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. 2021 Apr 9;12(1):2139.
doi: 10.1038/s41467-021-22428-1.

Direct electrosynthesis of 52% concentrated CO on silver's twin boundary

Can Tang  1 , Peng Gong  1 , Taishi Xiao  1 , Zhengzong Sun  2   3
Affiliations

Direct electrosynthesis of 52% concentrated CO on silver's twin boundary

Can Tang et al. Nat Commun. .

Abstract

The gaseous product concentration in direct electrochemical CO2 reduction is usually hurdled by the electrode's Faradaic efficiency, current density, and inevitable mixing with the unreacted CO2. A concentrated gaseous product with high purity will greatly lower the barrier for large-scale CO2 fixation and follow-up industrial usage. Here, we developed a pneumatic trough setup to collect the CO2 reduction product from a precisely engineered nanotwinned electrocatalyst, without using ion-exchange membrane. The silver catalyst's twin boundary density can be tuned from 0.3 to 1.5 × 104 cm-1. With the lengthy and winding twin boundaries, this catalyst exhibits a Faradaic efficiency up to 92% at -1.0 V and a turnover frequency of 127 s-1 in converting CO2 to CO. Through a tandem electrochemical-CVD system, we successfully produced CO with a volume percentage of up to 52%, and further transformed it into single layer graphene film.

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Conflict of interest statement

The authors declare no competing interests.

Figures

Fig. 1
Fig. 1. Silver catalysts with tunable TB density.
a TEM image of parallel TBs (scale bar: 10 nm). TB represents twin boundary. b The atomic arrangement of a representative TB in FFT-treated HR-TEM (scale bar: 1 nm). The two marked rhomboids represent the Burgers circuits. c The typical SAED pattern of silver’s TB. The white and yellow circles label diffraction spots of matrix and twin, respectively. d–f TEM images of Nt-10, Nt-18, and Nt-730, respectively (scale bar: 100 nm). The white dashed lines mark TBs. g–i The twin width distribution of Nt-10, Nt-18, and Nt-730, respectively. j The statistical histogram of TB density.
Fig. 2
Fig. 2. The CO production on the silver’s TBs.
LSV curves obtained on a Nt-10, b Nt-18, and c Nt-730 in N2-saturated and CO2-saturated electrolyte. d The FECO under different applied cathode potentials in CO2-saturated electrolyte. e The correlation between jCOEASA and TB density at different potentials. f Nyquist plots of Nt-10, Nt-18, and Nt-730 at −0.7 V in CO2-saturated solution. All electrochemical measurements were carried out in a 0.5 M KHCO3 solution.
Fig. 3
Fig. 3. Tandem system for graphene synthesis.
a The schematic diagram of “two-step” synthesis of graphene from CO2. b Cell voltages at a constant current density of 30 mA cm−2 in pneumatic-trough-based cell and H-type cell with/without Nafion 117 membrane. The area of the electrode is ~1 cm2. The “overflow” represents the applied voltage reaches the maximum of our electrochemical workstation (20 V). The κa represents the electric conductivity of anolyte. c The literature summary of FECO and initial CO concentration–,,. The red, green, gray, and blue spots represent the results of this work, carbonate reduction systems, GDE systems, and H-type cell systems, respectively. d The TEM image of graphene film edge (scale bar: 10 nm) The e raw and f FFT-treated HRTEM images of graphene film lattice (scale bar: 2 nm). g The SAED pattern of graphene film and the intensity profile of diffraction spots along (21¯1¯0), (11¯00), (01¯10), and (1¯1¯20) facet. h Raman spectrum of graphene film.
See this image and copyright information in PMC

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