MIL-100(V) derived porous vanadium oxide/carbon microspheres with oxygen defects and intercalated water molecules as high-performance cathode for aqueous zinc ion battery

The development of aqueous zinc ion battery cathode materials with high capacity and high magnification is still a challenge.Herein,porous vanadium oxide/carbon(p-VO_(x)@C,mainly VO_(2) with a small amount of V_(2)O_(3)) core/shell microspheres with oxygen vacancies are facilely fabricated by using a vanadium-based metal-organic framework(MIL-100(V)) as a sacrificial template.This unique structure can improve the conductivity of the VO_(x),accelerate electrolyte diffusion,and suppress structural collapse during circulation.Subsequently,H_(2)O molecules are introduced into the interlayer of VO_(x) through a highly efficient in-situ electrochemical activation process,facilitating the intercalation and diffusion of zinc ions.After the activation,an optimal sample exhibits a high specific capacity of 464.3 mA h g^(-1) at0.2 A g^(-1) and 395.2 mA h g^(-1) at 10 A g^(-1),indicating excellent rate performance.Moreover,the optimal sample maintains a capacity retention of about 89.3% after 2500 cycles at 10 A g^(-1).Density functional theory calculation demonstrates that the presence of oxygen vacancies and intercalated water molecules can significantly reduce the diffusion barrier for zinc ions.In addition,it is proved that the storage of zinc ions in the cathode is achieved by reversible intercalation/extraction during the charge and discharge process through various ex-situ analysis technologies.This work demonstrates that the p-VO_(x)@C has great potential for applications in aqueous ZIBs after electrochemical activation.

CuI/Nylon Membrane Hybrid Film with Large Seebeck Effect

Room-temperature thermoelectric materials are important for converting heat into electrical energy.As a widebandgap semiconductor material,CuI has the characteristics of non-toxicity,low cost,and environmental friendliness.In this work,CuI powder was synthesized by a wet chemical method,then CuI film was formed by vacuum assisted filtration of the CuI powder on a porous nylon membrane,followed by hot pressing.The film exhibits a large Seebeck coefficient of 600μV·K^(-1)at room temperature.In addition,the film also shows good flexibility(~95%retention of the electrical conductivity after being bent along a rod with a radius of 4 mm for 1000 times).A finger touch test on a single-leg TE module indicates that a voltage of 0.9 mV was immediately generated within 0.5 s from a temperature difference of 4 K between a finger and the environment,suggesting the potential application in wearable thermal sensors.

Three-phase interface induced charge modulation on MoO_(2)/Mo_(2)Ccarbon tube for enhanced hydrogen evolution

Exploring superior electrocatalyst for hydrogen evolution reaction(HER)is an urgent need for hydrogen production based on water splitting.The redistribution of electrons and the increase of active sites through multi-interface designing of electrocatalyst are powerful strategies to improve the catalytic efficiency.Herein,a three-phase interface structure of N,P co-doped carbon tube embedded with MoO_(2)/Mo_(2)C(MoO_(2)/Mo_(2)C-CT)was fabricated via a cooperative polymerizing-embedding and pyrolysis strategy.Work function and X-ray photoelectron spectroscopy(XPS)verified that the interfacial charge was quantificationally modulated,achieving an intrinsically enhanced charge transfer by an induced built-in electric field.Theoretical study of density functional theory(DFT)illustrated that triple-interface structure showed a lower energy for H*+H2O*than that of single-interface counterparts.The triple-interface MoO_(2)/Mo_(2)C-CT delivered a lower overpotential of 129 mV at 10 mA·cm^(−2)than that of either single-interface MoO_(2)-CT or Mo_(2)C-CT catalyst.This work may put forward an attractive approach for modulating electronic structure and provide insights into the understanding of triple-interface structure towards HER.

Facile anodization approach derived low-crystalline NiCoeOH/NiCoOOH composite films for ultra-high areal capacity and mass loading supercapacitors

The design of supercapacitor materials with both high areal capacity(C)and high mass loading is vitally important for enhancing energy density(E).Herein,we prepared a NiCosingle bondOH/NiCoOOH composite film consisting of NiCosingle bondOH/NiCoOOH nanosheets on an expanded graphite paper(EGP)by using a facial anodization method.The as-prepared NiCosingle bondOH/NiCoOOH film exhibits ultra-high C of 11 mA·h·cm^(-2)at a mass loading of 165 mg·cm^(-2),high rate capability of 71%and excellent cycling stability of 95%after 12000 cycles.The outstanding performance is ascribed to the low-crystalline feature of the NiCosingle bondOH/NiCoOOH nanosheets,and the synergistic effect of the NiCosingle bondOH and NiCoOOH phases and high conductive porous EGP.An aqueous asymmetric supercapacitor,assembled with the NiCosingle bondOH/NiCoOOH on EGP and Fe_(2)O_(3)on EGP as positive-and negative-electrode,respectively,shows a highest E of 3.8 mW·h·cm^(-2)at a power density(P)of 4 mW·cm^(-2)and a maximum P of 107 mW·cm^(-2)at an E of 2.7 mW·h·cm^(-2).

Facile preparation of poly(3,4-ethylenedioxythiophene): poly(styrenesulfonate)/Ag2Te nanorod composite films for flexible thermoelectric generator

In this work,poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate)(PEDOT:PSS)coated silver telluride(PCeAg2Te)nanorods were prepared by a wet-chemical method using the PEDOT:PSS coated tellurium(PCeTe)nanorods as the templates.Flexible PCeAg2Te nanocomposite film on polyethersulfone(PES)substrate was prepared through vacuum filtration followed by mechanical pressing process.An optimal PCeAg2Te nanocomposite film showed a maximum power factor of 143.3 mW/mK^(2) at room temperature and 221.7 μW/mK^(2 ) at 373 K.The electrical conductivity of the PCeAg2Te composite film decreased by3.3%after bending for 1000 times around a rod with a radius of 5 mm.An eight-leg thermoelectric generator assembled with the optimal PCeAg2Te nanocomposite film generated a maximum output power and output density of 209.4 nW and 141.5 mW/cm^(2) at a temperature gradient of 30.3 K.This work provides a facile method to prepare thermoelectric materials for flexible thermoelectric generators.