Phosphorus incorporation activates the basal plane of tungsten disulfide for efficient hydrogen evolution catalysis

The basal planes of transition metal dichalcogenides are basically inert for catalysis due to the absence of adsorption and activation sites,which substantially limit their catalytic application.Herein,a facile strategy to activate the basal plane of WS_(2) for hydrogen evolution reaction(HER)catalysis by phosphorous-induced electron density modulation is demonstrated.The optimized P doped WS_(2)(P-WS_(2))nanowires arrays deliver a low overpotential of 88 mV at 10 mA·cm^(-2)with a Tafel slope of 62 mV·dec^(-1)for HER,which is substantially better than the pristine counterpart.X-ray photoelectron spectroscopy confirms the surface electron densities of WS_(2) have been availably manipulated by P doping.Moreover,density functional theory(DFT)studies further prove P doping can redistribute the density of states(DOS)around EF,which endow the inert basal plane of PWS_(2) with edge-like catalytic activity toward hydrogen evolution catalysis.Our work offers a facile and effective approach to modulate the catalytic surface of WS_(2) toward highly efficient HER catalysis.

Quantitative defect regulation of heterostructures for sulfur catalysis toward fast and long lifespan lithium-sulfur batteries

The advancement of lithium-sulfur(Li-S)batteries is severely retarded by lithium polysulfides(LiPSs)shuttling behavior and sluggish redox kinetics.Herein,the heterogeneous composite with defective Bi_(2)Se_(3−x)nanosheets and porous nitrogen-doped carbon(Bi_(2)Se_(3−x)/NC)is prepared by selenizing bismuth metal-organic frameworks as a multifunctional sulfur host.The highly efficient immobilization-conversion on LiPSs is realized by the synergistic effect of structure construction strategy and defect engineering.It is found that Bi_(2)Se_(3−x)with the suitable amount of selenium vacancies achieves the best electrochemical performance due to the advantages of its structure and composition.These results confirm the intrinsic correlation between defects and catalysis,which are revealed by computational and experimental studies.Due to these superiorities,the developed sulfur electrodes exhibited admirable stability and a fairly lower capacity decay rate of approximately 0.0278%per cycle over 1,000 cycles at a 3 C rate.Even at the high sulfur loading of 6.2 mg·cm^(−2),the cathode still demonstrates a high discharge capacity of 455 mAh·g^(−1)at 1 C.This work may enlighten the development of mechanism investigation and design principles regarding sulfur catalysis toward high-performance Li-S batteries.