| In view of the increasing concern about the energy crisis and environmental issues,finding a clean and sustainable energy that can be widely used to replace the polluting fossil fuels has always been an important trend in the field of green chemistry research.In this context,high-performance electrocatalysts have attracted extensive research attention in recent years due to their crucial role in the processes of energy conversion and storage technologies（e.g.,fuel cells,water splitting,and carbon dioxide reduction,etc.）.Metal-Organic Frameworks（MOFs）,due to the interaction of organic ligands and metal atoms,provide highly tunable porous connection frameworks,large specific surface areas,fully exposed and dispersed electrocatalytic metal centers,Therefore,it shows great research value and application potential as a new class of non-precious metal electrocatalysts.The combination of different metals or organic ligands can introduce superior and more diverse functionalities to the resulting MOFs,thus bimetallic and polymetallic MOFs have received a lot of attention.The premise of the design of bimetallic MOFs is generally that different metal ions should have similar ionic radii and coordination modes,the correlation between coordination mode and electrocatalytic water oxidation behaviors are highly worth attention.Herein,we designed an iron-based MOF to realize the configuration varies from traditional mononuclear configuration（Fe-MOF-M）to the binuclear structure（Fe-MOF-B）.Successfully,we regulated configuration of Fe-MOF by p H control and introduced nickel into the iron-based MOF to obtain efficient heterogeneous electrocatalysts.Benefiting from the dual function of adding Ni atom,enhanced stability and optimized synergistic effect of different metal sites,the Ni0.8Fe0.2-MOF-B delivers a current density of 10 m A cm-2 at a low overpotential of 301 m V with a small Tafel slope of 62.3 m V dec-1 in 0.1M KOH.This work presents a simple method to adjust configuration and the Ni0.8Fe0.2-MOF-B plays a supporting role to investigate the impact of configuration on OER performance.In metal-organic frameworks,controlling the arrangement of different metal ions to achieve ordered heterogeneity has been a great challenge.In Chapter 4,we use a template-directed approach to first synthesize cobalt one-dimensional metal-organic polymers（Co-1D）,which contain well-defined binding sites and add secondary metal ions under the premise of serving as structural templates,thereby preparing an ordered bimetallic electrocatalyst CoCu-MOF-74-2.The resulting bimetallic MOF-74 possesses nearly 1:1 metal ratio and superior electrocatalytic performance than the one-pot obtained product CoCu-MOF-74-1.Oxygen reduction reaction（ORR）catalysts are of great significance for the long-term operation and wide application of fuel cells,and they can be used as cathode catalysts in proton exchange membrane fuel cells.To this end,in Chapter 3 we propose a rational and efficient comprehensive approach to synthesize ORR catalysts with significantly improved performance by incorporating Pt particles into the matrix with nanosheet morphology（Co-BDC-NSs）.The results show that Pt particles coated on the surface of Co-BDC-NSs can effectively catalyze the ORR process.Compared with the commercial ORR catalyst 20 wt.%Pt/C,Co Pt0.10-BDC-NSs exhibited an onset potential of 0.98 V vs.RHE,and a half-wave potential of 0.85 V vs.RHE,and its activity was comparable to that of the commercial catalyst Pt/C The onset potential is comparable to that of Pt/C,and it also shows good long-term stability in alkaline solutions.The optimized feed ratio,matrix with large specific surface area,and uniform distribution of Pt particles ensure the successful synthesis of Co Pt0.10-BDC-NSs composites.Our strategy is facile,economical,and has great potential to develop high-performance platinum electrocatalysts that are expected to play an important role in future fuel cell technologies. |
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