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.