Synthesis Of Two-Dimensional Nickel-Based Nanomaterials And Their Applications In Energy Conversion

Develpoing advanced energy conversion technologies,such as electrocatalytic water splitting,rechargeable metal-air battery and so on can not do without the development and utilization of high-performance electrocatalysts.As a promising substitute of conventional platinum-,iridium-,ruthenium-based catalysts,nickel with exciting electronic properties,rich reserves and synergistic effect has emergyed as useful constitutions to optimize materials’surface adsorption features and electronic structure to improve catalytic activity of materials.Moreover,nanostructure design also plays a pivotal role in catalytic performance.Two-demensional（2D）nano structure possess high surface atoms exposition proportion,rich edge sites,efficient charge/mass transfer features and thus it is helpful for the expose of active sites and enhancement of intrisinc activity of catalysts.However,how to utilize simple and efficient synthesis and modulation methodes to optimize electronic structure of materials,alleviate agglomeration of 2D nanosheets during the catalytic process and enhance structural stability are keys to develop 2D nickel-based electrocatalysts.This paper chooses 2D nickel-based compound as research objects and modulates their performance through elecment doping and heterojunction construction strategies.Meanwhile,X-ray photoelectron spectroscopy,electron spin resonance,in-suit Raman characterization technique and so on were used to characterize the structure of catalysts,monitor the catalytic process and explore the structure-property relationship of catalysts preliminarily.This paper provides references for optimization of catalytic activity and stability of 2D structure nickle-based nanomaterials.At first,Ni（OH）₂ with lamellar structure was chosen as a research object and Fe doping strategy can modulate its oxygen vacancy concentration and electronic structure of Nisites,making Ni_0.8Fe_0.2 hydroxide exhibits optimized oxygen catalytic activity.The zinc-air battery assembled with Ni_0.8Fe_0.2 hydroxide and zinc plate shows excellent charge-discharge cycling stability under a wide temperature（-10 ^oC-40 ^oC）.Moreover,utilizing Ru cation to modify the surface feature of 2D porous NiCo₂O₄ NSs.The characterization results show the introduction of Ru increases oxygen defects concentraction and electrochemical surface area and decreases charge transfer barrier of materials,which make Ru-NiCo₂O₄ NSs exhibit excellent catalytic performance.The alkaline water electrolyzer assembled with Ru-NiCo₂O₄ NSs can reach the current density of10 m A cm^-2 applied a cell voltage of 1.60 V.Both activity and stability of Ru-NiCo₂O₄ NSs system are superior to Pt/C||Ru O₂ overall water splitting system.Finally,electrodeposition-calcination methode was developed to synthesize 2D Ni-NiO NSs and the degree of crystallinity of NiO is tunable by adjusting calcination temperature（100 ^oC-400 ^oC）,obtaining series of crystalline Ni-amorphous NiO heterostructures and crystalline Ni-crystalline NiO heterostructure.Crystalline Ni-amorphous NiO sample calcined at 160 ^oC shows optimized HER performance,the overpotential of which at 10 m A cm^-2 is 76 m V.Compared with crystalline Ni-crystalline NiO,it shows lower work function and charge transfer impedance,which are conducive to accelerate electron transfer and improve HER catalytic activity.