Aerosol assisted chemical vapour deposition (AACVD) of 2D TMDCs for aqueous pollutant degradation

"Treatment of polluted water is becoming increasingly urgent as concerns about water quality and scarcity become increasingly prevalent. Consequently, catalytic degradation of water-borne pollutants is a research area attracting significant interest. An additional research driver is the United Nations Sustainable Development Goal to provide clear water to all. Accordingly, many different materials have been investigated as potential treatment catalysts.
There are many pollutants that can cause concern, one of which is antibiotics. Antibiotics such as tetracycline (TC) are extensively used in both human and veterinary medicine, as well as a feed additive in agriculture therefore, TC is often found at high levels in environmental water samples presenting a specific and significant environmental and human health risk e.g., the development of new antibiotic-resistant bacterial strains. This is motivating significant research into methodologies for removing TC from aqueous systems as part of water treatment strategies.
Two-dimensional (2D) transition metal dichalcogenides have been investigated as catalysts for environmentally relevant reactions including hydrogen generation, pollutant degradation etc. and show significant promise. The issue of how best to synthesise these materials in a form that is effective for catalysing these reactions is a difficult one. One method that offers many significant advantages is aerosol-assisted chemical vapour deposition (AACVD). The principal benefits that AACVD brings is that it naturally yields materials as thin, high surface area coatings on glass supports. High surface area is pivotal for catalytic applications, whilst the high temperature stability and transparency of the glass supports enable facile integration into thermal/photocatalytic operations.
AACVD has been utilised to produce 2D transition metal disulphides but to date 2D transition metal diselenides and ditellurides have proved elusive. Preliminary data indicates that the synthesis of 2D molybdenum diselenide has been achieved but more investigation is needed to obtain robust, high-quality materials. Additionally, AACVD requires substrates with high thermal stability, such as borosilicate glass, however a plethora of exciting new applications for these supported catalysts could be realised if supports such as conductive glasses (e.g., InSnO) were utilised. Accordingly, a second strand of this project will investigate the possibility of developing conducting supports and assessing them in electro-catalytic reactions. Currently such an approach is just not possible with conventional borosilicate-supported catalysts.
This project aims to go further in both the synthetic and applications focussed directions. Utilising novel substrates for the synthesis process will allow for a wider variety of types of catalysis to be tested for their efficacy in degrading these damaging pollutants. In this way the impacts of this work will be maximised. Not only will the work be of interest to those researching the AACVD method [6] and pollution degradation methods but the increased variety of substrates will open up the AACVD method to groups working on other applications (e.g., sensing and charge storage) who are currently prevented from utilising this method due to the inert nature of the substrates thus establishing me as an independent researcher in this field. Once the materials have been prepared using AACVD, the thermal, photocatalytic and electrocatalytic degradation of waterborne pollutants will be performed. Whilst initial work will be done using easily traceable dye compounds such as methylene blue, work will then move to considering degrading more topical pollutants such as antibiotics like tetracycline. Finally, real-world water samples will be assessed.
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