双金属电子诱导CoNi LDH-GO相变以提升其析氧和超级电容器性能

Bimetallic electron-induced phase transformation of CoNi LDH-GO for high oxygen evolution and supercapacitor performance

双功能能源材料在能量转换和储存方面具有重要的研究价值.本文通过双金属电子调节和氧化石墨烯(GO)辅助制备出双功能α相Co_(2)Ni_(1)LDH-GO.在不添加GO的情况下,Co_(2)Ni_(1)LDH主要由β相组成.与β相相比,α相Co_(2)Ni_(1)LDH-GO表现出更大的层间距,缩短了离子的转移路径和时间,从而提升了其电化学性能.作为能量转换中析氧的电催化剂,超薄α相Co_(2)Ni_(1)LDH-GO在10 mA cm^(-2)的电流密度下具有最低的过电位η10=218.5 mV.Ni^(2+)的协同电子调控促使Co–O键形成,使其具有良好的稳定性.随着Co–O键长的增加,吸附的OH-进一步将Co^(3+)氧化为Co^(4+).作为三电极储能超级电容器中的电极,Co_(2)Ni_(1)LDH-GO的比电容可达3317.5 F g^(-1).当用于不对称电容器(Co_(2)Ni_(1)LDH-GO//活性炭)时,Co_(2)Ni_(1)LDH-GO显示出大的电容(328.75 Fg^(-1))和出色的循环稳定性.本工作为通过相变方法改善多功能材料的析氧和超级电容器性能的研究提供理论依据.

Bifunctional energy materials in energy conversion and storage have a significant research value.Herein,bifunctionalα-phase Co_(2)Ni_(1)layered double hydroxide(LDH)-graphene oxide(GO)was prepared through bimetallic electronic regulation and GO assistance.Without GO addition,Co_(2)Ni_(1)LDH bulk is dominated by theβphase.Compared with theβ-phase type,theα-phase Co_(2)Ni_(1)LDH-GO shows a larger interlayer spacing,which shortens the ion movement path and time and thus improves the electrochemical performance.As an electrocatalyst for oxygen evolution in energy conversion,the ultrathinα-phase Co_(2)Ni_(1)LDH-GO possesses the lowest overpotentialη10of 218.5 mV at a current density of 10 mA cm^(-2).It also exhibits excellent stability mainly due to the Co-O bond by the cooperative electronic regulation of Ni^(2+).With the increase in Co-O bond length,the adsorbed OH-further oxidizes Co^(3+)to Co^(4+).As an electrode in a three-electrode supercapacitor for energy storage,the specific capacitance of Co_(2)Ni_(1)LDH-GO can reach 3317.5 Fg^(-1).When used in an asymmetric capacitor(Co_(2)Ni_(1)LDH-GO//activated carbon),Co_(2)Ni_(1)LDH-GO shows a remarkable capacitance of 328.75 Fg^(-1)and excellent cycling stability.This work provides a phase transformation approach to improve the oxygen evolution and supercapacitor performance of multifunctional materials.