Tuning crystal phase of NiSx through electro-oxidized nickel foam: A novel route for preparing efficient electrocatalysts for oxygen evolution reaction
By Li, Xiao; Shang, Xiao; Rao, Yi; Dong, Bin; Han, Guan-Qun; Hu, Wen-Hui; Liu, Yan-Ru; Yan, Kai-Li; Chi, Jing-Qi; Chai, Yong-Ming; Liu, Chen-Guang
Published in Applied Surface Science
2017
Abstract
Abstract A facile solvothermal sulfurization using electro-oxidized nickel foam (NF(Ox)) as support has been applied to prepare NiSx/NF(Ox) electrocatalyst with highly efficient activity for oxygen evolution reaction (OER). {XRD} patterns confirm the composition of NiSx/NF(Ox): two kinds of crystal phase including ?-NiS and Ni3S2. While using bare {NF} as support under identical conditions, only Ni3S2 phase can be detected. {SEM} images reveal two kinds of morphologies of NiSx/NF(Ox) including pyramids structure of ?-NiS and nanorod-like structure of Ni3S2, which implies the tuning effect of electro-pretreatment of {NF} on the selective preparation of NiSx crystal phase. It can be speculated that Ni(OH)2 layer derived from electro-oxidized {NF} is responsible for the growth of ?-NiS while metallic Ni is transformed into Ni2S3 during sulfurization. Electrochemical measurements for {OER} indicate the enhanced electrocatalytic activity of NiSx/NF(Ox) with a small overpotential of 72 mV to reach 10 mA cm?2 compared with Ni3S2/NF, which may be ascribed to the improved electron-transfer kinetics relating to the unique atomic configurations and crystalline structures of ?-NiS. The electro-oxidation pretreatment of nickel foam provides a simple and convenient method by tuning different NiSx crystal phases for preparing excellent {OER} eletrocatalysts.