Know4Nano

Presenters

Dr. Naresh Kumar

Senior Scientist and Lecturer in the Department of Chemistry and Applied Biosciences
Swiss Federal Institute of Technology (ETH) Zurich

Dr. Naresh Kumar is a Senior Scientist and Lecturer in the Department of Chemistry and Applied Biosciences at the Swiss Federal Institute of Technology (ETH) Zurich since 2020. Dr. Kumar earned his Bachelor of Technology in Engineering Physics from the Indian Institute of Technology Delhi and went on to receive his Master of Research in Physics at the Nanoscale from King’s College London, graduating with distinction. He obtained his PhD from Utrecht University, Netherlands, under the supervision of Prof. Bert Weckhuysen, where he focused on the development of Tip-Enhanced Raman Spectroscopy (TERS) and its application to heterogeneous catalysis. In 2011, Dr. Kumar joined NPL as a Research Scientist, where he spearheaded the development and application of TERS. He established a state-of-the-art AFM-TERS system at NPL and contributed to numerous interdisciplinary projects. His work spans diverse scientific fields, including heterogeneous catalysis, organic solar cells, polymer blends, nanoscale chemical imaging of solid-liquid interfaces, and 2D materials such as graphene and single-layer MoS2. For his scientific accomplishments, Dr. Kumar received the prestigious Rayleigh Early Career Award from NPL in 2016 and was promoted to Higher Research Scientist in 2017. From 2020 to 2023, Dr. Kumar served as an Visiting Professor at the School of Sciences, Hangzhou Dianzi University, China. In 2023, he received the esteemed Masao Horiba Award for advancements in optical nanospectroscopy to study novel semiconductor materials. Dr. Kumar is a frequently invited speaker at international scientific conferences in the fields of optical nanospectroscopy and nanoimaging.

Talk Title: Nanoscale chemical imaging of 2D materials using tip-enhanced optical spectroscopy

During the last decade, tip-enhanced optical spectroscopy has emerged as a powerful analytical tool for hyperspectral chemical imaging of 2D materials at the nanoscale. In this talk, I will discuss how atomic force microscopy (AFM) based-tip-enhanced Raman spectroscopy (TERS) can be used to visualize structural defects in pristine single-layer graphene [1,2] and determine the level and location of molecular disorder in chemically functionalized few-layer graphene [3], carboxyl-modified graphene oxide (Figures 1b-1d) [4] and graphene nanoribbons [5]. In addition, application of hyperspectral AFM-based tip-enhanced photoluminescence (TEPL) microscopy to probe excitonic processes in single-layer MoS2 [6], visualize optoelectronic behavior of grain boundaries grain boundaries in single-layer WSe2 [7] and probe nanoscale exciton funneling at wrinkles of twisted bilayer MoS2 [8] will also be presented.

References
1. S. Mignuzzi, N. Kumar, B. Brennan, I. S. Gilmore, D. R. Richards, A. J. Pollard, D. Roy “Probing individual point defects in graphene via near-field Raman scattering” Nanoscale 2015, 9, 19413-19418
2. W. Su, N. Kumar, N. Dai, D. Roy “Nanoscale chemical mapping of intrinsic defects in graphene using tip-enhanced Raman spectroscopy” Chemical Communications 2016, 52, 8227-8230
3. E. L. Legge, K. R. Paton, M. Wywijas, G. McMahon, R. Pemberton, N. Kumar et al. “Determining the level and location of functional groups on few-layer graphene and their effect on the mechanical properties of nanocomposites” ACS Applied Materials & Interfaces, 2020, 12, 13481-13493
4. W. Su, N. Kumar, A. Krayev, M. Chaigneau “In situ topographical chemical and electrical imaging of carboxyl graphene oxide at the nanoscale Nature Communications 2018, 9: 2891
5. W. Su, A. Esfandiar, O. Lancry, J. Shao, N. Kumar, M. Chaigneau “Visualising structural modification of patterned graphene nanoribbons using tip-enhanced Raman spectroscopy” Chemical Communications, 2021, 57, 6895-6898
6. W. Su, N. Kumar, S. Mignuzzi, J. Crain, D. Roy “Nanoscale mapping of excitonic processes in single layer MoS2 using tip-enhanced photoluminescence microscopy” Nanoscale 2016, 8, 10564-10569
7. W. Su, N. Kumar, H. Shu, O. Lancry, M. Chaigneau “In situ Visualization of Optoelectronic Behavior of Grain Boundaries in Monolayer WSe2 at the Nanoscale” The Journal of Physical Chemistry C, 2021, 125, 26883-26891
8. J. Shao, F. Chen, W. Su, N. Kumar, Y. Zeng, L. Wu, H. W. Lu “Probing Nanoscale Exciton Funneling at Wrinkles of Twisted Bilayer MoS2 Using Tip-Enhanced Photoluminescence Microscopy” The Journal of Physical Chemistry Letters, 2022, 13, 3304-3309

This project is funded by the European Union under Horizon Europe GA 101159710