The edge S sites of thermodynamically stable 2H MoS_(2)are active for hydrogen evolution reaction(HER)but the active sites are scarce.Despite the dominance of the basal S sites,they are generally inert to HER because ...The edge S sites of thermodynamically stable 2H MoS_(2)are active for hydrogen evolution reaction(HER)but the active sites are scarce.Despite the dominance of the basal S sites,they are generally inert to HER because of the low p-band center.Herein,we reported a synergistic combination of phase engineering and NH_(4)^(+) intercalation to promote the HER performance of MoS_(2).The rational combination of 1T and 2H phases raises the p-band center of the basal S sites while the intercalated NH4+ions further optimize and stabilize the electronic band of these sites.The S sites with regulated band structures afford moderate hydrogen adsorption,thus contributing to excellent HER performance over a wide pH range.In an acid medium,this catalyst exhibits a low overpotential of 169 mV at 10 mA·cm^(−2)and Tafel slope of 39 mV·dec^(−1)with robust stability,superior to most of recently reported MoS_(2)-based non-noble catalysts.The combined use of in/ex-situ characterizations ravels that the appearance of more unpaired electrons at the Mo 4d-orbital reduces the d-band center which upshifts the p-band center of the adjacent S for essentially improved HER performance.This work provides guidelines for the future development of layered transition-metal-dichalcogenide catalysts.展开更多
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 strate...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.展开更多
The asteroids are the most important small bodies in the solar system, while the movement of the near-earth-asteroids (NEAs) is specially concerned by the world. The focus on these asteroids is that they encounter the...The asteroids are the most important small bodies in the solar system, while the movement of the near-earth-asteroids (NEAs) is specially concerned by the world. The focus on these asteroids is that they encounter the earth. The orbital evolution of this kind of asteroid is studied by analyzing and comparing them; reasonable dynamical models and corresponding algorithm are given, and the formal numbered NEAs are calculated. The results of the minimal distance and the very closeapproach time with the earth agree well with those announced by the Minor Planet Center (MPC).展开更多
The high unoccupied d band energy of Ni_(3)N basically results in weak orbital coupling with water molecule,consequently leading to slow water dissociation kinetics.Herein,we demonstrate Cr doping can downshift the un...The high unoccupied d band energy of Ni_(3)N basically results in weak orbital coupling with water molecule,consequently leading to slow water dissociation kinetics.Herein,we demonstrate Cr doping can downshift the unoccupied d orbitals and strengthen the interfacial orbital coupling to boost the water dissociation kinetics.The prepared Cr-Ni_(3)N/Ni displays an impressive overpotential of 37 mV at 10 mA·cmgeo-2,close to the benchmark Pt/C in 1.0 M KOH solution.Refined structural analysis reveals the Cr dopant exists as the Cr-N_(6)states and the average d band energy of Ni_(3)N is also lowered.Density functional theory calculation further confirms the downshifted d band energy can strengthen the orbital coupling between the unpaired electrons in O 2p and the unoccupied state of Ni 3d,which thus facilitates the water adsorption and dissociation.The work provides a new concept to achieve on-demand functions for hydrogen evolution catalysis and beyond,by regulating the interfacial orbital coupling.展开更多
Spin engineering is recognized as a promising strategy that modulates the association between d‐orbital electrons and the oxygenated species,and enhances the catalytic kinetics.However,few efforts have been made to c...Spin engineering is recognized as a promising strategy that modulates the association between d‐orbital electrons and the oxygenated species,and enhances the catalytic kinetics.However,few efforts have been made to clarify whether spin engineering could make a considerable enhancement for electrocatalytic water oxidation.Herein,we report the spin engineering of a nanocage‐structured(Co,Ni)Se_(2)/C@FeOOH,that showed significant oxygen evolution reaction(OER)activity.Magnetization measurement presented that the(Co,Ni)Se_(2)/C@FeOOH sample possesses higher polarization spin number(μb=6.966μB/f.u.)compared with that of the(Co,Ni)Se_(2)/C sample(μb=6.398μB/f.u.),for which the enlarged spin polarization number favors the adsorption and desorption energy of the intermediate oxygenated species,as confirmed by surface valance band spectra.Consequently,the(Co,Ni)Se_(2)/C@FeOOH affords remarkable OER product with a low overpotential of 241 mV at a current of 10 mA cm^(-2) and small Tafel slope of 44 mV dec^(-1) in 1.0 mol/L KOH alkaline solution,significantly surpassing the parent(Co,Ni)Se_(2)/C catalyst.This work will trigger a solid step for the design of highly‐efficient OER electrocatalysts.展开更多
基金the National Natural Science Foundation of China(Nos.51901115 and 51802075)the Shandong Provincial Natural Science Foundation,China(Nos.ZR2019PEM001,ZR2019BB009,and ZR2020ZD08)the Young Talents Program in University of Hebei Province,China(No.BJ2019002).
