MXene nanomaterials are one of the most promising electrode material candidates for supercapacitors owing to their high conductivity,abundant surface functional groups and large surface area.However,electrodes based o...MXene nanomaterials are one of the most promising electrode material candidates for supercapacitors owing to their high conductivity,abundant surface functional groups and large surface area.However,electrodes based on MXene may result in low ion-accessible surface area and blocked ion transport pathways because of the self-restacking of MXene nanosheets.It is essential to suppress the self-res tacking of nanosheets and increase the electrochemical active sites in order to optimize the electrode.In this work,bidirectionally aligned MXene hybrid aerogel(A-MHA)assembled with MXene nanosheets and microgels is prepared using a facile bidirectional freeze casting and freeze-drying method.The bidirectionally aligned structure together with the three-dimensional structured microgels in the A-MHAs,can improve the ionaccessible surface area and provide more barrier-free channels by exposing more active sites and ensuring electrolyte transport freely.The A-MHA with MXene microgels content of 40 wt%exhibits a high specific capacitance of 760 F·g^(-1)at 1 A·g^(-1)and a remarkable cyclic performance of 97%after 10,000 cycles at100 mV·s^(-1)in 1 mol·L^(-1)H_(2)SO_(4)electrolyte.A-MHAs show remarkable electrochemical properties and are of potential application in energy storage.展开更多
Bioturbation plays a critical role in sediment mixing and biogeochemical cycling between sediment and seawater.An abundance of bioturbation structures, dominated by Thalassinoides, occurs in carbonate rocks of the Cam...Bioturbation plays a critical role in sediment mixing and biogeochemical cycling between sediment and seawater.An abundance of bioturbation structures, dominated by Thalassinoides, occurs in carbonate rocks of the Cambrian Series 2 Zhushadong Formation in the Dengfeng area of western Henan Province, North China. Determination of elemental geochemistry can help to establish the influence of burrowing activities on sediment biogeochemical cycling, especially on changes in oxygen concentration and nutrient regeneration. Results show that there is a dramatic difference in the bioturbation intensity between the bioturbated limestone and laminated dolostone of the Zhushadong Formation in terms of productivity proxies(Baex, Cu, Ni, Sr/Ca) and redox proxies(V/Cr, V/Sc, Ni/Co). These changes may be related to the presence of Thalassinoides bioturbators, which alter the particle size and permeability of sediments, while also increase the oxygen concentration and capacity for nutrient regeneration.Comparison with modern studies shows that the sediment mixing and reworking induced by Thalassinoides bioturbators significantly changed the primary physical and chemical characteristics of the Cambrian sediment,triggering the substrate revolution and promoting biogeochemical cycling between sediment and seawater.展开更多
基金financially supported by the National Natural Science Foundation of China(No.52002354)China Postdoctoral Science Foundation(No.2020M672256)。
文摘MXene nanomaterials are one of the most promising electrode material candidates for supercapacitors owing to their high conductivity,abundant surface functional groups and large surface area.However,electrodes based on MXene may result in low ion-accessible surface area and blocked ion transport pathways because of the self-restacking of MXene nanosheets.It is essential to suppress the self-res tacking of nanosheets and increase the electrochemical active sites in order to optimize the electrode.In this work,bidirectionally aligned MXene hybrid aerogel(A-MHA)assembled with MXene nanosheets and microgels is prepared using a facile bidirectional freeze casting and freeze-drying method.The bidirectionally aligned structure together with the three-dimensional structured microgels in the A-MHAs,can improve the ionaccessible surface area and provide more barrier-free channels by exposing more active sites and ensuring electrolyte transport freely.The A-MHA with MXene microgels content of 40 wt%exhibits a high specific capacitance of 760 F·g^(-1)at 1 A·g^(-1)and a remarkable cyclic performance of 97%after 10,000 cycles at100 mV·s^(-1)in 1 mol·L^(-1)H_(2)SO_(4)electrolyte.A-MHAs show remarkable electrochemical properties and are of potential application in energy storage.
基金Financial support for this study was provided by the Natural Science Foundation of China(Grant Nos.41872111,41902115,and 41902113)。
文摘Bioturbation plays a critical role in sediment mixing and biogeochemical cycling between sediment and seawater.An abundance of bioturbation structures, dominated by Thalassinoides, occurs in carbonate rocks of the Cambrian Series 2 Zhushadong Formation in the Dengfeng area of western Henan Province, North China. Determination of elemental geochemistry can help to establish the influence of burrowing activities on sediment biogeochemical cycling, especially on changes in oxygen concentration and nutrient regeneration. Results show that there is a dramatic difference in the bioturbation intensity between the bioturbated limestone and laminated dolostone of the Zhushadong Formation in terms of productivity proxies(Baex, Cu, Ni, Sr/Ca) and redox proxies(V/Cr, V/Sc, Ni/Co). These changes may be related to the presence of Thalassinoides bioturbators, which alter the particle size and permeability of sediments, while also increase the oxygen concentration and capacity for nutrient regeneration.Comparison with modern studies shows that the sediment mixing and reworking induced by Thalassinoides bioturbators significantly changed the primary physical and chemical characteristics of the Cambrian sediment,triggering the substrate revolution and promoting biogeochemical cycling between sediment and seawater.
