Encapsulated FeP nanoparticles with in-situ formed P-doped graphene layers: Boosting activity in oxygen reduction reaction

• Published in: Science China materials Vol. 64; no. 5; pp. 1159 - 1172
• Main Authors: Ni, Baoxia, Chen, Rui, Wu, Luming, Sun, Pingchuan, Chen, Tiehong
• Format: Journal Article
• Language: English
• Published: Beijing Science China Press 01.05.2021; Springer Nature B.V
• Subjects: Carbon; Catalysts; Charge transfer; Chemistry and Materials Science; Chemistry/Food Science; Electrocatalysts; Encapsulation; Graphene; Materials Science; Melamine; Nanocomposites; Nanoparticles; Nanostructure; Oxygen reduction reactions; Phosphorus; Pyrolysis; Work functions; FeP; encapsulation; oxygen reduction reaction; phosphorus-doped graphene layers; charge transfer
• ISSN: 2095-8226; 2199-4501
• DOI: 10.1007/s40843-020-1525-7

Nonprecious metal-based oxygen reduction reaction (ORR) electrocatalysts with high efficiency in both alkaline and acidic media are being intensively studied for the purpose of replacing expensive Pt-based catalysts; however, it is still a challenge to achieve superior ORR performances, especially in acidic media. Herein, by pyrolysis of mixed precursors of diammonium phosphate, melamine and hemin, we prepared a nanocomposite catalyst (denoted as FeP@PGL) composed of nitrogen-doped carbon nanosheets with embedded FeP nanoparticles (NPs), which were encapsulated by in-situ formed phosphorus-doped graphene layers. It is found that phosphorous was preferentially doped in the coating layers on FeP NPs, instead of in the carbon nanosheets. The FeP@PGL catalyst exhibited excellent ORR performance, with the onset and half-wave potential up to 1.01 and 0.90 V vs. the reversible hydrogen electrode (RHE) in alkaline media, and 0.95 and 0.81 V vs. RHE in acidic media, respectively. By thorough microscopy and spectroscopy characterizations, the interfacial charge transfer between the encapsulated FeP NPs and P-doped graphene layers was identified, and the local work function of the catalyst surface was also reduced by the interfacial interaction. The interfacial synergy between the encapsulated FeP and phosphorus-doped graphene layers was essential to enhance the ORR performance. This study not only demonstrates the promising ORR properties of the encapsulated-FeP-based nanocomposite catalyst, but also provides direct evidence of the interfacial charge transfer effect and its role in ORR process.