PhD Studentship: Direct Air Capture - Carbon sponge development

Description

We face a climate change crisis, and it is now accepted that we not only need to dramatically reduce our greenhouse gas emissions, but that we also need to remove greenhouse gases from the atmosphere. The Forse Group in the Yusuf Hamied Department of Chemistry are working on “direct air capture”, an approach where sponge-like materials are used to capture carbon dioxide directly from the atmosphere. The traditional sponge materials for this process have issues including poor long-term stability and/or the need for very high temperatures (up to 900 ºC) to regenerate the sponges for reuse. 

To tackle these issues, the Forse Group recently pioneered a new approach to make carbon sponges. Starting with cheap and readily available activated charcoal, the team developed a “charging” method similar to the charging of a battery. This process charges alkaline hydroxide molecules into the porosity of the charcoal to enhance its carbon capture ability. These materials show promising direct air capture performance, and they are stable, cheap, and can be regenerated at low temperatures (~100ºC). The group’s breakthrough study was recently published in Nature in 2024 and was highlighted in over 100 news stories, including in the BBC, The Independent, and CNN.

Professor Stuart Scott’s groups in the department of Engineering have been working on various novel carbon capture processes, from the material through to the process scale. The power required by a DAC depends on the both the “sponge” and how it is integrated into a process, e.g. low capacity can be compensated for by a shorter cycle, high energy requirements can be offset by energy recovery strategies. Therefore, the process and material must be evaluated simultaneously.  DAC is limited by the energy input needed to regenerate the sponge. Using heat forces the process to use much more energy than is needed. The sponges developed offer unique opportunities to electrify the DAC process either through joule heating, or via electromediated desorption.  However, the route to large scale utilisation still needs to be fully explored. 

The next steps for the work involve tackling four challenges to realise the full carbon removal potential of the new charcoal sponges:

1. Improve the capacity of the activated charcoal, since the first generation of the material captures less carbon than rival materials (although there are significant benefits with the activated charcoal).
2. Establish methods to improve the effectiveness of the material in higher humidity air, since this will enable the material to be used in a wider range of climate zones.
3. Establish feasibility of scaling up materials to practical DAC systems. 
4. Design and optimise an engineered direct air capture system built around the new material.

To tackle challenges 1 and 2, we are offering a PhD studentship on development of the carbon sponges. This work will leverage the tuneability of the sponges, where the initial materials used in the “charging” step can be readily varied. For challenge 1, it is proposed that by controlling the structure of the initial activated charcoal, it will be possible to charge more hydroxide molecules into the pores, thereby increasing carbon dioxide capacities. The target is a five-fold increase in capacities, to rival those of existing materials, while maintaining the advantages of improved stabilities and lower temperature regeneration. To address challenge 2, it is proposed to further modify carbon sponges to inhibit water uptake, using additives which repel water and thereby inhibit water binding while retaining carbon dioxide capture. This will enable the use of these materials in a wider range of locations around the Earth (in both dry and humid climates).

The University actively supports equality, diversity and inclusion and encourages applications from all sections of society.

*Funding will cover the student's stipend at the current Research Council rate and University Fees. The studentship will be funded for four years from October 2025. 

**This studentship is being kindly funded by Jamie Arnell and is tied to Downing College therefore the successful applicant will be allocated to Downing College for the duration of their programme.