Acid-treatment-assisted synthesis of Pt–Sn/graphene catalysts and their enhanced ethanol electro-catalytic activity

• A Pt–Sn/graphene catalyst has been synthesized through acid-treatment-assisted route.
• The treated Pt–Sn/graphene catalyst exhibits increased metal loading and ECSA.
• A mechanism for the influence of acid treatment on the treated catalysts is proposed.

Pt–Sn/graphene is a promising catalyst for use in direct ethanol fuel cells (DEFCs). However, under previous preparation conditions, its metal loading was found to be far lower than the nominal loading. In this study, to address this issue, improved Pt–Sn/graphene catalysts have been synthesized by an acid-treatment-assisted route. Compared with the original catalyst, we found that the Pt–Sn loading on graphene was increased due to the regulation of acid-base balance in the reaction solution, and the fragmentation of graphene sheets was also increased due to structural damage by the acid treatment. The changes in composition and microstructure resulted in an increased electrochemically active surface area (ECSA) of the Pt–Sn/graphene catalyst. The acid-treatment method can thus enhance the catalytic performance of Pt–Sn/graphene catalysts, as well as facilitate recycling of Pt and Sn lost in the preparation.