title: High-Density Nanosharp Microstructures Enable Efficient CO2Electroreduction.
abstract: Conversion of CO2to CO powered by renewable electricity not only reduces CO2pollution but also is a means to store renewable energy via chemical production of fuels from CO. However, the kinetics of this reaction are slow due its large energetic barrier. We have recently reported CO2reduction that is considerably enhanced via local electric field concentration at the tips of sharp gold nanostructures. The high local electric field enhances CO2concentration at the catalytic active sites, lowering the activation barrier. Here we engineer the nucleation and growth of next-generation Au nanostructures. The electroplating overpotential was manipulated to generate an appreciably increased density of honed nanoneedles. Using this approach, we report the first application of sequential electrodeposition to increase the density of sharp tips in CO2electroreduction. Selective regions of the primary nanoneedles are passivated using a thiol SAM (self-assembled monolayer), and then growth is concentrated atop the uncovered high-energy planes, providing new nucleation sites that ultimately lead to an increase in the density of the nanosharp structures. The two-step process leads to a new record in CO2to CO reduction, with a geometric current density of 38 mA/cm2at -0.4 V (vs reversible hydrogen electrode), and a 15-fold improvement over the best prior reports of electrochemical surface area (ECSA) normalized current density.
authors.affiliation: Department of Electrical and Computer Engineering, University of Toronto , 35 St George Street, Toronto, Ontario M5S 1A4, Canada.
authors.forename: Tina
authors.initials: T
authors.lastname: Saberi Safaei
authors.affiliation: Institute for 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 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 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.
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: 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: David
authors.initials: D
authors.lastname: Sinton
authors.affiliation: Institute for 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 , Toronto, Ontario M5S 3M2, Canada.|Department of Biochemistry, Faculty of Medicine, 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
keywords: CO2 electroreduction; catalysis; electroplating; gold nanoneedles