Well dispersed Fe 2 N nanoparticles on surface of nitrogen-doped reduced graphite oxide for highly efficient electrochem
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is important to fabricate iron-based nitride/conductive material composite to obtain good catalytic performance. In this work, Fe2N nanoparticles with diameter of approximately 30 nm have been successfully dispersed on the surface of nitrogen-doped graphite oxide (NrGO) by a facile sol–gel method and further ammonia atmosphere treatment. XPS, XRD, Raman, and TEM proved that Fe2N nanoparticles are well monodispersed, and nitrogen atoms are doped in NrGO. The composite possessed two merits, that is, the more catalytic active site in Fe2N nanoparticles due to the well monodispersion, and fast electron transfer due to the nitrogen dope in rGO. With the proper ratio, the composite exhibited brilliant catalytic activity and durability in acidic media. It possesses overpotential of 94 mV to approach 10 mA/cm2, a small Tefel slope of 49 mV/dec, and maintains the good electrocatalytic activity for 10 h. Cyclic voltammetry and electrochemical impedance spectroscopy indicated that the electrocatalyst possessed high catalytic active area and fast electron transfer. Our work may provide a new avenue for the preparation of low-cost iron-based nitride/NrGO composite for highly efficient electrochemical hydrogen evolution.
I. INTRODUCTION
Hydrogen gas (H2) fuel is a clean energy, which is a good energy source for social sustainable development.1 Among many methods to obtain H2 in a large scale, water splitting with applied potential is regarded as the most promising strategy.2,3 In general, H2 could be obtained with certain potential according the half reactions of 2H1 1 2e ! H2 (the hydrogen evolution reaction, HER). Platinum (Pt) is most effective catalyst for water splitting, but the expensive price limits its wide application.4–6 Thus, commercial electrocatalysts typically are inexpensive but inferior-performance materials, for example, nickel metal and its alloys.7,8 To obtain electrocatalysts with low-cost and high catalytic efficiency, many researchers have focused on the transition metal-based materials because they possess the similar electronic structure with Pt. Among these alternatives, iron-based nitride, sulfide, and phosphide materials possess good catalytic properties and lower prices. So, they have been identified as promising materials for catalyzing the HER.9–12 Furthermore, iron nitride is regarded as the most promised candidate because of it’s facile preparation and excellent chemical stability.13 Contributing Editor: Xiaobo Chen a) Address all correspondence to this author. e-mail: [email protected] DOI: 10.1557/jmr.2017.138
There also have some works about the catalytic activities of iron nitride-based materials with different structure and composition.14–16 It is observed that the catalytic efficiency is mainly related to the chemical composition, structure, and material conductivity of catalysts. The nanostructure exhibited better catalytic performance than bulk because the more catalytic active sites had been exposed. Usually, the iron nitride materials are prepared with the pyrolysis of iron-based precurs
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