Design And Photocatalytic/Electrocatalytic Properties Of The Nanostructured Composites Of Two-Dimensional Materials With Nickel-Based Materials

Hydrogen is a clean energy with high calorific value and no pollution.It is predicted that hydrogen energy industry will develop rapidly in the next three to five years.The method of producing hydrogen by decomposition of water is the most potential energy development means for obtaining hydrogen.The key to achieving this green approach is to find efficient and inexpensive non precious metal catalysts that can replace the catalysts for precious metals and precious metal groups.Two dimensional?2D?layered nanomaterials have received great attention in the field of catalysis due to their unique structure and electronic properties.Therefore,in this paper,a simple one step calcining method is used to improve the catalytic performance of non noble metal catalysts by structural design and modification of two-dimensional layered nanomaterials,which provides new ideas for the replacement of the catalysts for precious metals and precious metal groups.The main contents of this paper are as follows:?1?g-C₃N₄:Ni materials were prepared by one-step calcination using urea and nickel formate as precursors.The structure and morphology of g-C₃N₄:Ni were determined by XRD,XPS and TEM.The results show that metal Ni has entered the crystal lattice of g-C₃N₄ and exists in the form of Ni²⁺.The doping of Ni can effectively improve the separation efficiency of the photo-generated carriers of monomer g-C₃N₄.The experiment of degradation of methyl orange by g-C₃N₄:Ni material under visible light showed that the proper addition of nickel could improve the catalytic activity of g-C₃N₄,and the excess doping of Ni could inhibit the photocatalytic degradation of MO.When the mass ratio of nickel formic acid to urea is 1:40,the activity of g-C₃N₄:Ni material is the best,and the degradation rate of 80 min is basically 92.35%.By adding the active species scavenger of anthraquinone?removal of·OH?,isopropanol?removal of O₂^-?and sodium oxalate?removal of h⁺?,we know that the active species in the photocatalytic performance are mainly h⁺.Under the condition of 300 W xenon lamp irradiation and sacrificial agent TEOA,the photocatalytic hydrogen production efficiency of g-C₃N₄:Ni material is 1.6 times of that of monomer g-C₃N₄.By stability test,it is found that the catalyst has good stability,hydrogen production efficiency is maintained 90.26%.?2?MoS₂/Ni₃S₂ composites and MoS₂/Ni₃S₂/Ni composites were prepared by one step calcining method with the self-made ammonium thiomolybdate and nickel formate.And the catalytic activity of the composites in the electrocatalytic HER was tested.the characterization of XRD,XPS and TEM showed that the existence of Ni₃S₂ and single substance Ni effectively inhibited the growth of MoS₂ nanometers,and made MoS₂/Ni₃S₂/Ni composites have smaller particle size,more active sites and better conductivity.These characteristics in the HER of MoS₂/Ni₃S₂/Ni composite has better HER activity than that of pure MoS₂.MoS₂/Ni₃S₂/Ni 1:4 composite starting overpotential of 73 m V,Tafel slope is 65 mV/dec.By stability test,it is found that the prepared catalyst has good stability under acidic conditions.?3?Using the self-made graphene oxide and nickel formate as the precursor,the rGO/NiO composites and rGO/NiO/Ni composites were prepared by one step calcining method,and the catalytic activity of the composites in the electrocatalytic OER was tested.Through the analysis of XRD,TEM and XPS,the results show that nickel oxide and elemental nickel greatly enhance the interfacial interaction ability and electron transport capacity of the composite.That make the rGO/NiO/Ni composite material have better OER activity than the pure GO.When the current density is 10 mA·cm^-2,the overpotential of rGO/NiO/Ni 1:1.2 composite is 236 mV,and when the current density is 35 mA·cm^-2,the overpotential is 400 mV.The mass activity is 233.33 A/g,and the Tafel slope is 87 mV/dec...