Professor Zheng Xiao GUO – Materials Chemistry
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Syntheses & simulations of clusters,
catalysts & nanostructures
Low-D structures & architecturing
Molecular (H2, CO, O2, CO2) sorption,
storage, and catalysis
Electrochemical, electronic and photonic
structures/ devices
Batteries, fuel cells / biofuel cells and
biointerfaces
Department of Chemistry /
London Centre for Nanotechnology
University College London
20 Gordon Street
London WC1H 0AJ
Tel:
020 7679 7527
(Internal: 27527)
Fax:
020 7679 7463
Email: z.x.guo@ucl.ac.uk
Xiao Guo’s research interest focuses on multi-scale syntheses and simulations of materials and
nanostructures for applications in clean energy, information technology and healthcare, particularly in
photo-/electro-/chemical catalysis, electro-/chemical energy storage, CO2 capture, 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 atomic deposition, sol-gel, mechano-chemical, self-assembly, exfoliation and
co-precipitation methods.
Xiao Guo is a Professor of Materials and Chemistry, leading a team of 15-20 Postdocs, PhDs and other
researchers at UCL. The 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 £3~7million 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/utilisation and biological fuel cells. He has contributed over
200 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
GoogleScholar: https://scholar.google.com/citations?user=tuyd_OgAAAAJ&hl=en
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A. Research Activities in Energy Harvesting, Storage and Generation:
A1. 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
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.
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A3. Carbon Capture & Pollutant Control – from Simulations to Fossil-Fuel Plant Applications
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.
Hierarchically porous carbon
spheres for effective CO2
sorption
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
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.
Multiscale materials development
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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
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 Directing enzymes onto an electrode
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.
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B2. Molecular Dynamics Simulations of Electrodes and Enzymes in Biofuel Cells
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:
H2 interactions with a hydrogenase
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 H2SO4 and 30%H2O2 to form titania and then immersed in
silane solutions and organic solvents to generate monolayers with –OH, –COOH, –NH2 and –PO4H2
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
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.
Molecular interactions with inorganic
surfaces
Page 5 of 6
Selected Publications:
1) Srinivas Gadipelli and Z.X. Guo, “Graphene-based materials: Synthesis and gas sorption, storage
and
separation”,
Progress
10.1016/j.pmatsci.2014.10.004.
in
Materials
Science,
69
(2014)
1-60.
Doi:
2) Srinivas Gadipelli, Will Travis, Wei Zhou and Zhengxiao Guo, A thermally derived and optimised
structure from ZIF-8 with giant enhancement in CO2 uptake, Energy & Env. Sci,, 7(2014)
2232-2238.
3) Gadipelli Srinivas, Vaiva Krungleviciute, ZX Guo, and T Yildirim, “Exceptional CO2 capture in a
hierarchically porous carbon with simultaneous high surface area and pore volume”, Energy & Env.
Sci., 7(2014)335-342.
4) Xiao-Yu Han, Henry Morgan Stewart, Stephen Shevlin, Richard Catlow and Zhengxiao Guo, Strain
and Orientation Modulated Bandgaps and Effective Masses of Phosphorene Nanoribbons, Nano
Letters, 14(2014) 4607-4614. DOI: 10.1021/nl501658d.
5) G. Srinivas, H. Patel and Z.X. Guo, “Ultrahigh Pore Volume drives up Amine Stability and Cyclic
CO2 Capacity of a Solid Amine@Carbon sorbent”, Advanced Materials, 27 (2015) 4902-4902. DOI:
10.1002/adma.201502047
6) Qinghai Meng, Haiping Wu, Yuena Meng, Ke Xie, Zhixiang Wei and Zhengxiao Guo,
High-Performance All-Carbon Yarn Micro-Supercapacitor for an Integrated Energy System,
Advanced Materials, 26 (2014) 4100-4106.
7) Haiping Wu, Stephen A. Shevlin, Qinghai Meng, Wei Guo, Yuena Meng, Kun Lu, Zhixiang Wei and
Zhengxiao Guo, Flexible and Binder Free Organic Cathode for High Performance Lithium Ion
Batteries, Advanced Materials, 26(2014) 3338-3343.
8) David James Martin, Kaipei Qiu, Stephen Andrew Shevlin, Albertus Denny Handoko, Xiaowei Chen,
Zhengxiao Guo & Junwang Tang, Highly Efficient H2 Evolution from Water under visible light by
Structure-Controlled Graphitic Carbon Nitride, Angewandte Chemie Inter Ed., 53 (2014) 9240-9245.
DOI: 10.1002/anie.201403375.
9) Srinivas Gadipelli and Z.X. Guo, “Postsynthesis annealing of MOF-5 remarkably enhances the
framework structural stability and CO2 uptake”, Chem. Mater., 26 (2014) 6333–6338, DOI:
10.1021/cm502399q.
10) 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 Effect of Porous Morphology and In-Situ
Formed TiO2”, Energy & Env. Sci, 6(2013) 847-858.
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