Electrocatalytic Hydrogen And Oxygen Evolution Performances Of Porphyrin-based Polyporous Polymers And Their Co_1-xS Composite Electrocatalyst

Electrochemical water splitting holds the promise of meeting the needs of green and sustainable energy systems,because it can cleanly convert electrical energy into chemical energy in the form of hydrogen without any unwanted by-products.Although the precious metal Ru,Pt,Ir,and its metal oxides have excellent electrocatalytic effect on electrochemical water splitting,they are faced with the problems of high cost and scarcity.Therefore,the development of efficient,low-cost and environmentally friendly hydrogen evolution(HER)and oxygen evolution(OER)electrocatalysts has become a key issue in energy utilization and conversion.In view of the advantages of porphyrin porous organic polymers and metal sulfides,the main work of this paper is to take porphyrin as a unit to construct porous polymers,design and synthesis of new porphyrin-based polyporous polymers and Co_1-xS composites,in order to achieve the purpose of enhancing the activity of HER and OER,and study the mechanism of the improvement of their electrocatalytic performance.In the second chapter,a new covalent organic polymer of porous cobalt porphyrin(CoCOP)was prepared by Schiff base condensation reaction.The CoCOP was characterized by Infrared spectrum,¹³C solid state NMR spectrum,Gel permeation chromatography,X-ray photoelectron spectroscopy and other methods,which proved the successful synthesis of CoCOP.At the same time,the electrochemical test of the synthesized material shows that the prepared CoCOP not only has good HER and OER properties,but also has good chemical stability.Through experiments and theoretical calculations,it is found that the improvement of electrocatalytic performance of CoCOP is mainly due to the effective charge transfer effect between cobalt porphyrin(donor)and imine bond(receptor).In the third chapter,the porous titanium coordination polymer(TiCP-PCP)was successfully designed and prepared through the transesterification reaction between catechol porphyrin(TPP(OH)₈)and tetraisopropyl titanate.Through a series of physical and spectral characterization,it was proved that the TiCP-PCP successfully synthesized showed high electrocatalytic activity and good electrochemical stability in both acid and alkaline media.The experimental and theoretical results show that the enhancement of the electrocatalytic performance of TiCP-PCP is mainly due to the effective charge transfer between the porphyrin and the Ti group and its synergistic effect.The results provide a new idea for the design and synthesis of porous organic polymers with excellent structure and efficient electrocatalytic performance.In the fourth chapter,a series of TiCP-PCP-supported Co_1-xS composite catalyst TiCP-PCP@Co_1-xS were designed and prepared,and characterized by different spectroscopic techniques.The experimental results show that the TiCP-PCP has a significant effect on the activity of TiCP-PCP@Co_1-xS composite catalyst,and there is an optimal TiCP-PCP content in the composite material.When the TiCP-PCP content is 20 wt%,the OER activity of 0.2TiCP-PCP@Co_1-xS composite is the highest,and it has good long-term stability in alkaline solution.The combination of TiCP-PCP and Co_1-xS can significantly increase the number of active sites,regulate the electronic structure of Co_1-xS,and makes it have abundant Co³⁺active site centers on its surface,thus enhancing the intrinsic activity of OER.This work provides a new idea for the design of efficient composite electrocatalysts with non-noble metals and porous coordination polymers.