title: Enhanced electrocatalytic CO2reduction via field-induced reagent concentration.
abstract: Electrochemical reduction of carbon dioxide (CO2) to carbon monoxide (CO) is the first step in the synthesis of more complex carbon-based fuels and feedstocks using renewable electricity. Unfortunately, the reaction suffers from slow kinetics owing to the low local concentration of CO2surrounding typical CO2reduction reaction catalysts. Alkali metal cations are known to overcome this limitation through non-covalent interactions with adsorbed reagent species, but the effect is restricted by the solubility of relevant salts. Large applied electrode potentials can also enhance CO2adsorption, but this comes at the cost of increased hydrogen (H2) evolution. Here we report that nanostructured electrodes produce, at low applied overpotentials, local high electric fields that concentrate electrolyte cations, which in turn leads to a high local concentration of CO2close to the active CO2reduction reaction surface. Simulations reveal tenfold higher electric fields associated with metallic nanometre-sized tips compared to quasi-planar electrode regions, and measurements using gold nanoneedles confirm a field-induced reagent concentration that enables the CO2reduction reaction to proceed with a geometric current density for CO of 22 milliamperes per square centimetre at -0.35 volts (overpotential of 0.24 volts). This performance surpasses by an order of magnitude the performance of the best gold nanorods, nanoparticles and oxide-derived noble metal catalysts. Similarly designed palladium nanoneedle electrocatalysts produce formate with a Faradaic efficiency of more than 90 per cent and an unprecedented geometric current density for formate of 10 milliamperes per square centimetre at -0.2 volts, demonstrating the wider applicability of the field-induced reagent concentration concept.
authors.affiliation: Department of Electrical and Computer Engineering, University of Toronto, 35 St George Street, Toronto, Ontario M5S 1A4, Canada.
authors.forename: Min
authors.initials: M
authors.lastname: Liu
authors.affiliation: Department of Mechanical and Industrial Engineering, University of Toronto, 5 King's College Road, Toronto, Ontario M5S 3G8, Canada.
authors.forename: Yuanjie
authors.initials: Y
authors.lastname: Pang
authors.affiliation: Department of Electrical and Computer Engineering, University of Toronto, 35 St George Street, Toronto, Ontario M5S 1A4, Canada.|Department of Physics, East China University of Science and Technology, 130 Meilong Road, Shanghai 200237, China.
authors.forename: Bo
authors.initials: B
authors.lastname: Zhang
authors.affiliation: Department of Materials Science and Engineering, University of Toronto, 184 College Street, Toronto, Ontario M5S 3E4, Canada.
authors.forename: Phil
authors.initials: P
authors.lastname: De Luna
authors.affiliation: Department of Electrical and Computer Engineering, University of Toronto, 35 St George Street, Toronto, Ontario M5S 1A4, Canada.
authors.forename: Oleksandr
authors.initials: O
authors.lastname: Voznyy
authors.affiliation: Department of Electrical and Computer Engineering, University of Toronto, 35 St George Street, Toronto, Ontario M5S 1A4, Canada.
authors.forename: Jixian
authors.initials: J
authors.lastname: Xu
authors.affiliation: Department of Electrical and Computer Engineering, University of Toronto, 35 St George Street, Toronto, Ontario M5S 1A4, Canada.|Tianjin Key Laboratory of Composite and Functional Materials, School of Materials Science and Engineering, Tianjin University, Tianjin 300072, China.
authors.forename: Xueli
authors.initials: X
authors.lastname: Zheng
authors.affiliation: Department of Electrical and Computer Engineering, University of Toronto, 35 St George Street, Toronto, Ontario M5S 1A4, Canada.
authors.forename: Cao Thang
authors.initials: CT
authors.lastname: Dinh
authors.affiliation: Department of Electrical and Computer Engineering, University of Toronto, 35 St George Street, Toronto, Ontario M5S 1A4, Canada.
authors.forename: Fengjia
authors.initials: F
authors.lastname: Fan
authors.affiliation: Department of Mechanical and Industrial Engineering, University of Toronto, 5 King's College Road, Toronto, Ontario M5S 3G8, Canada.
authors.forename: Changhong
authors.initials: C
authors.lastname: Cao
authors.affiliation: Department of Electrical and Computer Engineering, University of Toronto, 35 St George Street, Toronto, Ontario M5S 1A4, Canada.
authors.forename: F Pelayo García
authors.initials: FP
authors.lastname: de Arquer
authors.affiliation: Department of Electrical and Computer Engineering, University of Toronto, 35 St George Street, Toronto, Ontario M5S 1A4, Canada.
authors.forename: Tina Saberi
authors.initials: TS
authors.lastname: Safaei
authors.affiliation: Institute of Biomaterials and Biomedical Engineering, University of Toronto, 164 College Street, Toronto, Ontario M5S 3G9, Canada.
authors.forename: Adam
authors.initials: A
authors.lastname: Mepham
authors.affiliation: Department of Chemistry, University of Toronto, 80 St George Street, Toronto, Ontario M5S 3H6, Canada.
authors.forename: Anna
authors.initials: A
authors.lastname: Klinkova
authors.affiliation: Department of Chemistry, University of Toronto, 80 St George Street, Toronto, Ontario M5S 3H6, Canada.
authors.forename: Eugenia
authors.initials: E
authors.lastname: Kumacheva
authors.affiliation: Department of Mechanical and Industrial Engineering, University of Toronto, 5 King's College Road, Toronto, Ontario M5S 3G8, Canada.
authors.forename: Tobin
authors.initials: T
authors.lastname: Filleter
authors.affiliation: Department of Mechanical and Industrial Engineering, University of Toronto, 5 King's College Road, Toronto, Ontario M5S 3G8, Canada.
authors.forename: David
authors.initials: D
authors.lastname: Sinton
authors.affiliation: Institute of Biomaterials and Biomedical Engineering, University of Toronto, 164 College Street, Toronto, Ontario M5S 3G9, Canada.|Department of Pharmaceutical Sciences, Leslie Dan Faculty of Pharmacy, University of Toronto, 144 College Street, Toronto, Ontario M5S 3M2, Canada.|Department of Biochemistry, University of Toronto, 1 King's College Circle, Toronto, Ontario M5S 1A8, Canada.
authors.forename: Shana O
authors.initials: SO
authors.lastname: Kelley
authors.affiliation: Department of Electrical and Computer Engineering, University of Toronto, 35 St George Street, Toronto, Ontario M5S 1A4, Canada.
authors.forename: Edward H
authors.initials: EH
authors.lastname: Sargent