3 research outputs found
CdSe Nanocrystal Assemblies on Anodized TiO<sub>2</sub> Nanotubes: Optical, Surface, and Photoelectrochemical Properties
The in situ preparation of high-quality organically synthesized
cadmium selenide (CdSe) nanocrystals on TiO<sub>2</sub> nanotubes
(T_NT) prepared by anodization is presented. The deposition of CdSe
nanocrystals has been facilitated under a high-pressure and low-viscosity
solvothermal process. The formation, growth, and assembly of CdSe
nanocrystals in the form of a dense film on T_NT have been studied
using thermal (thermogravimetry and calorimetry) and optical (UVâvis
and microscopy) techniques. It has been concluded that an organic
treatment, followed by annealing under a nitrogen atmosphere at reduced
temperatures, helps control CdSe nanocrystal morphology without causing
significant particle size growth. Photoelectrochemical measurements
indicate that the electrode assembly consisting of T_NT and CdSe can
achieve a stable photocurrent density of 6.7 mA/cm<sup>2</sup> and a charge-separation efficiency of 35%
Vacancy-mediated structural changes in AuâCu nanoparticles
<p>We report the formation of new phases in bimetallic AuâCu nanoparticles. These phases were observed in nanoparticle synthesised by adopting a three-step protocol in a single pot. Nanoparticles at 180°C for 1â
h led to the formation of single-phase solid solution of Cu in Au. Subsequent heat treatment at 290°C for 2â
h of these AuâCu nanoparticles revealed three new phases. One of them relates to the modification of occupancy of Cu in an ordered AuCu tetragonal phase (tP4). This cell although retains tetragonal symmetry but displays metrical properties akin to that of a cube. The other two relates to vacancy ordering along <111> directions in the {111} planes of an ordered AuCu3 cubic phase (cP4). On the one hand, statistical occupancy of vacancy on Cu site in this cell leads to the reduction of cell size from âŒ3.75â
Ă
to âŒ3.5â
Ă
whereas ordering of vacant layer on the other hand gives rise to symmetry breaking. Former continues to display cubic symmetry whereas latter transforms to a trigonal cell.</p
Engineered SolutionâLiquidâSolid Growth of a âTreelikeâ 1D/1D TiO<sub>2</sub> Nanotube-CdSe Nanowire Heterostructure: Photoelectrochemical Conversion of Broad Spectrum of Solar Energy
This
work presents a hitherto unreported approach to assemble a 1D oxide-1D
chalcogenide heterostructured photoactive film. As a representative
system, bismuth (Bi) catalyzed 1D CdSe nanowires are directly grown
on anodized 1D TiO<sub>2</sub> nanotube (T_NT). A combination of the
reductive successive-ionic-layer-adsorption-reaction (R-SILAR) and
the solutionâliquidâsolid (S-L-S) approach is implemented
to fabricate this heterostructured assembly, reported in this 1D/1D
form for the first time. XRD, SEM, HRTEM, and elemental mapping are
performed to systematically characterize the deposition of bismuth
on T_NT and the growth of CdSe nanowires leading to the evolution
of the 1D/1D heterostructure. The resulting âtreelikeâ
photoactive architecture demonstrates UVâvisible light-driven
electronâhole pair generation. The photoelectrochemical results
highlight: (i) the formation of a stable nân heterojunction
between TiO<sub>2</sub> nanotube and CdSe nanowire, (ii) an excellent
correlation between the absorbance vis-aÌ-vis light conversion
efficiency (IPCE), and (iii) a photocurrent density of 3.84 mA/cm<sup>2</sup>. This proof-of-concept features the viability of the approach
for designing such complex 1D/1D oxideâchalcogenide heterostructures
that can be of interest to photovoltaics, photocatalysis, environmental
remediation, and sensing