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

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.

Impact of Surface Composition Changes on the CO2-Reduction Performance of Au–Cu Aerogels

“…More importantly, a new redox peak pair at ≈0.88 and ≈0.82 V RHE is observed in the voltammograms of the Au 3 Cu and AuCu aerogels (cf. Figure d,f, respectively) and can be allotted to the oxidation and reduction of the alloyed Cu-phase previously reported for Au–Cu alloys elsewhere …”

“…Figure 2d,f, respectively) and can be allotted to the oxidation and reduction of the alloyed Cu-phase previously reported for Au−Cu alloys elsewhere. 42 In order to compare these novel bimetallic aerogels to other Au−Cu alloys documented in the literature, their ECSAs were determined using Pb-UPD, taking advantage of lead's ability to underpotentially deposit on both Au and Cu. 43−45 In general, metal UPD involves the electrosorption of (sub)monolayer amounts of the atoms of a designated metal on the surface of the substrate being investigated and at potentials positive of the theoretical value of bulk (i.e., multilayer) electrodeposition of that designated metal.…”