Effect of Sulfur Precursor on Dimensions of One-dimensional CdS Nanocrystals

One-dimensional CdS nanocrystals have been prepared by solvothermal method using cadmium acetate as a cadmium precursor, elemental sulfur and Na2S, as a sulfur precursor, and ethylenediamine as a solvent at 150℃ for 5 h. The nanocrystals were characterized by X-ray diffraction （XRD）, scanning electron microscopy （SEM）, transmission electron microscopy （TEM） and UV-Vis absorption spectroscopy. XRD patterns indicate that both Na2S and elemental sulfur as the sulfur precursor result in CdS nanorods with wutzite phase （hexagonal structure）. SEM and TEM images show that diameter of CdS nanorods can be decreased using Na2S instead of elemental sulfur. For the growth of CdS nanorods, a mechanism has been proposed. Uv-Vis absorption of CdS nanorods （sulfur precursor： Na2S） was shown blue shift to 485 nm due to the quantum size effect.

Energy funneling and charge separation in CdS modified with dual cocatalysts for enhanced H_(2) generation

Anchoring molecular cocatalysts on semiconductors has been recognized as a general strategy to boost the charge separation efficiency required for efficient photocatalysis.However,the effect of molecular cocatalysts on energy funneling(i.e.,directional energy transfer)inside semiconductor photocatalysts has not been demonstrated yet.Here we prepared CdS nanorods with both thin and thick rods and anchored the conjugated molecules 2‐mercaptobenzimidazole(MBI)and cobalt molecular catalysts(MCoA)sequentially onto the surface of nanorods.Transient absorption measurements revealed that MBI molecules facilitated energy funneling from thin to thick rods by the electronic coupling between thin and thick nanorods,which is essentially a light‐harvesting antenna approach to enhance the charge generation efficiency in the reaction center(here the thick rods).Moreover,MBI and MCoA molecules selectively extracted photogenerated holes and electrons of CdS nanorods rapidly,leading to efficient charge separation.Consequently,CdS/MBI/MCoA displayed 15 times enhanced photocatalytic H_(2) evolution(1.65 mL)than pure CdS(0.11 mL)over 3 h of illumination.The amount of H_(2) evolution reached 60 mL over 48 h of illumination with a high turnover number of 26294 and an apparent quantum efficiency of 71%at 420 nm.This study demonstrates a novel design principle for next‐generation photocatalysts.

Design and synthesis of ZnCo_(2)O_(4)/CdS for substantially improved photocatalytic hydrogen production

In this study,the hydrogen evolution performance of CdS nanorods is improved using ZnCo_(2)O_(4).ZnCo_(2)O_(4)nanospheres are synthesized using the hydrothermal and calcination methods,and CdS nanorods are synthesized using the solvothermal method.From the perspective of morphology,numerous CdS nanorods are anchored on the ZnCo_(2)O_(4)microspheres.According to the experimental results of photocatalytic hydrogen evolution,the final hydrogen evolution capacity of 7417.5μmol·g^(-1)·h^(-1)is slightly more than two times that of the single CdS,which proves the feasibility of our study.Through various characterization methods,it is proved that the composite sample has suitable optoelectronic properties.In addition,ZnCo_(2)O_(4)itself exhibits good conductivity and low impedance,which shortens the charge-transfer path.Overall,the introduction of ZnCo_(2)O_(4)expands the adsorption range of light and improves the performance of photocatalytic hydrogen evolution.This design can provide reference for developing high-efficiency photocatalysts.

Chiral CdSe/CdS quantum dot (in rod)-light-emitting diodes with circularly polarized electroluminescence

Chiral quantum dot(in rod)-light-emitting diodes(CQLEDs)with circularly polarized electroluminescence(CPEL)have driven interest in the future display,communication,and storage industries.However,the preparation of CQLEDs is still a challenging unresolved.Herein,we fabricated CQLEDs through spin-coating evaporation of chiral CdSe/CdS quantum rods(CCCQs)colloidal solution on indium tin oxide substrate.The CCCQs were synthesized via an isotropically epitaxial growth with cholic acid as the symmetry breaking agent,which induced one-direction chiral dislocation around the c axis of their hexagonal crystal structure.The CCCQs were ranked side-by-side in right-handed chiral arrangement with helical axis perpendicular to substrate due to chiral driving force of the cholic acid arrangement.The CQLEDs exhibited a negative CPEL signal at 600 nm with a|gEL|of 2×10^(−4),which is ascribable to the selective filtration on emission arising from the circular Bragg resonance by quasi-photonic crystal structures.

PERFORMANCE ENHANCEMENT OF CdS NANOROD ARRAYS/P3HT HYBRID SOLAR CELLS VIA N719 DYE INTERFACE MODIFICATION

Improved hybrid solar cells consisting of vertical aligned cadmium sulfide （CdS） nanorod arrays and interpenetrating polythiophene （P3HT） have been achieved via modification of CdS nanorod surface by using conjugated N719 dye. The complete infiltration of P3HT between CdS nanorods interspacing was verified by scanning electron microscopy. By employing absorption and photoluminescence spectra, and current-voltage characterization the interaction between N719 molecules and CdS nanorods/P3HT interface was explored, and the role of N719 dye on the improvement of device performance was discussed.