Fabrication Of N-doped Carbon Materials Based On Carbonized Bacterial Cellulose And Their Application In Catalyzing ORR

Since the beginning of the new century,traditional fossil energy has promoted the rapid development of human society,however it also brings great pollution to our environment.Moreover,the resources of fossil energy are limited and depleted,so the development of new energy systems that are renewable,safe and environmentally friendly is of importantance.Among various new energy systems,fuel cells are considered to possess broad prospects of development,owing to its excellent properties such as high energy efficiency,strong overload capacity,long operation life and environmental friendliness.However,the kinetic process of its key cathodic oxygen reduction reaction(ORR)is sluggish,which is one of the main factors hindering the large-scale application of fuel cells,therefore,it is necessary to introduce ORR catalysts with highly activity to solve the above problems.Nowadays,Pt-based catalysts are considered to be most efficient in catalyzing ORR.Unfortunately,the scarcity and unaffordable cost of Pt-based catalysts prevent the large-scale commercialization of fuel cells.Hence,using catalysts with high catalytic efficient and acceptable cost to replace expensive Pt-based catalysts are urgent for the large-scale application of fuel cells.Among the potential substitutes for Pt-based ORR catalysts,N-doped carbon materials have attracted the attention of researchers,owing to its advantages such as high catalytic activity,outstanding operation stability and methanol tolerance,low cost and environmental friendliness.As biomass carbon materials,Carbonized bacterials cellulose(CBC)are considered to be suitable for electrochemical energy stroge.Thus,two kinds of of N-doped porous carbon materials with different morphologies were prepared by using carbonized bacterial cellulose(CBC)as template,and the catalytic activity of the N-doped porous carbon materials were studied.The details are as follows:1.Nitrogen-Doped Carbon Nanofibers Network Derived from Bacterial Cellulose for the Oxygen Reduction ReactionIn this work,we successfully fabricated a superior N-doped carbon ORR electrocatalyst with the low-cost and eco-friendly biomass materials of BC and urea.Urea molecules are closely wrapped around BC nanofibers through hydrothermal process with the assistance of hydroxyl groups from BC.Finaly,the N-doped CBC carbon materials was prepared by pyrolyzing the above BC and Urea composite.During the preparation process,BC is not only act as the substrate coated with urea,but also precursor of the 3D nano-conducting networks in the pyrolysis product.And urea is converted into N-doped active sites anchored onto the surface of CBC nanofibers.We firstly investigated the specific surface area,conductivity and the N dopants of as prepared samples obtained under different pyrolyzation temperatures.The ORR catalytic activity was studied by electrochemical measurements,and the results showed that the as-prepared N-doped carbon electrocatalyst exhibits superb catalytic activity,and better durability and methanol tolerance in comparison with commercial Pt/C catalysts.The comprehensive analysis shows that the ORR catalytic activity of N-doped CBC can be attributed to the excellent structural characteristics of CBC and catalytic active sites provided by N dopants.2.Bacterial cellulose/ZIF-8 derived N-doped porous carbon for oxygen reduction reaction.In this work,we report a new strategy to prepare 1D MOFs-derived porous carbon by carbonizing BC@ZIF-8 composites.Firstly,BC@ZIF-8 was prepared by in situ crystallization of ZIF-8 crystals on the surface of BC nanofibers.Then,the porous N-doped carbon was obtained by pyrolyzing BC@ZIF-8 under Ar atmosphere.We subsequently investigate the microstructure and N dopants of the as-prepared materials.And the electrochemical tests reveal that,N-doped porous carbon catalyst exhibits excellent ORR catalytic activity,closing to that of commercial Pt/C electrocatalysts,and it also exhibits much better durability and methanol tolerance.