Collaborative integration of ultrafine Fe2P nanocrystals into Fe, N, P-codoped carbon nanoshells for highly-efficient oxygen reduction
Rui Ma, Xun Cui, Xiaoxue Xu, Yonglin Wang, Gaoqiang Xiang, Likun Gao, Zhiqun Lin, Yingkui Yang
Abstract
The rational design and facile synthesis of cost-effective and high-performance carbon-based catalysts for oxygen reduction reaction (ORR) is of great significance but remain challenging. Herein, we report the crafting of a robust Fe,N,P-codoped, ultrafine Fe 2 P nanocrystals decorated, highly hierarchical porous carbon nanoshells (denoted Fe,N,P-CNSs/Fe 2 P) via a simple yet robust one-step synergetic phosphorization and pyrolysis approach for highly-efficient ORR. Specifically, well-defined polypyrrole- co -polyaniline hollow nanospheres with a shell thickness of ≈ 43 nm (PPy- co -PANI-HNs) are first elaborately synthesized via a facile soft-templating (Triton X-100 micelles) copolymerization of pyrrole and aniline monomers . Subsequent one-step synergetic phosphorization and pyrolysis of PPy- co -PANI-HNs pre-impregnated with NaH 2 PO 2 ·H 2 O and FeCl 3 (H 2 PO 2 - ,Fe 3+ @PPy- co -PANI-HNs) yields Fe,N,P-CNSs/Fe 2 P with a well-crafted ultrathin nanoshell (shell thickness of ≈13 nm) architecture containing abundant hierarchical porosity . Remarkably, an alkaline electrolyte capitalizing on the resulting Fe,N,P-CNSs/Fe 2 P manifests excellent ORR performance with the half-wave and onset potentials ( E 1/2 of 0.854 V and E onset of 0.955 V) comparable to Pt/C, diffusion limited current density ( J L of −5.98 mA cm −2 ) higher than Pt/C, and long-time durability and methanol resistance better than Pt/C, demonstrating great potential as air cathode in zinc-air batteries (maximum power density of 170 mW cm −2 and specific capacity of 824.5 mA h g −1 ). Combined experimental and theoretical studies reveal that the impressive ORR performance of Fe,N,P-CNSs/Fe 2 P originates from simultaneous compositional (i.e., Fe,N,P-codoping and ultrafine Fe 2 P nanocrystals decorating) and structural (i.e., hierarchically porous ultrathin nanoshell architecture) tailoring enabled by the judicious one-step synergetic phosphorization and pyrolysis.