Professor Z. Xiao Guo

Research Overview

Xiao Guo’s research interest focuses on multiscale syntheses and simulations of materials and nanostructures for applications in clean energy and healthcare technologies, particularly in carbon capture, chemical/photo-electro-chemical catalysis, chemical/electrochemical energy storage, biofuel cells and biointerfaces. Fundamental theories are coupled with ab initio, molecular dynamics, cellular automata and finite element simulations for materials discovery, while selected materials are synthesised and harnessed by sol-gel, mechano-chemical, self-assembly, exfoliation, deposition and co-precipitation methods.

Xiao GUO is a Professor of Materials and Chemistry, leading a team of ~15 Postdocs and PhD students at UCL. The research team is in close collaboration with UK, other EU and/or international partners of high academic standing, involving a total grant value of ~£60m in the past 10 years and direct funding to own research group of ~£13m. Live research grants is around £2~5million at a given time, in the past five years. Current research activities focus on the understanding and development of materials, nanostructures and processes to provide low-cost and efficient solutions for clean energy, particularly in energy harvesting, storage, CO2 capture and biological fuel cells. He has contributed over 170 high-quality journal publications and over 300 conference papers/presentations in the field. He is a member of the editorial boards for several international journals. He was awarded the Beilby Medal 2000, jointly by the Society of Chemical Industry, the Royal Society of Chemistry, and the Institute of the Minerals, Metals and Materials. He received the Lee-Hsun Lecture Prize in 2002, by the Institute of Metal Research / Chinese Academy of Sciences. He has been involved in various UK-US, UK-Japan, UK-China and UK-Korea Hydrogen Energy links and is on Task 22 of the International Energy Agency.

He co-initiated the “International Conference on Multiscale Materials Modelling” series in 2002, and has been a member of the International Advisory Committee of subsequent conferences. He was UK EPSRC Task Panel member on Materials Modelling Initiative in 2003-2005, and is now Committee Member of “TYC- London Centre for Materials Theory and Modelling”. He also represents the UK on the European Energy Research Alliance’s Advanced Materials and Processes for Energy Applications (AMPEA) consortium.

Related Links:

EPSRC Funding: http://gow.epsrc.ac.uk/NGBOViewPerson.aspx?PersonId=44948

Google Scholars: http://scholar.google.co.uk/citations?user=tuyd_OgAAAAJ&hl=en

A. Research Activities in Energy Storage and Generation:

A1.  Grid-Scale Energy Storage in Flow Batteries

Grid-Scale Energy Storage in Flow Batteries

As a member of the UK consortium on “Energy Storage for Low-Carbon Grid”, we are involved in the development of specific catalysts and high-capacity electrode structures for vanadium and Metal-Air flow batteries. There are several challenges preventing the widespread takeup and utilisation of these technologies. These include: low cost and durable electrodes, highly selective and durable membranes, designing electrode structures that minimize transport loss, and identifying low-cost redox couples with high solubility. Typical electrolyte solvents typically contain acid compounds, which may degrade the battery. There is therefore a need for new materials and engineering approaches to overcome the disadvantages of current approaches, and allow technologies to be developed which meet the targets of cost, reliability and durability for grid scale application. In this proposal we will bring together two groups from UCL (Guo) and Imperial College (Brandon) to explore new concepts with the aim of significantly reducing the cost of current redox flow storage technologies. Our focus will be on: i) improved cell design to facilitate convection and thermal transport of electrolytes, ii) developing ZnO-based colloid suspensions for Zn-batteries, and iii) developing high capacity and durable electrode structures, including layered graphene and layered carbon-nitride hybrid structures.

