Enhanced sunlight driven photocatalytic activity of In2S3 nanosheets functionalized MoS2 nanoflowers heterostructures

Visible light-sensitive 2D-layered based photocatalytic systems have been proven one of the effective recent trends. We report the preparation of a 2D-layered based In2S3–MoS2 nanohybrid system through a facile hydrothermal method, capable of efficiently degrading of organic contaminants with remarkable efficiency. Transmission electron microscopy (TEM) results inferred the attachment of 2D-layered In2S3 sheets with the MoS2 nanoflakes. Field emission SEM studies with chemical mapping confirm the uniform distribution of Mo, In, and S atoms in the heterostructure, affirming sample uniformity. X-ray diffraction, X-ray photoelectron spectroscopy, and Raman spectroscopy results confirm the appearance of 2H-MoS2 and β-In2S3 in the grown heterostructures. UV-DRS results reveal a significant improvement in the optical absorbance and significant bandgap narrowing (0.43 eV) in In2S3–MoS2 nanohybrid compared to pristine In2S3 nanosheets in the visible region. The effective bandgap narrowing facilitates the charge transfer between MoS2 and In2S3 and remarkably improves the synergistic effect. Effective bandgap engineering and improved optical absorption of In2S3–MoS2 nanohybrids are favorable for enhancing their charge separation and photocatalytic ability. The photocatalytic decomposition efficiency of the pristine In2S3 nanosheets and In2S3–MoS2 nanohybrids sample is determined by the decomposing of methylene blue and oxytetracycline molecules under natural sunlight. The optimized In2S3–MoS2 nanohybrids can decompose 97.67% of MB and 76.3% of OTC-HCl molecules solution in 8 min and 40 min of exposure of sunlight respectively. 2D-layered In2S3-MoS2 nanohybrids reveal the tremendous remediation performance towards chemical contaminations and pharmaceutical waste, which indicates their applicability in industrial and practical applications.

Boosting of photocatalytic hydrogen evolution via chlorine doping of polymeric carbon nitride

Chlorine is found to be a suitable element for the modification of polymeric carbon nitride properties towards an efficient visible-light photocatalytic activity. In this study, chlorine-doped polymeric carbon nitride (Cl-PCN) has been examined as a photocatalyst in the hydrogen evolution reaction. The following aspects were found to enhance the photocatalytic efficiency of Cl-PCN: (i) unique location of Cl atoms at the interlayers of PCN instead of on its π-conjugated planes, (ii) slight bandgap narrowing, (iii) lower recombination rate of the electron–hole pairs, (iv) improved photogenerated charge transport and separation, and (v) higher reducing ability of the photogenerated electrons. The above factors affected the 4.4-fold enhancement of the photocatalytic efficiency in hydrogen evolution in comparison to the pristine catalyst.

ON THE CONTRIBUTION FACTORS OF ENHANCED PHOTOCATALYTIC ACTIVITY OF DOPED SEMICONDUCTORS: STRUCTURAL AND OPTICAL INTVESTIGATION OF CU2+ DOPED ZnO NANOPARTICLE

As a traditional direct bandgap oxide semiconductor, ZnO, showed as a promising photocatalytic candidate. Researchers worldwide reported many possibilities to improve its photocatalytic activity such as doped with metal, non-metal ions. As a result of heterojunction formation between ZnO and its intentional impurity, previous reports showed beneficial characteristics for enhancing photocatalytic activity in these ZnO-based materials, i.e. bandgap narrowing, recombination rate of photoelectron-hole prolonging, visible light absorption improving. This work will present the photocatalytic acitivity improvement of ZnO when doping with ion Cu2+ and try to illustrate the crucial photocatalytic enhancement factors.

Ultrafast photo-induced enhancement of electron-phonon coupling in metal-halide perovskites

In metal-halide perovskites (MHPs), the nature of organic cations affects both, the perovskite’s structure and its optoelectronic properties. Using ultrafast pump-probe spectroscopy, we demonstrate that in state-of-the-art mixed-cation MHPs ultrafast photo-induced bandgap narrowing occurs, and linearly depends on the excited carrier density in the range from 1016 cm− 3 to above 1018 cm− 3. Furthermore, time-domain terahertz (td-THz) photoconductivity measurements reveal that the majority of carriers are localized and that the localization increases with the carrier density. Both observations, the bandgap narrowing and carrier localization, can be rationalized by ultrafast (sub-2ps) photo-induced enhancement of electron-phonon coupling, originating from dynamic disorder, as clearly evidenced by the presence of a Debye relaxation component in the terahertz photoconductivity spectra. The observation of photo-induced enhancement of electron-phonon coupling and dynamic disorder not only provides specific insight into the polaron-strain distribution of excited states in MHPs, but also adds to the development of a concise picture of the ultrafast physics of this important class of semiconductors.

Oxygen vacancy mediated room-temperature ferromagnetism and bandgap narrowing in DyFe0.5Cr0.5O3 nanoparticles

We report on the magnetic and optical properties of DyFe0.5Cr0.5O3 nanoparticles synthesized by sol-gel method. Rietveld refinement of powder X-ray diffraction (XRD) pattern confirms the formation of orthorhombic disordered phase...