Increased photocatalytic activity and selectivity towards methane of trimetallic NiTiAl-LDH

Layered double hydroxides is a rising family of materials with interesting photocatalytic properties that are starting to be employed on the CO2 photoreduction to useful chemicals. However, the selectivity control towards high energy value products, such as methane or methanol, is one of the main issues of this process due to the easier formation of CO, which requires fewer electrons to be transferred, and the competition of hydrogen evolution reaction. In this work, a new LDH material containing Ni, Ti and Al within the structure was synthesised with the purpose of increasing the selectivity towards methane production. The material was tested under solar simulator conditions, yielding a methane production of 148 μmol g-1 h-1, with a selectivity of 86%, one of the highest values reported for this kind of material, while the competition from hydrogen evolution was almost suppressed. The role of Ti directing the selectivity towards methane was confirmed, since no CH4 was produced when NiAl-LDH catalyst was used instead.