Study On The Proton Conductivity Of Metal-Triazole Complex

With the continuous consumption of global energy,the energy shortage and environmental problems faced by mankind have become increasingly serious.All countries in the world have an increasingly strong demand for clean,low-carbon,safe and efficient new energy.Proton exchange membrane fuel cell has attracted more and more attention because of its advantages of high energy conversion efficiency and low pollution.Proton exchange membrane is an important component of proton exchange membrane fuel cell.It has become an important research topic to develop proton conduction materials with high efficiency,stability and wide operating temperature range for proton exchange membrane.Because of its definite structure,the proton conduction pathway and mechanism of crystalline proton-conductive materials can be deeply discussed at the molecular level,and its research will help us work out design strategies for obtaining ideal proton conductors.In recent years,the research on the proton conduction performance of crystalline solid materials such as metal-organic frameworks（MOFs）/coordination polymers（CPs）,covalent organic frameworks（COFs）,hydrogen bond organic frameworks（HOFs）and polyoxometalates（POMs）is increasing.Through the discussion of their structure and function,the strategies guiding the design and optimization of proton conduction materials are constantly being proposed.Triazole,because of its amphoteric characteristics（acting as a proton donor and proton acceptor at the same time）,is considered an excellent proton transfer agent.However,the use of triazole in the design of solid proton conductors is currently limited.In this paper,we have synthesized four metal-triazole complexes with triazole as the ligand,and studied their proton conduction properties.The specific research content is as follows:1.Triazole-modified molybdenum oxides,[MoO₃（trz）_0.5]（1）and[H（atrz）]₄[（atrz）₂(γ-Mo₈O₂₆)]·2H₂O（2）were synthesized by hydrothermal synthesis and traditional solution synthetic method.Their proton conductivity was studied,and their conduction path and mechanism were discussed in combination with the structure.The proton conductivity of compounds 1 and 2 are 1.94×10^-2 S cm^-1（85℃,95%RH）and 1.3×10^-3 S cm^-1（65℃,95%RH）,respectively.It should be noted that the proton conductivity of compound 1 is obviously higher than those of mostly reported proton-conducting materials based on molybdenum oxides,which is comparable to those of mostly excellent proton conduction materials obtained so far.Moreover,the long-term stability test of proton conductivity showed that proton conduction properties of compounds 1 and 2 has good stability.2.Triazole-modified metal-organic frameworks[Zn_2.5（trz）₂（btc）（H₂O）]·2H₂O（3）and[Zn（Htrz）（Hbtc）（H₂O）]·2H₂O（4）were synthesized,and large size single crystal of compound4 suitable for the proton conductivity test of single crystal samples were cultured.And focusing on the study of single crystal proton conductivity of compound 4.The conductivity test of single crystal sample shows that the proton conduction of compound 4 is anisotropic.At 65℃,98%RH,the proton conductivities in the b axis and c axis directions are 2.51×10^-3S cm^-1 and 2.02×10^-3 S cm^-1,respectively.The conduction pathway and mechanism of compound 4 were discussed in combination with the results of single crystal structure and single crystal sample proton conduction tests.In addition,we summarized the studies on the proton conductivity of single crystal samples reported in the literature and make a preliminary analysis of their rules.At present,the conductivity test of crystal conductors is generally used in powder compressed samples,but the conductivity test research using single crystal samples is still lacking.We can truly realize the correlation between the structure（conduction path）and the proton conductivity（with anisotropic）,find out the key factors affecting proton conduction,and guide the design and optimization of materials by combining the conductivity measurement of the single crystal sample with the single crystal structure.