Bismuth(Bi),as an alloy-based anode material,has attracted much atte ntion in the developme nt of sodiumion hybrid capacitors(SIHCs)due to its high theoretical capacity.However,the volume expansion of the Bi-based ano...Bismuth(Bi),as an alloy-based anode material,has attracted much atte ntion in the developme nt of sodiumion hybrid capacitors(SIHCs)due to its high theoretical capacity.However,the volume expansion of the Bi-based anode during the sodiation/desodiation process results in limited rate capability.In the present work,a porous Bi-based composite was constructed by a one-step hydrothermal method,and Bi was encapsulated in ligninderived nitrogen-doped porous carbon(Bi@LNPC)after carbonization.The obtained Bi nanoparticles could effectively adapt to the strain and shorten the diffusion distance of Na^(+).In addition,porous carbon skeleton provides a rigid conductive network for electronic transportation.Therefore,the assembled sodium-ion half-cell with Bi@LNPC anode shows ultra-high-rate capability.When the current density was enhanced from 0.1 to 50 A·g^(-1),the specific capacity decreased slightly from 351.5 to 342.8 mAh·g^(-1).Even at an extremely high current density of 200 A·g^(-1),it retains 81.3%capacity retention when compared to a current density of 1 A·g^(-1).The SIHCs assembled by Bi@LNPC show a high energy density of 63 Wh·kg^(-1).This work provides an effective method for developing high-rate Bi anode materials for sodium-ion hybrid capacitors(SIHCs)and sodium-ion batteries(SIBs).展开更多
A trimeric lignin model compound composed of α-O-4 and β-O-4 linkages was prepared by the microwave-assisted synthesis, which consisted of three steps: (a) the synthesis of 3-methoxy-4- benzyloxyacetophenone (2...A trimeric lignin model compound composed of α-O-4 and β-O-4 linkages was prepared by the microwave-assisted synthesis, which consisted of three steps: (a) the synthesis of 3-methoxy-4- benzyloxyacetophenone (2) from acetovanillone (1), (b) the bromination of compound 2 to produce 3- methoxy-4-benzyloxy-α-bromoacetophenone (3), and (c) followed by a nucleophilic substitution of compound (3) to obtain 3-methoxy-4-benzyloxy-α-(3-methoxy-4-(1-propenyl)phenol)-acetophenone (4). The target product was characterized by MS, 1H NMR and 13C NMR spectroscopy. It was found that the trimeric compound synthesized can be used as a preferable lignin model compound because it contains guaiacyl structural unit (3-methoxy-4-hydroxy phenyl propane) linked by α-O-4 and β-O-4 linkages. In addition, under the conditions of microwave irradiation, the reaction time of each step is significantly reduced, and the selectivity of target product is greatly improved. The yields of each step and the overall sequence are 95.31%. 87.3%. 90.6% and 75.4% (95.31%× 87.3% × 90.6%). respectively.展开更多
The lack of suitable lignin model compound limits the understanding of the characteristics of lignin, and hence hinders the efficient utilization of this kind of bioresource. A tetramer phenolic lignin model compound ...The lack of suitable lignin model compound limits the understanding of the characteristics of lignin, and hence hinders the efficient utilization of this kind of bioresource. A tetramer phenolic lignin model compound composed of 5-5, α-O-4 and β-5 linkages was prepared by a two-step of free radical reaction with hydrogen peroxide/horseradish peroxidase and S2O8^2- /Fe^2+ as the initiator. Compared with enzymatic process, this synthetic process gives a higher yield of 33.8% within a shorter time. HRMS and ^13C NMR spectroscopy show that synthesized model compound contains phenylpropane structure linked by 5-5, α-O-4 and β-5 bonds, which can mimic some chemical characteristics of lignin.展开更多
基金financially supported by the National Natural Science Foundation of China(No.22108044)the Research and Development Program in Key Fields of Guangdong Province(No.2020B1111380002)+1 种基金the Basic Research and Applicable Basic Research in Guangzhou City(No.202201010290)the financial support from the Guangdong Provincial Key Laboratory of Plant Resources Biorefinery(No.2021GDKLPRB07)。
文摘Bismuth(Bi),as an alloy-based anode material,has attracted much atte ntion in the developme nt of sodiumion hybrid capacitors(SIHCs)due to its high theoretical capacity.However,the volume expansion of the Bi-based anode during the sodiation/desodiation process results in limited rate capability.In the present work,a porous Bi-based composite was constructed by a one-step hydrothermal method,and Bi was encapsulated in ligninderived nitrogen-doped porous carbon(Bi@LNPC)after carbonization.The obtained Bi nanoparticles could effectively adapt to the strain and shorten the diffusion distance of Na^(+).In addition,porous carbon skeleton provides a rigid conductive network for electronic transportation.Therefore,the assembled sodium-ion half-cell with Bi@LNPC anode shows ultra-high-rate capability.When the current density was enhanced from 0.1 to 50 A·g^(-1),the specific capacity decreased slightly from 351.5 to 342.8 mAh·g^(-1).Even at an extremely high current density of 200 A·g^(-1),it retains 81.3%capacity retention when compared to a current density of 1 A·g^(-1).The SIHCs assembled by Bi@LNPC show a high energy density of 63 Wh·kg^(-1).This work provides an effective method for developing high-rate Bi anode materials for sodium-ion hybrid capacitors(SIHCs)and sodium-ion batteries(SIBs).
基金financially supported by the National Basic Research Program of China (No. 2012CB215302)National Natural Science Fundation of China (No. 20876064)the Guangdong Provincial Natural Science Fund (No. 9151064101000082)
文摘A trimeric lignin model compound composed of α-O-4 and β-O-4 linkages was prepared by the microwave-assisted synthesis, which consisted of three steps: (a) the synthesis of 3-methoxy-4- benzyloxyacetophenone (2) from acetovanillone (1), (b) the bromination of compound 2 to produce 3- methoxy-4-benzyloxy-α-bromoacetophenone (3), and (c) followed by a nucleophilic substitution of compound (3) to obtain 3-methoxy-4-benzyloxy-α-(3-methoxy-4-(1-propenyl)phenol)-acetophenone (4). The target product was characterized by MS, 1H NMR and 13C NMR spectroscopy. It was found that the trimeric compound synthesized can be used as a preferable lignin model compound because it contains guaiacyl structural unit (3-methoxy-4-hydroxy phenyl propane) linked by α-O-4 and β-O-4 linkages. In addition, under the conditions of microwave irradiation, the reaction time of each step is significantly reduced, and the selectivity of target product is greatly improved. The yields of each step and the overall sequence are 95.31%. 87.3%. 90.6% and 75.4% (95.31%× 87.3% × 90.6%). respectively.
基金financially supported by the National Basic Research Program of China(No.2012CB215302)the Major Program of National Natural Science Foundation of China(No.21376100)
文摘The lack of suitable lignin model compound limits the understanding of the characteristics of lignin, and hence hinders the efficient utilization of this kind of bioresource. A tetramer phenolic lignin model compound composed of 5-5, α-O-4 and β-5 linkages was prepared by a two-step of free radical reaction with hydrogen peroxide/horseradish peroxidase and S2O8^2- /Fe^2+ as the initiator. Compared with enzymatic process, this synthetic process gives a higher yield of 33.8% within a shorter time. HRMS and ^13C NMR spectroscopy show that synthesized model compound contains phenylpropane structure linked by 5-5, α-O-4 and β-5 bonds, which can mimic some chemical characteristics of lignin.