A2.  Predictive Design and Synthesis of Hydrogen Storage Materials and Nanostructures

Predictive Design And Synthesis of Hydrogen Storage Materials and Nanostructures

Climate change, limited oil& gas fuels, and pollution have led to a worldwide drive for the development of clean and renewable energy resources. Hydrogen is a clean energy vector, as it is the most abundant element in the universe, has the highest energy per unit weight of any chemical fuel, and is non-polluting. Material hydrides offer safe, compact and low pressure storage of hydrogen for many potential applications, e.g. fuel cells / batteries in future electronics and transportation. However, much of the technology is hindered by high-cost and low weight-specific power. The research aims to develop hydrogen storage nanostructures and systems of desirable properties, guided by theoretical predictions. Systems under consideration include LiH, MgH2, LiNH2, LiBH4, LiAlH4 and doped carbon nanostructures. Selected multi-component systems (Li, B, C, Mg, Al) are synthesised in an ultra-clean clean environment, modified by mechanical, chemical and catalytic means and by the design of reaction paths. Characterisations of particle size, lattice parameter, microstructure, and phase composition are performed using SEM, TEM, X-Ray diffraction and quantitative Rietveld analyses. Hydrogen desorption/absorption properties are evaluated using P-C-T facilities and coupled Thermogravimetry (TG), Differential Scanning Calorimetry (DSC), Mass Spectrometry (MS) and FT-IR techniques. The research activities are currently sponsored by the EPSRC SUPERGEN Initiative - UK Sustainable Hydrogen Energy Consortium (www.uk-shec.org), an EPSRC Platform Grant, in association with the International Energy Agency.

A3. Carbon capture /sequestration and pollutant control – from simulations to fossil-fuel plants

Carbon capture /sequestration and pollutant control - from simulations to fossil-fuel plants

Carbon (CO2) capture and sequestration (CCS) is an effective technology for reduction of CO2 emissions from power stations and hence to mitigate climate change. Effective adoption of CCS technologies require an in-depth understanding of CO2 adsorption on sorbent structures; and development of efficient, stable and low-cost sorbent systems. In collaborations with a number of UK and Chinese institutions and industry, the research team is involved in several research consortia focussing on: 1) first-principles simulation of CO2/N2 interactions with target specific functional groups, and then promising materials to understand the fundamental processes of adsorption and desorption pathways of CO2 / N2 with sorbent systems at atomic/molecular scales; 2) enhancement of surface area, gas activation and selectivity by co-doping / functionalisation of hierarchically porous structures of carbon and oxides; and 3) synthesis of hybrid structures of different sorbents to achieve synergistic functionalities for much enhanced selectivity and capacity. These efforts will be combined with the design of feasible capture processes for the integration of the capture technology into power plants.

A4.  Multiscale Simulations of Chemical Looping Reforming with CO2 Capture

As part of an EU consortium, this project is to create an efficient and cost effective multi-scale simulation platform based on free and open-source codes, to connect models spanning a wide range of scales from the atomic, particulate, cluster to continuum scales, linked with real dimentions of an industrial system. The consortium will develop an open and integrated framework for numerical design called Porto to be used and distributed in terms of the GNU Lesser General Public License (LGPL). A core co-simulation platform called COSI (also licensed as LGPL) will be established based on existing CFDEMcoupling (an open source particle and continuum modelling platform). To establish this software tool, the project will develop and improve models to describe the relevant phenomena at each scale, and will then implement them on the next coarser scale. This scientific coupling between scales will be supported by sophisticated software and data management in such a way that the actual model implementation in various software packages will be fully automatic. The resulting open source software platform will be used to facilitate the rational design of second generation gas-particle CO2 capture technologies based on nano-structured materials with a particular focus on Chemical Looping Reforming (CLR).

A4. Fundamental Study of molecular (H2 /CO2/H2O) interactions with nanostructures

Fudamental Study of molecular (H2/c02/h20) interactions with nanostructures

The overall aim is to clarify the nature of H2, CO2 and H2O interactions with various host structures and surfaces, so as to identify the most-effective H-storage systems, CO2 sorbents, water-splitting catalysts. Considerations are given to the influences of structural geometry, defects, charge and doping of nanostructures from first principles electronic structural simulations. Stability of nanostructures is evaluated from the electronic structures and binding energies, and energy barriers are determined from the Nudged Elastic Band method. Relative stabilities of different sorption sites and configurations are assessed for further clarification of H2 /CO2 sorption mechanisms. Well-tested first principles codes, e.g., WIEN2K and VASP, are used for the studies. The research activities are currently sponsored by the EPSRC SUPERGEN Initiative - UK Sustainable Hydrogen Energy Consortium, an EPSRC Platform Grant, in association with the International Energy Agency.

