Preparation And Electrocatalytic Performance Of Biomass-Derived Carbon Materials

As technology advances and environmental pollution increases,our demand for green and sustainable energy is increasing.Technologies such as metal-air batteries and fuel cells that can directly convert chemical energy into electrical and thermal energy have attracted people’s attention.The oxygen reduction reaction(ORR)and oxygen evolution reaction(OER),which are the core reactions of these clean energy technologies,have attracted people’s attention and exploration.At present,the widely used electrocatalysts are generally noble metal platinum-based electrocatalysts and iridium oxide electrocatalysts.Although the catalytic activity is excellent,but precious metals are very scarce and expensive,and the electrochemical reaction kinetics of these catalysts are slow.Therefore,we urgently need to prepare cheap,high-performance and fast reaction kinetics of electrocatalysts.As one of the main sources of carbon,biomass has the advantages of many types,wide sources,large output,and low price,but most of the biomass has to be effectively used but causes environmental pollution.Based on the above reasons,we used biomass kelp and sodium alginate as carbon carriers to synthesize two new electrocatalysts in a simple method for ORR and zinc-air batteries,respectively.It provides new ideas for the resource utilization of biomass,alleviating environmental pollution and designing highly active electrocatalysts.(1)The development of high-performance non-precious metal oxygen reduction electrocatalysts is of great significance to the application of fuel cell and other energy technologies.Here,we used seaweed biomass kelp as the carbon precursor and successfully synthesized a highly active nitrogen-doped kelp-based carbon material(NKC)as an oxygen reduction electrocatalyst by a simple hydrothermal-impregnation-pyrolysis method.The material has a good pore structure,a large specific surface area(1208.44 m2 g-1)and a high nitrogen content(8.13%),Compared with the precious metal Pt-based catalyst,the material NKC has better catalytic activity(half wave potential 0.84 V)and better stability.Therefore,this research work provides a new path for the development of cheap,highly active biomass-derived nitrogen-doped porous carbon nanomaterials for ORR electrocatalysis.(2)Here we select sodium alginate,an extract of algal biomass,as a carbon precursor,and embed bimetallic alloy particles into a nitrogen-doped porous carbon material.The highly active bifunctional electrocatalyst(NFeCo-SACA-PPy)was successfully prepared and used in rechargeable zinc-air batteries.Compared with the precious metal Pt-based catalyst,the material NFeCo-SACA-PPy has an excellent starting(vs.RHE 1.00 V)and half wave potential(vs.RHE 0.85 V).In addition,the liquid zinc-air battery with NFeCo-SACA-PPy as the air electrode showed better discharge and charging performance,greater power density(109.6 mW cm-2)and higher cycle stability.Therefore,this study provides a new design idea for the preparation of zinc-air battery bifunctional electrocatalyst using biomass as a carbon precursor.