Synergistic enhancement of photo-assisted water splitting by mesoporous TiO2/NiFe LDH composite nanomaterials

Abstract

In the last decade, photo-assisted water splitting to generate hydrogen and oxygen has become a key process in the quest for clean energy technologies. In this context, the sluggish kinetics of the oxygen evolution reaction (OER) is still a limitation. The combination of an efficient electrocatalyst with a light-absorbing species can provide an output boost by the additional input of solar energy. In this work, we used ordered mesoporous nanocrystalline TiO2 thin films as a photoactive phase that contain embedded NiFe-based double-layered hydroxides (NiFe-LDH) catalysts for the OER in the mesopores. The structural and electrochemical properties of these materials were studied, taking into account the effect of the Ni:Fe ratio and concentration. Our results indicate that this material shows synergy in the photo-assisted water-splitting activity, as the total current is higher than the combined contributions of dark NiFeOx electrocatalysis and TiO2 photocurrent. Optimization of the NiFe ratio (9:1) and deposition time (60 s) produced an enhancement of up to 18 % in the total current at 1.50 V.