Engineering PtRu bimetallic nanoparticles with adjustable alloying degree for methanol electrooxidation: Enhanced catalytic performance

PtRu bimetal is of particularly attractive in various electrocatalytic reactions owing to its synergistic effect, ligand effect and strain effect. Here, PtRu nanoalloy supported on porous graphitic carbon (PC) has been successfully prepared via a very facile method involving co-reduction the precursors of Pt and Ru at 300 degrees C by H-2 (PtRu/PC-L) followed by thermal treatment at high temperature (700 degrees C, PtRu/PC-H). Specifically, the electrocatalytic performance of PtRu/PC nanoalloy could be dramatically enhanced through high-temperature annealing. This strategy has synthesized smaller Pt and PtRu nanoparticles (ca. < 3 nm); what's more, they are all homogeneous deposited on the surface of PC. PtRu/PC-H nanocatalyst displays higher alloying degree and stronger electronic interaction between Pt and Ru atoms accompanied by the downshift of Pt d-band center. Studies of electrochemical tests indicate that the as-fabricated PtRu/PC-H sample exhibits superior electrocatalytic performance and excellent CO-poisoning tolerance compared with PtRu/PC-L and Pt/PC nanocatalysts. The mass activity and specific activity on PtRu/PC-H nanoalloy can be increased to 1674.2 mA mg(pt)(-1) and 4.4 mA cm(-2) for MOR, it is 4.08 and 8.80 times higher than that of the Pt/PC nanocatalyst, respectively. From in-situ FTIR spectra, we can discover PtRu/PC-H nanoalloy generates CO2 at a lower potential of -150 mV than those on PtRu/PC-L (0 mV) and Pt/PC (50 mV) nanocatalysts, dramatically improves the ability of cleavage C-H bond and alleviates the CO ads poisoning on active sites. The PtRu/PC-H nanocatalyst exhibits maximum power density of 83.7 mW cm(-2) in single methanol fuel cell test, which more than threefold than that of commercial Pt/C as the anode catalyst. Those experimental results open an effective and clean avenue in the development and preparation of high-performance Pt-based nanocatalysts for direct methanol fuel cells.