A5. Integration of Hydrogen Storage Materials into Power Systems

The focus here is to incorporate modified hydrogen storage materials or hybrid systems into storage tanks and then with fuel cells. The project builds on the current research activities to develop optimised hydrogen storage systems, which is integrated into storage tank designs and development with collaborating partners. Material stability and degradation due to hydrogen and temperature exposure are studied. There is a need for integration of tank design, heat transfer requirements, heat management, system geometry, and choice of materials for tank casing. Furthermore, hydrogen delivery issues to fuel cells are evaluated to ease of installation, energy efficiency, response time, safety and reliability.

A6. Chemical Synthesis of Cathode Materials for High Power Density Li-Ion Batteries

Due to continued industrial demand for high-performance Li-ion batteries, LiCoO2-based cathode materials have been under popular investigation for enhanced electrochemical capacity. Here, doped LiCo(1-x)MxO2, was synthesized by co-precipitation followed by freeze drying, milling and calcination. TG/DSC studies were performed on the ball-milled and freeze-dried precursors. The morphologies and structures of the as-prepared compounds were characterized by SEM and XRD, respectively. FTIR was also employed to investigate the compound structures in detail. The chemical method requires far less time than the traditional route, leading to much improved electrochemical performance.

B. Research Activities in Biofuel Cells and Biointerfaces:

B1. Synthesis and Modifications of Electrode Materials for Biological Fuel Cells

Synthesis and Modifications

The project aims to develop high power density biological fuel cells, converting chemical / biochemical energy into electrical energy using biocatalysts, generating fuel through metabolic processes or catalysing electron transfer between the fuel and the bioelectrode. A fuel cell is an electrochemical device that converts chemical energy to electricity. Unlike conventional fuel cells, a biological fuel cell converts biological matters into and/or uses bio-catalytic enzymes for electric energy. BioFCs operate at ambient temperatures, atmospheric pressure and neutral pH, of benefit to the environment, waste management, portable electronics and implantable medical devices. This multidisciplinary project aims at developing highly conductive and robust electrodes for biological fuel cells. Such biofuel cells may be implanted into human body to power medical devices at a very small scale, or set up in biomass and waste-water streams for electricity generation and water/waste treatment. Here, we are synthesising the important electrode structures, examination of the structures by SEM / XRD, and measurement of mechanical and electrical properties. The activities are currently sponsored by the EPSRC SUPERGEN Initiative – UK Biological Fuel Cells consortium

B2. Molecular Dynamics Simulations of Electrodes and Enzymes in Biofuel Cells

H2 interactions with a hydrogenase

This project is orientated for biological fuel cells that can directly convert biological matter into energy – electricity, making use of the unique capabilities of Molecular Dynamics (MD) to simulate interactions of inorganic and bio-molecular substances for understanding and design of biointerfaces with much improved immobilisation of catalytic enzymes and electronic transfer from the bio-substrate to the electrode. The activities are currently sponsored by the EPSRC SUPERGEN Initiative – UK Biological Fuel Cells consortium. 

B3: Self-Assembly for Surface Coatings of Improved Biocompatibility:

