Blue-shift of Nano-Y_2O_3 : Eu^(3+) Emission Spectra Excited by X-ray

Nano-Y_2O_3:Eu^(3+) powder was prepared by the homogeneous precipitation. With controlling the conditions of the reaction, nano powders with different grain size were obtained. It is found that the blue-shift phenomena exist in the nano-Y2O3:Eu3+ emission spectra excited by X-ray. The wave lengths of the peak (5D0→7F2) are related with the grain size of the powder

Co_(2)P/CoP heterostructures with significantly enhanced performance in electrocatalytic hydrogen evolution reaction:Synthesis and electron redistribution mechanism

Heterostructures are often constructed to modulate the electronic states of the two catalysts,achieving high-performance in alkaline hydrogen evolution reaction(HER).Various mechanisms have been proposed for the heterostructural catalysts,which however awaits further approvement.Herein,a heterostructure composed of Co_(2)P and CoP was successfully prepared with significantly enhanced HER catalytic activity relative to the endmembers.The ultraviolet photoelectron spectroscopy(UPS)and Xray photoelectron spectroscopy(XPS)revealed the effective promotion of the self-driven transferring of electrons from CoP to Co_(2)P and the accumulation of electrons on the P sites in Co_(2)P due to the strong electronic coupling of built-in electric field in the Co_(2)P/CoP interface.In situ electrochemical impedance spectroscopy(EIS)and poison experiments confirmed the Heyrovsky step of H*intermediate depleting on electronegative P sites and contributions of both metal and P to the reactivity in the Co_(2)P/CoP.Density functional theory(DFT)calculations clarify that the electronic structure at interface of the heterojunction significantly weakens the hydrogen adsorption free energy(ΔGH*ads)of P site in Co_(2)P/CoP to near zero.We also propose an electronic redistribution strategy for heterostructures that activates the multiple routes mechanism and production of more active sites.The working mechanism is expected to be further extended to other transition metal compounds for efficient HER activity.

Lithographic printing inspired in-situ transfer of MXene-based films with localized topo-electro tunability for high-performance flexible pressure sensors

MXene-based films have been intensively explored for construction of piezoresistive flexible pressure sensors owing to their excellent mechanical and electrical properties.High pressure sensitivity relies on pre-molding a flexible substrate,or regulating the micromorphology of MXene sheets,to obtain a micro-structured surface.However,the two avenues usually require complicated and time-consuming microfabrication or wet chemical processing,and are limited to non-adjustable topographicelectrical(topo-electro)properties.Herein,we propose a lithographic printing inspired in-situ transfer(LIPIT)strategy to fabricate MXene-ink films(MIFs).In LIPIT,MIFs not only inherit ridge-and-valley microstructure from paper substrate,but also achieve localized topo-electro tunability by programming ink-writing patterns and cycles.The MIF-based flexible pressure sensor with periodical topo-electro gradient exhibits remarkably boosted sensitivity in a wide sensing range(low detection limit of 0.29 Pa and working range of 100 kPa).The MIF sensor demonstrates versatile applicability in both subtle and vigorous pressuresensing fields,ranging from pulse wave extraction and machine learning-assisted surface texture recognition to piano-training glove(PT-glove)for piano learning.The LIPIT is quick,low-cost,and compatible with free ink/substrate combinations,which promises a versatile toolbox for designing functional MXene films with tailored morphological-mechanical-electrical properties for extended application scenarios.

Enhancing the photoelectrochemical performance of p-silicon through TiO_(2)coating decorated with mesoporous MoS_(2)

MoS_(2)is a promising electrocatalyst for hydrogen evolution reaction and a good candidate for cocatalyst to enhance the photoelectrochemical(PEC)performance of Si-based photoelectrode in aqueous electrolytes.The main challenge lies in the optimization of the microstructure of MoS_(2),to improve its catalytic activity and to construct a mechanically and chemically stable cocatalyst/Si photocathode.In this paper,a highly-ordered mesoporous MoS_(2)was synthesized and decorated onto a TiO_(2)protected p-silicon substrate.An additional TiO_(2)necking was introduced to strengthen the bonding between the MoS_(2)particles and the TiO_(2)layer.This meso-MoS_(2)/TiO_(2)/p-Si hybrid photocathode exhibited significantly enhanced PEC performance,where an onset potential of+0.06 V(versus RHE)and a current density of-1.8 mA/cm^(2)at 0 V(versus RHE)with a Faradaic efficiency close to 100%was achieved in 0.5 mol/L H_(2)SO_(4).Additionally,this meso-MoS_(2)/TiO_(2)/p-Si photocathode showed an excellent PEC ability and durability in alkaline media.This paper provides a promising strategy to enhance and protect the photocathode through high-performance surface cocatalysts.