Research On Carbon Nitride And Intercalation Compounds As A Direct Methanol Fuel Cell Anode Materials

With simple structure,high energy conversion coefficiency and being pollution-free,direct methanol fuel cell(DMFC)has,attracted many attention as a promising alternative for conventional power sources.The most important anodic catalyst for DMFC is platinum loaded on carbon support.However,platinum was easy to be poisoned by the intermediates produced during methanol electrooxidation,and the price of platinum is also very expensive,which limits the large-scale production and application of DMFC.Therefore,to find catalyst of highly catalytic activity and low prices is essential for DMFC.Carbon nitride,a new type material with special optical and electronic properties,is similar to carbon both in structure and properties.But researches on its electrochemical properties and application are quite rare.In this thesis,the structure,properties and synthesis of carbon nitride,and the fundamentals of DMFC,the progress of anodic catalysts and the mechanism for electrooxidation of methanol were summarized.And then,the electrochemical properties of both powder and nanotubes of carbon nitride was examined for non-noble metal catalyst and anodic catalyst support.Experiments showed that the graphite-like carbon nitride in sulfuric acid and the sulfuric acid containing methanol is very stable,they has no significant catalytic activity towards methanol electrooxidation.While graphite-like carbon nitride nanotubes in these systems is not stable and show somewhat catalytic activity towards methanol electrooxidation.The intercalated carbon nitrides with K⁺,Mg²⁺,Al³+,SO₄^2-and NO₃^2-as guest ions were also examined for catalyst and support for DMFC.The intercalated carbon nitrides were prepared by electrolysis of carbon nitride powder in the saturated solution of potassium sulfate,magnesium nitrate and aluminum sulfate.The intercalation degree can be precisely controlled by electrolysis for different intervals.By changing the intercalation degrees,the electron density within the layers and therefore the electron donation of the intercalation compounds were adjusted.The experiments showed that the intercalation compounds are not stable both in sulfuric acid and sulfuric acid containing methanol.This suggested that as the oxidation number of the intercalated ions increased, the stability of the intercalated samples became more unstable,important.The intercalated carbon nitride with Mg²⁺and Al³⁺have catalytic activity towards methanol electrooxidation.The influence of intercalation degree on the properties in complicated. The intercalated carbon nitride with SO₄^2-and NO₃^2-with ambiguous catalytic activity towards methanol can also activated the electrooxidation of carbon nitride.The catalytic activity increased with increasing intercalation degrees.