Carbon nanobowl supported chemically functionalized PtRh nanocrystals: a highly active and methanol tolerant electrocatalyst towards the oxygen reduction reaction

Abstract

The cathodic oxygen reduction reaction (ORR) is a key half-reaction for direct methanol fuel cells (DMFCs). Enhancing the electroactivity and selectivity of cathodic Pt-based ORR electrocatalysts is pivotal for accelerating the commercialization of DMFCs because of the scarcity of Pt metal and the inherent electroactivity of Pt-based electrocatalysts towards the methanol electrooxidation reaction. Herein, highly dispersed carbon nanobowl (CNBs) supported 1-butyl-3-methylimidazolium tetrafluoroborate ionic liquid (BmimBF₄) functionalized Pt₁Rh₁ alloy nanocrystal nanohybrids (Pt₁Rh₁@BmimBF₄/CNBs) are successfully synthesized by reducing mixed BmimBF₄-Pt^II and BmimBF₄-Rh^III complex precipitates with NaBH₄ solution. During the reduction process, PtRh alloy nanocrystals are simultaneously functionalized by BmimBF₄ because of the strong N–metal interaction. Pt₁Rh₁@BmimBF₄/CNBs nanohybrids with the optimal chemical composition reveal significantly enhanced ORR electroactivity and fascinating ORR selectivity (i.e., methanol tolerance) compared to Pt₁Rh₁/CNBs nanohybrids without BmimBF₄ because of the carrier effect, alloy effect, and particular metal–organic interface.