Electrochemical CO₂ Reduction Using Electrons Generated from Photoelectrocatalytic Phenol Oxidation

Abstract Electrochemical CO₂ reduction (ECCO₂R) requires electrons, for example, from oxygen evolution reaction (OER). However, such a multiple‐electron‐involved reaction is complicated and kinetically slow, leading to high overpotential. Herein, OER is replaced with photoelectrocatalytic phenol oxidation reaction (PECPOR) that provides electrons for ECCO₂R. In an integrated cell, ECCO₂R is conducted on the cathode of Cu nanowires and PECPOR is performed on the anode of SnO₂ and Sb coated TiO₂ nanotubes. Significant improvement of ECCO₂R into CO and hydrocarbons is realized when PECPOR is conducted at a high current density. The use of this integrated system results in the reduction of the specific energy consumption by a factor of 51.33%, compared with the utilization of two half‐cells for individual ECCO₂R and PECPOR. This study thus proposes a novel strategy to couple ECCO₂R with PECPOR and eventually to tackle the problems of environmental pollution and energy crisis.