Construction of multiple active sites by solution-free self-generating dual-template strategy: Boosting the ORR performance of NiFe/N-doped 3D porous carbon nanosheets

The oxygen reduction reaction (ORR) that occurs at the cathode of fuel cells has vital influence on the overall performance of the related electrochemical energy conversion devices. Metal-nitrogen-carbon (M-N-C) catalysts are expected to take the place of traditional expensive commercial Pt-C as a new generation of ORR electrocatalyst. In this paper, a self-generating dual-template strategy was used to efficiently synthesize NiFe/N-doped 3D porous carbon nanosheets. In the specific synthesis process, the precursor of PBA (Ni3[Fe(CN)6]2) and the protective nitrogen-containing carbon source can be used as a primary pore-forming agent for in-situ forming of pore for the catalyst. The KCl and FeNi alloy produced in the synthesis process can also be used as an in-situ secondary template for pore forming of the electrocatalyst. The self-generating dual-template can not only produce porous structure to provide more interfaces and improve mass transfer, but also fabricate more active sites provided by N-doping and bimetal. The obtained NiFe/N-doped 3D porous carbon nanosheet (NFCN-MP4000) exhibits excellent electrocatalytic methanol tolerance and durability in alkaline electrolytes. Its ORR activity was comparable to that of commercial Pt/C (20 wt%), and showed a limiting current density superior to that of Pt/C (6.10 mA cm−2). This work provides a strategy for the construction of electrocatalytic materials with high performance for methanol tolerance and durability.