Insights into the Performance of Co_<i>x</i>Ni_1–<i>x</i>TiO₃ Solid Solutions as Photocatalysts for Sun-Driven Water Oxidation

Co_<i>x</i>Ni_1–<i>x</i>TiO₃ systems evaluated as photo- and electrocatalytic materials for oxygen evolution reaction (OER) from water have been studied. These materials have shown promising properties for this half-reaction both under (unbiased) visible-light photocatalytic approach in the presence of an electron scavenger and as electrocatalysts in dark conditions in basic media. In both situations, Co_0.8Ni_0.2TiO₃ exhibits the best performance and is proved to display high faradaic efficiency. A synergetic effect between Co and Ni is established, improving the physicochemical properties such as surface area and pore size distribution, besides affecting the donor density and the charge carrier separation. At higher Ni content, the materials exhibit behavior more similar to that of NiTiO₃, which is a less suitable material for OER than CoTiO₃