Solar water purification by inorganic photochemistry

Lead Supervisor: Prof Julia Weinstein, Department of Chemistry
Co-Supervisor(s): Prof David Kelly, Department of Molecular Biology and Biotechnology

Project Description
Sunlight can be used for a vast variety of purposes – from making chemicals to treating illnesses.  It can also help water disinfection – by using light-absorbing molecules that act as photosensitisers of highly reactive singlet oxygen, which in turn can kill bacteria.

This project aims to develop light-harvesting metal complexes as photosensitisers of singlet oxygen linked to solid support. It combines chemical synthesis, laser spectroscopy to understand the mechanism of action of photosensitisers and interfacial electron transfer, surface analysis, molecular biology, and potentially, device design.

The direction of the project can be tailored to individual interests. The project will use state of the art synthesis, microscopy and laser spectroscopy facilities at Sheffield, and at National Facilities.

Candidates should have: 1st or second upper class degree in Chemistry or related discipline, interests in solar energy, and willingness to take part in multidisciplinary collaborations in the UK and abroad.

Untreated water often contains multi-resistant bacteria, which present obvious health risk. Singlet oxygen (1O2), a highly reactive state of dioxygen, is a powerful and non-discriminatory killing agent for bacteria. 1O2 can be produced from dioxygen using energy of sunlight using a photosensitiser (PS). The PS is a compound which upon absorption of light is promoted to its higher energy, electronic excited state PS*. PS* then transfers energy to the dioxygen molecule in a bimolecular collision, generating 1O2 and regenerating the PS.  Depending on the stability of the PS, the cycle can repeat itself for hours, or years.  Metal complexes are excellent PS since the presence of heavy atom facilitates the formation of long-lived (microseconds to milliseconds) triplet excited states.

The project aims to develop robust photosensitisers based on metal complexes which will be immobilised onto solid or polymeric support, and use them to kill diverse range of bacteria in water under sunlight. The direction of the project can be tailored to individual interests, ranging from synthesis, to laser spectroscopy to understand the mechanism of action of photosensitisers which involve interfacial electron transfer, and biochemistry. The PhD student will be part of a multidisciplinary group of researchers from chemistry, biology, physics, and engineering backgrounds, and will learn accordingly diverse skills during their PhD.

Keywords: Photosensitiser, singlet oxygen, energy transfer, electron transfer, lasers, water purification, sunlight, antibacterial, PDT

Funding notes
This four-year studentship will be fully funded at Home/EU or international rates. Support for travel and consumables (RTSG) will also be made available at standard rate of £2,627 per annum, with an additional one-off allowance of £1,000 for a computer in the first year.  Students will receive an annual stipend of £17,336.  Applications should be received and complete by Monday 26th March 2018.

What to include in the application
Your application for this studentship should be accompanied by a CV and a 200 word supporting statement. Your statement should outline your aspirations and motivation for studying in the Grantham Centre for Sustainable Futures. You should also outline any relevant experience and interests that you have in sustainability issues.

Please select ‘Standard PhD’ and the department of this project’s lead supervisor. Fill in the title of your desired project and the name(s) of the supervisors. The starting date of the PhD will be the start of the next academic year – 1 Oct 2018. The ‘Funding stage’ on the form will be ‘project studentship’.