The water oxidation in alkaline media is a kinetically sluggish process and it requires an active electrocatalyst for overall water splitting which is a challenging task to date.Herein,we formulate a platform for the ...The water oxidation in alkaline media is a kinetically sluggish process and it requires an active electrocatalyst for overall water splitting which is a challenging task to date.Herein,we formulate a platform for the design of efficient NiCo_(2)S_(4)/C nanocomposite using earth abundant and nonprecious materials.The nanocomposites are prepared by scale up hydrothermal method using different carbon contents from acid dehydrated sucrose.They are structurally and morphologically character-ized by various analytic techniques.The scanning electron microscopy has shown few microns flower-like morphology of nanocomposite and hexagonal crystalline phase is identified by X-ray diffraction(XRD).Further,high-resolution transmission electron microscopy supported the XRD results,and C,Ni,Co and O elements were found in the composition nanocomposite as investigated by energy-dispersive spectroscopy.The most active nanocomposite reaches a current density of 20 mA·cm^(−2) at potential of 285 mV vs reversible hydrogen electrode.The nanocomposite is kinetically supported by 61 mV·dec^(−1) as small Tafel slope.The nanocomposite is stable and durable for 40 h.The electrochemical impedance spectroscopy described a small charge transfer resistance of 188.4Ω.These findings suggest that the NiCo_(2)S_(4)/C nanocomposite could be used as a promising material for an extended range of applications particularly in energy technology.展开更多
Within the class of two-dimensional materials, transition metal dichalcogenides (TMDs), are extremely appealing for a variety of technological applications. Moreover, the manipulation of the layered morphology at the ...Within the class of two-dimensional materials, transition metal dichalcogenides (TMDs), are extremely appealing for a variety of technological applications. Moreover, the manipulation of the layered morphology at the nanoscale is a knob for further tailoring their physical and chemical properties towards target applications. Here, the combination of atomic layer deposition (ALD) and chemical vapour deposition (CVD) is presented as a general approach for the fabrication of TMD layers arranged in arbitrary geometry at the nanoscale. Indeed, following such all-chemical based approach, high-resolution electron microscopy shows the conformal growth of MoS2 to nano-trench pattern obtained in SiO2 substrates on large area. Growth is uniform not only in the flat region of the pattern but also at the hinges and throughout vertical faces, without rupture, all along the rectangular shape profile of the trenches. Furthermore, MoS2 bending dramatically affects the electron-phonon coupling as demonstrated by resonant Raman scattering. The proposed approach opens the door to the on-demand manipulation of the TMDs properties by large-scale substrate pattern design.展开更多
基金Raffaello Mazzaro and Vittorio Morandi gratefully acknowledge the European Union’s Horizon 2020 research and innovation programme under Graphene Core2785219-Graphene Flagship for partial fundingWe extend our sincere appreciation to the Researchers Supporting Project(No.RSP-2020/79)at King Saud University,Riyadh,Saudi Arabia.
文摘The water oxidation in alkaline media is a kinetically sluggish process and it requires an active electrocatalyst for overall water splitting which is a challenging task to date.Herein,we formulate a platform for the design of efficient NiCo_(2)S_(4)/C nanocomposite using earth abundant and nonprecious materials.The nanocomposites are prepared by scale up hydrothermal method using different carbon contents from acid dehydrated sucrose.They are structurally and morphologically character-ized by various analytic techniques.The scanning electron microscopy has shown few microns flower-like morphology of nanocomposite and hexagonal crystalline phase is identified by X-ray diffraction(XRD).Further,high-resolution transmission electron microscopy supported the XRD results,and C,Ni,Co and O elements were found in the composition nanocomposite as investigated by energy-dispersive spectroscopy.The most active nanocomposite reaches a current density of 20 mA·cm^(−2) at potential of 285 mV vs reversible hydrogen electrode.The nanocomposite is kinetically supported by 61 mV·dec^(−1) as small Tafel slope.The nanocomposite is stable and durable for 40 h.The electrochemical impedance spectroscopy described a small charge transfer resistance of 188.4Ω.These findings suggest that the NiCo_(2)S_(4)/C nanocomposite could be used as a promising material for an extended range of applications particularly in energy technology.
文摘Within the class of two-dimensional materials, transition metal dichalcogenides (TMDs), are extremely appealing for a variety of technological applications. Moreover, the manipulation of the layered morphology at the nanoscale is a knob for further tailoring their physical and chemical properties towards target applications. Here, the combination of atomic layer deposition (ALD) and chemical vapour deposition (CVD) is presented as a general approach for the fabrication of TMD layers arranged in arbitrary geometry at the nanoscale. Indeed, following such all-chemical based approach, high-resolution electron microscopy shows the conformal growth of MoS2 to nano-trench pattern obtained in SiO2 substrates on large area. Growth is uniform not only in the flat region of the pattern but also at the hinges and throughout vertical faces, without rupture, all along the rectangular shape profile of the trenches. Furthermore, MoS2 bending dramatically affects the electron-phonon coupling as demonstrated by resonant Raman scattering. The proposed approach opens the door to the on-demand manipulation of the TMDs properties by large-scale substrate pattern design.
