N-doped Fe nanoparticles confined in carbon matrix for high-performance oxygen evolution reaction

Abstract

Fe-based nanoparticles are promising oxygen evolution reaction (OER) electrocatalysts. However, they often suffer from serious agglomeration during the electrocatalytic process, which leads to significant attenuation of catalytic performance. Herein, highly dispersed Fe nanoparticles with small sizes of ∼7 nm are confined in amorphous carbon matrix by pulsed laser deposition technology. Based on this, a simple N2 radio frequency plasma strategy is proposed to introduce N doping in the Fe nanoparticles. Electrochemical measurements suggest that N-doped Fe nanoparticles exhibit enhanced OER activity and stability, which offers a low overpotential of 246 mV at 10 mA cm−2 and the Tafel slope of 50 mV dec−1 in 1 M KOH solution. Based on experimental measurements combined with first-principles calculations, the outstanding OER performance of N-doped Fe nanoparticles can be attributed to the synergistic effect of the unique confined structure and N doping, which not only enhances the electrochemical surface area and improves electrical conductivity but also weakens the adsorption of intermediates and reduces the energy barrier of OER reaction. This work provides a facile method for the construction of metal nanoparticles with confined nanostructure and controlled N doping, which will greatly promote the development of OER electrocatalysts.