Constructing efficient catalysts for N ₂ reduction into value added ammonia under ambient conditions is a considerable challenge.

Photoactive anodes consisting of Ru(bpy)₃ type photosensitizer 1 and molecular catalysts 2 and 3 on nanostructured TiO₂ have been assembled in functional devices for successful light driven water splitting. From their performance measurements we found that the photoanode TiO₂(1 + 3) in which the molecular ruthenium catalyst and the phosphonate anchoring group are linked by a flexible –CH₂CH₂CH₂– chain showed a significantly higher photocurrent density than the photoanode TiO₂(1 + 2) with only –CH₂– linkage. The possible reasons for the different water splitting performance of otherwise identical devices are discussed.