Synthesis and Characterisation Characterisation Synthesis and of - PowerPoint PPT Presentation

Synthesis and Characterisation Characterisation Synthesis and of ZnO-WS 2 Nanowires, of ZnO-WS 2 Nanowires, a Model Material for Nanotribology Nanotribology and Manipulation and Manipulation a Model Material for a , Boris a , b , Jelena Butikova Butikova a , Boris Polyakov Polyakov a , Sergei Sergei Vlassov Vlassov b , Jelena b a , b , Sven Butanovs a Antsov b , Oras b Edgars Butanovs , Mikk Mikk Antsov Sven Oras Edgars a Institute of Solid State Physics, University of Latvia b Institute of Physics, University of Tartu TiN17, Trieste

Outline • Synthesis of ZnO-WS 2 core-shell nanowires • Characterisation of ZnO-WS 2 core-shell nanowires • Tribological experiments on ZnO-WS 2 nanowires • Future plans 2

Why core-shell nanowires? • New advanced properties - Mechanical - Electrical - Optical • Functional properties & applications - Radial p-n junction diode - Electroluminiscence - Photocatalysis and water splitting 3

ZnO-WS 2 nanowires 2D WS 2 ZnO NWs ZnO-WS 2 4

Synthesis Three - step process: ZnO nanowire growth a-WO 3 layer deposition Annealing in sulphur (chemical vapour transport; by DC magnetron : atmosfere Au catalyst) reactive sputtering in O 2 /Ar atmosphere 5

SEM characterisation ZnO nanowires ZnO-WS 2 NWs ZnO / a-WO 3 6

Raman spectroscopy Raman spectrum of WS 2 Raman spectrum of ZnO-WS 2 2D nanoplates nanowires 7

Photoluminescence PL spectrum of WS 2 2D nanoplates PL spectrum of ZnO and ZnO-WS 2 nanowires 8

TEM morphology (a, b) ZnO nanowire with a-WO 3 layer (c, d, e, f) ZnO-WS 2 nanowires 9

TEM diffraction (c, e) WS 2 layer tungstenite structure, <1213> zone axis (d, f) Hexagonal ZnO-zincite structure, <1120> zone axis 10

Core-shell nanowires Polyakov et al ( 2016) J. Phys. Chem. C 120: 21451–21459 11

AFM measurements Young modulus is size-dependent 12

ZnO-WS 2 nanowires s kin = 0.5 MPa Measurement of kinetic friction (rotation) of ZnO-WS 2 in SEM 13

ZnO-WS 2 nanowires Measurement of static friction of ZnO-WS 2 in SEM 14

For more information on nanomanipulations , please visit our poster Synthesis of of Core-shell Core-shell Synthesis Nanoparticles and and Nanowires Nanowires Nanoparticles with 2D 2D Transition Transition Metal Metal with Disulfides Shell Shell Disulfides 15

Future plans: • Synthesis of core-shell Me-MeS 2 nanoparticles using laser ablation in liquid • Nanotribology experiments: manipulations with Me- MeS 2 nanoparticles in SEM 16

Our team Boris Polyakov Sergei Vlassov Edgars Butanovs Mikk Antsov Sven Oras 17

Thanks a lot for your attention! 18