Preparation And Electrocatalytic Performance Of Transition Metal Oxygen(Phosphorus)/Nitrogen Doped Carbon Composites

Much attention has been put to develop efficient clean energy conversion technologies due to growing demand for clean energy.In particular,hydrogen,as one of the cleanest energy sources,has received worldwide attention.At the same time,fuel cells have become a hot research topic because of their high efficiency,high specific energy density,environmental protection and low pollution.However,the cathode oxygen reduction reaction?ORR?of the fuel cell,the electrolysis hydrogen evolution reaction?HER?and the oxygen evolution reaction?OER?have high overpotentials and slow kinetic rates,which becomes an obstacle to the development of related technologies.Therefore,the development of cheap,efficient,and stable catalysts is the core technology to promote the development of the corresponding technology.Based on the above research background,this paper aims at development non-precious metal catalysts that are cheap,efficient and stable,and the following studies were carried out:?1?A series composite catalysts of mixed metal phosphide and nitrogen-doped carbon material CoP/Fe₂P/NC were prepared by using CoCl₂ and FeCl₃ as the metal source,2-aminoterephthalic acid and 2-methylimidazole as the C/N source.The as-prepared catalysts exhibited high OER and HER bifunctional catalytic activities.When the optimized sample was used as catalyst,it obtained the lowest overpotential of 350mV?j=10 mA/cm²?and a Tafel slope of 46 mV/dec for OER in 0.1 M KOH,which is superior to commercial RuO₂.The catalyst also obtained the lowest overpotential of173 mV?j=10 mA/cm²?and a Tafel slope of 64 mV/dec for HER in 0.5 M H₂SO₄.This catalyst is competitive in the list of analogous catalysts reported for HER.Moreover,the catalyst exhibited long-term durability for both OER and HER.?2?Fe₂O₃/nitrogen-doped carbon composite catalysts were prepared by pyrolyzing the mixture of the complex of 2-aminoterephthalic acid with FeCl₃ and glycylglycine.The as-prepared catalysts exhibited high OER and ORR bifunctional catalytic activities.When the optimized sample was used as catalyst,it obtained the lowest overpotential of 278 mV?j=10 mA/cm²?for OER in 0.1 M KOH,which is 97 mV lower than commercial RuO₂.The catalyst also obtained a oneset potential and half-wave potential of 0.962 V and 0.847 V for ORR in 0.1 M KOH,which was 11 mV and 7 mV positive than the commercial Pt/C?20%?.The catalyst also exhibited high stabilities in both OER and ORR.?3?Co₂P/Fe₂P/N-doped carbon composite catalysts were prepared by using FeCl₃and CoCl₂ as metal sources and 2-aminoterephthalic acid as C/N sources.The as-prepared catalysts exhibited high HER and OER bifunctional catalytic activities.When the optimized sample was used as catalyst,it obtained an overpotential of 152 mV?j=10mA/cm²?and a Tafel slope of 60 mV/dec for HER in 0.5 M H₂SO₄.The catalyst also obtained an overpotential of 340 mV?j=10 mA/cm²?for OER in 0.1 M KOH,which is 35 mV lower than commercial RuO₂.This catalyst is competitive in the list of analogous catalysts reported for HER and OER.Moreover,the catalyst exhibited long-term durability for both HER and OER.