Uniform Metal Sulfide@N-doped Carbon Nanospheres for Sodium Storage: Universal Synthesis Strategy and Superior Performance

Nitrogen-doped carbon-coated transition-metal sulfides(TMS@NCs)have been considered as efficient anodes for sodium-ion batteries.However,the uncontrollable morphology and weak core-shell binding forces significantly limit the sodium storage performance and life.Herein,based on the reversible ring-opening reaction of the epoxy group of the tertiary amino group-rich epoxide cationic polyacrylamide(ECP)at the beginning of hydrothermal process(acidic environment)and the irreversible ring-opening(cross-linking reactions)at the late hydrothermal period(alkaline environment),47 nm-sized ZnS@NCs were prepared via a one-pot hydrothermal process.During this process,the covalent bonds formed between the ZnS core and elastic carbon shell significantly improved the mechanical and chemical stabilities of ZnS@NC.Benefiting from the nanosize,fast ion/electron transfer,and high stability,ZnS@NC exhibited a high reversible capacity of 421.9 mAh g^(−1) at a current density of 0.1 A g^(−1) after 1000 cycles and a superior rate capability of 273.8 mAh g^(−1) at a current density of 5 A g^(−1).Moreover,via this universal synthesis strategy,a series of TMS@NCs,such as MoS_(2)@NC,NiS@NC,and CuS@NC were developed with excellent capacity and cyclability.

Size effect enabling additive-free MXene ink with ultrahigh conductivity for screen printing of wireless electronics

Facile preparation of additive-free inks with both high viscosity and high conductivity is critical for scalable screen printing of wireless electronics,yet very challenging.MXene materials exhibit excellent conductivity and hydrophilicity,showing great potential in the field of additive-free inks for screen printing.Here,we demonstrate the synthesis of additive-free two-dimensional(2D)titanium carbide MXene inks,and realize screen-printed MXene wireless electronics for the first time.The viscosity of MXene ink is solely regulated by tuning the size of MXene nanosheet without any additives,hence rendering the printed MXene film extremely high conductivity of 1.67×10^(5) S/m and fine printing resolution down to 0.05 mm on various flexible substrates.Moreover,radio frequency identification(RFID)tags fabricated using the additive-free MXene ink via screen printing exhibit stable antenna reading performance and superb flexibility.This article,thus offers a new route for the efficient,low-cost and pollution-free manufacture of printable electronics based on additive-free MXene inks.

Smart ZnS@C filler for super-anticorrosive self-healing zinc-rich epoxy coating

The zinc-rich epoxy cathodic protection coating is the most widely used anticorrosion material for marine steel.However,traditional conductive fillers lack the intelligent self-healing effect,which limits the long-term anticorrosion performance.Herein,with uniform carbon-coated ZnS(ZnS@C)nanoballs as the smart active release filler,we propose an anticorrosive and self-healing zinc-rich maleic anhydride epoxy coating.Due to the high pore filling efficiency of the nanoballs,the water vapor transmission rate of the coating with an initial corrosion efficiency of 99.92%and a low-frequency impedance of|Z|f=10mHz=3.88×10^(10) Ω·cm^(2),was reduced by 52%.The carbon-shell of the nanoball increases electron transmission paths in the coating and improves conductivity by nearly two orders of magnitude,which effectively activates more Zn-sites and extends the cathodic protection time.Moreover,once the steel-substrate undergoes regional corrosion,the SO_(4)^(2-)hydrolyzes from the ZnS-core of the nanoball and reacts with iron ions on the corroded area accurately and intelligently to fill the gap and self-heals into a new dense barrier layer(Fe_(2)(SO_(4))_(3),etc.),which significantly improves the shielding protection ability during the long-term usage of the coating.The effective anticorrosion time of the proposed coating could be up to 3,400 h.