XAFS Study on the Structure and Performance of Oxyhydroxide Nanosheets for Oxygen Evolution
 2016-05-04  Font Size:[Large Medium Small]

With the rapid development of global economy and technology, the excessive consumption of traditional oil and other fossil energy has caused a serious environmental pollution and energy shortage problem in the world. Solar or electrical water splitting for hydrogen production has been regarded as an effective way to solve the worldwide energy and environment crisis. However, the development of photoelectrochemical water splitting is now hindered by the high overpotential and low mass activity in the transition-metal oxide (TMO) catalyst materials.
To solve the above problem, the researchers of Prof. Qinghua Liu and Prof. Shiqiang Wei in National Synchrotron Radiation Laboratory (NSRL) of Hefei used the synchrotron radiation X-ray absorption spectroscopy (XAFS) technique to study the local atomic and electronic structures of low dimensional nanostructure catalytic materials, and disclosed the influence of surface structure on the catalytic activity of TMO-based water oxidation catalytic materials. In experiment, the researchers designed an atomically thin cobalt oxyhydroxide (γ-CoOOH) nanosheet as an efficient electrocatalyst for water oxidation, which can effectively oxidize water with extraordinarily large mass activities of 66.6 A/g and low overpotential of ~300 mV at 10 mA/cm2. X-ray absorption spectroscopy and first-principles calculations reveal that the local structure distortion of the surface CoO6−x octahedron greatly enhances the electrophilicity of H2O and facilitates the interfacial electron transfer between Co ions and adsorbed –OOH species to form O2, resulting in the high electrocatalytic activity of layered γ-CoOOH for water oxidation.
This result is published on Angew. Chem. Int. Ed. 2015, 54, 8722, and it enriches peoples’ comprehension of using two-dimension confinement effect to improve the catalytic water oxidation activity and provides some new hints for manipulation of the performance of transition metal oxide catalytic materials.

Structure and performance relationship of γ-CoOOH nanosheets.

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