To improve the electrocatalytic activity of catalysts for ethanol oxidation, PtxAuy/SnO2GN with a double-junction structure of PtxAuy and SnO2 is designed and synthesized, in which the atom ratios of Pt and Au are 1:0, 1:1, 1:2, 1:3, 1:4, and 1:5. Raman spectroscopy, Brunauer–Emmet–Teller method, X-ray diffraction, transmission electron micrography, and X-ray photoelectron spectroscopy are used to characterize the prepared catalysts. It is found that Pt and Au form an alloy, and the alloy is uniformly distributed around SnO2 on graphene (GN). The catalytic properties of PtxAuy/SnO2GN for ethanol electrooxidation are studied by electrochemical tests such as cyclic voltammetry, linear sweep voltammetry, chronoamperometry, and CO stripping. The results show that Pt1Au3/SnO2GN has the largest electrochemically activated surface area (ECSA), the lowest ethanol oxidation onset potential, the highest ethanol oxidation peak current density, and the best ethanol oxidation stability. Combined with electrochemical in situ infrared spectroscopy, the excellent catalytic performance of Pt1Au3/SnO2GN is attributed to its unique double-junction structure of PtAu alloy and SnO2 on GN enhancing the tolerance to CO-like toxic species, as well as the alloy of Pt and Au and their appropriate atomic ratio properly changing the electronic structure of Pt and increasing the ECSA, which are conducive to the easier electrooxidation of ethanol.
Developing catalysts for the stable electrooxidation of ethanol have been a goal pursued by scientists. The present work reports a facile synthesis of catalysts with a double junction structure of Pt and SnO 2 on graphene (Pt/SnO 2 GN) through sol–gel combined with glycol hydrothermal reduction method. The physicochemical analyses show that the reduced Pt uniformly dispersed on GN is located adjacent to SnO 2 and has electronic interaction with the composite carrier. The electrochemical results exhibit that Pt/SnO 2 GN has better catalytic performance for ethanol electrooxidation than PtSnO 2 /GN and PtSn/GN. The ethanol oxidation peak current density on Pt/SnO 2 GN, after 1500 cycles of voltammetric testing, can still maintain 99.2% of the highest. The excellent catalytic stability of Pt/SnO 2 GN is ascribed to the double junction structure and the appropriate interaction between Pt and SnO 2 on GN, which enlarge the ECSA of Pt, improve the structural integrity, accelerate the charge transfer kinetics and increase the CO tolerance.
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