| The coordination molecule clusters,as a diversified and designable zero-dimensional organic-inorganic hybrid system,can achieve its functional loading and modification in the fields of luminescence,magnetism and catalysis by designing and regulating organic ligands and metal ions.As a material system with precise structural information,the chemical bonding at the atomic and molecular levels,spatial structure and interaction of coordination clusters not only helps to understand the structure-activity relationship of materials,but also are beneficial to directional design and improvement of the function of materials.More chemists are committed to the design and rich performance of the novel structure of coordination molecule clusters,which has promoted its long-term development in the field of coordination chemistry.However,how to fully combine the advantages of coordination molecular clusters in structural design,further expand its functionalization and derivatization within the interdisciplinary scope,and develop its functional design and application development in the frontier field is urgent needed.In this thesis,a novel co-crystalline brucite disk cluster with?3-CN-bridges was designed by using o-vanillin Schiff base ligand,and the conversion process of clusters to the derivatized nanomaterial and its application in electrocatalytic oxygen evolution reaction(OER)were explored.In addition,a series of nickel clusters based on cubic structural units were constructed.The solid-liquid structure information was explored by X-ray diffraction and electrospray ionization mass spectrometry(ESI-MS),and its electrocatalytic urea oxidation reaction(UOR)application was expanded.The full text has been divided into three chapters:Chapter 1 is the preface,which summarizes the research background and scientific challenges of metal-organic framework(MOFs)-derived carbon-based nanocomposites for OER,further introduces the material system and development in UOR,and finally analyzes the important progress and advantages of the current coordination molecular clusters in the field of energy storage and conversion research.It also introduces the significance of the topic selection and the progress made combined with the rich accumulation in the design,assembly process and mechanism research and function exploration of coordination molecular clusters in our group.Chapter 2 mainly describesthata novel co-crystalline Brucite disk cluster{[Co7(L1)6(?3-CN)6][Co Cl3N(CN)2]}(Compound 1)with discrete[Co Cl3N(CN)2]2-anion and in-situ generated?3-CN-bridge was obtained by selecting N,O-double chelate ligand2-methoxy-6-((methylimino)methyl)phenol(HL1).The decomposition of dicyanamide avoids the direct use of highly toxic cyanide.The presence of?3-CN-bridges at the center,in place of the usual?3-OH-,-OCH3-or-N3-with retention of the planarity and the cyanide exhibits the very rare bonding via the nitrogen atom.The introduction of the?3-CN-bridges effectively increases the N/C and N/Co content in the molecular structure.Its low oxygen content proceeds with a gradual thermal decomposition under inert atmosphere to Co@NC nanostructures,which is tracked and systematically analyzed by thermogravimetric-mass spectrometry(TG-MS)for the first time.Combining crystallographic and TG-MS capture of small molecular fragments such as CH3+,H2O+,CO+,CO2+,CHO+and CH2Cl+,it is speculated that possible decomposition sites,aggregation sites and the reaction steps involved in the pyrolysis process such as,decomposition,polymerization,redox and aromatization at high temperature.It is proposed that the dissociation of small molecule fragments and the presence of?3-CN-can promote the immobilization and formation of active ligand fragments by self-polymerization or copolymerization to participate in the fixation and formation of the nitrogen-doped carbon network framework to increase the effective nitrogen content.The nanostructure and morphology of Co@NC were analyzed by serial material characterization and it was found that Co@NC-600 has a more uniform distribution and reasonable ID:IG,high specific surface area and more balanced N hybridization method and content.In addition,the pyrolyzed Co@NC nanomaterial can be used as an effective OER catalyst for electrocatalytic water oxidation.In a 1.0 M KOH electrolyte solution,the Co@NC-600 sample has achieved an ultra-low overpotential of 257 m V and a low Tafel slope of78.9 m V dec-1at current density of 10 m A cm-2and maintained high stability during 15 hours,exhibiting more efficient catalytic activity and comparable kinetic efficiency compared to the commercial precious metal catalyst Ru O2.Chapter 3 introduces the design and synthesis of three Ni-based coordination molecular clusters with cubic or absent cubane configuration:[Ni4(L1)4(L2)2]·2CH3OH(Compound 2),[Ni8(L1)6(L2)4](Cl O4)2·2CH3CN(Compound 3)and[Ni4(L3)3(CH3O)(CH3OH)3](CH3COO)(Compound 4)based on o-vanillin Schiff base ligands HL1,2-hydroxy-3-methoxybenzaldehyde oxime(H2L2)and 3-((2-hydroxy-3-methoxybenzylidene)amino)propane-1,2-diol(H3L3).The three clusters with different structures shows common structural features:1)cluster core structure formed by structural motifs with Ni(OH)2-like structures,and 2)peripheral organic ligands around the cluster core to achieve critical core structures protection.Furthermore,it is revealed that the strong stability of clusters from the protective effects of organic ligand by the solid-liquid structure information and the X-ray powder diffraction after immersed in strong alkaline electrolyte.Besides,as for the electrocatalytic performance of compound 4,it was found the corresponding overpotential of 10 m A cm-2in 1 M KOH solution was only 320 m V and the overpotential corresponding to 10 m A cm-2in 1 M KOH+0.33 M solution was only 1.337 V with the maximum current density of 310 m A cm-2,exhibiting both high-efficiency electrocatalytic OER and UOR properties,which can be used as the first coordination molecule cluster based-crystalline dual-function OER/UOR electrocatalyst for energy conversion. |
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