Facile synthesis of Fe3C/rGO via an in situ assembly route as an effective cocatalyst of Pt toward methanol electrooxidation

Abstract

The high noble metal loading and easy poisoning of Pt catalysts are the major obstacle s to the commercialization of direct methanol fuel cell (DMFC) technology. Herein, iron carbide anchored on reduced graphene oxide (Fe₃C/rGO) is proposed as an effective promoter of Pt in the methanol oxidation reaction (MOR) based on an in situ assembly strategy, involving the in situ anchoring of the Prussian blue (PB, ferric hexacyanoferrate) precursor on GO firmly, followed by a calcination treatment for the formation of Fe₃C and the reduction of GO synchronously, and a final growth of Pt on Fe₃C/rGO. It is shown that Fe₃C is anchored on rGO with well-fined size and good dispersivity, being beneficial for the post-deposition of Pt on Fe₃C/rGO to form a strongly coupled Fe₃C–Pt structure. The strong interaction between Fe₃C and Pt, proved by characterization using XRD, TEM, XPS etc., is favorable for increasing the CO anti-poisoning ability of Pt and so an active and stable Pt catalyst with low Pt loading (7.5 wt%) can be achieved. Electrochemical tests indicate that the as-prepared Pt–Fe₃C/rGO catalyst delivers significantly higher electrocatalytic current density (808.5 mA mg_Pt⁻¹), which is 2.54 and 4.37 times higher than those of Pt/rGO (310.8 mA mg_Pt⁻¹) and Pt/C (185.2 mA mg_Pt⁻¹). Moreover, it also exhibits excellent CO anti-poisoning ability and remarkable stability. The remarkable performance of Pt–Fe₃C/rGO is ascribed to the comprehensive effects of the catalyst, in which the strong interaction between Fe₃C and Pt can enhance the activity and CO-tolerance ability, while the rGO as an efficient support facilitates electron transport.