Microbial System Inspired Transition Metal Catalyst Design And Its Application In Water Electrolysis

With the rapid growth of the global population,freiendly and green energy is urgently acquired,which promotes the development and investigation of renewable clean energy sources.Hydrogen energy as one of the most promising sustainable energy shows less restriction of natural conditions,high energy density,and non-polluting products.At present,water electrolysis is regarded as the most effective hydrogen production program.In actual process of water electrolysis,complex electron transfer is involved in the reactions of the cathode and the anode,thus producing a certain catalytic energy barrier.Traditional precious metal catalysts are limited by high cost and low reserves in practical applications.In order to continue to promote the commercial application of electrolyzed water,there is an urgent need to explore a simple,efficient,low-cost and conducive to large-scale preparation of transition metal catalysts.Inspired by the complex and diverse microbial systems in nature,this thesis is concentrated on the study of microorganisms,the environment of microorganisms and the process of microbial corrosion,and uses the characteristics to design transition metal catalysts in the catalytic reaction of electrolyzed water.The main research contents are as follows:In chapter 3,a common microorganism（chlorella）in nature was selected to synthesize Co-Co₂P@NPC/r GO with a mesoporous structure by taking advantage of its spherical structure and rich phosphorus source characteristics.A superior hydrogen evolution property was exhibited with an overpotential of only 153 m V（0.5 M H₂SO₄）at 10 m A cm^-2.The addition of GO was conductive to promote the dispersion of chlorella spheres and reduce the sintering of active materials.Co-Co₂P played an essential role in strengthening the hydrogen evolution.Additionally,the synergistic effect of the r GO together promoted the catalytic performance.Microorganisms as natural carbon templates was employed to synthesize metal nanocatalysts due to its own abundant non-metal sources,which is conductive to design the transition metal-based catalysts of broad application.In chapter 4,inspired by the living environment of microorganisms in nature,a chemical corrosion strategy was developed to prepare transition metal catalysts.The as-obtained layered nano-sheet Ni（Fe）（OH）₂ could be applied into the oxygen evolution reaction of the anode in water splitting.During the electrochemical activation process,it would undergo phase transformation to form Ni（Fe）OOH,which achieved an overpotential of 275 m V at current density of 10 m A cm^-2,indicating outstanding stability under long-term cycle.Theoretical calculation data showed that the phase-transformed Ni（Fe）OOH was more conducive to the adsorption/desorption of the active intermediate during the reaction process,explaining the better OER performance.Microbial corrosion environment is inspired to construct an efficient oxygen evolution catalyst,implying a novel idea for the rapid synthesis and large-scale preparation of the catalyst.In chapter 5,benefiting from the inspiration of natural microbial corrosion behavior,the microbiological corrosion strategy was further developed to prepare high-efficiency oxygen evolution catalysts.Among them,the corrosion process of iron foam（IF）in the microbial iron oxidizing bacteria（IOB）system was investigated.Through the characteristics of microbial enhancement of corrosion efficiency,nano-sheet-shaped Fe₂O₃-Ni Fe（OH）_x/IF was prepared with overpotential only 234 m V at the current density of 10 m A cm^-2.The presence of microorganisms was able to accelerate the corrosion of IF,generate more iron oxides through self-metabolism and form Fe₂O₃-Ni Fe（OH）_x heterojunction structure.The existence of Fe₂O₃-Ni Fe（OH）_x exhibited a superior overall water splitting performance.The combination of bioengineering and nanomaterial preparation provides a forward-looking new strategy for enhanced catalytic performance.