Synthesis Of Transition Bimetallic Sulfide And Their Performances For Electrocatalytic Water Splitting

Fossil energy such as petroleum is the main energy source in today’s society.Due to its non-renewability and its heavry usage acound the wold,it has caused serious shortage of fuel;In addition,the consumption of fossil energy has brought serious environmental pollution and greenhouse effect.In order to meet the needs of people’s lives,the consumption of fossil raw materials is gradually increasing,and environmental pollution is becoming more and more serious.Hence,people are in urgent need of a green and clean renewable resource.As the best clean energy for future human society development,H₂ is considered to be the best substitute for fossil fuels because of its clean and efficient characteristics,and will be called the energy carrier of the optimal potential in the future.The traditional hydrogen production method is mainly realized by consuming non-renewable petroleum resources,but the electrocatalytic decomposition of water technology can not only store renewable energy and convert hydrogen energy for a long time to meet the needs of people’s daily life,but also conforms to the current“sustainable”development requirements.At present,the electrocatalysts used in industrial production are the precious metals,such as Pt/C and RuO₂,however their high price and reserves limit the large-scale use.Therefore,in order to further save costs and simplify the device,it is a hot research topic to design a dual-function electrocatalyst with high efficiency,stability and low cost.Considering the issues discussed above,this masterthesis takes bimetallic sulfide as the research object,and develops high-efficiency and stable electrocatalyst by manupulafing regulating its micronano structure.The main contents are as follows:1.Successfully synthesize the unique ZnS@C@MoS₂ core-shell nanostructure with a simple etching method and a“bottom-up”strategy.Firstly,the ZnS nanospheres with uniform particle size were synthesized by hydrothermal method.Then,the PDA film was assembled on the surface of ZnS nanospheres with the self-assembly method,and then subjected to high temperature carbonization,strong acid etching treatment,and finally etched by one-step hydrothermal method.Ultrathin MoS₂ nanosheets were grown in situ on the surface of ZnS@C.We observed that ZnS@C@MoS₂ exhibits excellent electrochemical performance with an initial potential of only 69 mV and an overpotential of only 118 mV at a current density of 10 mA cm^-2.In addition,ZnS@C@MoS₂ is in the base.When tested for 12 h in the electrolyte,the retention rate was as high as 84%,indicating excellent stability.2.The Zn-Co-S colloidal nanocrystal clusters（CNCs）were prepared for the overall water decomposition（HER and OER）reaction using a one-pot water-heat assisted homogeneous precipitation strategy.The prepared Zn-Co-S CNCs exhibit a clear spherical shape and are formed by the assembly of interconnected primary nanoparticles.Under alkaline conditions,the Zn-Co-S electrocatalyst only needs an overpotential of 157 mV vs.RHE（HER）and 320 mV vs.RHE（OER）to achieve a current density of 10mA cm^-2.In addition,when used for the overall water decomposition,in a two-electrode alkaline water decomposition system,a battery voltage of only 1.64 V was required at a current density of 10 mA cm^-2,and continuous at a current density of 30 mA cm^-2.After electrolysis for 12 h,the corresponding voltage remains almost unchanged.3.A three-dimensional highly open CuCo₂S₄ nanoflower structure was synthesized by one-step solvothermal method for the study of total water decomposition（hydrogen evolution and oxygen evolution）.It was found by electrochemical performance test that the flower-shaped nanosphere prepared by the solvothermal method has good hydrogen evolution and oxygen evolution performance,and can reach 10 mA cm^-2 only under the driving voltage of 1.68 V in the whole water decomposition process.At a certain applied voltage,the current density and continuous electrolysis for 12 hours,the current density remains almost unchanged.