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

Abstract

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 Omega 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 timol 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. (C) 2021 Elsevier Ltd. All rights reserved.