Low-Crystallinity and Heterostructured AuPt-Ru@CNTs as Highly Efficient Multifunctional Electrocatalyst

The catalytic activity of the catalysts is strongly dependent on the structure of the catalysts, and the exploration of their correlation and structure-controlled synthesis of the high-performance catalysts are always at the central. Currently, platinum (Pt) is the optimum catalyst for hydrogen evolution reaction (HER), oxygen reduction reaction (ORR) and alcohol oxidation reaction, while ruthenium (Ru) behaves as the champion catalyst for oxygen evolution reaction (OER) during water splitting. Preparing alloy catalysts with these precious metals can modulate the catalytic activity of these catalysts from the perspective of strain effect, ensemble effect and ligand effect. Here, we developed a strategy to deposit AuPt alloy as a solid solution phase on amorphous Ru supported on CNTs, thus forming AuPt-Ru heterostructures. The well-defined AuPt-Ru heterostructured catalysts were examined by X-ray diffraction and elemental mapping in high-angle annular dark-field scanning transition electron spectroscopy (HAADF-STEM). As compared to the high crystallinity AuPt alloy, AuPt alloy in AuPt-Ru heterostructure became amorphous, and AuPt-Ru showed superior catalytic activity toward ethanol oxidation reaction (EOR), achieving the mass activity of Pt as high as 21.44 A·mg^-1 due to the high tolerance toward the poisoning species. The intermediates species of the EOR were also examined by in-situ FTIR spectroscopy. The stability of the catalysts toward EOR was also excellent and the degradation in the activity of the catalysts was strongly related to the loss of Ru content during the stability test. The heterostructured AuPt-Ru catalysts also exhibited the excellent alkaline HER and OER performances, superior to those of commercial Pt/C and RuO₂ catalysts, ascribing to the amorphous state of AuPt-Ru heterostructure, and the modulation by strain and ensemble effects. This work highlights the importance in the design of the multicomponent heterostructures for the synthesis of high-performance and multifunctional electrocatalysts.