Construction And Performance Investigation Of Wood Electrodes Based On Transition Metal Cobalt And Nickel Compounds

Due to the serious energy crisis and environmental problems,there is an urgent need to search for renewable energy sources to replace traditional fossil fuels.As an energy carrier,hydrogen energy is supposed to be the green-energy with the most development potential in the future because of its advantages of high energy density,no carbon emission and environmental friendliness,which can effectively alleviate the increasingly severe pollution problem.Electrolytic water cracking sets a precendent in the entire catalytic reforming process and can also be seen as one of the most promising hydrogen production technologies for converting intermittent energy（such as solar,wind and hydropower）into electricity to address future world energy needs.At present,the most effective catalysts are precious metals and their compounds.However,high prices and limited reserves still restrict their industrialization process to achieve large-scale production.Therefore,the exploitation and design of efficient and low-cost non-noble metal catalysts are the focus of electrocatalytic hydrogen production.Wood possesses a natural three-dimensional pore structure and abundant surface active functional groups,which can be used as an ideal substrate material for the preparation of catalysts of electrolysis water with high catalytic activity and excellent stability.According to the above discussion,in this thesis,cobalt-based and nickel-based compounds with different components were constructed based on the structural characteristics of wood,and their electrocatalytic activities of hydrogen and oxygen evolution were systematically studied.The main research contents and results of this paper are as follows:（1）Nickel sulfide（NiS₂）with a 3D porous structure was prepared by simple electrodeposition and solvothermal method.In this 3D porous structure,a large number of active sites are fully exposed to avoid agglomeration and improve the transport efficiency of electrolyte.It not only shows excellent oxygen evolution reaction（OER）activity in an alkaline medium,but also can be used as a bifunctional catalyst for complete water hydrolysis.（2）NiS precursor was synthesized by solvothermal method,and Pd nanoparticles were introduced by the constant piezoelectric deposition method to prepare an efficient Pd-NiS/CW self-supported electrode.Porous,low-bending microchannels,excellent hydrophilicity and hydrophobicity effectively promote the exposure of active sites and transport of electrons,ions and H₂.It shows excellent hydrogen evolution（HER）activity in alkaline solution and has extremely long durability.In addition,DFT calculation further showed that there was a strong electron interaction between Pd and NiS,which effectively regulated the hydrolytic dissociation and adsorption/desorption capacity of H,optimized the inherent activity of NiS,and thus improved the catalytic activity.（3）NiCo bimetallic hydroxide（NiCo-LDH）was synthesized by a one-step hydrothermal method.The Nico-LDH prepared by this process is firmly embedded in the wood substrate,and the thin and ordered nanosheet lamellar structure enables it to exhibit excellent performance in oxygen evolution reaction（OER）.