Vertically oriented cobalt selenide/NiFe layered-double-hydroxide nanosheets supported on exfoliated graphene foil: an efficient 3D electrode for overall water splitting

• Published in: Energy & environmental science Vol. 9; no. 2; pp. 478 - 483
• Main Authors: Hou, Yang, Lohe, Martin R, Zhang, Jian, Liu, Shaohua, Zhuang, Xiaodong, Feng, Xinliang
• Format: Journal Article
• Language: English
• Published: 01.01.2016
• Subjects: Catalysts; Current density; Foils; Graphene; Iron compounds; Nanostructure; Nickel base alloys; Three dimensional
• ISSN: 1754-5692; 1754-5706
• DOI: 10.1039/c5ee03440j

Developing cost-effective electrocatalysts for both oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) in basic media is critical to renewable energy conversion technologies. Here, we report a ternary hybrid that is constructed by in situ growth of cobalt selenide (Co sub(0.85)Se) nanosheets vertically oriented on electrochemically exfoliated graphene foil, with subsequent deposition of NiFe layered-double-hydroxide by a hydrothermal treatment. The resulting 3D hierarchical hybrid, possessing a high surface area of 156 m super(2) g super(-1) and strong coupling effect, exhibits excellent catalytic activity for OER, which only requires overpotentials of 1.50 and 1.51 V to attain current densities of 150 and 250 mA cm super(-2), respectively. These overpotentials are much lower than those reported for other non-noble-metal materials and Ir/C catalysts. The hybrid also efficiently catalyzes HER in base with a current density of 10 mA cm super(-2) at an overpotential of -0.26 V. Most importantly, we achieve a current density of 20 mA cm super(-2) at 1.71 V by using the 3D hybrid as both a cathode and an anode for overall water splitting, which is well comparable to the integrated performance of Pt/C and Ir/C catalysts.