Building three-dimensional(3D) current collectors is a promising strategy to surmount the bottlenecks of lithium metal anodes(LMAs), but the regulation methodology of a 3D current collector has seldom been considered ...Building three-dimensional(3D) current collectors is a promising strategy to surmount the bottlenecks of lithium metal anodes(LMAs), but the regulation methodology of a 3D current collector has seldom been considered comprehensively concerning both skeleton architectures and surface coatings. Herein, a robust porous 3D nickel skeleton(NS) with lithiophilic NiN nanocoatings(NiN@NS) is synthesized via an integrative route of powder metallurgy/plasma-enhanced nitridation technics. The facile powder metallurgical method facilitates the adjustment of NS architectures toward sufficient electrolyte adsorption and even current density distribution, while the followed plasma-enhanced chemical vapor deposition(PECVD) method can induce compact NiN nanocoatings on NS, which reduces the Li nucleation overpotential, accelerates the Li-ion transfer, and facilitates a highly reversible oriented texture of Li deposition morphology owing to the dense and homogenous deposition of Li into the pores. The optimized NiN@NS current collector shows a high averaged Coulombic efficiency(CE) of 98.8% over 350cycles, a prolonged lifespan of 1000 h(at 2 mA cm^(-2)) in symmetrical cells, together with the significant performance in full cells. The ingenious methodology reported in this work can also be broadly applicable for the controllable production of other 3D skeletons with nitride nanocoatings for various applications.展开更多
The interstitial structure and weak Ni-N interaction of Ni3N lead to high unoccupied d orbital energy and unsuitable orbital orientation,which consequently results in weak orbital coupling with H2O and slow water diss...The interstitial structure and weak Ni-N interaction of Ni3N lead to high unoccupied d orbital energy and unsuitable orbital orientation,which consequently results in weak orbital coupling with H2O and slow water dissociation kinetics for alkaline hydrogen evolution catalysis.Herein,we successfully lower the unoccupied d orbital energy of Ni3N to strengthen the interfacial electronic coupling by employing the strong electron pulling capability of oxygen dopants.The prepared O-Ni3N catalyst delivers an overpotential of 55 mV at 10 mA cm−2,very close to the commercial Pt/C.Refined structural characterization indicates the oxygen incorporation can decrease the electron densities around the Ni sites.Moreover,density functional theory calculation further proves the oxygen incorporation can create more unoccupied orbitals with lower energy and superior orientation for water adsorption and dissociation.The concept of orbital-regulated interfacial electronic coupling could offer a unique approach for the rational design of hydrogen evolution catalysts and beyond.展开更多
Photocatalytic H2 production via water splitting in a noble-metal-free photocatalytic system has attracted much attention in recent years.In this study,noble-metal-free Ni3N was used as an active cocatalyst to enhance...Photocatalytic H2 production via water splitting in a noble-metal-free photocatalytic system has attracted much attention in recent years.In this study,noble-metal-free Ni3N was used as an active cocatalyst to enhance the activity of g-C3N4 for photocatalytic H2 production under visible-light irradiation(λ>420 nm).The characterization results indicated that Ni3N nanoparticles were successfully loaded onto the g-C3N4,which accelerated the separation and transfer of photogenerated electrons and resulted in enhanced photocatalytic H2 evolution under visible-light irradiation.The hydrogen evolution rate reached^305.4μmol h^-1 g^-1,which is about three times higher than that of pristine g-C3N4,and the apparent quantum yield(AQY)was^0.45%atλ=420.Furthermore,the Ni3N/g-C3N4 photocatalyst showed no obvious decrease in the hydrogen production rate,even after five cycles under visible-light irradiation.Finally,a possible photocatalytic hydrogen evolution mechanism for the Ni3N/g-C3N4 system is proposed.展开更多
基金supported by the National Natural Science Foundation of China(U1904216)。
文摘Building three-dimensional(3D) current collectors is a promising strategy to surmount the bottlenecks of lithium metal anodes(LMAs), but the regulation methodology of a 3D current collector has seldom been considered comprehensively concerning both skeleton architectures and surface coatings. Herein, a robust porous 3D nickel skeleton(NS) with lithiophilic NiN nanocoatings(NiN@NS) is synthesized via an integrative route of powder metallurgy/plasma-enhanced nitridation technics. The facile powder metallurgical method facilitates the adjustment of NS architectures toward sufficient electrolyte adsorption and even current density distribution, while the followed plasma-enhanced chemical vapor deposition(PECVD) method can induce compact NiN nanocoatings on NS, which reduces the Li nucleation overpotential, accelerates the Li-ion transfer, and facilitates a highly reversible oriented texture of Li deposition morphology owing to the dense and homogenous deposition of Li into the pores. The optimized NiN@NS current collector shows a high averaged Coulombic efficiency(CE) of 98.8% over 350cycles, a prolonged lifespan of 1000 h(at 2 mA cm^(-2)) in symmetrical cells, together with the significant performance in full cells. The ingenious methodology reported in this work can also be broadly applicable for the controllable production of other 3D skeletons with nitride nanocoatings for various applications.
基金This work was supported by the National Natural Science Foundation of China(21771169,51801075,11722543)the National Key Research and Development Program of China(2017YFA0206703)+1 种基金Anhui Provincial Natural Science Foundation(BJ2060190077)Recruitment Program of Global Expert,and the Fundamental Research Funds for the Central Universities(WK2060190074,WK2060190081,WK2310000066).
文摘The interstitial structure and weak Ni-N interaction of Ni3N lead to high unoccupied d orbital energy and unsuitable orbital orientation,which consequently results in weak orbital coupling with H2O and slow water dissociation kinetics for alkaline hydrogen evolution catalysis.Herein,we successfully lower the unoccupied d orbital energy of Ni3N to strengthen the interfacial electronic coupling by employing the strong electron pulling capability of oxygen dopants.The prepared O-Ni3N catalyst delivers an overpotential of 55 mV at 10 mA cm−2,very close to the commercial Pt/C.Refined structural characterization indicates the oxygen incorporation can decrease the electron densities around the Ni sites.Moreover,density functional theory calculation further proves the oxygen incorporation can create more unoccupied orbitals with lower energy and superior orientation for water adsorption and dissociation.The concept of orbital-regulated interfacial electronic coupling could offer a unique approach for the rational design of hydrogen evolution catalysts and beyond.
基金financially supported by the National Key Research and Development Program of China(2017YFA0402800)the National Natural Science Foundation of China(51772285,21473170,51878004)+1 种基金the Natural Science Fund of of Anhui Province(1808085ME139)the Fundamental Research Funds for the Central Universities~~
文摘Photocatalytic H2 production via water splitting in a noble-metal-free photocatalytic system has attracted much attention in recent years.In this study,noble-metal-free Ni3N was used as an active cocatalyst to enhance the activity of g-C3N4 for photocatalytic H2 production under visible-light irradiation(λ>420 nm).The characterization results indicated that Ni3N nanoparticles were successfully loaded onto the g-C3N4,which accelerated the separation and transfer of photogenerated electrons and resulted in enhanced photocatalytic H2 evolution under visible-light irradiation.The hydrogen evolution rate reached^305.4μmol h^-1 g^-1,which is about three times higher than that of pristine g-C3N4,and the apparent quantum yield(AQY)was^0.45%atλ=420.Furthermore,the Ni3N/g-C3N4 photocatalyst showed no obvious decrease in the hydrogen production rate,even after five cycles under visible-light irradiation.Finally,a possible photocatalytic hydrogen evolution mechanism for the Ni3N/g-C3N4 system is proposed.
