Efficiently utilizing ammonia(carbon-free fuel)via low-temperature fuel cells is severely hindered by the sluggish kinetics of ammonia oxidation reaction(AOR).Herein,platinum-iridium-tungsten nanocubes(PtIrW-NCBs)with...Efficiently utilizing ammonia(carbon-free fuel)via low-temperature fuel cells is severely hindered by the sluggish kinetics of ammonia oxidation reaction(AOR).Herein,platinum-iridium-tungsten nanocubes(PtIrW-NCBs)with exposed{100}-rich facets were synthesized by a glucose-assisted solvent-thermal method,in which alloying W not only can facilitate the formation of such specific nanostructures to expose more active sites for AOR,but also modulate the electronic structure of PtIr to promote the kinetics of AOR.The PtIrW-NCBs featuring the small nanoparticle size of 5.05±0.07 nm exhibit superior AOR performance,wherein the onset potential is down to 0.319 V and the mass activity is 30.15 A g_((PGM=Pt,Ir))^(-1)at 0.50 V vs.RHE,significantly higher than those of reported majority of AOR catalysts and even commercial PtIr/C.Meanwhile,in situ Fourier transform infrared spectroscopy measurement further reveals that AOR on PtIrW-NCBs dominantly undergoes the dimerization path of NH_(x)(1≤x≤2).In addition,the theoretical calculations also identify that alloying W into PtIr can contribute additional electrons to 5d orbitals of PtIr,enabling the d-band center approaching the Femi level,which in turn induces the high-filling of bonding orbitals of N-N bond in^(*)N_(2)H_(4),promoting the dimerization of^(*)NH_(2)to^(*)N_(2)H_(4)and thus leading to high AOR activity of PtIrW.This work provides new insights for designing efficient AOR electrocatalysts.展开更多
基金supported by the National Natural Science Foundation of China(22379031)the Guangxi Science and Technology Project of China(AB16380030)+1 种基金the National Research Foundation,SingaporeA*STAR(Agency for Science,Technology and Research)under its LCER Phase 2 Programme Hydrogen&Emerging Technologies FI,Directed Hydrogen Programme(U2305D4003)。
文摘Efficiently utilizing ammonia(carbon-free fuel)via low-temperature fuel cells is severely hindered by the sluggish kinetics of ammonia oxidation reaction(AOR).Herein,platinum-iridium-tungsten nanocubes(PtIrW-NCBs)with exposed{100}-rich facets were synthesized by a glucose-assisted solvent-thermal method,in which alloying W not only can facilitate the formation of such specific nanostructures to expose more active sites for AOR,but also modulate the electronic structure of PtIr to promote the kinetics of AOR.The PtIrW-NCBs featuring the small nanoparticle size of 5.05±0.07 nm exhibit superior AOR performance,wherein the onset potential is down to 0.319 V and the mass activity is 30.15 A g_((PGM=Pt,Ir))^(-1)at 0.50 V vs.RHE,significantly higher than those of reported majority of AOR catalysts and even commercial PtIr/C.Meanwhile,in situ Fourier transform infrared spectroscopy measurement further reveals that AOR on PtIrW-NCBs dominantly undergoes the dimerization path of NH_(x)(1≤x≤2).In addition,the theoretical calculations also identify that alloying W into PtIr can contribute additional electrons to 5d orbitals of PtIr,enabling the d-band center approaching the Femi level,which in turn induces the high-filling of bonding orbitals of N-N bond in^(*)N_(2)H_(4),promoting the dimerization of^(*)NH_(2)to^(*)N_(2)H_(4)and thus leading to high AOR activity of PtIrW.This work provides new insights for designing efficient AOR electrocatalysts.
