Structural Regulation And Performance Research Of PPS-based Carbon Nanocatalysts For Energy Conversio

Fuel cells,metal-air batteries and electrocatalytic hydrogen production from water splitting are considered as the most promising technologies for future energy storage and conversion.However,constructing high efficiency,more stable and low-cost multi-functional electrocatalysts for oxygen reduction reaction（ORR）,oxygen evolution reaction（OER）and hydrogen evolution reaction（HER）is a prerequisite,which can promote the industrial application of energy conversion technologies.Carbon nanomaterials have the advantages of high conductivity,low-cost,good stability,large specific surface area and adjustable structure,and show broad application prospects in the field of electrocatalysis.Based on these,a series of PPS-based carbon nanocatalysts with different structures and different transition metal loadings were constructed in this paper,which used polyphenylene sulfide（PPS）as the S-containing carbon source,using techniques such as self-propagating high-temperature synthesis,targeted oxidation modification,thermally induced phase separation,gas ion migration and high-temperature pyrolysis.At the same time,we deeply analyzed the structure-effect relationships between the interfaces,components and structures of these catalysts and their efficient electrocatalytic activities.The main research contents were as follows:（1）Based on the self-propagating high-temperature synthesis technology,topologically defect-rich hollow carbon nanoboxes（S-CNBs）were constructed using PPS resin as the S-containing carbon source.Then,the Co nanocluster loaded topologically defect-rich hollow carbon nanoboxes（Co-N/S-CNBs）were prepared by impregnating metal ionic salts at the room temperature and pyrolyzed by high-temperature technology.Co-N/S-CNBs showed the excellent ORR and OER bifunctional catalytic activity,with a half-wave potential of 0.89 V for ORR and an overpotential of 347 m V for OER at a current density of 10 m A cm^-2.In addition,the peak power density and specific capacity of the Zn-air battery driven by Co-N/S-CNBs reached 194.8 m W cm^-2 and 715 m Ah g _Zn^-1,respectively.（2）Based on the oxidative modification technology,PPSO fibers without melting shrinkage properties at high temperature were constructed using PPS fibers as the substrate.Subsequently,PPSO fibers were transformed into honeycomb-like porous carbon（S-HPC）using KOH activation method,and then honeycomb-like porous carbon with ultrahigh specific surface area embedded with Fe-based core-shell structure compounds（Fe-N/S-HPC）was prepared by impregnating metal ionic salts and secondary pyrolysis.Fe-N/S-HPC has a specific surface area as high as 2223.31 m² g^-1and shows the excellent bifunctional catalytic activity for both ORR and OER,with a half-wave potential of 0.85 V for ORR and an overpotential of 339 m V for OER at a current density of 10 m A cm^-2.The peak power density and specific capacity of the Zn-air battery assembled with Fe-N/S-HPC reached 188.4 m W cm^-2 and 688 m Ah g _Zn^-1,respectively.（3）Based on the targeted oxidation modification technology,the skin structure of PPS fibers was targeted and regulated by the skin controlled oxidation method.The skin-core structure composite fiber（OPPS）was constructed with the core layer still being PPS and the skin layer being an oxidation-resistant acid component,followed by controlled dissolution of the core PPS composition of OPPS fibers using strong oxidizing acid to obtain PPS-based hollow fibers.Finally,PPS-based hollow carbon fibers（Ni-NS-HCFs）loaded with Ni nanoparticles were prepared by combining metal ionic salts immersion and high-temperature pyrolysis technology.By a similar strategy,PPS-based flexible hollow carbon cloth loaded with Ni nanoparticles（Ni-NS-HCC）was prepared by PPS needle felts as the substrate.Ni-NS-HCFs exhibited the excellent ORR performance with a half-wave potential of 0.887 V.The peak power density and specific capacity of the Zn-air battery driven by Ni-NS-HCFs reached 163.1 m W cm^-2and 730 m Ah g _Zn^-1.Ni-NS-HCC showed the excellent HER performance with overpotentials of 87.8 and 205 m V at current densities of 10 and 100 m A cm^-2,respectively.（4）Based on the thermally induced phase separation technology,PPS flat membranes with mutually cross-linked pore structures（P-PPS-M）were constructed by PPS resin as the S-containing carbon source.Subsequently,the melting shrinkage of P-PPS-M at high temperatures was solved by using the above oxidative modification technology,and finally Cu atom-anchored defect-rich porous carbon（Cu-N-SC-1100）was prepared by combining strong Lewis acid-base interactions,gas ion migration and high-temperature pyrolysis technology.Cu-N-SC-1100 exhibited the excellent ORR,OER and HER trifunctional catalytic activity,with a half-wave potential of 0.89 V for ORR,and the overpotentials for OER and HER at a current density of 10 m A cm^-2 are 330and 125.4 m V,respectively.The high power density of Zn-air battery driven by Fe-N/S-HPC was 197.9 m W cm^-2 and the specific capacity was up to 732 m Ah g _Zn^-1.When Cu-N-SC-1100 was used as the catalyst for the cathode and anode of the electrolytic water device,the potential is only 1.64 V when the current density is 10 m A cm^-2.