To develop an efficient electrochemical CO_(2)reduction reaction(CO_(2)RR)for the production of C_(2)chemicals,improvements in the Cu catalyst are necessary.Doping is widely used for catalyst enhancement;however,only ...To develop an efficient electrochemical CO_(2)reduction reaction(CO_(2)RR)for the production of C_(2)chemicals,improvements in the Cu catalyst are necessary.Doping is widely used for catalyst enhancement;however,only a few elements have been examined.This study proposes guidelines for the selection of Cu catalyst dopants to promote ethylene production.It was hypothesized that the dopant chemical state highly influences the CO_(2)RR catalytic activity.In the case of dopants possessing a standard reduction potential within the CO_(2)RR potential region(e.g.,Mn and Ni),low Faradaic efficiency(FE)toward ethylene production was obtained owing to the presence of a metallic dopant(10.7%for Ni dopant).In contrast,a low standard reduction potential led to a stable high oxidation state for the dopant,yielding abundant Cu^(δ+)species with modified electronic structures and enhancing the CO_(2)RR catalytic activity for ethylene production(42.1%for Hf dopant).We expected that a dopant with a low standard reduction potential is difficult to reduce,which leads to a stable Cu-O-X bond and induces a stable Cu^(δ+)species.Our study provides insights into how to select dopant for various catalyst to enhance CO_(2)RR catalytic activity.展开更多
Carbon super-heterostructures with high nitrogen contents from the covalent hybrid precursors of covalent triazine frameworks(CTFs)and zeolitic imidazolic frameworks(ZIFs)are scarcely explored because of CTF's ord...Carbon super-heterostructures with high nitrogen contents from the covalent hybrid precursors of covalent triazine frameworks(CTFs)and zeolitic imidazolic frameworks(ZIFs)are scarcely explored because of CTF's ordered structure and toxic superacid that dissolves or destabilizes the metal nodes.To solve this problem,herein,we report a straightforward two-step pathway for the covalent hybridization of disordered CTF(d–CTF)–ZIF composites via preincorporation of an imidazole(IM)linker into ordered CTFs,followed by the imidazole-site-specific covalent growth of ZIFs.Direct carbonization of these synthesized d–CTF−IM−ZIF hybrids results in unique hollow carbon super-heterostructures with ultrahigh nitrogen content(>18.6%),high specific surface area(1663m^(2)g^(−1)),and beneficial trace metal(Co/Zn NPs)contents for promoting the redox pseudocapacitance.As proof of concept,the obtained carbon super-heterostructure(Co–Zn–NC_(SNH)–800)is used as a positive electrode in an asymmetric supercapacitor,demonstrating a remarkable energy density of 61Wh kg^(−1)and extraordinary cyclic stability of 97%retention after 30,000 cycles at the cell level.Our presynthetic modifications of CTF and their covalent hybridization with ZIF crystals pave the way toward new design strategies for synthesizing functional porous carbon materials for promising energy applications.展开更多
基金supported by Research Project for‘Carbon Upcycling Project for Platform Chemicals’of the National Research Foundation(NRF)funded by the Ministry of Science and ICT,Republic of Korea(grant number:2022M3J3A1050053)supported by the National Research Council of Science&Technology(NST)grant by the Korean government(MSIT)(No.CAP21011-100)+1 种基金supported by the National Research Foundation of Korea(NRF)grant funded by the Korean government(MSIT)(RS-2023-00302697)institutional program grants from the Korea Institute of Science and Technology。
文摘To develop an efficient electrochemical CO_(2)reduction reaction(CO_(2)RR)for the production of C_(2)chemicals,improvements in the Cu catalyst are necessary.Doping is widely used for catalyst enhancement;however,only a few elements have been examined.This study proposes guidelines for the selection of Cu catalyst dopants to promote ethylene production.It was hypothesized that the dopant chemical state highly influences the CO_(2)RR catalytic activity.In the case of dopants possessing a standard reduction potential within the CO_(2)RR potential region(e.g.,Mn and Ni),low Faradaic efficiency(FE)toward ethylene production was obtained owing to the presence of a metallic dopant(10.7%for Ni dopant).In contrast,a low standard reduction potential led to a stable high oxidation state for the dopant,yielding abundant Cu^(δ+)species with modified electronic structures and enhancing the CO_(2)RR catalytic activity for ethylene production(42.1%for Hf dopant).We expected that a dopant with a low standard reduction potential is difficult to reduce,which leads to a stable Cu-O-X bond and induces a stable Cu^(δ+)species.Our study provides insights into how to select dopant for various catalyst to enhance CO_(2)RR catalytic activity.
基金Ministry of Trade,Industry&Energy of Korea,Grant/Award Number:RS‐2022‐00155717National Research Foundation of Korea,Grant/Award Numbers:2020H1D3A1A04081472,2022M3J1A1054323。
文摘Carbon super-heterostructures with high nitrogen contents from the covalent hybrid precursors of covalent triazine frameworks(CTFs)and zeolitic imidazolic frameworks(ZIFs)are scarcely explored because of CTF's ordered structure and toxic superacid that dissolves or destabilizes the metal nodes.To solve this problem,herein,we report a straightforward two-step pathway for the covalent hybridization of disordered CTF(d–CTF)–ZIF composites via preincorporation of an imidazole(IM)linker into ordered CTFs,followed by the imidazole-site-specific covalent growth of ZIFs.Direct carbonization of these synthesized d–CTF−IM−ZIF hybrids results in unique hollow carbon super-heterostructures with ultrahigh nitrogen content(>18.6%),high specific surface area(1663m^(2)g^(−1)),and beneficial trace metal(Co/Zn NPs)contents for promoting the redox pseudocapacitance.As proof of concept,the obtained carbon super-heterostructure(Co–Zn–NC_(SNH)–800)is used as a positive electrode in an asymmetric supercapacitor,demonstrating a remarkable energy density of 61Wh kg^(−1)and extraordinary cyclic stability of 97%retention after 30,000 cycles at the cell level.Our presynthetic modifications of CTF and their covalent hybridization with ZIF crystals pave the way toward new design strategies for synthesizing functional porous carbon materials for promising energy applications.
