Tailored dodecahedral polyoxometalates nanoframes with in situ encapsulated Co, N, C for oxygen evolution reaction

Abstract

Hollow nanoframes with three-dimensional open architecture have diverse applications but their acquirement is still a big challenge. Herein, a crystal morphological evolution mechanism is proposed for the synthesis of dodecahedral [Co(CN)6]3-@POMs (polyoxometalates) frame-like nanostructure. Through an inside-out etching process, K3PW12O40 (POMs) dodecahedron are transformed to dodecahedral POMs nanoframes with encapsulation of [Co(CN)6]3- inside the nanochannels, which can be transformed to Co, N, C co-doped POMs nanoframes (CNCP) by a further N2-pyrolysis process. The hybrid nanoframes possess unique yolk-shell structure with multi-heteroatoms doping, showing great advantages for oxygen evolution reaction (OER). As an OER catalyst, it exhibits excellent electrochemical catalytic activities with a low overpotential of 241 mV at 10 mA cm−2, a small Tafel slope of 75.8 mV dec-1 and a long-term electrochemical stability. Our work not only provides novel dodecahedral Keggin-type polyoxometalates yolk-shell structure and nanoframes, but also provides a facile strategy to in situ encapsulate active components inside porous substrates, and thus will open a new perspective for the further utilization of POMs nanomaterials as potential catalysts for energy storage and conversion.