One of the feasible strategies to enhance the photocatalytic property of TiO2 is to broaden the visible light response range and accelerate the separation rate of photo-induced electron-hole (e−-h+) pair...

To study the influence of the construction of heterojunction on the visible-light response range and the photo-generated charge carriers separation efficiency of TiO2, two dimensional/three dimensional (2D/3D) ZnIn2S4/TiO2 heterojunctions were synthesized by high-temperature calcination followed by a facile oil bath method, and were investigated for the photodegradation of Rhodamine B (RhB) and tetracycline (TC). X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS) were applied to investigate the composition, crystal structure, and morphology of the as-prepared specimens. UV-visible diffuse reflectance spectra (UV-vis DRS), electrochemical impedance spectroscopy (EIS), photocurrent measurement, photoluminescence (PL) spectra, and first-principles calculation were also performed to investigate the photoelectric property. The results showed TiO2 maintains the morphology of metal-organic frameworks (MOFs) with narrow visible-light response range and high photo-generated charge recombination efficiency. After coupling with ZnIn2S4 nanosheets, a larger specific surface area was obtained with offering more active sites for photocatalytic reaction. The band gap of the composite was reduced from 3.23 eV of TiO2 to 2.52 eV of ZnIn2S4/TiO2-II, and thus obtaining an extended visible-light response range and enhancing visible light utilization rate. The energy band structure acquired from the UV-vis DRS and XPS valence band spectra indicated a construction of type II heterojunction in the ZnIn2S4/TiO2 composite, and thus improving the separation and transfer efficiency of photo-generated carrier pairs, which was confirmed by the PL, EIS and photocurrent test results. Under the visible light, ZnIn2S4/TiO2 displayed significantly enhanced photocatalytic activity than bare TiO2 and ZnIn2S4. Among of ZnIn2S4/TiO2 photocatalysts, ZnIn2S4/TiO2-II possessed the highest photocatalytic degradation efficiency (93%) of RhB solution within 60 min, which was nearly 18 and 2 times higher than pristine TiO2 and ZnIn2S4, respectively. Besides, the ZnIn2S4/TiO2-II photocatalyst also showed enhanced photocatalytic activity for TC degradation than pure TiO2 and ZnIn2S4. The cycle experiment showed that the ZnIn2S4/TiO2-II photocatalyst could maintain good reusability, and it could still photodegrade 83% RhB after 5-cycle test. This work demonstrates that constructing 2D/3D ZnIn2S4/TiO2 heterojunction based on MOFs-derived TiO2 is an efficient strategy for significantly enhancing the photocatalytic activity of TiO2.

A novel ternary photocatalyst CdS/ZnIn2S4/g-C3N4 was designed and constructed by a calcination and two-step in situ deposition method with high-efficiency visible-light photocatalytic performance.

In this study, carbonized silicon carbide/graphitic carbon nitride ((SiC/C)/g-C3N4) composites were fabricated via a facile calcination method. The optimal SiC/C/g-C3N4 composite shows an excellent visible-light photocatalytic activity for water splitting, with the highest hydrogen evolution amount being 200.2 μmol, which is four times higher than that of pure g-C3N4 when triethanolamine and platinum (1.0 wt%) are used as the sacrificial agent and cocatalyst, respectively. With an intimate interface between SiC/C and g-C3N4, the energy band structure of g-C3N4 was well engineered for photocatalytic H2 production. This study provides a novel method for fabricating g-C3N4-based heterojunctions for application in environmental conservation.

In this study, Mo-glycerate was used as a precursor to create MoS2 hollow nanospheres (HNS), which were then used for the first time to modify ZnIn2S4 nanosheets to create MoS2 HNS/ZnIn2S4 photocatalysts. The findings demonstrate that MoS2 HNS/ZnIn2S4 heterojunctions exhibited remarkably boosted photocatalytic properties and excellent reusability for both RhB degradation and H2 evolution without the use of Pt as a co-catalyst. Among the heterojunctions, the RhB degradation and H2 evolution efficiencies of the optimized MoS2 HNS/ZnIn2S4-3 wt % composite were almost 5 and 34 times higher than those of ZnIn2S4, respectively. The excellent performance of MoS2 HNS/ZnIn2S4-3 wt % might be attributed to the expansion of the visible-light response range and the accelerated separation efficiency of photo-induced carriers, according to the findings of the optical property tests. Based on the established band gap position and characterization results, a potential mechanism for appealing photocatalytic activity over MoS2 HNS/ZnIn2S4 heterojunctions was also postulated.