Mesoporous nickel-iron binary oxide nanorods for efficient electrocatalytic water oxidation

• Published in: Nano research Vol. 10; no. 6; pp. 2096 - 2105
• Main Authors: Liu, Guang, Gao, Xusheng, Wang, Kaifang, He, Dongying, Li, Jinping
• Format: Journal Article
• Language: English
• Published: Beijing Tsinghua University Press 01-06-2017; Springer Nature B.V
• Subjects: Atomic/Molecular Structure and Spectra; Biomedicine; Biotechnology; Catalysis; Catalysts; Charge transfer; Chemical synthesis; Chemistry and Materials Science; Condensed Matter Physics; Coordination polymers; Dopants; Doping; Electrocatalysts; Electrolysis; Fabrication; Genetic transformation; Hematite; Iron oxides; Materials Science; Nanorods; Nanotechnology; Nickel; Nickel ferrites; Nickel oxides; Oxidation; Oxides; Oxygen; Oxygen evolution reactions; Polymers; Research Article; Ruthenium oxide; Surface area; Thermal decomposition; Water splitting; Ni–Fe binary oxide; oxygen evolving; water splitting; nanorods; electrocatalytic
• ISSN: 1998-0124; 1998-0000
• DOI: 10.1007/s12274-016-1398-x

The design and fabrication of low-cost, high-effidency, and stable oxygen-evolving catalysts are essential for promoting the overall efficiency of water electrolysis. In this study, mesoporous Ni1-xFexOy （0 〈 x 〈 1, 1 〈y 〈 1.5） nanorods were synthesized by the facile thermal decomposition of Ni-Fe-based coordination polymers. These polymers passed their nanorod-like morphology to oxides, which served as active catalysts for oxygen evolution reaction （OER）. Increasing the Fe-doping amount to 33 at.% decreased the particle size and charge-transfer resistance and increased the surface area, resulting in a reduced overpotential （-302 mV） at 10 mA/cm^2 and a reduced Tafel slope （-42 mV/dec）, which were accompanied by a far improved OER activity compared with those of commercial RuO2 and IrO2 electrocatalysts. At Fe-doping concentrations higher than 33 at.%, the trend of the electrocatalytic parameters started to reverse. The shift in the dopant concentration of Fe was further reflected in the structural transformation from a NiO （〈33 at.% Fe） rock-salt structure to a biphasic NiO/NiFe204 （33 at.% Fe） heterostructure, a NiFe204 （66 at.% Fe） spinel structure, and eventually to α-fe203 （100 at.% Fe）. The efficient water-oxidation activity is ascribed to the highly mesoporous one-dimensional nanostructure, large surface area, and optimal amounts of the dopant Fe. The merits of abundance in the Earth, scalable synthesis, and highly efficient electrocatalytic activity make mesoporous Ni-Fe binary oxides promising oxygen-evolving catalysts for water splitting.