Self-Supported Defect-Rich Au-Based Nanostructures as Robust Bifunctional Catalysts for the Methanol Oxidation Reaction and Oxygen Reduction Reaction in an Alkaline Medium

Dongwei Li,Hongyu Gong,Xiu Liang,Guanchen Xu,Yuanyuan Tao,Yong Li,Yingzhou Chen,Na Zhang,Xifeng Jiang

doi:10.3390/nano11092193

Abstract

Recently, alkaline direct methanol fuel cells have made great progress with the development of alkaline electrocatalysis, and a wide variety of catalysts have been explored for methanol oxidation reaction (MOR)and oxygen reduction reaction (ORR). However, the slow kinetics of the MOR and ORR remain a great challenge. In this paper, self-supported defect-rich AuCu was obtained by a convenient one-pot strategy. Self-supported AuCu presented a branched, porous nanostructure. The nanobranch consisted of several 13 nm skeletons, which connected in the kink of the structure. Different growth directions co-existed at the kink, and the twin boundaries and dislocations as defects were observed. When the Au-based nanostructure functioned as an electrocatalyst, it showed robust MOR and ORR performance. For the MOR, the forward peak current was 2.68 times greater than that of Au/C; for the ORR, the activity was close to that of Pt/C and significantly better than that of Au/C. In addition, it possessed superior electrochemical stability for MOR and ORR. Finally, an in-depth exploration of the impact of surface defects and electrochemical Cu removal on MOR and ORR activity was carried out to explain the MOR and ORR’s catalytic performance.

Highlights

Along with the clean energy conversion, the slow kinetics of methanol oxidation reaction (MOR) and oxygen reduction reaction (ORR) seriously restrict the progress of electrocatalysis; efficient catalysts are necessary for MOR and ORR [3]
Octadecylamine, with more lipophilic groups (−CH3 ) than hydrophilic groups (−NH2 ), was used as an oil phase and surfactant; dimethyl sulfoxide (DMSO) as polar organic matter played the role of cosurfactant, and the precursors of Au and Cu as electrolytes were in water phase
MOR and ORR performance, and the impacts of surface defects and electrochemical Cu removal on MOR and ORR performance were explored in depth

Summary

Introduction

Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations. Many problems encountered in hydrogen fuel cell technology, those of hydrogen storage and distribution, can be circumvented by replacing hydrogen with liquid fuels, such as methanol [1]. Two important reactions in direct methanol fuel cells, the methanol oxidation reaction (MOR) and the oxygen reduction reaction (ORR), have received great attention in recent years [2]. Along with the clean energy conversion, the slow kinetics of MOR and ORR seriously restrict the progress of electrocatalysis; efficient catalysts are necessary for MOR and ORR [3]. For MOR, Pt/Rh are representative highly active catalysts [4–7]. As the most common and efficient catalyst, has been widely investigated [4,5], and hydroxide species forming on the surface

Methods

Results

Conclusion