Photoelectrocatalytic degradation of formic acid using a porous titanium dioxide thin-film electrode

Abstract

The degradation of formic acid (HCOOH) using titanium dioxide (TiO[sub 2]) in photocatalytic and photoelectrocatalytic reactions was investigated in order to determine whether electrical biasing could improve the efficiency of photocatalytic reactions. This study addressed the effects of film thickness, biasing potential, presence of oxygen, and added inorganic electrolytes on the photocatalytic degradation of HCOOH. The results of these experiments showed that the degradation of HCOOH in this system was due only to the photocatalytic as opposed to homogeneous photolysis reactions. Degradation efficiency of the photocatalytic reaction was roughly proportional to the TiO[sub 2] film thickness. In the photoelectrocatalytic reaction, positive potentials (vs saturated calomel electrode, SCE) improved the degradation efficiency and +0.0 V (vs SCE) was enough to obtain a maximum efficiency. The supply of oxygen was essential in the photocatalytic reaction, while the photoelectrocatalytic reaction was not significantly affected by the removal of oxygen. The presence of inorganic electrolytes lowered the efficiency of the photocatalytic degradation of HCOOH. However, the efficiency of photoelectrocatalytic degradation was not affected by inorganic electrolytes. Overall, when used with the bias, the system showed efficient degradation over a wide range of conditions. 21 refs., 9 figs.