Piezoelectric‐Effect‐Enhanced Full‐Spectrum Photoelectrocatalysis in p–n Heterojunction

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Abstract
Photoelectrochemical (PEC) water splitting offers a promising strategy for converting solar energy to chemical fuels. Herein, a piezoelectric‐effect–enhanced full‐spectrum photoelectrocatalysis with multilayered coaxial titanium dioxide/barium titanate/silver oxide (TiO2/BTO/Ag2O) nanorod array as the photoanode is reported. The vertically grown nanorods ensure good electron conductivity, which enables fast transport of the photogenerated electrons. Significantly, the insertion of a piezoelectric BaTiO3 (BTO) nanolayer at the p‐type Ag2O and n‐type TiO2 interface created a polar charge‐stabilized electrical field. It maintains a sustainable driving force that attract the holes of TiO2 and the electrons of Ag2O, resulting in greatly increased separation and inhibited recombination of the photogenerated carriers. Furthermore, Ag2O as a narrow bandgap semiconductor has a high ultraviolet–visible–near infrared (UV–vis–NIR) photoelectrocatalytic activity. The TiO2/BTO/Ag2O, after poling, successfully achieves a prominent photocurrent density, as high as 1.8 mA cm−2 at 0.8 V versus Ag/Cl, which is about 2.6 times the TiO2 nanorod photoanode. It is the first time that piezoelectric BaTiO3 is used for tuning the interface of p‐type and n‐type photoelectrocatalyst. With the enhanced light harvesting, efficient photogenerated electron–hole pairs' separation, and rapid charge transfer at the photoanode, an excellent photoelectrocatalytic activity is realized.
Funding Information
  • National Natural Science Foundation of China (81471784, 51802115)
  • Youth Innovation Promotion Association of the Chinese Academy of Sciences (2015023)
  • Natural Science Foundation of Shandong Province (ZR2018BEM010)
  • Natural Science Foundation of Shandong Province (ZR2018ZC0843)

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