Catalysts for photochemical carbon dioxide reduction to green fuels and chemicals

Climate change and the greenhouse effect are mainly related to the increasing concentration in the atmosphere of a molecule that traps heat, namely CO2 or carbon dioxide. As a strategy to address CO2 increasing levels, carbon capture and utilisation (CCU) is gaining more attention in scientific research. This project applies photochemical catalysis to activate and transform carbon dioxide into dense energy carriers and chemical precursors, including carbon monoxide, alcohols and acids.
To drive the photocatalytic reduction of carbon dioxide suitable semiconducting photocatalysts have to be developed. When these interact with solar light irradiation, the sun's energy is transferred to the semiconductor creating excited states which can be used in the reduction of carbon dioxide to valuable chemicals. This research aims to understand the semi-conductor/catalyst excited states and electronic structures and delineate structure-performance relationships through modifications. The work targets low-temperature and pressure processes, using metal/metal oxide/sulfide materials as both absorbers and catalysts.
The photochemical mechanisms for carbon dioxide reduction are complex and more research is needed to understand factors controlling rates, selectivity and product formation pathways. This project will develop stable photocatalysts that can help elucidate the mechanism of photocatalytic CO2 reduction and in the second stage, improve the solar-to-chemical conversion efficiencies. In the first phase, UV light-absorbing catalysts such as SrTiO3 (strontium titanate) will be modified with copper (Cu) nanoparticles. Inexpensive, earth-abundant Cu is considered the best candidate due to its strong track record as a catalyst for MeOH (methanol) synthesis in thermal reactions and its track record in electrocatalysis producing C2+ products from carbon dioxide. The thesis will compare different means to produce copper nanoparticles, including electrosynthesis, photoredox synthesis and chemical synthesis. The particle-catalyst surface chemistry will be explored using techniques such as atomic layer deposition and by exploiting chemical functionality/reactivity. Catalyst-particle interfaces will be studied and characterized and catalytic activity tested photochemically under a range of different conditions.
This strategy will give us more insight into the factors that govern product selectivity and catalyst activity and will result in an efficient photocatalytic system based on earth-abundant materials for CO2 reuse. This specific target performance has the impact to give a large contribution to addressing one of the main challenges of this century and support society and the ESPRC to transition towards a low- carbon future while protecting the environment. As such, this project falls within the EPSRC Energy research area.

The primary impact of the OxICFM CDT will be the highly-trained world-class scientists that it delivers. This impact will encompass both the short term (during their doctoral studies), the medium term (subsequent employment) and ultimately the longer timescale defined by their future careers and consequent impact on science, engineering and policy in the UK.

The impact of OxICFM students during their doctoral studies will be measured by the culture change in graduate training that the Centre brings about - in working at the interface between inorganic synthesis and manufacturing, and fostering cross-sector industry/academia working practices. By embedding not only from larger companies, but also SMEs, we have developed a training regime that has broader relevance across the sector, and the potential for building bridges by fostering new collaborations spanning enormous diversity in scientific focus and scale. Moreover, at a broader level, OxICFM offers to play a unique role as a major focus (and advocate) for manufacturing engagement with academic inorganic synthetic science in the UK.

From a scientific perspective, OxICFM will be uniquely able to offer a broad training programme incorporating innovative and challenging collaborative projects spanning all aspects of fundamental and applied inorganic synthesis, both molecular and materials based (40+ faculty). These will address key challenges in areas such as energy provision/storage, catalysis, and resource provision/renewal necessary to enhance the capability and durability of UK plc in the medium term. To give some idea of perspective, the output from previous CDTs in Oxford's MPLS Division include two start-up companies and in excess of 30 patents.

It is not only in the industrial and scientific realms that students will have impact during their timeframe of their doctorate. Part of the training programme will be in public engagement: team-based challenges in resource development/training and outreach exercises/implementation will form part of the annual summer school. These in turn will constitute a key part of the impact derived from the CDT by its engagement with the public - both face-to-face and through electronic/web-based media. As the centre matures, our aspiration is that our students - from diverse backgrounds - will act as ambassadors for the programme and promote even higher levels of inclusion from all parts of society.

For our partners, and businesses both large and small in the manufacturing sector, it will be our students who are considered the ultimate output of the OxICFM CDT. Our programme has been shaped by the need of such companies (frequently expressed in preliminary discussions) to recruit doctoral graduates who can apply themselves to a broad spectrum of multi-disciplinary challenges in manufacturing-related synthesis. OxICFM's cohort-based training programme integrates significant industry-led training components and has been designed to deliver a much broader skill set than standard PhD schemes. The current lack of CDT training at the interface of inorganic chemistry and manufacturing (and the relevance of inorganic molecules/materials to numerous industrial sectors) heightens the need for - and the potential impact of - the OxICFM CDT. Our students will represent a tangible and valuable asset to meet the long-term skills demand for scientists to develop new materials and nanotechnology identified in the UK Government's 2013 Foresight report.

In the longer term, the broad and relevant training delivered by OxICFM, and the uniquely wide perspective of the manufacturing sector it will deliver, will allow our graduates to obtain (and thrive in) positions of significant responsibility in industry and in research facilities/institutes. Ultimately we believe that many will go on to be future research leaders, driving innovation and changing research culture, and thereby making a lasting contribution to the UK economy.