Synthesis of Co3O4/WO3 Nanoheterojunction Photocatalyst for the Decomposition of Organic Pollutants Under Visible Light Irradiation

Enhanced Photoreduction Activity of Carbon Dioxide over Co3O4/CeO2Catalysts under Visible Light Irradiation

“…The red shift of the CeO 2 sample might be attributed to trivalent ionic cerium compounds. Similarly, the band gap of Co 3 O 4 is estimated to be 2.0 eV, which is matched with the reported band gap (2.07 eV) [20]. In contrast to CeO 2 , the Co 3 O 4 /CeO 2 have strong absorption in the visible region ( > 400 nm) and the visible light absorbance increases along with the addition of Co 3 O 4 (Figure 3(c)).…”

“…Due to the special f and d electron orbital structure of cerium atom, some metal oxide semiconductors like TiO 2 [13], Bi 2 O 3 [14], and Cu 2 O [11] can be easily doped with pure CeO 2 to enhance visible light absorption and quantum efficiency. Cobalt-based catalysts have been recently reported as photocatalysts for water oxidation [15][16][17][18], hydrogen production [19], and organic pollutants degradation [20][21][22]. Co is significantly less abundant than other transition metals like Fe, Mn, and Ni, but it is emerging as a potential metal for catalytic processes because of its light harvesting and electron mediating properties [19].…”

“…Cobalt oxides, for example, CoO and Co 3 O 4 , are p-type semiconductors with interesting electronic and magnetic properties [23]. The p-n heterojunction semiconductor structure combined with cobalt oxide and other n-type semiconductors such as BiVO 4 [23] or WO 3 [20] has been investigated as an effective way to improve the photocatalytic activities under visible light irradiation. In this case, CeO 2 as an n-type semiconductor with wide band gap may possibly bring out a similar heterojunction structure with Co 3 O 4 to enhance the efficiency of visible light absorption by shortening the band gap, in which such p-n 2 International Journal of Photoenergy heterojunction structure can hardly work to reduce carbon dioxide according to the band theory because the conduction band potential of Co 3 O 4 is too positive to start the reduction.…”

Synthesis of Three‐dimensionally Ordered Macroporous TiO2 and TiO2/WO3 Composites and Their Photocatalytic Performance

“…To achieve this goal, researchers have doped TiO 2 with transition metals (Pt, Zn, W, and Ag) and nitrogen and dispersed it on a carrier . WO 3 is an n‐type semiconductor photocatalyst with a relatively narrow bandgap (2.6–2.8 eV) and its photocatalytic activity towards organic substances is very low without a suitable co‐catalyst …”

Structural evolution of cobalt oxide–tungsten oxide nanowire heterostructures for photocatalysis

“…Moreover, tungsten oxide (WO 3 ) is n-type semiconductor with band gap energy of $2.8 eV while cobalt oxide (Co 3 O 4 ) is a p-type semiconductor with band gap energy $1.6 eV for O 2À to Co 3+ charge transfer and $2.2 eV for O 2À to Co 2+ charge transfer [19,24,25]. Recently Chakraborty et al [26] studied their combination of Co 3 O 4 and WO 3 , which has been proved to be able to form a stable p-n junction at the interface and further generate a constant electric field at equilibrium [12,27]. Under illumination, the photo-excited electrons are prone to move to the positive field and the holes flow into the negative field.…”