Positively Charged Hollow Co Nanoshells by Kirkendall Effect Stabilized by Electron Sink for Alkaline Water Dissociation.
basic_science · Level V
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- Record sourced from PubMed, PMID 39022849.
- Also identified by DOI 10.1002/adma.202405386.
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Abstract
While cobalt (Co) exhibits a comparable energy barrier for H<sup>*</sup> adsorption/desorption to platinum in theory, it is generally not suitable for alkaline hydrogen evolution reaction (HER) because of unfavorable water dissociation. Here, the Kirkendall effect is adopted to fabricate positive-charged hollow metal Co (PHCo) nanoshells that are stabilized by MoO<sub>2</sub> and chainmail carbon as the electron sink. Compared to the zero-valent Co, the PHCo accelerates the water dissociation and changes the rate-determining step from Volmer to Heyrovsky process. Alkaline HER occurs with a low overpotential of 59.0 mV at 10 mA cm<sup>-2</sup>. Operando Raman and first principles calculations reveal that the interfacial water to the PHCo sites and the accelerated proton transfer are conducive to the adsorption and dissociation of H<sub>2</sub>O molecules. Meanwhile, the upshifted d-band center of PHCo optimizes the adsorption/desorption of H<sup>*</sup>. This work provides a unique synthesis of hollow Co nanoshells via the Kirkendall effect and insights to water dissociation on catalyst surfaces with tailored charge states.