Efficient Photoelectrochemical Reduction of Carbon Dioxide to Formic Acid: A Functionalized Ionic Liquid as an Absorbent and Electrolyte

Abstract

Photoelectrochemical (PEC) reduction of carbon dioxide (CO ) is a potential method for production of fuels and chemicals from a C1 feedstock accumulated in the atmosphere. However, the low solubility of CO in water, and complicated processes associated with capture and conversion, render CO conversion inefficient. A new concept is proposed in which a PEC system is used to capture and convert CO into formic acid. The process is assisted by an ionic liquid (1-aminopropyl-3-methylimidazolium bromide) aqueous solution, which functions as an absorbent and electrolyte at ambient temperature and pressure. Within this PEC reduction strategy, the ionic liquid plays a critical role in promoting the conversion of CO to formic acid and suppressing the reduction of H O to H . At an applied voltage of 1.7 V, the Faradaic efficiency for formic acid production is as high as 94.1 % and the electro-to-chemical efficiency is 86.2 %.

Catholyte‐Free Electrocatalytic CO2 Reduction to Formate

“…Interestingly,as the reaction temperature rises from 303 Kto363 K, the partial current density (PCD) of formate improves more than two times with 52.9 mA cm À2 ,despite the decrease in CO 2 solubility. [2,[10][11][12][13] Despite these significant results,t heir kinetics of CO 2 Rconversion into formate is still limited by the low CO 2 concentration in electrolytes.I nr ecent years,s ome research groups reported remarkable improvement in the current density of CO 2 Rt of ormate using gas diffusion electrodes (GDEs) with metal nanoparticles. [1][2][3][4] There are several electrochemical pathways to convert CO 2 into valuable products, [1,5,6] among which formic acid or formate has received particular attention over the past few years because the CO 2 Ri nto formic acid is regarded as as uitable reaction for industrial scale production.…”

“…[2,[10][11][12][13] Despite these significant results,t heir kinetics of CO 2 Rconversion into formate is still limited by the low CO 2 concentration in electrolytes.I nr ecent years,s ome research groups reported remarkable improvement in the current density of CO 2 Rt of ormate using gas diffusion electrodes (GDEs) with metal nanoparticles. [2,[10][11][12][13] Despite these significant results,t heir kinetics of CO 2 Rconversion into formate is still limited by the low CO 2 concentration in electrolytes.I nr ecent years,s ome research groups reported remarkable improvement in the current density of CO 2 Rt of ormate using gas diffusion electrodes (GDEs) with metal nanoparticles.…”

“…Some efforts have been reported to overcome the solubility limitation and enhance the current density of formate production, including development of ah ighly porous structure of SnO 2 ,t unable alloys,a nd ionic liquids (ILs). [2,[10][11][12][13] Despite these significant results,t heir kinetics of CO 2 Rconversion into formate is still limited by the low CO 2 concentration in electrolytes.I nr ecent years,s ome research groups reported remarkable improvement in the current density of CO 2 Rt of ormate using gas diffusion electrodes (GDEs) with metal nanoparticles. [5,[14][15][16][17][18][19] This type of electrode provides at hree-phase interface of gas/ electrolyte/ catalyst, in which the CO 2 molecules only have to diffuse through av ery thin liquid layer of electrolyte to reach the catalyst surface.…”

Artificial Photosynthesis of Methanol by Mn:CdS and CdSeTe Quantum Dot Cosensitized Titania Photocathode in Imine‐Based Ionic Liquid Aqueous Solution

“…It is well known that the electrodes and electrolytes are all of great importance in the reduction of CO 2 . In the imine‐based [APMIm]Br IL electrolytes, an [APMIm−CO 2 ] + complex can be generated quickly through a hydrogen bonding interaction between CO 2 and the [APMIm] + cation, and then CO 2 reduction takes place in the photocathode. Initially, the QDs sensitizer absorbs light energy to make the electrons of the VB jump into the CB as active photoelectrons, which can transfer efficiently into the CO 2 reduction reactions.…”

Recent progress on advanced design for photoelectrochemical reduction of CO2 to fuels

“…Recently, this merit has been applied to the PEC CO 2 reduction. The utilization of ionic liquid (i.e., 1-aminopropyl-3-methylimidazolium bromide) significantly promotes the conversion of CO 2 to HCOOH and suppresses the competitive hydrogen evolution [74].…”