Cu-Ni nanowire-based TiO2 hybrid for the dynamic photodegradation of acetaldehyde gas pollutant under visible light

Abstract

One-dimensional bimetallic nanowires were introduced into TiO2-based matrix to enhance their photocatalysis efficiency and expand their light absorption range in this work. Recently, metal nanowires have attracted many attention in photocatalyst research fields because of their favorable electronic transmission properties and especially in the aspect of surface plasmon resonance effects. Moreover, Cu-Ni bimetallic nanowires (Cu-Ni NWs) have shown better chemical stability than ordinary monometallic nanowires in our recent works. Interestingly, it has been found that Ni sleeves of the bimetallic nanowires also can modify the Schottky barrier of interface between TiO2 and metallic conductor, so that be beneficial to the separation of photogenerated carriers in the Cu-Ni/TiO2 network topology. Hence, a novel heterostructured photocatalyst composed of Cu-Ni NWs and TiO2 nanoparticles (NPs) was fabricated by one-step hydrolysis approach to explore its photocatalytic performance. TEM and EDX mapping images of this TiO2 NPs @Cu-Ni NWs (TCN) hybrid displayed that Cu-Ni NWs were wrapped by compact TiO2 layer and retained the one-dimensional structure in matrix. In experiments, the photocatalytic performance of the TCN nanocomposite was significantly enhanced comparing to pure TiO2. Acetaldehyde, as a common gas pollutant in the environment, was employed to evaluate the photodegradation efficiency of a series of TCN nanocomposites under continuous feeding. The TCN exhibited excellent potodegradation performance, where the dynamic photocatalytic efficiency of TCN containing 3wt% Cu-Ni NWs was about 88% and 56% (continuous 500ppm CH3CHO feeding, 20 SCCM) under UV and visible light, respectively. ESR results proved that the recombination of photo-generated electron-hole pairs was inhibited significantly in TCN nanocomposite. Finally, the mechanism for electron-hole pairs’ separation and transmission at Schottky barrier interface between Cu-Ni NWs and TiO2 layers has been proposed based on the above analyses.