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Atomically Thin Gold – Synthesis and Electronic Skin Application

PGR-P-855

Key facts

Type of research degree
PhD
Application deadline
Ongoing deadline
Project start date
Friday 1 October 2021
Country eligibility
International (open to all nationalities, including the UK)
Funding
Competition funded
Source of funding
Doctoral training partnership
Supervisors
Dr Kevin Critchley and Professor Stephen Evans
Schools
School of Physics and Astronomy
Research groups/institutes
Molecular and Nanoscale Physics
<h2 class="heading hide-accessible">Summary</h2>

We recently discovered a method for the fabrication of atomically thin gold nanosheets (AuNS) - the world&amp;rsquo;s thinnest free-standing gold. AuNS are flexible, transparent, conducting, and have superior catalytic and enzymatic performance over other gold nanoparticles. In this project, we aim to establish: i) a deeper understanding of the growth mechanism, including how to control the lateral dimensions of the AuNS, the ability to functionalise them with organic ligands and to investigate their potential for application as stretchable electronic materials, as required for electronic skins, with properties mimicking those in biology, such as touch sensitivity.

<h2 class="heading hide-accessible">Full description</h2>

<p><strong>Background.</strong>&nbsp;We recently discovered a method for the fabrication of atomically thin gold nanosheets (AuNS). The material, the world&rsquo;s thinnest free-standing gold, it is flexible, and has demonstrated superior catalytic and enzymatic performance over gold nanoparticles, per unit mass.[1] However, such materials could have a much broader range of application. In this project, we aim to establish: i) a deeper understanding of the growth mechanism, including how to control the lateral dimensions of the AuNS, the ability to functionalise them with organic ligands and the potential to extend the methodology to other noble metals and ii) their potential for application as stretchable electronic materials.</p> <p><strong>Project description</strong>. The first part of this project addresses our understanding and morphological control of the production of AuNS.&nbsp;&nbsp;The AuNS are produced in aqueous solution, at room temperature, via the reduction of gold salt in the presence of low concentrations of methyl orange (MO). The method requires good vibrational and temperature stability (~1 &ordm;C) and the growth is slow (up to 12 h). A characteristic property of MO is its combination of amphiphilic nature and rigid aromatic core &ndash; such lyotropic &lsquo;chromonic phase&rsquo; materials are known to self-assemble into 2D sheets and 3D stacks/columns, often with no critical concentration required for assembly.</p> <p>We propose to explore the growth more systematically, we will construct a temperature-controlled and vibrationally isolated chamber to allow investigations to be made for extended periods, up to 24 hr, under well-defined conditions.&nbsp;</p> <p>The combination of factors affecting LC assembly as well as the parameters for AuNS synthesis provides a large phase-space of conditions to be explored to help better understand the formation mechanism and to develop control over morphology. For example, we will look at the importance of the different functional groups (head, tail, and aromatic core) in controlling AuNS growth, eg Methyl Red Fenaminosulf and 4-Dodecylbenzenesulfonic). Further, different mesogens assemble into different structures, eg CI RED acid 266, forms hollow chimney structures opening the intriguing possibility of templating large-diameter atomically thin Au nanotubes (which are predicted by theory to be stable. In addition to the different lyotropic mesogen type, the concentration, temperature, presence of salts, and pH are all known to play a role in their assembly.&nbsp;&nbsp;Where known behaviour will be mapped onto existing phase-diagrams (or will be complemented with NMR / UV-vis studies of the chromonic systems formed). We will additionally investigate, independently, the role of Au salt and citrate reductant concentration on the number of nucleation centers and reaction rates.&nbsp;&nbsp;Through the combination of these studies, we aim to achieve morphological control over the NS produced.&nbsp;</p> <p>The surface-modified AuNS will be characterised using XPS, UPS, AFM, Scanning Kelvin Probe, surface-enhanced Raman (SERS), and correlative TEM (fluorescence and TEM).&nbsp;</p> <p>In the second part of the project, we will investigate one potential application of such materials &ndash; towards the development of electronic skin. Firstly, the electrical properties of single AuNS will be determined using 4-probe STM. This allows either 2- or 4- independently controlled STM tips to be brought into contact on an object under SEM guidance and has been extensively used in our labs for the characterisation of nanomaterials.[2]&nbsp;&nbsp;Finally, we will build the AuNS into polymeric matrices to create polymer-based conductive materials and investigate their conductivity as a function of stretch &ndash; this is an important factor for the development of new materials such as electronic skin.[3]</p> <p><strong>References</strong></p> <p>1.&nbsp;Ye et al. Adv.Science 2019, DOI:10.1002/advs.201900911.&nbsp;&nbsp;</p> <p>2. G&oacute;rzny et al. Adv. Func. Mater. 2010, 20 1295.&nbsp;&nbsp;</p> <p>3.&nbsp;Hong S, et al.&nbsp;<em>Proceedings of the IEEE</em>&nbsp;2019 doi: 10.1109/jproc.2019.2909666</p>

