Literature Presentation 14 th Jan 2015 By Saurav Chandra Sarma

Characterizations XRDSEMEDSHRTEMUV-Vis-DRSPL

Schematic illustration of the synthesis process XRD patterns of a)Pure TiO2 nanobelt b)Scaly Sn3O4 nanoflakes c)Sn3O4/TiO2 Molar ratio Sn/Ti=2/1 TiO2 is in anatase phase Sn3O4 has triclinic phase

SEM images SEM images of scaly Sn3O4/TiO2 (molar ratio Sn/Ti=2/1) heterostructure obtained at different synthetic stages of (a) 1 h; (b) 4 h; (c) 12 h.

SEM images a)TiO2 nanobelts b)Sn3O4 nanoflakes c,d) Sn3O4/TiO2 nanobelts Sn3O4 nanoflakes are assembled perpendicular to the surface of TiO2 nanobelts.

HRTEM images a)(101) layered structure of triclinic Sn3O4 b)The distance between the lattice fringes agree well with the triclinic Sn3O4 phase. c)Individual scaly nanobelt heterostructure. d)Sn3O4 and TiO2 at the interface level. e-h) EDS elemental mapping analysis.

UV-Vis Diffuse Reflectance Spectrum Indirect band gap using Kubelka-Munk method a)Sn3O4 (475 nm) b)Sn3O4/TiO2 (479 nm) c)TiO2 (380 nm)

Photocatalytic Dye degradation Dye: Methyl Orange Irradiated with UV and simulated solar lights After regular interval aliquot collected, centrifuged and studied with UV-vis spectrophotometer.

Photocatalytic Dye degradation

Photocatalytic Hydrogen Evolution Schematic diagram of electron transfer in Sn 3 O 4 /TiO 2 heterostructure Comparison of the phtocatalytic hydrogen evolution activities of different samples

Photocatalytic Hydrogen Evolution PL spectra of (a)TiO 2 nanobelts, (b)(b) Sn 3 O 4 /TiO 2 (molar ratio Sn/Ti= 2:1) heterostructure, (c) Sn 3 O 4 nanoflakes.

Photoelectrochemical measurements Mott-Schottky plots of (a) scaly Sn 3 O 4 and (b) TiO 2 nanobelt at different frequencies in a 0.1 M Na 2 SO 4 solution (0.1 M; pH= 6.8) electrolyte.

Conclusions  The hydrothermal growth of Sn3O4 resulted in crystallographic connection of (1-11) plane of Sn 3 O 4 and (101) plane of TiO 2.  Sn 3 O 4 /TiO 2 nanobelts can absorb both in the UV and visible range.  The heterostructure exhibits superior photocatalytic pollutant degradation and hydrogen evolution under either UV or visible light irradiation.

Partial cation exchange synthesis Scheme of the synthesis of pristine Cu2S NCs and their exchange reactions to CIS and CIZS NCs Sequence exchange Combined Exchange

TEM images of Cu 2 S and CIS a)Parent Cu 2 S NCs, b)Exchanged CIS NCs, c,d) HRTEM image, FT analysis of e) Cu2S, f) NCs with axial projection Cu 2 S (7.9 nm) CIS (5.7 nm) Slight etching by TOP

PXRD pattern

TEM images of CIZS

X-ray Photoelectron Spectroscopy (XPS)

Absorption Spectrum

Cyclic Voltammogram

Conclusions  Sequentially synthesized CIZS form core/shell like structure whereas combining two precursors in one pot forms homogeneously alloyed CIZS NCs.  Sequential exchange with Zn2+ leads to a sufficient increase of the PL efficiency.  PL peak can be tuned from 850 nm to 1030 nm by carefully controlling the Cu:In:Zn ratio in the NCs.  Combination of optical characterization with cyclic voltammetry results provides a further insight into the electronic structure of the NCs.