Synthesis And Propeties Of Single Atom Catalysts Based On Carbon Quantum Dots

With the continuous depletion of fossil fuels and the increasingly prominent environmental issues,the exploration of renewable energy has become a hot research topic.At present,studies of new energy devices,such as fuel cells?FCs?and Dye-sensitized solar cells?DSSCs?,can help solve environmental pollution and energy problems.Among them,the common electrocatalysts used in FCs and DSSCs are the precious metal Pt and Pt base composite materials.However,the precious metal Pt is limited in reserves,high in price and poor in stability.Therefore,it is an urgent problem to find cheap and stable catalyst to replace Pt materials.Single-atom catalysts?SACs?have excellent catalytic activity,selectivity,and stability properties in electrocatalytic and other important catalytic reactions because of their unique structure and electronic properties.However,due to the high dispersion of single-atom surface energy and thermodynamic instability,the construction of stable SACs is one of the important challenges in the field of catalysis.In this paper,non-precious metal monatomic catalyst was prepared by using Carbon quantum dots?CQDs?as the support and strong metal-support interactions,and applied in fuel cells and Dye-sensitized solar cells.The specific research results are as follows:?1?Using CQDs as support materials,metal iron was loaded according to the fluorescence quenching effect,and single atomic iron catalysts were successfully prepared and applied to the cathodic oxygen reduction reaction?ORR?of the fuel cell.The spherical aberration-corrected high-resolution transmission electron microscope study showed that in the single atomic iron catalysts we prepared,metallic iron was uniformly distributed on the surface of the support as a single atom.Inductively coupled plasma emission spectroscopy?ICP?tests the iron content at about 1.52 wt%.ORR results showed that the initial potential and cathodic current potential of the single atomic iron catalyst were 0.92 V?vs RHE?and0.83 V?vs RHE?,respectively,and the current density reached-5.43 mA?cm^-22 at 0.4 V?vs RHE?.The number was 3.96 and the H₂O₂ yield was 2.17%,which was comparable to commercial Pt/C,and had good stability?the half-wave potential dropped only 3 m V after5000 cycles?and resistance to methanol.?2?This paper further studies the catalytic performance of different metals with carbon quantum dots as support load Co metal ions.Therefore,CQDs-cobalt composite catalyst?CQDs-salt-Co-acid?was prepared and used as DSSCs electrode to study the catalytic activity for iodine reduction reaction.The ICP test Co doping amount is about 2.77 wt%.Experimental tests show that the photoelectric efficiency of the CQDs-salt-Co-acid catalyst is7.78%,which is equivalent to 8.04%of the Pt electrode,and the peak potential difference E_pp=260 mV is smaller than that of the Pt electrode,showing excellent DSSCs catalytic performance.The experimental results show that the supported catalyst with carbon quantum dots has excellent electrocatalytic activity.