<h2 class="heading">How to apply</h2>

<p>Formal applications for research degree study should be made online through the&nbsp;<a href="http://www.leeds.ac.uk/rsa/prospective_students/apply/I_want_to_apply.html">University&#39;s website</a>. Please state clearly in the research information section&nbsp;that the research degree you wish to be considered for is <em>Atomically Thin Gold &ndash; Synthesis and Application</em>&nbsp;as well as&nbsp;Stephen Evans as your proposed supervisor.</p> <p>If English is not your first language, you must provide evidence that you meet the University&#39;s minimum English language requirements (below).</p> <p><em>We welcome applications from all suitably-qualified candidates, but UK black and minority ethnic (BME) researchers are currently under-represented in our Postgraduate Research community, and we would therefore particularly encourage applications from UK BME candidates. All scholarships will be awarded on the basis of merit.</em></p>

<h2 class="heading heading--sm">Entry requirements</h2>

Applicants to research degree programmes should normally have at least a first class or an upper second class British Bachelors Honours degree (or equivalent) in an appropriate discipline. The criteria for entry for some research degrees may be higher, for example, several faculties, also require a Masters degree. Applicants are advised to check with the relevant School prior to making an application. Applicants who are uncertain about the requirements for a particular research degree are advised to contact the School or Graduate School prior to making an application.

<h2 class="heading heading--sm">English language requirements</h2>

The minimum English language entry requirement for research postgraduate research study is an IELTS of 6.0 overall with at least 5.5 in each component (reading, writing, listening and speaking) or equivalent. The test must be dated within two years of the start date of the course in order to be valid. Some schools and faculties have a higher requirement.

<h2 class="heading">Funding on offer</h2>

<p>A highly competitive EPSRC Doctoral Training Partnership Studentship consisting of<strong>&nbsp;</strong>the award of fees with a maintenance grant of &pound;15,609&nbsp;for session 2021/22&nbsp;for 3.5 years.&nbsp;</p> <p>This opportunity is open to all applicants, with a small number of awards for Non-UK applicants limited by UKRI to 1.&nbsp; All candidates will be placed into the EPSRC Doctoral Training Partnership Studentship Competition and selection is based on academic merit.</p> <p>The <a href="https://www.ukcisa.org.uk/">UKCISA</a> website will be updated in due course with information regarding Fee Status for Non-UK Nationals starting from September/October 2021.</p>

<h2 class="heading">Contact details</h2>

<p>For further information regarding your application,&nbsp;please contact Doctoral College Admissions<br /> e:&nbsp;<a href="mailto:maps.pgr.admissions@leeds.ac.uk">maps.pgr.admissions@leeds.ac.uk</a></p> <p>For further information regarding the project,&nbsp;please contact Professor Stephen Evans e:&nbsp;<a href="mailto:s.d.evans@leeds.ac.uk">s.d.evans@leeds.ac.uk</a></p>


<h3 class="heading heading--sm">Linked funding opportunities</h3>
<h3 class="heading heading--sm">Linked research areas</h3>