Effects of crystalline phase and morphology on the visible light photocatalytic H₂-production activity of CdS nanocrystals

Abstract

Visible light photocatalytic H2-production from aqueous solutions is of great importance for its potential application in converting solar energy into chemical energy. In this study, a series of CdS nanostructures with different contents of wurtzite (WZ) and zinc blende (ZB) phases were successfully synthesized by a simple solvothermal route in an ethylenediamine and ethylene glycol mixed solution. The solvent volume ratio of ethylenediamine in the mixed solution (R) exhibited an obvious influence on the crystalline phase and morphology of the resulting CdS products. With increasing R, the percentage of wurtzite first increased and then decreased, whilst the morphology changed from nanoparticles to multi-armed nanorods, and finally to long rods and sheets. The prepared multi-armed CdS nanorod samples showed especially high and stable photocatalytic H2-production activity with Pt (0.25 wt%) as a co-catalyst and lactic acid aqueous solution as a sacrificial reagent under visible light irradiation. The optimized CdS nanorods with the highest percentage (64%) of the WZ phase exhibited a high H2-production rate of 231.4 μmol h(-1) (about 16.6 times higher than that of CdS nanoparticles with a low percentage (38.4%) of WZ CdS) and with a quantum efficiency (QE) of 28% at 420 nm. This high photocatalytic H2-production activity could be attributed to the results of the positive synergistic effects of the hexagonal WZ phase and morphology of multi-armed nanorods.

CdS‐Nanoparticles‐Decorated Perpendicular Hybrid of MoS2 and N‐Doped Graphene Nanosheets for Omnidirectional Enhancement of Photocatalytic Hydrogen Evolution

“…The diffraction peaks at 24.8, 26.5, and 28.2° in the XRD patterns of both CdS and CdS@MNRGO corresponded to the (1 0 0), (0 0 2), and (1 0 1) planes of hexagonal CdS, respectively (JCPDS NO.41‐1049). Compared with other crystal phases, the hexagonal phase has been found to favor higher photocatalytic activity . Notably there was only a small peak of MNRGO in the XRD pattern of CdS@MNRGO probably owing to the low content of MNRGO or slight face‐to‐face stack of two‐dimensional sheets .…”

One‐Step Solid‐Phase Synthesis of 2D Ultrathin CdS Nanosheets for Enhanced Visible‐Light Photocatalytic Hydrogen Evolution

“…The above results indicate that the controlled calcination time for the formation of 2D CdS nanosheet is of crucial importance. 2D CdS structure could be obtained by changing the calcination temperature and time, which plays a major role in the preparation and regulation of highly active photocatalytic materials . This simple one‐step solid‐phase synthetic method shows a great potential of 2D CdS nanosheets and also suggests the fabrication of other favorable photocatalysts with 2D structures.…”

Organic pollutants removal in wastewater by heterogeneous photocatalytic ozonation

“…The photocatalytic ozonation of monochloroacetic acid and pyridine led to 6 and 24 times higher degradation rates than without TiO 2 and 4 and 18 times higher rates than without ozone Kopf et al (2000) Formic acid, acetic acid and propionic acid in solution are very efficient non-selective oxidizers, which result in the oxidation and eventual mineralization of organic compounds. Photocatalysts typically include TiO 2 (Gaya and Abdullah, 2008;Wang and Jing, 2014), ZnO (Kaur and Singhal, 2014;Xu et al, 2014a), WO 3 Katsumata et al, 2014), CdSe (Elmalem et al, 2008;Li et al, 2014), CdS (Chronopoulos et al, 2014;Lang et al, 2014), a-Fe 2 O 3 Wei et al, 2014), SnO 2 (Wang et al, 2002a;Jana et al, 2014) and Ag 3 PO 4 (Bi et al, 2011;Zhang et al, 2014a). Among these semiconductor materials, TiO 2 is the most extensively and intensively studied one due to its high photoconductivity, chemical stability, low toxicity, low costs and wide commercial availability.…”