In this paper, the photoelectrocatalytic (PEC) reduction of Cr(VI) over anodized TiO₂ nanotube arrays under UV-light irradiation using the half-wave pulsed direct current (h-DC) as the applied voltage was reported. This mode of voltage brings about better separation of photogenerated electrons and holes, resulting in much higher photoelectrocatalytic efficiency than either the conventional direct current (DC) or the alternate current (AC). Under the half-wave pulsed direct current, the influence factors such as the value and frequency of the voltage, also concentration of the electrolyte (NaCl), on the PEC reduction of Cr(VI) were investigated. The PEC reduction rate increased with increasing voltage and frequency, but could be restrained by a high frequency. The concentration of NaCl exhibited little effect on the PEC reduction reaction of Cr(VI), for the weak function of active chlorine species and electric conduction in the heavy metal reduction system.

Key words: TiO₂ nanotubes, Cr(VI), half-wave pulsed direct current, alternate current, photoelectrocatalytic reduction