Pd(1 1 1)/SnO2(1 0 1) heterostructure on porous N-carbon material as enhanced catalyst for formic acid electrooxidation

Abstract

High specific surface area carbon materials act as a critical factor of fuel cell catalyst carriers. In this study, the PtxPdy/SnO2/GC nanocatalysts were successfully synthesized at different molar ratios of Pt and Pd to conduct the formic acid oxidation. In addition, the N-doped porous carbon carrier (GC) was prepared with graphene oxide and gelatin through the solvated volatilization/nanometer SiO2 template/KOH activation, and the prepared carrier GC took up a large specific surface area (SBET = 1104.5 m2/g). The fine-tuning of the atomic ratio of Pt and Pd was demonstrated to further guide the growth of ultra-small nanocrystals that achieved an average size of 2.52 nm and displayed uniform distributions on the prepared GC carrier. Compared with PtPd/GC, PtSnO2/GC and Pt/GC catalysts, Pt1Pd1/SnO2/GC took up a larger electrochemical activity area of 528.93 cm2/mg, and the positive sweep peak current density reached 2258.45 mA/mgPt at 0.75 V. As confirmed by the DFT analysis, the heterojunction structure formed between the Pt-Pd (111) and SnO2 (101) surfaces would contribute to the electron transport. The optimal electrochemical performance was reasonably attributed to the synergistic effect exerted by PtPd alloy and SnO2, as well as N-doped porous carbon carrier.