Increased utilization and mass activity of PtRu on reduced graphene oxide by heat treatment of its aerogel followed by composite with nanomaterials

Abstract

The method to increase PtRu utilization and its catalytic activity of PtRu nanoparticles supported on reduced graphene oxide (RGO) by avoiding its restacking was proposed with the aim of developing an active catalyst for a direct methanol fuel cell. The heat treatment at 200 °C of the GO aerogel (GOA) prepared by freeze drying of GO ice was introduced to weaken the attractive force of the hydrogen bonding between the GO sheets followed by the composite with the nanoparticles, i.e., ketjenblack (KB), TiO₂ and Ti₄O₇, at different weight ratios. The catalyst supported on the heat-treated GOA (RGOA), PtRu/RGOA, improved the PtRu utilization to some extent and also increased the ECSA and mass activity compared to that of PtRu/RGO. RGOA had fewer oxygen functional groups, especially the epoxy groups. Due to the treatment and composite, the PtRu utilization was increased from 66.5% for PtRu/RGO to 128.6 % for PtRu/RGOA + Ti₄O₇ (4:1) and the mass activity was improved from 50.7 A/g-_PtRu for PtRu/RGO to 130.5 A/g-_PtRu for PtRu/RGOA + Ti₄O₇ (1:1). The Ti₄O₇ nanoparticles showed the best catalytic performance for the composite suggesting that the strong interaction between Ti₄O₇ and the Pt nanoparticles was effective due to its high electronic conductivity.