydrogen (H2) fuel has been thought as a promising solution and received considerable attention. The anodic half reaction, i.e., oxygen evolution reaction (OER), becomes the current research focus because of its slow kinetics that causes large overpotentials at desired current densities [1, 2]. IrO2 and RuO2 are generally considered as the state-of-the-art OER catalysts, however, their practical adoption is largely limited because of the poor availability and high cost [3–5]. Recently, non-precious metal materials with high activity and stability have been developed as alternative catalysts, such as transition metal oxides [6, 7], hydroxides [8, 9], nitrides [10, 11], and phosphides [12–14]. Among these catalysts, nickel-based transition metal selenides display very promising electrocatalytic activity and durability for OER, resulting from the suitable d-electron configuration. As a Pauli paramagnetic metal, nickel diselenide (NiSe2) possesses an impe
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