Preparation Of Transition Metal/Nonmetal Heteroatoms Co-Doped Nano-Carbon Materials And Their Electrocatalytic Properties

The rapid development of fuel cells is an ideal alternative to fossil energy.Compared with traditional heat engines,fuel cells are characterized by green cleaning,high conversion efficiency and sustainability.However,precious metal Pt-based catalysts are rare and expensive,which seriously hinders the large-scale commercialization of fuel cells.Some researchers have focused their research on non-Pt catalysts,so improving the activity and stability of non-Pt catalysts is a key issue in fuel cell industrialization.In order to synthesize low-cost and high-efficiency non-noble metal oxygen reduction catalysts,we prepare atomic-dispersed Zn,Co bimetallic sites confined in N,S co-doped dendritic carbon material catalysts?Zn,Co?/NSC and the double metal atomic siteof N,B co-doped carbon nanocage catalyst NiCo/NBC.The electrocatalytic activity and stability of the material were tested,and applied in Zinc-air batteries.The main research contents of the experiment are as follows:?1?The prepared?Zn,Co?/NSC catalyst has a unique dendritic structure,and the difference in electronegativity between Zn??=1.65?and Co??=1.88?makes the electronic structure of the two metal elements which results in a more optimized structure,making the bimetallic atomic sites have higher catalytic activity than the single metal atomic catalyst.Sulfurwith a larger atomic radius and lower electronegativity??=2.58?than N atoms can change the electronic structure and active center by forming a Zn/Co-N_x-C-S_y structure.The unique Zn/Co-N_x-C-S_y structure imparts rich defects and excellent oxygen reduction catalytic performance.The half-wave potential(E_1/2)in alkaline medium was 0.893 V,which was 67 mV higher than that of commercial Pt/C catalyst,and E_1/2/2 was also equivalent to Pt/C in an acidic electrolyte.The liquid Zinc-air battery based on the catalyst has a peak power density of 150 mW/cm².The solid state flexible Zinc-air battery based on this catalyst exhibits a higher voltage?1.5 V?and a power density?15 mW/cm²?.?2?N,B-codoped carbon nanocage NiCo/NBC catalysts with bimetallic atomic sites were prepared by coprecipitation-assisted chemical vapor deposition.The resulting NiCo/NBC catalyst has a unique carbon nanocage morphology that facilitates the diffusion of O₂ and the transport of ORR-related intermediates.Through comparative experiments,it was found that the synergistic effect of bimetallic Co and Ni can enhance the activity of oxygen reduction reaction.Doping of Boron??=2.04?facilitates further optimization of electronic structure and improves ORR activity.The NiCo/NBC catalyst exhibited higher ORR catalytic activity than the commercial Pt/C,and its half slope potential?0.882 V?was 56 mv higher than the commercial Pt/C?0.826 V?.The current retention rate after the 70000s stability test is still 88%,and the ability of methanol-resistance is excellent.