Spectroscopy-driven design of an efficient photocatalyst for CO2 reduction (Ext.)

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This is an extension of the original Fellowship "Spectroscopy-driven design of an efficient photocatalyst for CO2 reduction"There is sufficient solar energy incident on the UK to provide for all of our energy needs. However the insolation level varies hugely both within a day and on a seasonal level. For any energy technology to be viable it is essential that it is reliable. A route to overcoming the intermittency of supply issue is to use the solar energy to drive the production of a chemical fuel which can be stored and transported to be available when and where it is needed. Sustainable carbon-based solar fuels and feedstocks (e.g. CH4, CH3OH, CO) can be produced by the coupling of light driven water oxidation to the reduction of CO2. This is an exciting prospect but to realise the goal of low carbon-intensity fuel economy breakthroughs are required for both fuel generation and utilisation systems. Current materials for CO2 reduction and water oxidation do not achieve the required level of efficiency and stability at a viable cost. Similarly the most promising clean technologies for electricity generation on demand from carbon fuels, fuel cells, often suffer from relatively low efficiencies and intolerances to impurities in the fuel feed.The original fellowship has been highly successful in delivering new low-cost catalysts that can either be driven directly by sunlight (photocatalysts) or indirectly using electrical energy (which could in principle come from a PV panel) to reduce CO2 to CO, an important liquid fuel precursor. Part of the original fellowship developed new capabilities within the UK for a highly sensitive surface sensitive spectroscopy, IR-Vis Sum Frequency Generation Spectroscopy. This experiment has been used to identify with an incredible level of detail the mechanisms of catalysts at surfaces. These, and our wider spectroscopic studies, have been critical in guiding our own catalyst design programme. But the need for mechanistic insights extends beyond our own synthetic programme. A lack of understanding of the mechanisms of catalysis occurring on the surface of electrodes and photoelectrodes is a limiting factor for the entire field preventing the rational development of new materials. Therefore our spectroscopy driven programme will be expanded to address both the crucial reactions of fuel generation (water oxidation and CO2 reduction) as well as to fuel utilisation chemistry, through the study of state of the art metal-oxide fuel cells. The project is ambitious, aiming not just to provide the first identification of all key intermediates during water oxidation on the most commonly studied photoelectrode (hematite), but also to explore how secondary interactions with water and electrolyte salts control the activity. A similar level of mechanistic detail is also sought from leading CO2 reduction catalysts and fuel cell electrodes. This level of mechanistic detail that we aim to deliver could be transformative to our own, collaborators and the wider communities programmes of material development. The delivery of scalable, efficient materials for solar fuels production and utilisation is a challenging goal but the potential impact is enormous. An improved understanding of surface mechanisms on current materials would represent an important step towards this ambition.