Visible‐Light Photocatalytic and Photo‐bactericidal Activity of Ni‐CuWO₄/OTiO₂ Composite^†

Abstract

A series of nickel-doped copper tungstate/oxygen-rich TiO 2 heterojunction-constructed composites of xNi-CuWO 4 /OTiO 2 were successfully prepared to demonstrate the enhancement of the visible-light photoactivity through promoting the photogenerated charge carrier separation efficiency. Of all these composites, 0.2Ni-CuWO 4 /OTiO 2 exhibits excellent and stable visible light photoactivity for the photooxidative coupling of benzylamine to the corresponding N-benzyl-1-phenymethanimine (BPMI) in air atmosphere. The conversion of benzylamine and the selectivity to BPMI reach 97% and 99%, respectively. The catalyst shows good cyclability with the conversion of benzylamine decreasing just by 22% after being repeated six times with the well-maintained selectivity of BPMI. The composite also exhibits excellent photo-bactericidal ability, which greatly inhibits the reproducing of both the Gram-positive bacteria (e.g., S. epidermidis) and Gram-negative bacteria (e.g., E. coli).

Hybrid ZnO@Au Nanorod Array for Fast and Repeatable Bacteria Inactivation

“…The value of the exponent n depends on the nature of the transition in sample, n = 4 for indirect transition while n = 1 for direct transition. [ 25 ] As shown in Figure 3b, the band gap energies of ZnO and ZnO@Au1 were calculated to be 3.2 eV and 3.07 eV, respectively. The reduction in the band gap for ZnO@Au1, suggests the possibility of superior photocatalytic performance by efficient separation of photogenerated charge carriers.…”

“…For piezoelectric mechanism, Au NPs enhance the ROS generation through the Mott‐Schottky junction formed at interface (as discussed above), which facilitates charge separation and prevents recombination of electron‐hole pairs. [ 18,25 ] More efficient charge separation and transport enhance the generation of ROS. For the photocatalytic mechanism, introducing Au NPs extends the LSPR from short wavelength (bare ZnO array, below 400 nm) to long wavelength (ZnO@Au1 array) due to the LSPR of Au, as suggested by the significantly enhanced optical response in visible region (Figure 3a) as well as the obvious color changes (Figure 2).…”

Ni(II)-doped CuWO4 photoanodes with enhanced photoelectrocatalytic activity

“…Nickel(II) was chosen as dopant species because Ni 2+ has an ionic radius similar to that of Cu 2+ , which would favor the substitution of copper ions within the CuWO 4 lattice. Furthermore, very recent studies have focused on the CuWO 4 /NiWO 4 heterojunction [41] and on nickel-containing copper tungstate coupled with other materials for different applications [42][43][44] and evidenced an increased PEC performance attained upon partial Ni 2+ for Cu 2+ substitution in CuWO 4 , though the origin of such an effect was not investigated. Our results evidence an increased photocurrent generated by Ni(II)-doped photoanodes compared to pure CuWO 4 , with the 10% Ni(II)-doped material being best performing, mainly due to a 50% increase in charge separation efficiency.…”