Oxygen(O_(2))is an abundant material with its highly positive redox potential,making it a cost-effective choice for the cathodic active material of aqueous flow batteries(AFBs).However,utilizing O_(2)as an active mate...Oxygen(O_(2))is an abundant material with its highly positive redox potential,making it a cost-effective choice for the cathodic active material of aqueous flow batteries(AFBs).However,utilizing O_(2)as an active material may induce a high overpotential issue for oxygen reduction reaction(ORR).To address this problem,this study proposes a new AFB system employing iron-2,2-bis(hydroxymethyl)-2,2′,2″-nitrilotriethanol complex(Fe(BIS-TRIS))and O_(2)as redox couple and cobalt(triisopropanolamine)complex(Co(TiPA))as the redox mediator.Co(TiPA)can mitigate ORR overpotential through a mediated electron transfer(MET)mechanism.More specifically,during the charging step,in the catholyte,Co(II)(TiPA)s are oxidized to Co(III)(TiPA)s at the cathode,while HO_(2)-s are oxidized in the electrolyte tank,producing O_(2).During the discharging step,Co(III)(TiPA)s are reduced to Co(II)(TiPA)s.The resulting Co(II)(TiPA)then chemically reacts with O_(2)in the electrolyte tank,regenerating Co(III)(TiPA).Namely,this cycle ensures that Co(III)(TiPA)is electrochemically reduced to Co(II)(TiPA)at the cathode,while the reduced Co(II)(TiPA)is chemically re-oxidized in the electrolyte tank,effectively mediating electron transfer between electrode and oxygen.This process facilitates ORR without direct electrochemical reaction at the cathode,thereby alleviating its overpotential.UV-Vis spectroscopic analysis verifies that Co(TiPA)spontaneously reacts with O₂and mediates ORR.Fe(BIS-TRIS)-O_(2)AFB maintains 79.1%of its initial capacity over 170 h,demonstrating the feasibility of Co(TiPA)as the redox mediator.However,its structural degradation under oxygen evolution reaction is observed,limiting the long-term stability of Fe(BIS-TRIS)-O_(2)AFB.Thus,its structural modifications or development of alternative redox mediators are required.展开更多
A new polythreaded Mn^(Ⅱ)-MOF based on a tridentate N-containing ligand was synthesized via a hydrothermal method,namely,[Mn_(2)(Tipa)_(2)(1,4-bdc)_(2)(H_(2)O)_(2)]·3H_(2)O(MnTB),where Tipa and 1,4-bdc are short...A new polythreaded Mn^(Ⅱ)-MOF based on a tridentate N-containing ligand was synthesized via a hydrothermal method,namely,[Mn_(2)(Tipa)_(2)(1,4-bdc)_(2)(H_(2)O)_(2)]·3H_(2)O(MnTB),where Tipa and 1,4-bdc are short for tri(4-imidazolylphenyl)amine and 1,4-benzenedicarboxylate.MnTB possesses a fascinating 2D→2D polyrotaxane layer with a(4^(2)·6)(4^(2)·6^(3)·8)topology.展开更多
基金supported by the National Research Foundation of Korea(NRF)grant funded by the Korean government(MSIT)(No.2023R1A2C2002444).
文摘Oxygen(O_(2))is an abundant material with its highly positive redox potential,making it a cost-effective choice for the cathodic active material of aqueous flow batteries(AFBs).However,utilizing O_(2)as an active material may induce a high overpotential issue for oxygen reduction reaction(ORR).To address this problem,this study proposes a new AFB system employing iron-2,2-bis(hydroxymethyl)-2,2′,2″-nitrilotriethanol complex(Fe(BIS-TRIS))and O_(2)as redox couple and cobalt(triisopropanolamine)complex(Co(TiPA))as the redox mediator.Co(TiPA)can mitigate ORR overpotential through a mediated electron transfer(MET)mechanism.More specifically,during the charging step,in the catholyte,Co(II)(TiPA)s are oxidized to Co(III)(TiPA)s at the cathode,while HO_(2)-s are oxidized in the electrolyte tank,producing O_(2).During the discharging step,Co(III)(TiPA)s are reduced to Co(II)(TiPA)s.The resulting Co(II)(TiPA)then chemically reacts with O_(2)in the electrolyte tank,regenerating Co(III)(TiPA).Namely,this cycle ensures that Co(III)(TiPA)is electrochemically reduced to Co(II)(TiPA)at the cathode,while the reduced Co(II)(TiPA)is chemically re-oxidized in the electrolyte tank,effectively mediating electron transfer between electrode and oxygen.This process facilitates ORR without direct electrochemical reaction at the cathode,thereby alleviating its overpotential.UV-Vis spectroscopic analysis verifies that Co(TiPA)spontaneously reacts with O₂and mediates ORR.Fe(BIS-TRIS)-O_(2)AFB maintains 79.1%of its initial capacity over 170 h,demonstrating the feasibility of Co(TiPA)as the redox mediator.However,its structural degradation under oxygen evolution reaction is observed,limiting the long-term stability of Fe(BIS-TRIS)-O_(2)AFB.Thus,its structural modifications or development of alternative redox mediators are required.
基金was supported by the Qing Lan Project of Jiangsu Province,the National Natural Science Foundation of China(21901120,21371098)the Natural Science Foundation of Jiangsu Province(BK20180514,SBK2019040146,BK20131314)+2 种基金the China Postdoctoral Science Foundation(2015M570430)the Jiangsu Postdoctoral Science Foundation(1401007C)Jiangsu province entrepreneurship training program for college students(86717408).
文摘A new polythreaded Mn^(Ⅱ)-MOF based on a tridentate N-containing ligand was synthesized via a hydrothermal method,namely,[Mn_(2)(Tipa)_(2)(1,4-bdc)_(2)(H_(2)O)_(2)]·3H_(2)O(MnTB),where Tipa and 1,4-bdc are short for tri(4-imidazolylphenyl)amine and 1,4-benzenedicarboxylate.MnTB possesses a fascinating 2D→2D polyrotaxane layer with a(4^(2)·6)(4^(2)·6^(3)·8)topology.
