Here we introduce bismuth-based catalysts for the efficient electrochemical reduction of CO_(2)to formic acid(HCOOH),which are composed of petal-shaped Bi_(2)O_(2)CO_(3)(BOC)that spontaneously formed from Bi thin film...Here we introduce bismuth-based catalysts for the efficient electrochemical reduction of CO_(2)to formic acid(HCOOH),which are composed of petal-shaped Bi_(2)O_(2)CO_(3)(BOC)that spontaneously formed from Bi thin film in aqueous carbonate solution at room temperature.During the electrochemical reduction process,the BOC petals transform to reduced BOC(R-BOC)consisting of individual BOC and Bi domains.Lattice mismatch between both domains induces biaxial strain at the interfaces.Density functional theory calculations suggest that the tensile strain on the Bi domain stabilizes the*OCHO intermediate,reducing the thermodynamic barrier toward CO_(2)conversion to HCOOH.Together with the thermodynamic benefit and the unique nanoporous petal-shaped morphology,R-BOC petals have a superior Faradaic efficiency of 95.9%at-0.8 V_(RHE)for the electrochemical conversion of CO_(2)to HCOOH.This work demonstrates that the spontaneously formed binary phases with desirable lattice strain can increase the activity of bismuth catalysts to the CO_(2)reduction reaction;such a strategy can be applicable in design of various electrocatalysts.展开更多
We theoretically and experimentally demonstrate an RGB achromatic metalens that operates concurrently at three visible wavelengths(λ=450, 532, and 700 nm) with a high numerical aperture of 0.87. The RGB metalens is d...We theoretically and experimentally demonstrate an RGB achromatic metalens that operates concurrently at three visible wavelengths(λ=450, 532, and 700 nm) with a high numerical aperture of 0.87. The RGB metalens is designed by simple integration of metalens components with the spatial interleaving method. The simulated spatial interleaving metalens shows RGB achromatic operation with focusing efficiencies of 25.2%, 58.7%, and66.4% at the wavelengths of 450, 532, and 700 nm, respectively. A 450 μm diameter metalens operating at three designated wavelengths is fabricated with low-loss hydrogenated amorphous silicon. The fabricated metalens has the measured focusing efficiencies of 5.9%, 11.3%, and 13.6% at λ = 450, 532, and 700 nm, respectively. The Strehl ratios of 0.89, 0.88, and 0.82 are obtained at given wavelengths, which show a capability of diffractionlimited operation.展开更多
基金supported by the Korea Institute of Energy Technology Evaluation and Planning(KETEP)and the Ministry of Trade,Industry&Energy(MOTIE)of the Republic of Korea(20212010100040)in part by the National Research Foundation of Korea(NRF)grant funded by the Korea government(MSIT)(2019R1A2C1091158)in part by Brain Korea 21 FOUR project for Education and Research Center for Future Materials(F21YY7105002)
文摘Here we introduce bismuth-based catalysts for the efficient electrochemical reduction of CO_(2)to formic acid(HCOOH),which are composed of petal-shaped Bi_(2)O_(2)CO_(3)(BOC)that spontaneously formed from Bi thin film in aqueous carbonate solution at room temperature.During the electrochemical reduction process,the BOC petals transform to reduced BOC(R-BOC)consisting of individual BOC and Bi domains.Lattice mismatch between both domains induces biaxial strain at the interfaces.Density functional theory calculations suggest that the tensile strain on the Bi domain stabilizes the*OCHO intermediate,reducing the thermodynamic barrier toward CO_(2)conversion to HCOOH.Together with the thermodynamic benefit and the unique nanoporous petal-shaped morphology,R-BOC petals have a superior Faradaic efficiency of 95.9%at-0.8 V_(RHE)for the electrochemical conversion of CO_(2)to HCOOH.This work demonstrates that the spontaneously formed binary phases with desirable lattice strain can increase the activity of bismuth catalysts to the CO_(2)reduction reaction;such a strategy can be applicable in design of various electrocatalysts.
基金Samsung Electronics(IO201211-08042-01,IO201215-08187-01)POSCO(POSCO-POSTECH-RIST Convergence Research Center Program)National Research Foundation of Korea(NRF-2022M3C1A3081312,CAMM-2019M3A6B3030637,NRF-2019R1A2C1091158)。
文摘We theoretically and experimentally demonstrate an RGB achromatic metalens that operates concurrently at three visible wavelengths(λ=450, 532, and 700 nm) with a high numerical aperture of 0.87. The RGB metalens is designed by simple integration of metalens components with the spatial interleaving method. The simulated spatial interleaving metalens shows RGB achromatic operation with focusing efficiencies of 25.2%, 58.7%, and66.4% at the wavelengths of 450, 532, and 700 nm, respectively. A 450 μm diameter metalens operating at three designated wavelengths is fabricated with low-loss hydrogenated amorphous silicon. The fabricated metalens has the measured focusing efficiencies of 5.9%, 11.3%, and 13.6% at λ = 450, 532, and 700 nm, respectively. The Strehl ratios of 0.89, 0.88, and 0.82 are obtained at given wavelengths, which show a capability of diffractionlimited operation.
