TiO₂/TaS₂ with superior charge separation and adsorptive capacity to the photodegradation of gaseous acetaldehyde

Differing from the photocatalysis of liquid contaminant, the capture of gaseous molecule is an essential factor on the photocatalytic activity because of the fast and random motion of gaseous molecule. TaS₂ is a two-dimensional material with good conductivity and large specific area, which are beneficial to the adsorption of gaseous pollutant and the separation of photo-induced e⁻-h⁺ pairs. Here, P25/TaS₂ (P25: commercial TiO₂) was synthesized for the first time to explore the effect of the addition of TaS₂ on the photocatalytic degradation of gaseous acetaldehyde. It turned out that the existence of TaS₂ provided two merits: on the one side, the adsorptive capacity of P25/TaS₂ for gaseous acetaldehyde boosted greatly with the highest adsorptive amount of 234.4 mL, which was three times of that of P25 (76.4 mL); on the other side, the separation efficiency of e⁻-h⁺ pairs of P25/TaS₂ also increased extremely with the highest photo-current response of 15.5 μA/cm², which was almost four times of that of P25 (4.2 μA/cm²). These two merits made P25/TaS₂ have superior photocatalytic activity for the degradation of gaseous acetaldehyde with the highest removal ratio of 98%, which was twice of that of P25 (48%). The cyclic experiments verified that P25/TaS₂ could keep excellent cycling stability after 6 cycles usage. In addition, proved by electron spin resonance (ESR) analyses and radicals quenching tests, superoxide radical was the decisive active species for the degradation of gaseous acetaldehyde compared with hydroxyl radical. Briefly, this work not only created the pioneer of the application of TaS₂ in the photocatalytic field but also verified TaS₂ an efficient co-catalyst in gaseous photocatalysis.