Dr Qian He
University Research Fellow
My research interests focus on the development and application of electron microscopy techniques for the study of energy and environment related materials. Specific technical interests include imaging and chemical analysis using aberration-corrected scanning transmission electron microscopy, electron 3D tomography, low dose imaging, in-situ electron microscopy and etc. My recent research has been focused on catalytic nanomaterials and material interfaces, aiming to achieve microscopy-informed design of novel functional materials.
Qian He obtained his BSc in Material Science and Engineering from Tsinghua University (China) in 2006. He did his MSc in the same department until 2008, studying on aluminium alloys with Professor Jian-Guo Li. He then joined Professor Chris Kiely’s group in Lehigh University (USA), studying Au and Au-based nanoalloy catalysts using advanced electron microscopy techniques, and obtained his Ph.D. in 2013. From 2013 to 2016, He did postdoctoral research in the STEM group in Oak Ridge National Laboratory (USA), working on characterizing complex oxides interfaces with Dr. Albina Borisevich. He was awarded the University Research Fellowship from Cardiff University and joined the Cardiff Catalyst Institute, School of Chemistry since June 2016. He has received several awards including the postdoctoral scholar award from the International Microscopy Congress in 2014 and the presidential scholar award from the Microscopy Society of America in 2016.
CHT219 - Preparation and Evaluation of Heterogeneous
Some of the recent research interests include
- Mechanistic investigation of heterogeneous catalysis
- Developing methods for synthesizing multi-metallic nanoparticles for catalysis applications
- Understanding and controlling interfaces in heterogeneous catalysts
- Developing novel electron microscopy methods for
1. Mechanistic investigation of heterogeneous catalysis
The properties of heterogeneous catalysts are largely, if not all, depending on the atomic structures and the population of the active components. Comparing with bulk and surface characterization techniques, electron microscopy provides unique capability of investigating local chemical and structural information of practical catalysts. Such information can be correlated with catalytic properties, and thus created opportunities for us to identify active sites and obtain mechanistic insights of the catalysts.
Q. He†, S.J. Freakley†, J.K. Edwards, A.F. Carley, A.Y. Borisevich, Y. Mineo, M. Haruta, G.J. Hutchings and C.J. Kiely. “Polulation and Hierarchy of Active Species in Gold Catalysts for Low Temperature Carbon Monoxide Oxidation”. Nature Communications, 2016, 7, 12905.
2. Characterizing and synthesizing multi-metallic nanoparticles for catalysis applications
Multi-metallic nanoparticles often exhibit exceptional catalytic properties compared to their monometallic counterparts. However, making such nanoparticles is non-trivial, as different physical and chemical properties of the component metals make it very difficult to control simultaneously. We have developed several synthesis strategies, both in the gas phase and the aqueous phase. Electron microscopy plays a key role in such process as it can characterize different metal distributions within and among nanoparticles. The aim of this research is to develop effective methods for various systems to achieve controlled synthesis over particle size, composition and morphology distribution, in order to maximize catalyst atomic efficiency as well as obtain mechanistic insights.
Q. He, P. J. Miedziak, L. Kesavan, N. Dimitratos, M. Sankar, J. A. Lopez-Sanchez, M. M. Forde, J. K. Edwards, D. W. Knight, S. H. Taylor, C. J. Kiely, and G. J. Hutchings, “Switching-off toluene formation in the solvent-free oxidation of benzyl alcohol using supported trimetallic Au–Pd–Pt nanoparticles,” Faraday Discuss., vol. 162, p. 365, 2013.
M. Sankar, Q. He, M. Morad, J. Pritchard, S. J. Freakley, J. K. Edwards, S. H. Taylor, D. J. Morgan, A. F. Carley, D. W. Knight, C. J. Kiely, and G. J. Hutchings, “Synthesis of stable ligand-free gold-palladium nanoparticles using a simple excess anion method,” ACS Nano, vol. 6, no. 8, pp. 6600–6613, 2012.
M. M. Forde, L. Kesavan, M. I. Bin Saiman, Q. He, N. Dimitratos, J. A. Lopez-Sanchez, R. L. Jenkins, S. H. Taylor, C. J. Kiely, and G. J. Hutchings, “High activity redox catalysts synthesized by chemical vapor impregnation,” ACS Nano, 2014, 8(1), 957–969.
3. Understanding and engineering interfaces in heterogeneous catalysts
Interfaces play a critical role in heterogeneous catalysts. In supported nanoparticles, metal-support interface dictates their electronic interaction and controls the metal nanoparticle stability. In many cases, the interface itself can be the active sites. In oxides catalysts, interfaces among different phases have unique cation arrangements that are different compared to the bulk phase and therefore can create active sites. Electron microscopy is uniquely capable of probing chemical and structural information of such interfaces. The goal is to engineer such interface to achieve highly stable and active catalysts.
S.J. Freakley†*, Q. He†, J. Harrhy, L Lu, DA. Crole, DJ. Morgan, EN. Ntainjua, JK. Edwards, AF. Carley, A Borisevitch, CJ. Kiely and GJ. Hutchings. “Palladium-tin catalysts for the direct synthesis of H2O2 with high selectivity”. Science, 2016, 351(6276), 965-968.
Q. He*, J. Woo, A. Belianinov, VV. Guliants, A. Borisevich, “Better Catalysts through Microscopy: Mesoscale M1/M2 intergrowth in Molybdenum-Vanadium Based Complex Oxide Catalysts for propane Ammoxidation”, ACS Nano. 2015, 9(4), 3470–3478.
4. Advancing the electron microscopy techniques
Some of the big challenges in characterizing nanomaterials using electron microscopy include i) getting full 3D atomic structure of the catalyst nanoparticles ii) characterizing e-beam sensitive materials, such as certain oxides, nanoparticles smaller than 1-2 nm and particle surfaces. Iii) observing the catalyst structures in realistic synthesizing/working conditions. I am interested in pursuing potential solutions of these problems include quantitative electron microscopy, electron tomography, low-dose imaging, and in-situ/operando electron microscopy.
Q. He*, R. Ishikawa, A.R. Lupini, L. Qiao, E.J. Moon, O.Ovchinnikov, S.J. May, M.D. Biegalski, and A. Borisevich. "Towards 3D Mapping of BO6 Octahedron Rotations at Perovskite Thin Film Heterointerfaces, Unit Cell by Unit Cell." ACS Nano, 2015, 9(8), 8412–8419.
Q. He*, A. Belianinov, A. Dziaugys, P. Maksymovych, Y. Vysochanskii, S.V. Kalinin and A.Y. Borisevich. “Antisite Defects in Layered Multiferroic CuCr0.9In0.1P2S6”. Nanoscale, 2015, 7, 18579-18583.