Synergistic Photoelectrochemical Synthesis of Formate from CO2 on {12(1)over-bar} Hierarchical Co3O4

To propel the thermodynamically unfavorable conversion of greenhouse CO2 to renewable fuel with remarkable efficacy, we here proposed a visible-light-driven synergistic photoelectrochemical (PEC) synthesis of formate from CO2. Formate was the only Cl product photoelectrochemically generated on the fabricated hierarchical Co3O4 electrode. Results showed that up to 384.8 +/- 7.4 mu mol of formate was produced within 8 h owing to the synergistic PEC reduction process. This enhanced production of formate, outnumbering most of the reported work, was further found to be indispensable of the superior photocatalytic and electrocatalytic reduction performance of the as-prepared electrode. Research further elucidated that the photocatalytic activity was intimately related with the hierarchical Co3O4 microstructure, in which a single-crystalline microflower was interconnected by thin nanopetals on one-dimensional rhombus nanorod. Additionally, the construction of {12 (1) over bar} facet allowed high Co3+ exposure on Co3O4 surface, remarkably enhancing the transient and steady state photoelectrochemical reductive response of CO2 and HCO3- than other electrodes. It further revealed that the judicious merging of these superior photocatalytic and electrocatalytic performances as synergistic photoelectrochemical contributed to the considerably increasing utilization of surface reduction active sites for CO2 and HCO3-.