Titanium and its alloys are frequently used as surgical implants in load bearing situations due to their good biocompatibility. However, the materials do not readily bond to bone in the early post-implantation stage. Various methods have been proposed to introduce calcium phosphate (CaP) coatings onto metal implant surfaces to improve and accelerate their integration with bony tissue, but none of the methods offers satisfactory results. A self-assembly technique is under development here to modify the surfaces of titanium and its alloys so as to improve their biocompatibility. Several kinds of molecules with specific bioactive functionalities were immobilised on spontaneously formed nanoscale self-assembled monolayers (SAMs). Titanium based samples were first treated with concentrated H 2SO 4 and 30%H 2O 2 to form titania and then immersed in silane solutions and organic solvents to generate monolayers with –OH, –COOH, –NH 2 and –PO 4H 2 terminal groups. Atomic force microscopy and contact angle goniometer were used to characterise the SAM surfaces and confirm the presence of various functional groups. Simulated body fluids (SBFs) were utilised to generate calcium phosphates over these functional groups. Scanning electron microscopy and X-ray diffraction were applied to characterise the calcium phosphate layer. The results clearly show that the SAM modified surfaces greatly enhance the formation of calcium phosphates . This low-temperature process is able to produce uniform coatings onto complex-shaped and/or micro-porous samples and the phases and crystallinity of the deposited material can be readily controlled, even with possible addition of growth-factors.

B4.  Multiscale Simulations of Biointerfaces

Multi Simulations of Biointerfaces

Biointerfaces refer to those between a physiological environment and an inorganic material, such as implant/tissue and biosensor/bio-fluid interfaces. Understanding of such interfaces is very important in improving the biocompatibility of implants and in optimising the design and function of drug delivery / bio-sensory devices and gene chips. The aim of this project is to use molecular dynamic simulations to study the complex interactions across the bio-interfaces, so as to provide some insight into the specific area of bio-interface science. The interfaces between selected proteins and inorganic substrates will be simulated using coupled QM/MM and coarse-graining approaches, in order to identify: 1) specific binding sites and binding mechanisms of proteins after contact with the substrate; and 2) effects of surface chemistry, orientation and topography on enzyme/protein apposition on metal/electrode substrates. Comparison between predictions and experiments will be made where possible.

Selected Publications :

1) S.A. Shevlin and Z.X. Guo, “MgH2 Dehydrogenation Thermodynamics: Nanostructuring and Transition Metal Doping”, J. Phys. Chem. C, 117 (2013) 10883-10891.

2) J.Gu, M.X. Gao, H.G. Pan, Y.F. Liu, B.Li, Y.J. Yang, C. Liang, H.L.Fu, and Z.X. Guo, “Improved Hydrogen Storage Performance of Ca(BH4)2: A Synergetic Effec of Porous Morphology and In-Situ Formed TiO2”, Energy & Env. Sci, 6(2013) 847-858.

3) Gadipelli Srinivas, W. Travis, J. Ford, H. Wu, ZX Guo and T. Yildirim, “Nanoconfined ammonia borane in a flexible metal–organic framework Fe–MIL-53: clean hydrogen release with fast kinetics”, J. Mat. Chem. A, 1 (2013) 4167-4172.

4) S. A. Shevlin, C. Cazorla, and Z. X. Guo, Structure and Defect Chemistry of Low- and High-Temperature Phases of LiBH4, J. Phys. Chem. C, 116 (2012) 13488-13496.

5) T. C. Drage, C.E. Snape, L.A. Stevens, J. Wood, J.Wang, A. I. Cooper, R. Dawson, (Z.) X. Guo, C. Satterley and R.N. Irons, “Materials challenges for the development of solid sorbents for post-combustion carbon capture”, J. Mater. Chem., 22 (2012) 2815-2823.

6) S. A. Shevlin, B. Kerkeni and Z. X. Guo, Dehydrogenation mechanisms and thermodynamics of MNH2BH3 (M = Li, Na) metal amidoboranes as predicted from first principles, Phys. Chem. Chem. Phys., 2011, 13, 7649–7659.

7) Cazorla, C., Shevin, S. A., Guo, Z. X., “Calcium-Based Functionalization of Carbon Materials for CO2 Capture: A First-Principles Computational Study” J Phys. Chem. C 115(2011), 10990-10995.

8) C. Cazorla, S. A. Shevlin and Z. X. Guo, “First-principles study of the stability of calcium-decorated carbon nanostructures”, PHYSICAL REVIEW B 82 (2010) 155454 _2010.

