Study On The Influence Of Gold Nanoparticles On The Electrochemical Performance Of Non-carbon-based Electrode Materials

Supercapacitors,as a new type of energy storage,have been paid much attention owing to fast discharge,long cycle life and high power density et al.Comparing to carbon materials,metal oxides and conducting polymers,as pseudocapacitor electrode materials,have attracted more researchers'eyes due to their high specific capacitance and energy density,however,cycle stability and high power character are poor caused by lower conductivity.In order to overcome the challenge,Au nanoparticles were used to dope and modify to metal oxides and conducting polyme rs in this paper.Meanwhile,influence and mechanism of Au nanoparticles on composite electrode structure,properties and electrochemical behaviror were investigated in detail.The main research contents are as follows:1.Gold nanoparticles/nickel oxides?AuNP/NiO?composites and gold nanopar-ticles/molybdenum dioxide/molybdenum nitride?AuNP/MoO₂/Mo₂N?composites were fabricated via thermal decomposition method.The influence of Au nanoparticles on crystalline grain size and morphology was studied and the effects and mechanism of Au nanoparticles size and amounts on composites electrochemical properties were investigated in detail.The results showed:HAuCl₄ could have an effect on crystalline grain size and morphology during the thermal process;as Au mass increasing,both Au nanoparticles size and electroactive materials grain size increased and could be aggregation at much more mass loading;with Au amount increasing,the specific capacitance of composites first increased and then decreased.Moreover,the charge transfer of composites electrode could decrease owing to Au nanoparticles introduction,improving kinetics of electrochemistry and then enhancing electrochem ical properties.The highest specific capacitance of AuNP/NiO composite reached 597 F g^-1 while the Au amount and size were 1.54%and 12 nm,respectively.The highest specific capacitance was achieved to 348 F g^-1 for AuNP/MoO₂/Mo₂N composite at the Au amount of 1.08%.2.Gold nanoparticles/cobalt oxide?AuNP/Co₃O₄?composites were synthesized via in-situ reduction method.The relationship between Au content and electrochemical behavior was studied in detail.As Au amounts increasing from 0.3%to 1.2%,the specific capacitance of composites first increased and then decreased.When Au amount was 0.9%and the size was about 15 nm,the highest specific capacitance of681 F g^-11 was reached.Au nanoparticles were introduced into Co₃O₄ materials,the charge transfer of composites electrode could be decreased and conductivity could be increased,enhancing electrochemical properties.3.Au nanoparticles/polyaniline?AuNP/PANI?composites were fabricated by physical blending method.We investigated the effects of structure,morphology,Au content and size on electrochemical performance in detail.1)As prolonging reaction time,the specific capacitance?SC?could increase firstly and then decrease,and the highest specific capacitance was 79 F g^-1.The AuNP@PANI yolk shell showed lower specific capacitance for the existing space between Au and PANI,affecting contact and charge transfer of them.2)The obtained AuNP@PANI core-shell material showed higher specific capacitance than AuNP@PANI yolk-shell material,because of good and close interface contact between Au and PANI.As reaction time prolonging,the specific capacitance appeared the trend of increasing firstly and then decreasing.In addition,the specific capacitance kept the same trend as AuNP@PANI core shell samples.The highest capacitance of 285 F g^-11 was reached for AuNP@PANI core shell with Au amount of 1.44%and Au size of ca.18.5 nm.3)Owing to Au introduction,the thermal stability was improved and charge transfer resistance decreased,enhancing electrochemical performance of as-prepared AuNP/PANI composite.And it exhibited the highest capacitance of 462 F g^-11 with Au amount of 1.64%and Au nanoparticles of about 20 nm.4)The obtained AuNP/PANI composites were prepared via co-oxide agents.As Au amount increasing,the specific capacitances increased firstly and then decreased and Au nanoparticles size also increased.It exhibited the highest capacitance of 392 F g^-11 with Au amount of 19.15%and Au nanoparticles size of 20 nm.Lower specific capacitance of 392 F g^-1 and higher Au amount of 19.15%were than above AuNP/PANI composite owing to PANI structure and strong oxidation of HAuCl₄,leading to high oxidation state of PANI.4.Gold nanoparticles/polyether sulfone/polyaniline?AuNP/PES/PANI?membrane were fabricated via in-situ reduction method to apply in the field of flexible supercapacitor.AuNP/PES/PANI membrane exhibited the highest capacitance of 446F g^-1 and better power rate ability than PES/PANI membrane(305 F g^-1).Owing to Au introduced into PES/PANI membrane,the resistance and charge transfer resistance were all decreased,enhancing electrochemical performance.In summary,electroactive electrode materials were decorated with Au nanopar-ticles via different methods to improve electrochemical performance;and the effects and mechanism of Au nanoparticles on electrochemical performance of Non-carbon-based electrode materials were investigated in detail.The improved electrochemical performance was owing to the contact of gold metal conductor and electroactive electrode materials semiconductor,that is to say,synergistic effects,to improve charge transfer and decrease resistance,enhancing kinetic characteristic and promote electrochemical performance.When Au nanoparticles size in the range of10²0 nm and content of 0.9%¹.7wt%,composites electrode materials showed best electrochemical performance.