Pseudocapacitive Ni-Co-Fe Hydroxides/N-Doped Carbon Nanoplates-Based Electrocatalyst for Efficient Oxygen Evolution.

Abstract

The oxygen evolution reaction (OER) catalytic activity of a transition metal oxides/hydroxides based electrocatalyst is related to its pseudocapacitance at potentials lower than the OER standard potential. Thus, a well-defined pseudocapacitance could be a great supplement to boost OER. Herein, a highly pseudocapacitive Ni-Fe-Co hydroxides/N-doped carbon nanoplates (NiCoFe-NC)-based electrocatalyst is synthesized using a facile one-pot solvothermal approach. The NiCoFe-NC has a great pseudocapacitive performance with 1849 F g-1 specific capacitance and 31.5 Wh kg-1 energy density. This material also exhibits an excellent OER catalytic activity comparable to the benchmark RuO2 catalysts (an initiating overpotential of 160 mV and delivering 10 mA cm-2 current density at 250 mV, with a Tafel slope of 31 mV dec-1 ). The catalytic performance of the optimized NiCoFe-NC catalyst could keep 24 h. X-ray photoelectron spectroscopy, electrochemically active surface area, and other physicochemical and electrochemical analyses reveal that its great OER catalytic activity is ascribed to the Ni-Co hydroxides with modular 2-Dimensional layered structure, the synergistic interactions among the Fe(III) species and Ni, Co metal centers, and the improved hydrophily endowed by the incorporation of N-doped carbon hydrogel. This work might provide a useful and general strategy to design and synthesize high-performance metal (hydr)oxides OER electrocatalysts.