9) S.A. Shevlin and Z.X. Guo (Critical Review, invited as part of the 2009 Renewable Energy Issue), “Density functional theory simulations of complex hydride and carbon-based hydrogen storage materials”, Chem. Soc. Reviews, 38 (2009) 211-225.

10) Yang Lei, Stephen A. Shevlin, Wenguang Zhu, and Zheng Xiao Guo, “Hydrogen-induced magnetization and tunable hydrogen storage in graphitic structures”, Phys. Rev. B 77, 134114_2008.

11) S.A. Shevlin and Z.X. Guo, High-Capacity Room-Temperature Hydrogen Storage in Carbon Nanotubes via Defect-Modulated Titanium Doping, J. Phys. Chem. C, 112 (44) (2008) 17456–17464.

12) S.F.Li, L.M. Gao, X.G. Gong and Z.X. Guo, “No Cage, No Tube: Relative Stabilities of Nanostructures”, J. Phys.Chem.C, 112 (2008) 13200-13203..

13) Anna R. Ridley, A. Ian Stewart, Katrin Adamczyk, Hirendra N. Ghosh, Boutheı¨na Kerkeni, Z. Xiao Guo,| Erik T. J. Nibbering, Christopher J. Pickett, and Neil T. Hunt, Multiple-Timescale Photoreactivity of a Model Compound Related to the Active Site of [FeFe]-Hydrogenase, Inorganic Chemistry (Communication), 47 (2008) 7453-7455..

14) J. Jin, S.A. Shevlin, and Z.X. Guo, “Multiscale Simulations of Onset Plasticity during Nanoindentation of Al (001) Surface”, Acta Materialia, 56 (2008) 4358-4368.

15) Y. Lei, Z.X. Guo, W. Zhu, S. Meng, and Z. Zhang (2007), “Initial interactions between water molecules and Ti-adsorbed carbon nanotubes”, Applied Physics Letters, 91,161906.

16) Kondo-Francois Aguey-Zinsou, Jinhan Yao, and Z. Xiao Guo (2007), “Reaction paths between LiNH2 and LiH with effects of nitrides”, Journal of Physical Chemistry B, 2007, 111 (43), 12531 -12536.

17) S.A. Shevlin and Z.X. Guo (2007), “Hydrogen storage in defective hexagonal boron nitride sheets and boron nitride nanotubes, Physical Review B, 76, 024104.

18) Y.Song and Z.X. Guo (2006), “Electronic structure, stability and bonding of the Li-N-H hydrogen storage system”, Physical Review B, 74, 195120.

19) Y.Song and Z.X. Guo (2006), “Metastable MgH2 Phase Predicted by First-Principles Simulations”, Applied Physics Letters, 89, 111911.

20) S. A. Shevlin and Z.X. Guo (2006), “Transition metal-doping enhanced hydrogen storage in BN systems”, Applied Physics Letters, 89, 153104.

(Edited Books)

  1. Z.X. Guo,Book Editor, “Multiscale Materials Modelling - Fundamentals and Applications”, ISBN978-1-84569-071-7, CRC & Woodhead Publishing Ltd, Cambridge, 2007.
  2. Z.X. Guo, Book Editor, “The Deformation and Processing of Structural Materials”, ISBN 1 85573 738 8, 352 pages, CRC & Woodhead Publishing Ltd, Cambridge, 2005.

Recent Visibilities:

  • Editorial Boards : Journal of Nano Research; Journal of Multiscale Modelling; Materials Technology; Acta Metallurgica Sinica; Journal of Materials Science & Technology.
  • Guest Professors : Institute of Metal Research /Chinese Academy of Sciences; Zhejiang University, Shanghai Jiao Tong University; Chong-Qing University; Chong-Qing Institute of Technology; Southeast University / Nanjing; Harbin Institute of Technology.
  • Lee-Hsun Lecture Award , Institute of Metal Research / Chinese Academy of Sciences, 2002.
  • Beilby Medal & Prize , jointly by the IoM 3, the Royal Society of Chemistry; and the Society of Chemical Industry, 2000.