Preparation Of Metal-organic Complex-derived Composite Materials And Their Photo/electrocatalytic Propertie

The development of novel photo/electrocatalysts are extremely important for developing clean energy and treating environmental water pollution.Metal-organic complexes,constructed by metal ions/clusters and organic linkers,exhibiting the advantages of large specific surface area,high porosity and tunable structure,and abundant active sites,have been intensively employed as templates/precursors.However,their inherent low electrical conductivity and poor stability limits the practical applications in the field of catalysis.In this paper,metal-organic frameworks（Co-MOF）and Imine-based metal-organic complexes（Imine-MOC）were compounded with nickel foam and melamine foam,respectively,and then carbonized to prepare self-supporting electrocatalysts composed of 2D MOFs nanosheets and three-dimensional porous heterojunction photocatalystscatalysts.The performance of electrocatalyst for overall water splitting in alkaline medium and photocatalysts for degrading antibiotics were studied.The specific content is outlined as follows:The first work demonstrated an in situ growth of 2D Co-MOF nanosheet arrays on nickel foam using a CoO nanowall template induced strategy,and the subsequent pyrolysis treatment converts the 2D Co-MOF nanosheet arrays into Ni@CoO@Co-MOFC composites,which can be directly applied as a self-supported electrode for electrocatalysis.Remarkably,at a current density of 10 m A cm^-2,Ni@CoO@Co-MOFC as a promising electrocatalyst exhibits an excellent electrocatalytic overpotentials of 138 and 247 m V for the HER and OER,the Tafel slopes are 92 m V dec^-1 and 59 m V dec^-1,respectively,More importantly,a two-electrode electrolyzer fabricated from Ni@CoO@Co-MOFC displays a low overpotential of 1.61 V(η₁₀)toward overall water splitting.The excellent performance of water splitting is mainly attributed to the in situ growth of the self-supporting electrocatalyst Ni@CoO@Co-MOFC on the Ni foam substrate with open macroporous structure,which can ensure enhanced electron transfer and transport;secondly,the 2D nanosheet structure enables much more effective exposure of active sites and enhances the electrical conductivity.Simultaneously,the synergistic advantages between Co and CoO ensure more suitable charge transfer dynamics for both the HER and the OER.Furthermore,the self-supported structure without binders expedites mass transfer and promotes the release of gas bubbles.This study provides new insights into the development of 2D MOF nanosheet arrays and derived self-supported electrodes with high performance for overall water-splitting.The second work is to prepare four g-C₃N₄/Ti O₂/CNOT photocatalyst structures via a reasonable design and control of the amount of Imine-MOC crystal materials.g-C₃N₄/Ti O₂/CNOT photocatalysts have a 3D porous structure,high surface area and heterojunction interface between g-C₃N₄ and Ti O₂,which together enhance the adsorption and photocatalytic performance.The 3D porous structure of g-C₃N₄/Ti O₂/CNOT supplied multidimensional adsorption-enrichment sites,and the heterojunction promoted the separation of the photogenerated electrons and holes.The g-C₃N₄/Ti O₂/CNOT-15photocatalyst with the highest surface area reached up to 1644.1 m² g^-1.Heterojunctions promoted the separation and migration of the photogenerated electrons and holes.Benefiting from the above-mentioned excellent characteristics,g-C₃N₄/Ti O₂/CNOT exhibits efficient synergistic adsorption–photocatalysis performance for the removal of chlortetracycline hydrochloride（CTC-HCl）.Apparently,g-C₃N₄/Ti O₂/CNOT-15 shows the highest CTC-HCl photocatalytic efficiency up to 97.8%after 60 min in the static system.In the dynamic system,the maximum CTC-HCl removal rate reached 35.5%and equilibrium removal rate was 19.9%.Free radical trapping experiments demonstrated that˙O₂^-radical,˙OH radical and holes serving as active species work together to promote photocatalytic reactions.