Towards optimal photocatalytic hydrogen generation from water using pyrene-based metal-organic frameworks

Metal organic frameworks (MOFs) are promising materials for the photocatalytic H2 evolution reaction (HER) from water. To find the optimal MOF for a photocatalytic HER one has to consider many different factors. For example, studies have emphasized the importance of light absorption capability, optical band gap and band alignment. However, most of these studies have been carried on very different materials. In this work, we present a combined experimental and computation study of the photocatalytic HER performance, of a set of isostructural pyrene-based MOFs (M-TBAPy, where M = Sc, Al, Ti, and In). We systematically studied the effects of changing the metal in the node on the different factors that contribute to the HER rate (e.g., optical properties, the band structure, water adsorption). In addition, for Sc-TBAPy we also studied the effect of changes in crystal morphology on the photocatalytic HER rate. We used this understanding to improve photocatalytic HER efficiency of Sc-TBAPy, to exceed the one reported for Ti-TBAPy, in the presence of co-catalyst.