Photoelectrochemical Reduction of CO<sub>2</sub> Promoted by a Molecular Hybrid Made Up of Co(II)Pc on Graphene Oxide under Visible Light Illumination
Neha Nandal, Nilesh R. Manwar, B. Moses Abraham, Praveen K. Khatri, Suman L. Jain
Abstract
The present article describes an efficient photoelectrode material consisting of cobalt phthalocyanine tetrasulfonamide (CoPcS) chemically attached to carboxylated graphene oxide (GO-COOH) for a photoelectrochemical CO2 reduction reaction (PEC CO2RR). The chemical attachment of CoPcS complex units to the carboxylated GO support provided a proficient interface for the adsorption of CO2 and enhanced CO2 concentration for higher conversion. In the present study, we achieved high current density (−1.5 mA/cm2) at a voltage of −1.0 V vs Ag/AgCl under simulated sunlight with the selective formation of formate at a rate of 2.35 mmol h–1 cm–2. The photocurrent density of hybrid CoPcS/GO-COOH was found to be reasonably higher than those of pristine CoPcS and GO-COOH. However, AC impedance (EIS) indicated significantly increased charge carriers and decreased e–/h+ pair recombination in the hybrid system. Moreover, the developed hybrid molecular system exhibited improved PEC CO2RR compared to several existing systems. Overall, the results are supported by DFT calculations. A significant overlapping in the electronic bands of hybrid CoPcS/GO-COOH indexed by the density of states (DOS) led to the high PEC conversion.