Synergetic dielectric loss and magnetic loss towards superior microwave absorption through hybridization of few-layer WS2 nanosheets with NiO nanoparticles

WS2 nanomaterials have attracted great attention in the field of electromagnetic wave absorption due to their high specific surface area,layered structure,and peculiar electronic properties.However,further improvements on their limited electromagnetic absorbing(EMA)capacity and bandwidth are urgently required for their practical application as EMA absorbents.In this work,WS2/NiO hybrids with heterostructures are prepared by a hydrothermal method and developed into EMA absorbents.The maximum reflection loss of the hybrids with 20%NiO loading could reach-53.31 dB at a thickness of 4.30 mm;the bandwidth with a reflection loss value of less than-10 dB is determined to be13.46 GHz(4.54–18 GHz)when the thickness of the absorbent is between 3.5 and 5.5 mm.It is found that the enhanced EMA performance of WS2/NiO hybrids is caused by the addition of magnetic NiO,which could result in the interfaces between WS2 and NiO being responsible for the synergetic magnetic loss and dielectric loss in the hybrids.This work provides a new approach for the design of excellent EMA materials for practical applications.

Intimately coupled WS_(2) nanosheets in hierarchical hollow carbon nanospheres as the high-performance anode material for lithium-ion storage

Lithium-ion hybrid capacitors(LIHCs)have drawn extensive attention in fleld of energy storage.However,the absence of appropriate electrode materials with rapid kinetics restricted the overall performance of the capacitors.Herein,hierarchical N,P-codoped hollow car-bon nanospheres coupling with WS_(2) nanosheets(N,P-codoped HCNS/WS_(2)NSs)were fabricated for boosting lithium storage materials.Specially,the WS_(2) nanosheets with several layers embedded in the N,P-codoped hollow carbon nanospheres could not only enhance the conduc-tivity of composites,but also provide abundant channels for the rapid transfer of ions.As a result,as-prepared N,P-codoped HCNS/WS_(2) NSs demonstrated superior rate performance and long-term cycling stability.The reversible discharge capacity of 725.2 mAh·g^(-1) could be preserved after 1000 cycles at a current density of 1.0 A·g^(-1).Fur-thermore,LIHCs devices were assembled by using N,P-codoped HCNS/WS_(2) NSs and activated carbon(AC)as the cathode and anode,which exhibited high energy density of 166.7 Wh·kg^(-1) and power density of 5312.4 W·kg^(-1).Last but not least,the capacity almost had no obvious deterioration after 6000 cycles at a high current density of 10.0 A·g^(-1).

Triggering heteroatomic interdiffusion in one-pot-oxidation synthesized NiO/CuFeO_(2) heterojunction photocathodes for efficient solar hydrogen production from water splitting

Delafossite CuFeO_(2) is a promising photocathode material for cost-efficiently photoelectrochemical(PEC)water splitting,but the unfavorable conductivity and fast recombination dynamics of photogenerated carriers limit its PEC activity for water reduction.Here,we developed a heterostructure photocathode consisting of the Cu-doped NiO(Cu:NiO)hole selective layer(HSL)and Ni-doped CuFeO_(2)(Ni:CuFeO_(2))active layer by simply annealing a homogeneous Cu-Fe oxalate layer grown on the Ni film deposited on the fluorine doped tin oxide(FTO)substrate.The obtained heterostructure of Cu:NiO/Ni:CuFeO_(2) with enhanced charge carrier transportability and high-quality interface greatly promotes the separation of photogenerated carriers.Accordingly,the Cu:NiO/Ni:CuFeO_(2) photocathode exhibits a high photocurrent density of~0.9 mA·cm^(-2 )at 0.2 V(vs.reversible hydrogen electrode,RHE),outperforming most of the reported bare CuFeO_(2) photocathodes in the literature.And the photocurrent density can be further improved to 1.2 mA·cm^(-2) after decorating NiSx cocatalyst.