Photoelectrochemical devices based on dye-sensitized wide bandgap semiconductors are the key components of photovoltaic devices, such as dye-sensitized solar cells (DSSCs), as well as artificial photosynthetic schemes, i.e. dye-sensitized photoelectrosynthetic cells (DSPECs). In the current work, we present the use of two free-base and two zinc-metallated porphyrin-ruthenium(II) polypyridine dyads, as sensitizers in DSSCs and in DSPECs using both n-type (TiO2) and p-type (NiO) semiconductors.Two of the dyads contain the well-known Ru(bpy)3 unit (HOOC-DMP-Ru(bpy)3 and HOOC-(Zn)DMP-Ru(bpy)3), while in the other two terpyridine-Ru(Cl)-bypiridine was used (HOOC-DMP-tpy-Ru and HOOC-(Zn)DMP-tpy-Ru). The photovoltaic measurements revealed that the presence of the ruthenium complex improves the overall performance of the dyads with the most efficient dyad being HOOC-(Zn)DMP-tpy-Ru in both n- and p-type DSSCs. Consequently, HOOC-(Zn)DMP-tpy-Ru was used to fabricate n- and p-DSPECs towards the oxidation of methoxy-benzyl alcohol and the reduction of CO2, respectively. On both semiconductors, the linear sweep voltammetry (LSV) experiments demonstrate that this dyad clearly exhibits higher photocurrent density when the electrolyte contains a substrate that can be consumed by the Ru catalyst (alcohol for TiO2 photoanode and CO2 for NiO photocathode). The study of two different types of photoelectrochemical devices (DSSC and DSPEC) offers the possibility to determine the optimum conditions to fabricate the photoelectrodes and to select the most promising systems to develop DSPECs. Thus, the present study can be employed as a guide for the development of better performing photocatalytic systems by identifying the weak points of each system.

Photoelectrochemical properties of dyads composed of porphyrin/ruthenium catalyst grafted on metal oxide semiconductors

ACS Spring Meeting 2021

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