New materials to boost hydrogen production

The rising population on Earth is the driving force behind increasing energy demands that in turn leads to greater carbon dioxide (CO2) amounts stemming from fossil-fuel burning. Tapping the unlimited Sun's bountiful energy is the only way to break this cycle that is highly intertwined with an unsustainable energy future.

Although in its early research and development phase, artificial photosynthesis is a viable energy source. Significant challenges are associated with constructing molecular machinery mimicking the way plants split water into oxygen and convert CO2 to glucose. Protons resulting from water splitting can be used for hydrogen production.

EU-funded scientists initiated the 'Photocatalytic cluster complexes for artificial photosynthesis applications' (PCAP) project to produce metal complexes that could be used as catalysts for solar cell applications.

By carefully controlling reagents and metal ions, scientists prepared several manganese–calcium clusters and determined their crystal structures. A calcium ion rod-like arrangement decorated with manganese complexes was a particularly appealing structure. Except for the manganese ions, a plethora of other transition metal ions were tested in the presence of coordination polymers constructed by carboxylic acid ligands. Crystal structures of several complexes were collected, revealing water pockets and cavities for gas sorption.

Considering that redox active molecular systems are invaluable for activating small molecules, scientists prepared porphyrin compounds and ligands based on terpyridine. Although the performance of the ferrocenyl-porphyrin derivative for solar cell applications was poor, detailed studies revealed the system's fast excited-state quenching.

PCAP work paved the way to producing hydrogen from sunlight and water. The exchange programme gave researchers the opportunity to visit Romania and the United Kingdom, with plans in place for future visits to Moldova. This aspect of the project also proved a key means for achieving its goals. Dissemination activities included seminars, meetings and exchange visits.