Surface crystallization effects on the optical and electric properties of CdS nanorods

Abstract

We synthesized CdS nanorods through a conventional solvothermal method and studied their photoluminescence and electric transport properties before and after annealing. High-resolution transmission electron microscopy indicated that the surface layer of the annealed CdS nanorods was well crystallized, while that of the unannealed nanorods was amorphous. Energy-dispersive x-ray spectrography, x-ray photoelectron spectrography and thermogravimetric analysis were used to demonstrate that the amorphous layer at the surface of the as-prepared nanorods was pure CdS. The photoluminescence spectra showed that after annealing the intensity of the band-edge emission increased several times and the surface state emission at 548 nm disappeared. The unannealed CdS nanorods had approximately linear I-V characteristics and the conductance suddenly increased about 100 times upon visible light illumination by a halogen lamp. The annealed CdS nanorods exhibited nonlinear conductance with a turn-on voltage at about 2.2 V. These properties show that CdS nanorods have potential applications in nanophotoelectric or sensing devices.

Fabrication of NiS modified CdS nanorod p–n junction photocatalysts with enhanced visible-light photocatalytic H2-production activity

“…3b) clearly shows the crystal lattice fringes and the measured lattice spacing are in agreement with a typical hexagonal CdS (002) lattice plane (0.335 nm), indicating that the CdS NRs grow along the direction of the c-axis. 36,37 The SAED pattern shown in Fig. 3b (inset) indicates that the CdS nanorods are a single crystal of hexagonal CdS, and the bright diffraction spots are indicative of their high crystallinity.…”

CdS Nanorod-Amorphous Molybdenum Oxide Nanocomposite for Photocatalytic Hydrogen Evolution

“…Moreover, the bright diffraction spots of the SAED pattern of the CdS nanorod imply the high crystallinity of CdS (SI Figure S2b). The preferential growth along the c -axis direction represents the [001] zone axis of hexagonal CdS. , …”

“…Two obvious emission bands of CdS at 532 and 665 nm were observed, which is in line with other studies. 32,33 The fluorescence emissions of CdS/a-MoO x -32.6 wt % became obviously weak because of the fabrication of the heterojunction, indicating that the recombination of photogeneration electron−hole pairs in composites was effectively prevented through the Z scheme system because of the fast separation of electron−hole pairs between the interfaces. Figure 7f shows that the fluorescent lifetime of the CdS/a-MoO x composites is longer than that of CdS alone after forming the Z-scheme system.…”

“…To further investigate the reasons for the strongly enhanced photocatalytic H 2 production by amorphous molybdenum oxides, the PL spectra were obtained and fluorescent lifetime characterization was employed to study the migration of the photogenerated charges. 33 As presented in Figure 7e, laser excitation (405 nm) was used in the PL characterization. Two obvious emission bands of CdS at 532 and 665 nm were observed, which is in line with other studies.…”

“…The preferential growth along the c-axis direction represents the [001] zone axis of hexagonal CdS. 32,33 Figure 1e and f display the TEM and HRTEM images of the CdS/a-MoO x photocatalyst with 32.6 wt % of amorphous molybdenum oxides. It can be observed that the amorphous molybdenum oxides are closely connected with the CdS surface.…”