Tailoring lattice oxygen and photo-induced polarons to control reaction mechanisms and boost catalytic activity

Photoelectrochemistry can revolutionise our way of life by harnessing sunlight to produce renewable fuels and chemicals and by helping us preserve the planet for future generations. However, enhancing the efficiency and selectivity of photoelectrochemical (PEC) reactions remains a challenge, especially for the photo-transformation of organic compounds required in industry. The problem stems from the difficulty of characterising the catalytic interface of heterogenous systems under working conditions. This prevents us from elucidating the reaction mechanisms and, so far, has dramatically limited our ability to control reactivity in a similar way to what can be achieved with homogeneous molecular catalysis. A particular challenge of solids is that they are prone to form defects during catalysis. However, how defects and lattice distortions impact the steps of the catalytic cycle remains unknown. Such mechanistic understanding is critical to redesign new materials and boost catalytic efficiencies.PhotoDefect will address this gap in our understanding by applying new methodologies to the study of oxidation reactions at metal oxide photoelectrodes. Our approach is to combine operando mass spectrometry and electrochemistry with optical and X-ray lasers to provide unprecedented insights into the polarised interface. Our strategy is to detect, in situ, the formation of reactive intermediates, defects and catalytic products in order to map out reaction mechanisms and establish ways to control them on demand.We will use cutting-edge methodologies to establish whether defects and photoinduced structural distortions or polarons participate in the steps of the catalytic mechanisms. Most importantly, if successful, our results will reveal new ways to tune the yield and selectivity of PEC reactions by controlling defects and polarons. These results will influence the way we synthesise PEC materials and the theoretical models we use to understand reaction mechanisms.