The flux growth of single-crystalline CoTiO₃ polyhedral particles and improved visible-light photocatalytic activity of heterostructured CoTiO₃/g-C₃N₄ composites

Abstract

Highly crystalline and idiomorphic CoTiO single crystals with a well-defined polyhedral morphology were grown successfully for the first time by a facile flux method. Herein, the effects of the molten salt type and cobalt precursor on the phase composition, crystallization habit and morphology of the CoTiO products were also investigated. Importantly, using the flux-grown CoTiO crystal as the visible-light sensitizer due to its narrow band gap to couple with graphitic carbon nitride (g-CN) by a direct in situ thermal induced polycondensation route, novel CoTiO/g-CN composite photocatalysts were obtained. The as-synthesized samples were systematically characterized by XRD, EDS, SEM, TEM, SAED, HRTEM, FT-IR, XPS, DRS and PL techniques. The results revealed that CoTiO polyhedral crystals were closely combined with g-CN nanosheets leading to the formation of a heterojunction structure at the interface between CoTiO and g-CN. Photocatalytic evaluation showed that the heterostructured CoTiO/g-CN composite exhibited much higher photocatalytic activity for the degradation of methyl orange under visible light irradiation than that of individual CoTiO and g-CN, which could be mainly ascribed to the synergistic effect between CoTiO and g-CN, including the enhanced visible-light harvesting ability and more efficient separation and longer lifetime of photogenerated charge carriers. Furthermore, the composite photocatalyst showed an excellent stability and reusability during four successive cycles. Finally, a possible mechanism responsible for the charge separation and improved photocatalytic activity was proposed.

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

“…The photocatalytic degradation mechanism of Rh B has been reported in the literature and is shown in Scheme . In addition, to better explain the contents in the figure, the atom's Mulliken definition of electronegativity, E VB = χ – E c + 0.5 E g and E CB = E VB – E g , must be used to calculate the conduction band ( E CB ) and valence band ( E VB ) edge potentials of titanium dioxide and tungsten oxide.…”

“…E c is the energy of the free electrons on the hydrogen scale (ca. 4.5 eV) and E g is the bandgap energy. The calculated E VB and E CB of TiO 2 are 2.91 and –0.29 eV, respectively, and 3.4 and 0.78 eV for WO 3 , respectively .…”

“…4.5 eV) and E g is the bandgap energy. The calculated E VB and E CB of TiO 2 are 2.91 and –0.29 eV, respectively, and 3.4 and 0.78 eV for WO 3 , respectively . The E VB and E CB values of TiO 2 and WO 3 indicate that photogenerated electrons will transfer from the CB of TiO 2 to the CB of WO 3 , and photogenerated holes will transfer from the VB of WO 3 to the VB of TiO 2 under simulated sunlight irradiation.…”

Fabrication and photocatalytic property of magnetic SrTiO3/NiFe2O4 heterojunction nanocomposites

“…4.5 eV), E g is the band gap energy of the semiconductor, and c is the absolute electronegativity of the semiconductor. 52,53 Therefore, the E VB and E CB of NiFe 2 O 4 are calculated to be 2.62 eV and 0.80 eV, respectively, whereas the E VB and E CB of SrTiO 3 are about 2.02 eV and À1.13 eV, respectively. According to the above results, the possible photocatalytic mechanism of the SrTiO 3 /NiFe 2 O 4 nanocomposites is illustrated in Fig.…”

Highly crystalline Na0.5Bi0.5TiO3 of a photocatalyst valence-band-controlled with Bi(iii) for solar water splitting

“…A flux method is useful to control bulk properties of a material such as morphology and crystallinity. [29][30][31][32] In the present study, we synthesized Na 0.5 Bi 0.5 TiO 3 of a photocatalyst VB-controlled with Bi6s orbitals by a solid state reaction and a flux method, and investigated their photocatalytic water splitting with loading suitable cocatalysts.…”