Main Article Content
Energy demand is increasing with the increasing global population and the natural source of energies such as petroleum, natural gas, coal are very limited and are continuously depleting. Moreover, prolonged use of these fossil fuels release greenhouse gases and pollutes the environment. Therefore, the present world requires a clean and renewable energy source to fulfil the energy demand as well as to safeguard the environment. Generation of hydrogen and oxygen by electrochemical water splitting would be a quality choice, since the by-product here is water and the source is also water [1-2]. To date, noble metal based electrocatalysts such as Pt/C, RuO2, and IrO2 are the best-known electrocatalysts for hydrogen and oxygen evolution reactions (HER, OER) with an overpotential close to the theoretical values and have superior catalytic behaviour [3-4]. However, it remains a great challenge to produce hydrogen and oxygen at a large scale using noble materials, due to their high cost and less abundance. In search of alternatives for noble materials, transition metal based catalysts can be a good choice, since they are cost effective, more abundant and have good electrical conductivities [5-6]. Among them, transition metal dichalcogenides and their bimetallic counter parts are well known for their superior electrochemical properties and high catalytic activities . Moreover, inducing defects in the crystal structure creates more active sites, which enhance the electrocatalytic performance towards HER and OER . Herein, for the first time we report a defect-induced FexNi1-xSe2 for the electrochemical water splitting. The electrocatalyst FexNi1-xSe2 of different molar ratios were developed by hydrothermal method and the defects were created by calcination. Thus prepared materials were characterized by XRD, TEM and EDX mapping. Before and after calcination, all the XRD peaks remain same which indicates that the phase of the crystal structure is unaffected however, the peak distortion after calcination indicates the occurrence of the defects in the crystal structure. The TEM images of both Fe0.25Ni0.75Se2 and DI- Fe0.25Ni0.75Se2 (defect induced) show the “d” spacing with an average distance of 0.18 nm corresponds to (311) plane and 0.26 nm corresponds to (210) plane, which confirms that even after calcination there is no change in the “d” spacing but, DI-Fe0.25Ni0.75Se2 exhibits disordered lattice fringes which are due to distortion in the crystal structure. Among different molar ratios of FexNi1-xSe2, DI-Fe0.25Ni0.75Se2 showed the high HER activity with a low overpotential of 128 mV to reach a current density of 10 mA/cm2 with a Tafel slope of 37.9 mV/dec in 0.5 M H2SO4. Similarly, for OER, it showed high performance at a low overpotential of 205 mV for 10 mA/cm2 current density with a Tafel slope of 55.5 mV/dec in 1 M KOH. Moreover, the developed electrocatalyst was stable in the acidic and alkaline medium even after continuous electrolysis for 12 h.
How to Cite
Hydrogen evolution reaction, oxygen evolution reaction, bimetallic, defect induced transition metal selenides, electrocatalyst.
 Z. Dai, H. Geng, J. Wang, Y. Luo, B. Li, Y. Zong, J. Yang, Y. Guo, Y. Zheng, X. Wang, Q. Yan, ACS Nano, 2017, 11, 11031-11040. https://doi.org/10.1021/acsnano.7b05050
 M. Zhou, Q. Weng, Z. Zhang, X. Wang, Y. Xue, X. Zeng, Y. Bando, D. Golberg, J. Mater. Chem. A, 2017, 5, 4335-4342. https://doi.org/10.1039/C6TA09366C
 J. Jiang, S. Lu, W.K. Wang, G. X. Huang, B. C. Huang, F. Zhang, Y. J. Zhang, H. Q. Yu, Nano Energy, 2018, 43, 300-309. https://doi.org/10.1016/j.nanoen.2017.11.049
 J. S. Chen, J. Ren, M. Shalom, T. Fellinger, M. Antonietti, ACS Appl. Mater. Interfaces 2016, 8, 5509-5516. https://doi.org/10.1021/acsami.5b10099
 H. Fan, H. Yu, Y. Zhang, Y. Zheng, Y. Luo, Z. Dai, B. Li, Y. Zong, Q. Yan, Angew. Chemie - Int. Ed, 2017, 56, 12566-12570. https://doi.org/10.1002/anie.201706610
 D. Xiaogiang, M. Guangyu, Z. Xiaoshuang, ACS Sustainable chemistry & Engineering, 2019, 23, 19257-19267. https://doi.org/10.1021/acssuschemeng.9b05514
 L. Yesheng, T. Zilong, Z. Junying, Z. Zhongtai, J. Phys. Chem. C 2016, 120, 18, 9750–9763, https://doi.org/10.1021/acs.jpcc.6b00457