An all-metallic nanovesicle for hydrogen oxidation

Abstract

Vesicle, a microscopic unit that encloses a volume with an ultrathin wall, is ubiquitous in biomaterials. However, it remains a huge challenge to create its inorganic metal-based artificial counterparts. Here, inspired by the formation of biological vesicles, we proposed a novel biomimetic-strategy to curling the ultrathin nanosheets into nanovesicles, which was driven by the interfacial strain. Trapped by the interfacial strain between initially formed substrate Rh layer and subsequently formed RhRu overlayer, the nanosheet begins to deform to release a certain strain. Density functional theory (DFT) calculations reveal that the Ru atoms make the curling of nanosheet more favorable in thermodynamics. Owing to the unique vesicular structure, the RhRu nanovesicles/C displays excellent hydrogen oxidation reaction (HOR) activity and stability, which has been proven by both the experiments and DFT calculations. Specifically, the HOR mass activity of RhRu nanovesicles/C are 7.52 A mg(Rh+Ru)−1 at an overpotential of 50 mV in rotating disk electrode (RDE) level; this is 24.19 times higher than that of commercial Pt/C (0.31 mA mgPt−1). Moreover, the hydroxide exchange membrane fuel cell (HEMFCs) with RhRu nanovesicles/C displays a peak power density of 1.62 W cm−2 in H2-O2 condition, much better than that of commercial Pt/C (1.18 W cm−2). This work creates a new biomimetic strategy to synthesize inorganic nanomaterials, paving out a pathway for designing catalytic reactors.