Seeing is believing: In-situ visualising dynamic evolution in CO2 electrolysis

CO₂ reduction reaction (CO₂RR), as a promising carbon neutral strategy, enables the production of valuable chemicals and fuels from greenhouse gas. Despite tremendous efforts in developing CO₂RR catalysts to improve activity, selectivity and stability, mechanisms behind the catalytic performance, however, are still under-explored owing largely to limited characterisation capability. In this review, advances in in-situ imaging technologies for studying CO₂RR have been overviewed. These technologies emerge as powerful tools to track the transformation of catalyst materials over real-time and space, under CO₂RR operating conditions. The review discusses emerging opportunities in the direction of combined in-situ characterisation techniques and machine learning to aid further discovery of structure–function relationships in CO₂RR.