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Keywords:

  • adsorption;
  • oxygen;
  • photocatalysis;
  • photogenerated charge separation;
  • Titanium dioxide

Abstract

In general, an increase in O2 adsorption is highly desirable for efficient photocatalysis. Herein, commercial P25 TiO2 is modified with an F127-containing SiO2 sol, and post-treated with phosphoric acid. It is confirmed, on the basis of O2 temperature-programmed desorption measurements, that the O2 adsorption of commercial P25 TiO2 is greatly promoted through its modification with porous SiO2, especially in the phosphate-treated case. The promotion of O2 adsorption is attributed to the introduction of [BOND]Si[BOND]OH and [BOND]P[BOND]OH as surface ends, and to the slightly increased surface area. Interestingly, it is concluded that the promotion of O2 adsorption is favorable for the separation of photogenerated charge carriers, as seen from the steady-state surface photovoltage spectra, transient-state surface photovoltage responses, and measurements of the hydroxyl radicals produced. This is responsible for the clear enhancement in the photocatalytic activity of modified TiO2 for the degradation of gas-phase acetaldehyde and liquid-phase phenol as colorless pollutants. This work provides a feasible route for improving the photocatalytic activity of TiO2.