Effect of TiO₂ support on immobilization of cobalt porphyrin for electrochemical CO₂ reduction

Electrochemical reduction of CO₂ is a promising strategy to manage the global carbon balance by transforming CO₂ into chemicals. The efficiency of CO₂ electroreduction is largely dependent on the design of hybrid electrode where both support and catalyst govern the performance of the electrolyzer. In this work, TiO₂ calcined at different temperatures, was used as a support for immobilization of cobalt tetraphenyl porphyrin (CoTPP) and its effect on CO₂ reduction was studied. It is demonstrated that the crystalline phase of TiO₂ and doping of TiO₂ apparently affecting CO₂ electroreduction. It is found that anatase phase exhibits higher activity and selectivity compared to rutile due to the enhanced conductivity which in turn enables faster electron transfer between the support and CoTPP. As for dopants, the carbon doping in anatase TiO₂ is proven to further enhance its conductivity, consequently resulting in the enhanced performance. This study implies that the rational design of supports is important for the performance of the hybrid electrode towards electrochemical CO₂ reduction.