Fern-like Nickel Cobalt Sulfide Electrocatalyst Prepared By Electrodeposition and Subsequent Sulfur Ion Exchange for Water Electrolysis

Tuesday, 3 October 2017
Prince George's Exhibit Hall D/E (Gaylord National Resort and Convention Center)
H. Kim, J. Kim (Chung-Ang University), J. H. Kim (Chung-Ang Univ.), and S. H. Ahn (Chung-Ang University)
Recently, the attention on development of eco-friendly sustainable energy have been gradually increased, owing to the fossil fuel depletion and global warming. Among them, the utilization of hydrogen energy produced from water electrolysis is the one of the prominent methods to solve the problems due to the environmental-friendly characteristic of hydrogen energy. Representative study on water electrolysis is focusing on highly efficient and lower cost electrode development. It has been known that the Pt and IrO2 is the most activate catalyst for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER), respectively. However, they are very rare and expensive, indicating that the severe cost problem is still remained for hydrogen production from water electrolysis. To solve the problem many efforts have been conducted to the development of non-noble metal based catalysts as comparably active as Pt for HER and IrO2 for OER. In particular, the researches on transition metal compounds: M-X (M=Ni, Co, Fe and X= S or P) catalysts have been dominative during the past few years. In this study, we have fabricated the fern-like NixCoyS1-x-y catalyst for water electrolysis. Firstly, NixCoyO1-x-y was electrodeposited on the carbon paper (CP) by two-step galvanostatic deposition. The morphology and composition of fern-like NixCoyO1-x-y were controlled by varying deposition conditions. Then, annealing process was conducted to further oxidization of NixCoyO1-x-y. As a last step, sulfur ion exchange was carried out on the NixCoyO1-x-y by changing dipping time in sodium sulfide solution at 90 °C. Through field emission scanning electron microscope, energy dispersive spectroscopy and X-ray diffraction, formation of fern-like NixCoyS1-x-y was confirmed after the sufficient dipping time. Based on the electrochemical surface area, the intrinsic activity of NixCoyS1-x-y catalysts showed compositional dependence activity for water electrolysis.