Promoting the Electrochemical Performances by Chemical Depositing of Gold Nanoparticles Inside Pores of 3D Nitrogen-Doped Carbon Nanocages.

Carbon Nanomaterials are excellent electrode materials due to their extraordinary conductivity, prolific structures, and morphologies. Herein, a novel nanocarbon-based material (Au@NCNC) was synthesized by embedding gold nanoparticles (AuNPs) inside the pores of three-dimensional hierarchical nitrogen-doped carbon nanocages (NCNC) through an in situ chemical deposition method. The resultant Au@NCNC was employed as an electrochemical catalyst for the oxygen reduction reaction (ORR) and as an electrode material for supercapacitors. The conductivity and hydrophilicity of Au@NCNC were much more improved than those of pristine NCNC. Meanwhile, the bubble adhesive force on the Au@NCNC film was much lower underwater than that of NCNC, which provided easy accessibility to the active sites of reactants, such as hydrated O2. Therefore, the deposition of AuNPs inside pores of NCNC facilitated the transfer of electrons and diffusion of ions, promoting the electrocatalytic performance of Au@NCNC. As a result, Au@NCNC exhibited high performance toward ORR, which manifested in high numbers of electron transfer (3.7-3.9), high kinetic current density, enhanced electrocatalytic stability, and remarkable methanol durability. Moreover, Au@NCNC displayed high specific capacitance, good rate capability, and cycling stability with ∼97% of its initial capacitance retained at the high current density of 10 A g-1 after 5000 cycles. This could be attributed to the synergetic effect of ultrafine gold nanoparticles, the hierarchical porous structure, and the hydrophilic surface of NCNC as well. This work offers an excellent alternative for Pt-based catalysts in fuel cells, ORR, and supercapacitive electrode materials by enhancing the conductivity and surface hydrophilicity of electrocatalysts.