文摘The edge S sites of thermodynamically stable 2H MoS_(2)are active for hydrogen evolution reaction(HER)but the active sites are scarce.Despite the dominance of the basal S sites,they are generally inert to HER because of the low p-band center.Herein,we reported a synergistic combination of phase engineering and NH_(4)^(+) intercalation to promote the HER performance of MoS_(2).The rational combination of 1T and 2H phases raises the p-band center of the basal S sites while the intercalated NH4+ions further optimize and stabilize the electronic band of these sites.The S sites with regulated band structures afford moderate hydrogen adsorption,thus contributing to excellent HER performance over a wide pH range.In an acid medium,this catalyst exhibits a low overpotential of 169 mV at 10 mA·cm^(−2)and Tafel slope of 39 mV·dec^(−1)with robust stability,superior to most of recently reported MoS_(2)-based non-noble catalysts.The combined use of in/ex-situ characterizations ravels that the appearance of more unpaired electrons at the Mo 4d-orbital reduces the d-band center which upshifts the p-band center of the adjacent S for essentially improved HER performance.This work provides guidelines for the future development of layered transition-metal-dichalcogenide catalysts.
基金This work is supported by the National Natural Science Foundation of China(No.52122702)Natural Science Foundation of Heilongjiang Province of China(No.JQ2021E005)Fundamental Research Foundation for Universities of Heilongjiang Province(No.LGYC2018JQ006).
文摘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.
文摘The asteroids are the most important small bodies in the solar system, while the movement of the near-earth-asteroids (NEAs) is specially concerned by the world. The focus on these asteroids is that they encounter the earth. The orbital evolution of this kind of asteroid is studied by analyzing and comparing them; reasonable dynamical models and corresponding algorithm are given, and the formal numbered NEAs are calculated. The results of the minimal distance and the very closeapproach time with the earth agree well with those announced by the Minor Planet Center (MPC).
基金The work was supported by the National Natural Science Foundation of China(Nos.21771169 and 11722543)the National Key Research and Development Program of China(No.2017YFA0206703)+1 种基金Anhui Provincial Natural Science Foundation(No.BJ2060190077)Collaborative Innovation Program of Hefei Science Center,CAS,and the Fundamental Research Funds for the Central Universities(Nos.WK2060190074,WK2060190081,WK2310000066,and WK2060000015).
文摘The high unoccupied d band energy of Ni_(3)N basically results in weak orbital coupling with water molecule,consequently leading to slow water dissociation kinetics.Herein,we demonstrate Cr doping can downshift the unoccupied d orbitals and strengthen the interfacial orbital coupling to boost the water dissociation kinetics.The prepared Cr-Ni_(3)N/Ni displays an impressive overpotential of 37 mV at 10 mA·cmgeo-2,close to the benchmark Pt/C in 1.0 M KOH solution.Refined structural analysis reveals the Cr dopant exists as the Cr-N_(6)states and the average d band energy of Ni_(3)N is also lowered.Density functional theory calculation further confirms the downshifted d band energy can strengthen the orbital coupling between the unpaired electrons in O 2p and the unoccupied state of Ni 3d,which thus facilitates the water adsorption and dissociation.The work provides a new concept to achieve on-demand functions for hydrogen evolution catalysis and beyond,by regulating the interfacial orbital coupling.
文摘Spin engineering is recognized as a promising strategy that modulates the association between d‐orbital electrons and the oxygenated species,and enhances the catalytic kinetics.However,few efforts have been made to clarify whether spin engineering could make a considerable enhancement for electrocatalytic water oxidation.Herein,we report the spin engineering of a nanocage‐structured(Co,Ni)Se_(2)/C@FeOOH,that showed significant oxygen evolution reaction(OER)activity.Magnetization measurement presented that the(Co,Ni)Se_(2)/C@FeOOH sample possesses higher polarization spin number(μb=6.966μB/f.u.)compared with that of the(Co,Ni)Se_(2)/C sample(μb=6.398μB/f.u.),for which the enlarged spin polarization number favors the adsorption and desorption energy of the intermediate oxygenated species,as confirmed by surface valance band spectra.Consequently,the(Co,Ni)Se_(2)/C@FeOOH affords remarkable OER product with a low overpotential of 241 mV at a current of 10 mA cm^(-2) and small Tafel slope of 44 mV dec^(-1) in 1.0 mol/L KOH alkaline solution,significantly surpassing the parent(Co,Ni)Se_(2)/C catalyst.This work will trigger a solid step for the design of highly‐efficient OER electrocatalysts.
