Fe-Doped Ni–Co Phosphide Nanoplates with Planar Defects as an Efficient Bifunctional Electrocatalyst for Overall Water Splitting
Mingjing Guo, Shuyi Song, Shasha Zhang, Ya Yan, Ke Zhan, Junhe Yang, Bin Zhao
Abstract
Highly efficient and low-cost bifunctional electrocatalysts in the same medium are indispensable for overall water splitting. Herein, Fe-doped Ni–Co phosphide nanoplates with a hierarchical nanostructure were successfully fabricated on a carbon cloth (Fex-NiCoP) via a facile method with electrodesposition and PH3 plasma treatment. Benefiting from the hierarchical structure, two-dimensional nanoplates comprising fine nanocrystals and doping effects of Fe, the Fex-NiCoP demonstrates excellent electrocatalytic performance for both the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER), which is sensitive to the Fe content. By controlling the Fe content, Fe1-NiCoP achieves 10 mA cm–2 at a low overpotential of 60 mV for the HER, while Fe2-NiCoP with a higher Fe doping content drives 50 mA cm–2 at only 293 mV for the OER. Upon high-resolution transmission electron microscopy, some planar defects were observed in the Fe-doped NiCoP nanocrystals, which may account for the increased exposure of active sites. When the optimal Fex-NiCoP electrodes were employed as the anode and cathode for water electrolysis in the alkaline electrolyte, the electrolyzer achieves 10 mA cm–2 at a low cell voltage of 1.61 V. Our work might shed light on rational design of the efficient multimetallic phosphide bifunctional electrocatalysts for overall water splitting.