Dopant-induced electron localization drives CO2 reduction to C2 hydrocarbons
Authors: Haipeng Xie
Edward H Sargent
Chengqin Zou
Min Liu
Phil De Luna
Eva Bladt
Yansong Zhou
Haifeng Yuan
Rafael Quintero-Bermudez
David Sinton
Peining Chen
Zhiqiang Wang
Zhiqin Liang
Sara Bals
Jun Li
Gang Chen
Tsun-Kong Sham
Hongmei Li
Fanglin Che
Johan Hofkens
Journal: Nature Chemistry (2018)
Discipline: CHEMISTRY
Keywords: electrochemical reduction; CO2; multi-carbon products; value-added; carbon-based fuels
Affiliations: Department of Electrical and Computer Engineering, University of Toronto, Toronto, Ontario, Canada., MIIT Key Laboratory of Critical Materials Technology for New Energy Conversion and Storage, School of Chemistry and Chemical Engineering, Harbin Institute of Technology, Harbin, China., Institute of Super-Microstructure and Ultrafast Process in Advanced Materials, School of Physics and Electronics, Central South University, Changsha, China., State Key Laboratory of Power Metallurgy, Central South University, Changsha, China., Department of Materials Science and Engineering, University of Toronto, Toronto, Ontario, Canada., Department of Chemistry, KU Leuven, Leuven, Belgium., Department of Mechanical and Industrial Engineering, University of Toronto, Toronto, Ontario, Canada., Department of Chemistry, University of Western Ontario, London, Ontario, Canada., EMAT, University of Antwerp, Antwerp, Belgium., MIIT Key Laboratory of Critical Materials Technology for New Energy Conversion and Storage, School of Chemistry and Chemical Engineering, Harbin Institute of Technology, Harbin, China. ., Department of Electrical and Computer Engineering, University of Toronto, Toronto, Ontario, Canada. .

Abstract:  The electrochemical reduction of CO2 to multi-carbon products has attracted much attention because it provides an avenue to the synthesis of value-added carbon-based fuels and feedstocks using renewable electricity. Unfortunately, the efficiency of CO2 conversion to C2 products remains below that necessary for its implementation at scale. Modifying the local electronic structure of copper with positive valence sites has been predicted to boost conversion to C2 products. Here, we use boron to tune the ratio of Cuδ+ to Cu0 active sites and improve both stability and C2-product generation. Simulations show that the ability to tune the average oxidation state of copper enables control over CO adsorption and dimerization, and makes it possible to implement a preference for the electrosynthesis of C2 products. We report experimentally a C2 Faradaic efficiency of 79 ± 2% on boron-doped copper catalysts and further show that boron doping leads to catalysts that are stable for in excess of ~40 hours while electrochemically reducing CO2 to multi-carbon hydrocarbons. 

Retracted: No

PubPeer comments:
 The identification of B element by using the angle-dependent XPS is quite subjective. Especially for Figure S39 f and g, the noise level is almost the sample everywhere and no obvious peak can be resolved. So I am curious about how the red fit curve can be generated. ![file] , 
 In Figure S39, we provided angle-dependent B 1s spectra of post-reacted Cu(B) to check for the presence of B after CO2RR. We provided original (unsmoothed) data (blue), and we also provided, juxtaposed, the smoothed data (red). The smoothing procedure was performed using Origin software using the Savitzky-Golay method (Analytical Chemistry. 36 (8): 1627; Analytical Chemistry. 61 (15): 921A), 120 point window, and polynomial order of 2. ![file] Figure S39. Angle-dependent B 1s spectra of Cu(B) sample after post-5h CO2RR. (a) 90u00ba, (b) 100u00ba, (c) 110u00ba, (d) 120u00ba, (e) 130u00ba,(f) 140u00baand (g) 150u00ba. We used the same smoothing procedure to process the B 1s spectrum of sample Cu(H), as provided in Figure S15a, a sample into which we did not introduce B: ![file] Comparison of the Cu(B) vs. Cu(H) spectra shows the presence of B in the Cu(B) case. In Cu(B) samples, B is more readily discerned at the lower angles (u2264130u00ba). Given the penetration depth of XPS at 130u00b0 angle, this suggests that B is particularly present in the near-surface region ( top 5 nm) of the electrocatalyst. Since these studies are post-reaction, they support the finding that B is present in Cu(B) across the CO2RR timeframe studied. ,