Metal-organic-framework-derived bi-metallic sulfide on N, S-codoped porous carbon nanocomposites as multifunctional electrocatalysts Binling Chen a , Guiping Ma a, b , Yanqiu Zhu a , Jinbo Wang c , Wei Xiong c , Yongde Xia a, * a College of Engineering, Mathematics and Physical Sciences, University of Exeter, Exeter, EX4 4QF, United Kingdom b State Key Laboratory of Chemical Resource Engineering, Beijing Laboratory of Biomedical Materials, Beijing University of Chemical Technology, Beijing, 100029, PR China c School of Chemistry and Chemical Engineering, Chongqing University of Science and Technology, Chongqing, PR China highlights graphical abstract  Ni-Co based bi-metallic sulfide/ porous carbon nanocomposites were facilely prepared.  Ni1Co4S@C-1000 shows superior electrocatalytic activity and stability towards OER.  The nanocomposites are also active electrocatalysts for ORR and HER. article info Article history: Received 5 March 2016 Received in revised form 5 October 2016 Accepted 6 October 2016 Keywords: Bi-metallic sulfide Porous carbon MOFs Electrocatalyst Oxygen evolution reaction Oxygen reduction reaction Hydrogen evolution reaction abstract A novel type of composite, consisting of a bi-metallic sulfide/carbon nanocomposite system, was developed as a multifunctional electrocatalyst. The nanocomposite system was facilely generated via a one-step simultaneous carbonization and sulfurization of a selected metal-organic framework. Sample Ni 1 Co 4 S@C-1000 is one of the most efficient electrocatalysts and exhibited superior activity and stability in oxygen evolution reaction (OER) due to the Ni substitution, the high porosity, the homogeneous dispersion of active components and the effect of N, S-codoping. This novel material showed a low onset potential of 1.43 V (vs reversible hydrogen electrode) and a stable current density of 10 mA cm 2 at 1.51 V in a 0.1 M KOH alkaline solution over a long-term operation, which is better than IrO 2 /C and other composites synthesized under the same conditions. The Ni 1 Co 4 S@C-1000 sample can also efficiently catalyse oxygen reduction reaction (ORR), with a four-electron pathway for reversible oxygen evolution and reduction. Furthermore, Ni 1 Co 4 S@C-800 showed enhanced electrocatalytic activity for hydrogen evolution reaction (HER) in water splitting. These findings pave a way to develop effective and promising alternative electrocatalysts towards OER, ORR and HER in the next generation of energy storage and conversion technologies. © 2016 Elsevier B.V. All rights reserved. 1. Introduction With the growing global energy demands, energy storage and conversion technologies such as fuel cells, metal-air batteries and water splitting system, have drawn considerable research interest [1,2]. Among these next generations of energy technologies, oxygen * Corresponding author. E-mail address: y.xia@exeter.ac.uk (Y. Xia). Contents lists available at ScienceDirect Journal of Power Sources journal homepage: www.elsevier.com/locate/jpowsour http://dx.doi.org/10.1016/j.jpowsour.2016.10.022 0378-7753/© 2016 Elsevier B.V. All rights reserved. Journal of Power Sources 334 (2016) 112e119