Super-Nernstian pH sensors based on WO3 nanosheets

Chao Yin Kuo, Shui Jinn Wang, Rong Ming Ko, Hung Hao Tseng

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4 Citations (Scopus)


The effects of the surface morphology of hydrothermally grown WO3 nanosheets (NSs) and sputtering WO3 film on the performance of pH sensing electrodes are presented and compared in the pH range of 2-12. Using a separated electrode of an extended-gate field-effect transistor (EGFET) configuration, the WO3 nanosheet (NS) pH sensor shows a sensitivity of 63.37 mV/pH, a good linearity of 0.9973, a low voltage hysteresis of 4.79 mV, and a low drift rate of 3.18 mV/h. In contrast, the film-type one shows a typical sensitivity of only 50.08mV/pH and a linearity of 0.9932. The super-Nernstian response could be attributed to the significant increase in the number of surface ion adsorption sites of the NS structure and the occurrence of local electric field enhancement over the sharp edges and corners of WO3 NSs.

Original languageEnglish
Article number04FM09
JournalJapanese Journal of Applied Physics
Issue number4
Publication statusPublished - 2018 Apr

All Science Journal Classification (ASJC) codes

  • Engineering(all)
  • Physics and Astronomy(all)

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