Synthesis of TiO2/RGO with plasmonic Ag nanoparticles for highly efficient photoelectrocatalytic reduction of CO2 to methanol toward the removal of an organic pollutant from the atmosphere

• Published in: Environmental pollution (1987) 2021-07, Vol.281, p.116990-116990, Article 116990
• Main Authors: Bharath, G., Prakash, J., Rambabu, K., Venkatasubbu, G. Devanand, Kumar, Ashok, Lee, Seungjun, Theerthagiri, Jayaraman, Choi, Myong Yong, Banat, Fawzi
• Format: Article
• Language: English
• Subjects: CO2 reduction; Heterogeneous electrocatalysts; Methanol; Photocathode; Plasmonics; Sustainable liquid fuels
• ISSN: 0269-7491; 1873-6424
• DOI: 10.1016/j.envpol.2021.116990

The synergistic photoelectrochemical (PEC) technology is a robust process for the conversion of CO2 into fuels. However, designing a highly efficient UV–visible driven photoelectrocatalyst is still challenging. Herein, a plasmonic Ag NPs modified TiO2/RGO photoelectrocatalyst (Ag–TiO2/RGO) has been designed for the PEC CO2 reduction into selective production of CH3OH. HR-TEM analysis revealed that Ag and TiO2 NPs with average sizes of 4 and 7 nm, respectively, were densely grown on the few-micron-sized 2D RGO nanosheets. The physicochemical analysis was used to determine the optical and textural properties of the Ag–TiO2/RGO nanohybrids. Under VU-Vis light illumination, Ag–TiO2/RGO photocathode possessed a current density of 23.5 mA cm−2 and a lower electrode resistance value of 125 Ω in CO2-saturated 1.0 M KOH-aqueous electrolyte solution. Catalytic studies showed that the Ag–TiO2/RGO photocathode possessed a remarkable PEC CO2 reduction activity and selective production of CH3OH with a yield of 85 μmol L−1 cm−2, the quantum efficiency of 20% and Faradic efficiency of 60.5% at onset potential of −0.7 V. A plausible PEC CO2 reduction mechanism over Ag–TiO2/RGO photocathode is schematically demonstrated. The present work gives a new avenue to develop high-performance and stable photoelectrocatalyst for PEC CO2 reduction towards sustainable liquid fuels production. [Display omitted] •Photoelectrocatalytic activity of TiO2/RGO was tailored with plasmonic Ag NPs.•5-fold higher photocurrent response of Ag–TiO2/RGO than the TiO2/RGO was achieved.•High PEC CO2 reduction was performed with the Ag–TiO2/RGO photocathode.•Ag–TiO2/RGO exhibits CH3OH yield of 85 μmol L−1cm−2 with FE = 60.5% and QE = 20%.•An effective PEC CO2 reduction offered a global environmental health.