Preparation Of Biomass-Based Carbon Materials And Its Application In Fuel Cells Applied Research

With the increasing demand for electricity,unstable rising oil prices and increasingly serious environmental problems,the development of renewable energy has become a social consensus.Fuel cell is one of the most promising environmentally friendly energy conversion technologies due to its wide range of applications,high efficiency,environmental friendliness and non-pollution.High cost and low efficiency cathode catalysts and slow oxygen reduction（ORR）are still the main bottlenecks in the practical application of direct glucose alkaline fuel cells（DGAFCs）.Heteroatom doped activated carbon has become a research hotspot because of its good electrocatalytic activity for oxygen reduction.However,it still needs to further reduce its preparation cost and improve its efficiency.Herein,sponge-like porous carbons fortified with transition metal,nitrogen,and phosphorus（denoted by M-N-PKCC）were synthesized for the first time from highly available algal biomass of chlorella.The results showed that all the M（Fe,Co,Cu）-N-PKCC catalysts exhibited excellent electrocatalytic performance for ORR.Especially,Fe-N-PKCC obtained a half wave potential of 0.852 V（vs RHE）and a limiting current density of 4.4 mA?cm^-2,which are comparable to those of commercial 10%Pt/C catalyst(E_1/2=0.815 V,J_d=4.4 mA?cm^-2).In addition,Fe-N-PKCC presents outstanding long-term stability and methanol resistance.A simple direct glucose fuel cell was assembled to further evaluate the catalytic ability of Fe-N-PKCC.The fuel cell equipped with a Fe-N-PKCC cathode achieved a peak power density of 30.53±1.69W?m^-2 under ambient condition,which is superior to that with a 10%Pt/C cathode.This investigation provides a readily achievable route based on function-oriented fortification towards development of cost efficient ORR catalysts for DGAFCs.Nitrogen-doped porous carbon was obtained from Enteromorpha prolifera,Chlorella vulgaris and Kelp by H₃PO₄-KOH activation.The results showed that the specific surface area of Enteromorpha proliferated activated carbon（PKEC）reach to2709.84 m²?g^-1,and showed better catalytic capacity for oxygen reduction.Cobalt phthalocyanin（CoPc）was used as cobalt source to prepare multi-doped Co-PKEC catalysts.CV and LSV characterization showed that the ORR catalytic activity in alkaline condition was comparable to that in commercial 10%Pt/C.According to K-L,the transfer electron transfer number of Co-PKEC in alkaline medium is calculated to be 4.2-4.7,which indicates that the oxygen reduction process occurring on the surface of Co-PKEC electrode is an efficient 4e^-electrochemical reduction.In the direct alkaline glucose fuel cell test,the maximum current density is 96.53 A?m^-2,and the maximum power density is 33.12±1.35 W?m^-2.In this study,heteroatom-doped activated carbon was synthesized from algae biomass with low cost and rapid growth.It has excellent ORR catalytic activity,stability and methanol tolerance.Algal biomass,such as Chlorella and Enteromorpha proliferata,is an ideal precursor for the preparation of heteroatom-doped activated carbon because of its wide distribution,rapid growth,high CO₂ fixation efficiency,rich protein and strong ion exchange capacity.Compared with the existing platinum noble metal ORR catalysts,heteroatom-doped algae biomass carbon catalysts have a wide range of sources and low cost,and have potential for wide-scale application.