Palladium-supported cobalt hydroxide(Co(OH)_(2)-Pd) nanoplates were fabricated in an aqueous solution and employed as a catalyst for the reduction of 4-nitrophenol.For the preparation of Co(OH)2-Pd,Pd nanoparticles we...Palladium-supported cobalt hydroxide(Co(OH)_(2)-Pd) nanoplates were fabricated in an aqueous solution and employed as a catalyst for the reduction of 4-nitrophenol.For the preparation of Co(OH)2-Pd,Pd nanoparticles were anchored on the Co(OH)_(2) nanoplates after the reduction of Na;PdCl;by ascorbic acid in the absence of a stabilizer at room temperature.The observations under transmission and scanning electron microscopy reveal that Pd nanoparticles with a size of 2-5 nm are uniformly dispersed on the surface of the Co(OH)_(2) nanoplates.In catalytic test,the conversion of 4-nitrophenol to 4-aminophenol is completed within 6 min in the presence of Co(OH)_(2)-Pd(1000) nanoplates with2.18 at.% Pd,and the corresponding kinetic constant is 0.0089 s;in the first test.The catalyst retains relatively high activity after several cycles.The results demonstrate that the Co(OH)_(2)-Pd(1000) nanoplates exhibit high catalytic activity toward the reduction of 4-nitrophenol in the presence of NaBH;.展开更多
The intrinsic activity of Co(OH)_(2) for oxygen evolution reaction(OER)may be elaborately improved through the suitable valence adjustment.Ce modification at electronic level is proved to be an efficient strategy owin...The intrinsic activity of Co(OH)_(2) for oxygen evolution reaction(OER)may be elaborately improved through the suitable valence adjustment.Ce modification at electronic level is proved to be an efficient strategy owing to the flexible transformation of Ce^(3+)/Ce4+.Herein,Ce0.21@Co(OH)_(2) with the optimized Ce doping have been fabricated to tailor the fast electron transfer for the enhanced activity and stability for OER.Firstly,the obtained core-shell structure composed of vertical loose Co(OH)_(2) sheets not only exposes a large number of active sites,but also provides channels for Ce doping.Secondly,the high pressure microwave with instantaneous heating can fast introduce Ce into Co(OH)_(2),obtaining Cex@Co(OH)_(2) with well dispersion and close integration.The intimated interaction between Ce and Co species may provide the"d-f electronic ladders"for accelerating electron transfer of the catalytic surface.Meanwhile,Ce promotes the formation of Co-superoxide intermediate and/or the release of oxygen,which is considered to be the rate-determining step for OER.The electrochemical measurements confirmed the low overpotential of 300 m V at 10 m A cm^(-2) and great stability of Ce0.21@Co(OH)_(2) for OER.This work demonstrates a meaningful approach to realize the tuned electronic structure through metal doping.展开更多
The shuttling diffusion of polysulfides is a bottleneck that seriously limits the performance of Li-S batteries.Purposeful construction of sulfur cathodes with reliable trapping ability of polysulfides is the key to o...The shuttling diffusion of polysulfides is a bottleneck that seriously limits the performance of Li-S batteries.Purposeful construction of sulfur cathodes with reliable trapping ability of polysulfides is the key to overcome such limitation.Herein,a hierarchical porous architecture,i.e.,Co(OH)_(2)sheets bonded Ti_3C_(2)T_x MXene aerogel(Co(OH)_(2)/MXA),is constructed via a facile selfassembled approach and used as an efficient free-standing polysulfides reservoir.The interconnected three-dimensional(3D)porous network with void space and strong interfacial interaction not only enables high sulfur loading but facilitates fast ion and electron transport.Experimental and theoretical results confirm the hetero-framework exhibits outstanding immobilization and conversion ability for polysulfides due to its polar surface and bifunctional catalytic activities toward both formation and decomposition of Li2S.The optimized Co(OH)_(2)/MXA cathode delivers excellent rate capability(407 mAh·g^(-1)at 5C)with a sulfur loading of 2.7 mg·cm^(-2),and ultra-stable cycling performance as an extremely small capacity decay of~0.005%per cycle within 1700 cycles at 1C is achieved with a high sulfur loading of 6.7 mg·cm^(-2).More significantly,our design structural/componential methodology here promises the MXene-based aerogel electrodes for LiS batteries and beyond.展开更多
基金the financial supports from the National Natural Science Foundation of China (Nos. 51974116, 51874128)the Science Foundation of Hunan Province, China (Nos. 2020JJ4273, 2020JJ5130)。
文摘Palladium-supported cobalt hydroxide(Co(OH)_(2)-Pd) nanoplates were fabricated in an aqueous solution and employed as a catalyst for the reduction of 4-nitrophenol.For the preparation of Co(OH)2-Pd,Pd nanoparticles were anchored on the Co(OH)_(2) nanoplates after the reduction of Na;PdCl;by ascorbic acid in the absence of a stabilizer at room temperature.The observations under transmission and scanning electron microscopy reveal that Pd nanoparticles with a size of 2-5 nm are uniformly dispersed on the surface of the Co(OH)_(2) nanoplates.In catalytic test,the conversion of 4-nitrophenol to 4-aminophenol is completed within 6 min in the presence of Co(OH)_(2)-Pd(1000) nanoplates with2.18 at.% Pd,and the corresponding kinetic constant is 0.0089 s;in the first test.The catalyst retains relatively high activity after several cycles.The results demonstrate that the Co(OH)_(2)-Pd(1000) nanoplates exhibit high catalytic activity toward the reduction of 4-nitrophenol in the presence of NaBH;.
