Enhanced Electrocatalytic Water Oxidation of Ultrathin Porous Co(3)O(4) Nanosheets by Physically Mixing with Au Nanoparticles

Ultrathin porous Co(3)O(4) nanosheets are synthesized successfully, the thickness of which is about three unit-cell dimensions. The enhanced oxygen evolution reaction (OER) performance and electronic interaction between Co(3)O(4) and Au is firstly reported in Co(3)O(4) ultrathin porous nanosheets by physically mixing with Au nanoparticles. With the loading of the Au nanoparticles, the current density of ultrathin porous Co(3)O(4) nanosheets is enhanced from 9.97 to 14.76 mA cm(−2) at an overpotential of 0.5 V, and the overpotential required for 10 mA cm(−2) decreases from 0.51 to 0.46 V, smaller than that of commercial IrO(2) (0.54 V). Furthermore, a smaller Tafel slope and excellent durability are also obtained. Raman spectra, XPS measurement, and X-ray absorption near edge structure spectra (XANES) show that the enhanced OER ascribed to a higher Co(2+)/Co(3+) ratio and quicker charge transfer due to the electronic interaction between Au and ultrathin Co(3)O(4) nanosheets with low-coordinated surface, and Co(2+) ions are beneficial for the formation of CoOOH active sites.