Cost-Effective and Facile Preparation of Fe2O3 Nanoparticles Decorated N-Doped Mesoporous Carbon Materials: Transforming Mulberry Leaf into a Highly Active Electrocatalyst for Oxygen Reduction Reactions

Tingting Zhang,Lin Peng,Manchao Wang,Changqing Li,Jiahui Wang,Junfeng Zhao,Yuqing Lin,Lihao Guan

doi:10.3390/catal8030101

Abstract

Herein, a promising method to prepare efficient N-doped porous carbon-supported Fe2O3 nanoparticles (Fe2O3/N-PCs) ORR electrocatalysts is presented. The porous carbon was derived from a biomass i.e., mulberry leaf through a cost-effective approach. The existence of diverse compounds containing carbon, oxygen, nitrogen and sulfur in mulberry leaf benefit the formation and uniform dispersion of Fe2O3 nanoparticles (NPs) in the porous carbon. In evaluating the effects of the carbon support on the Fe2O3 NPs towards the ORR, we found that the sample of Fe2O3/N-PCs-850 (Fe2O3/N-PCs obtained at 850 °C) with high surface area of 313.8 m2·g−1 exhibits remarkably superior ORR activity than that of materials acquired under other temperatures. To be specific, the onset potential and reduction peak potential of Fe2O3/N-PCs-850 towards ORR are 0.936 V and 0.776 V (vs. RHE), respectively. The calculated number of electron transfer n for the ORR is 3.9, demonstrating a near four-electron-transfer process. Furthermore, it demonstrates excellent longtime stability and resistance to methanol deactivation compared with Pt/C catalyst. This study provides a novel design of highly active ORR electrocatalysts from low-cost abundant plant products.

Highlights

The fuel cell with its high-efficiency and low-pollution has been deemed as one of the future power sources; catalysts for cathode reaction referred to as oxygen reduction reaction (ORR) are vital for the scalable commercialization of fuel cell technologies [1,2,3]
The Fe2 O3 /N-PCs composites were prepared by using a hydrothermal, heat treatment processes (Scheme 1), in which organic-rich biomass, i.e., mulberry leaves, serve as a carbon and nitrogen source; FeCl3 acted as an iron source and contributed to the formation systems
Fe2O3/N-PCs-850 with the highest surface area may contribute to the exposure of catalytic active sites and mass transport involved in ORR, which is favorable for improved electrocatalytic performance

Summary

Introduction

The fuel cell with its high-efficiency and low-pollution has been deemed as one of the future power sources; catalysts for cathode reaction referred to as oxygen reduction reaction (ORR) are vital for the scalable commercialization of fuel cell technologies [1,2,3]. In spite of great achievements made in noble-metal electrocatalysts, the high cost, scarcity and instability impede its further application [4,5] In this respect, enormous viable noble-metal-free catalysts (Fe, Co, etc.) [6,7], or metal oxide [8], sulphide [9], nitride [10], carbide [11], metal-free carbon based materials [12] and nitrogen-doped carbon [13] have been actively pursued. The confinement of metal oxide NPs within carbon-based substrates can enhance the accessible interface area and to minimize the dissolution and agglomeration of NPs, contributing to the enhancement of the electrochemical activity and stability of the Fe2 O3 /N-PCs hybrids. It is expected that our work may provide a rational design for the synthesis of heteroatom-doped porous carbon supported metal oxide catalysts on a large scale

Results and Discussion

Nitrogen desorption-adsorption isotherm of Fe

O3indicating

Cyclic voltammograms of Fein

Electrochemical Measurements

Conclusions