Pt/graphene aerogel deposited in Cu foam as a 3D binder-free cathode for CO2 reduction into liquid chemicals in a TiO2 photoanode-driven photoelectrochemical cell

Abstract

A nanostructured Pt/graphene aerogel directly deposited in Cu foam (Pt/GA/CF) was used as a 3D binder-free cathode to convert CO2 into liquid chemicals in a TiO2 photoanode-driven photoelectrochemical cell. The surface morphology, microstructure, mineralogical and elemental compositions, and electrochemical performance of the Pt/GA/CF electrode were characterized via SEM/EDX, TEM, X-ray diffraction, X-ray photoelectron spectroscopy, electrochemical impedance spectroscopy (EIS), and chronocoulometry (CC). EIS analysis revealed that Pt/GA/CF with reduced impedance possessed a better electron transfer capacity than the electrode that combines Pt-modified reduced graphene oxide with CF through polymer binders (Pt/RGO/CF). SEM and CC analyses confirmed that the uniform dispersion of 3D nanoporous Pt/GA in CF scaffold effectively prevented its self-agglomeration and increased the electrochemical adsorption surface area of Pt/GA/CF to 15 times higher than that of Pt/RGO/CF. The efficient charge transportation and high reactant adsorptivity of the Pt/GA/CF electrode significantly improved CO2 reduction and facilitated the conversion of C1 products to high-order products. Formic acid, acetic acid, propionic acid, methanol, and ethanol were detected as the liquid products of CO2 reduction. The carbon atom conversion rate of CO2 reduction on Pt/GA/CF markedly increased to 5040nmol/(hcm2).