This journal is © The Royal Society of Chemistry 2019 Chem. Commun. Cite this: DOI: 10.1039/c8cc10128k Inert V 2 O 3 oxide promotes the electrocatalytic activity of Ni metal for alkaline hydrogen evolution† Dan Ji, Lishan Peng, * Jingjun Shen, Mingming Deng, Zhanxin Mao, Lianqiao Tan, Minjie Wang, Rui Xiang, Jian Wang and Syed Shoaib Ahmad Shah Here, we develop inert V 2 O 3 oxide to enhance the HER activity of industrial Ni catalysts with the assistance of abundant metal/oxide interfaces. The as-synthesized Ni/V 2 O 3 catalyst exhibits over 5 times the activity of a pure Ni sample due to the particle size control and metal/oxide interaction, and excellent durability as a result of oxide anchoring. Hydrogen production via water electrolysis is an effective method to store the intermittent electric power generated from large-scale renewable energy. 1–4 Developing stable and active hydrogen evolution reaction (HER) catalysts based on cheap transition metals is extremely desirable for water electrolysis in industrial-scale applications. 5–9 Nickel (Ni) is the most com- mon HER catalyst used for industrial water electrolysis in basic solutions, 10–12 owing to its chemical stability, earth abundance, excellent conductivity, etc. However, the Ni metal is still not as competent as an ideal water reduction catalyst due to its high overpotential and large Tafel slope. 6 Besides, Ni undergoes serious deactivation as a cathode during water electrolysis in an alkaline solution. 13 Hence, maximizing the potential of Ni to its ultimate limit via facile routes is a great challenge and a trending issue today. A rational design and fabrication of sufficient active inter- faces between metal and oxide seems to be an effective strategy to facilitate the catalytic performances of metal-based catalysts. Recently, various metals such as Pt, Pd, Au, Cu, and Ni supported on reducible metal oxides (e.g., TiO x , CeO x , and FeO x ) have been reported to exhibit improved catalytic proper- ties for a number of important reactions, including CO oxida- tion, CO 2 hydrogenation, and water–gas shift reactions. 14–24 In our pervious work, the nature of the interface-induced synergistic effect of metal/metal oxide composite catalysts for alkaline HER has been deeply studied and a ‘‘chimney effect’’ of metal/metal oxide for the improved HER activity has been identified. 25 By means of DFT calculation, the neighbouring sites of the interface are immune to the H 2 O* and OH* adsorption, but beneficial for the smooth adsorption/ desorption of the reactant (H*) to form product H 2 . The special adsorption/desorption behaviour of the reactant species greatly accelerated the HER process and the hydrogen product could be manufactured continuously through the metal/oxide inter- face like a ‘‘chimney’’. However, all those reported metal/oxide catalysts involve reducible metal cations in oxides, and promo- tional effects of non-reducible metal oxides (also known as inert oxides) are rarely reported. Herein, we demonstrate that inert V 2 O 3 greatly promotes the HER activity of Ni by creating highly active metal/oxide inter- faces. In this work, highly dispersed ultrafine metallic Ni nanoparticles on V 2 O 3 oxide (Ni/V 2 O 3 ) were designed and fabricated by selectively segregating the Ni element in the original mixed metal oxide to the surface of the inert metal oxide. The inert V 2 O 3 not only provides anchoring sites for size control and uniform dispersion of the Ni nanoparticles but also serves as electron conduction pathways during electrocatalytic processes. Besides, the metallic Ni migrated towards the surface of V 2 O 3 in situ generate the desired Ni/V 2 O 3 interfaces, which greatly promote the dissociation of water molecules and lower the hydrogen binding energy. Benefitting from the combined effects of particle size control, oxide anchoring, and metal/oxide interaction, the elaborately designed Ni/V 2 O 3 exhibits a higher activity for HER with a low overpotential of À140 mV at À10 mA cm À2 , a small Tafel slope (À112 mV dec À1 ), and improved stability for over 18 h during operation in a basic solution. The inert V 2 O 3 supported ultrafine Ni nanoparticles was synthesized through hydrogen reduction from the Ni x V 1Àx O 2 precursor with a uniform Ni incorporation. During the hydro- gen treatment, the Ni element grew out of the original pre- cursors as the Ni ions migrated towards the surface and were reduced by H 2 . The morphologies of the Ni x V 1Àx O 2 precursors Chongqing Key Laboratory of Chemical Process for Clean Energy and Resource Utilization, School of Chemistry and Chemical Engineering, Chongqing University, Chongqing 400044, China. E-mail: lishanpeng@cqu.edu.cn † Electronic supplementary information (ESI) available. See DOI: 10.1039/ c8cc10128k Received 21st December 2018, Accepted 21st February 2019 DOI: 10.1039/c8cc10128k rsc.li/chemcomm ChemComm COMMUNICATION Published on 21 February 2019. Downloaded by Chongqing University on 2/27/2019 2:42:06 PM. View Article Online View Journal