Photocatalytic hydrogen (H2) production from water splitting represents one of the most promising and challenging strategies for resolving the global energy demand and environmental problems associated with the use of fossil fuels. On this scenario, the European Commission through The European Strategic Energy Technology Plan (SET-Plan) desires to accelerate the development and deployment of low-carbon technologies and to develop clean energy technologies and bring down costs by coordinating national research efforts and helping to finance projects. Moreover, the discovery of new materials should encourage the emergence of new technologies as well as the progress of the already known ones. In fact, in the Materials Roadmap from SET-Plan one focus area is dedicated to novel materials solutions or novel combination of known materials to emerge beyond 2020.
In this sense to the Photoactivated Process Unit of Fundación IMDEA Energía the search for novel and more efficient photocatalyst beyond metal oxide semiconductors is one of the most important pillars in its scientific research plan.
In a recent collaborative article* with ICMM-CSIC, we describes novel hybrid photocatalyst systems comprised by both TiO2 and a couple of Porous Polymers based on Truxene moiety (TxPPs) which exhibited intensely enhanced photocatalytic activity compared to TiO2 or TxPPs alone. In the presence of platinum (1 wt %) as co-catalyst, HER from TxPP1@TiO2 is significantly boosted, reaching values above 21000 μmol·g−1·h−1, which, to the best of our knowledge, represents the highest HER reported for hybrids based on TiO2 and conjugated porous polymers. Interestingly, small structural differences of the corresponding truxene monomers result in different photocatalytic behavior. We focused here on gaining insight on the charge transfer mechanism and rationalizing the different photocatalytic performances in order to establish clear structure−activity relationships. In fact, photoluminescence and transient absorption spectroscopy demonstrated that the remarkably enhanced photocatalytic activity of the most active hybrids (TxPP1@TiO2) can be attributed to the efficiently photogenerated electron−hole separation by a direct Z-scheme mechanism, while lower performance ofTxPP2@TiO2 is probably due to a less efficient heterojunction type II charge transfer mechanism.
(*) Valverde-González, A.; López Calixto, C. G.; Barawi, M.; Gomez-Mendoza, M.; de la Peña O’Shea, V. A.; Liras, M.; Gómez-Lor, B.; Iglesias, M. Understanding Charge Transfer Mechanism on Effective Truxene-Based Porous Polymers–TiO2 Hybrid Photocatalysts for Hydrogen Evolution. ACS Appl. Energy Mater. 2020, 3, 4411–4420. https://doi.org/10.1021/acsaem.0c00118
More information: Marta Liras, Senior assistant researcher, Photoactivated Process Unit firstname.lastname@example.org