The improvement of the embedded Ag nanoislands on the performance of Au/Ag/HfOx/HfO2/Ag-NIs/Au devices

Oxygen defect regulation, catalytic mechanism, and modification of HfO2 as a novel catalyst for lithium–oxygen batteries

“…6a shows the Hf 4f XPS spectra in four states. The peaks at 16.92 eV and 18.53 eV are characteristic peaks of Hf 4f7/2 and Hf 4f5/2 of HfO 2 (Hf 4+ ), respectively; the peaks at 12.76 eV and 14.04 eV are attributed to Hf 4f7/2 and Hf 4f5/2 of Hf 3+ , 54,55 respectively. According to the area ratio of Hf 4+ /Hf 3+ , the Hf 4+ contents can be calculated as 92.86% (state 1) and 81.36% (state 2) during the discharge process, which returns to 86.38% (state 3) and 97.66% (state 4) during the charge process.…”