基金financially supported by the National Natural Science Foundation of China(21776314)the Qingdao Science and Technology Benefiting People Special Project(20-3-4-8-nsh)+2 种基金the Fundamental Research Funds for the Central Universities(20CX02212A)the Development Fund of State Key Laboratory of Heavy Oil Processingthe Postgraduate Innovation Project of China University of Petroleum(YCX2020046)。
文摘The intrinsic activity of Co(OH)_(2) for oxygen evolution reaction(OER)may be elaborately improved through the suitable valence adjustment.Ce modification at electronic level is proved to be an efficient strategy owing to the flexible transformation of Ce^(3+)/Ce4+.Herein,Ce0.21@Co(OH)_(2) with the optimized Ce doping have been fabricated to tailor the fast electron transfer for the enhanced activity and stability for OER.Firstly,the obtained core-shell structure composed of vertical loose Co(OH)_(2) sheets not only exposes a large number of active sites,but also provides channels for Ce doping.Secondly,the high pressure microwave with instantaneous heating can fast introduce Ce into Co(OH)_(2),obtaining Cex@Co(OH)_(2) with well dispersion and close integration.The intimated interaction between Ce and Co species may provide the"d-f electronic ladders"for accelerating electron transfer of the catalytic surface.Meanwhile,Ce promotes the formation of Co-superoxide intermediate and/or the release of oxygen,which is considered to be the rate-determining step for OER.The electrochemical measurements confirmed the low overpotential of 300 m V at 10 m A cm^(-2) and great stability of Ce0.21@Co(OH)_(2) for OER.This work demonstrates a meaningful approach to realize the tuned electronic structure through metal doping.
基金financially supported by the National Natural Science Foundation of China(Nos.52072151,52171211,52102253,52271218 and U22A20145)Jinan Independent Innovative Team(No.2020GXRC015)+1 种基金the Major Program of Shandong Province Natural Science Foundation(No.ZR2021ZD05)the Science and Technology Program of University of Jinan(Nos.XKY2119 and XKY2304)。
文摘The shuttling diffusion of polysulfides is a bottleneck that seriously limits the performance of Li-S batteries.Purposeful construction of sulfur cathodes with reliable trapping ability of polysulfides is the key to overcome such limitation.Herein,a hierarchical porous architecture,i.e.,Co(OH)_(2)sheets bonded Ti_3C_(2)T_x MXene aerogel(Co(OH)_(2)/MXA),is constructed via a facile selfassembled approach and used as an efficient free-standing polysulfides reservoir.The interconnected three-dimensional(3D)porous network with void space and strong interfacial interaction not only enables high sulfur loading but facilitates fast ion and electron transport.Experimental and theoretical results confirm the hetero-framework exhibits outstanding immobilization and conversion ability for polysulfides due to its polar surface and bifunctional catalytic activities toward both formation and decomposition of Li2S.The optimized Co(OH)_(2)/MXA cathode delivers excellent rate capability(407 mAh·g^(-1)at 5C)with a sulfur loading of 2.7 mg·cm^(-2),and ultra-stable cycling performance as an extremely small capacity decay of~0.005%per cycle within 1700 cycles at 1C is achieved with a high sulfur loading of 6.7 mg·cm^(-2).More significantly,our design structural/componential methodology here promises the MXene-based aerogel electrodes for LiS batteries and beyond.
