MoS_(2)-Decorated/Integrated Carbon Fiber:Phase Engineering Well-Regulated Microwave Absorber

Phase engineering is an important strategy to modulate the electronic structure of molybdenum disulfide(MoS_(2)).MoS_(2)-based composites are usually used for the electromagnetic wave(EMW)absorber,but the effect of different phases on the EMW absorbing performance,such as 1T and 2H phase,is still not studied.In this work,micro-1T/2H MoS_(2) is achieved via a facile one-step hydrother-mal route,in which the 1T phase is induced by the intercalation of guest molecules and ions.The EMW absorption mechanism of single MoS_(2) is revealed by presenting a comparative study between 1T/2H MoS_(2) and 2H MoS_(2).As a result,1T/2H MoS_(2) with the matrix loading of 15%exhibits excellent microwave absorption property than 2H MoS_(2).Furthermore,taking the advantage of 1T/2H MoS_(2),a flexible EMW absorbers that ultrathin 1T/2H MoS_(2)grown on the carbon fiber also performs outstanding performance only with the matrix loading of 5%.This work offers necessary reference to improve microwave absorption performance by phase engineering and design a new type of flexible electromagnetic wave absorption material to apply for the portable microwave absorption electronic devices.

Nanohollow Carbon for Rechargeable Batteries:Ongoing Progresses and Challenges

Among the various morphologies of carbon-based materials,hollow carbon nanostructures are of particular interest for energy storage.They have been widely investigated as electrode materials in different types of rechargeable batteries,owing to their high surface areas in association with the high surface-to-volume ratios,controllable pores and pore size distribution,high electrical conductivity,and excellent chemical and mechanical stability,which are beneficial for providing active sites,accelerating electrons/ions transfer,interacting with electrolytes,and giving rise to high specific capacity,rate capability,cycling ability,and overall electrochemical performance.In this overview,we look into the ongoing progresses that are being made with the nanohollow carbon materials,including nanospheres,nanopolyhedrons,and nanofibers,in relation to their applications in the main types of rechargeable batteries.The design and synthesis strategies for them and their electrochemical performance in rechargeable batteries,including lithium-ion batteries,sodium-ion batteries,potassium-ion batteries,and lithium–sulfur batteries are comprehensively reviewed and discussed,together with the challenges being faced and perspectives for them.

One‑Pot Rational Deposition of Coaxial Double‑Layer MnO_(2)/Ni(OH)_(2) Nanosheets on Carbon Nanofibers for High‑Performance Supercapacitors

Constructing“nanoglue”between inorganic electroactive species and conductive carbon scaffolds is an effective strategy to improve their compatibility and binding interaction,holding a great promise for fabricating high-performance hybrid electrodes for supercapacitors.However,multistep reactions are usually required to obtain these multicomponent systems,thus giving rise to the complicated and time-consuming issues.Herein,we for the first time,demonstrate a green one-pot method to anchor coaxial double-layer MnO_(2)/Ni(OH)_(2)nanosheets on electrospun carbon nanofibers(CNFs)(denoted as MNC),where the intermediate MnO_(2)layer serves as the“nanoglue”to couple the vertically aligned Ni(OH)_(2)nanosheets and conductive CNFs.Benefiting from the unique chemical composition and hierarchical architecture,the resultant electrode delivers outstanding electrochemical performance,including an excellent specific capacitance(1133.3 F g^(-1)at 1 A g^(-1))and an ultrahigh rate capability(844.4 F g^(-1)at 20 A g^(-1)).Moreover,the asymmetric supercapacitor assembled by using the MNC as positive electrode and the CNF as negative electrode can achieve an optimal energy density of 35.1 Wh kg^(-1)and a maximum power density of 8000 W kg^(-1).The one-pot strategy that stabilizes electroactive metal hydroxides on conductive carbons using a MnO_(2)“nanoglue”to design advanced hybrid electrodes is expected to be broadly applicable not only to the supercapacitor technology but also to other electrochemical applications.

Fundamentals,On‑Going Advances and Challenges of Electrochemical Carbon Dioxide Reduction

Electrochemical carbon dioxide reduction(ECR)is an attractive pathway to synthesize useful fuels and chemical feedstocks,especially when paired with renewable electricity as the energy source.In this overview,we examine the recently witnessed advances and on-going pursuits of ECR in terms of the key fundamental mechanisms,basic experimentation principles,electrocatalysts and the electrochemical setup for ECR,aiming at offering timely key insights into solving the unsettled bottleneck issues.The reaction pathways are discussed in relation to the generation of single-,double-and multi-carbon products by the ECR,as well as the underlying principles in catalyst design to form them both efficiently and selectively.For the rational design of electrocatalysis,we look into the critically important roles played by various in situ and operando experimental techniques and computational simulations,where the key priorities are to engineer the highly active and selec-tive ECR catalysts for the specifically targeted products.Indeed,with the purposely designed high activity and selectivity,one would be able to“magically”transform a bottle of CO_(2)-riched“coke drink”to a glass of“beer”with the desired alcohol product in a layman term,instead of a bottle of formic acid.Nonetheless,there are still considerable complications and challenges ahead.As a dynamically rapid-advancing research frontier for both energy and the environment,there are great opportunities and obstacles in the ECR scale up.

Polydopamine-derived carbon layer anchoring NiCo-P nanowire arrays for high-performance binder-free supercapacitor and electrocatalytic hydrogen evolution

Transition metal phosphides(TMPs)have been extensively and deeply researched as electrode materials for energy-related applications.However,the inferior stability is still a bottleneck restricting their substantive development.Herein,a freestanding three-dimensional hierarchical nanostructure(marked as CC@NC/NiCo-P)is delicately designed for high-performance supercapacitors and electrocatalytic hydrogen evolution,where the nitrogen-doped carbon(NC)layer derived from polydopamine serves as an interface coupling bridge for anchoring electroactive nickel cobalt phosphide(NiCo-P)nanowire arrays on flexible carbon cloth(CC)substrate.Thanks to the robust interaction between the conductive carbon support and NiCo-P nanowires,the resultant CC@NC/NiCo-P electrode delivers an ultrahigh capacitance(2175.5 F/g at 1 A/g)and a distinguished rate capability with a capacity retention of 85.8%.The assembled asymmetric supercapacitor can achieve a superior energy density of 28.47 Wh/kg and an ultralong lifespan of 10000 cycles.In addition,the CC@NC/NiCo-P electrode shows favorable electrocatalytic activity toward the hydrogen evolution reaction.These results indicate that the strong binding between the NC layer and metal species in TMPs notably improves the stability and electrochemical activity of CC@NC/NiCo-P.It is expected that this effective strategy to design innovative electrode materials may be promising for the applications in energy-related fields.