Composition-controlled synthesis of LixCo3−xO4 solid solution nanocrystals on carbon and their impact on electrocatalytic activity toward oxygen reduction reaction

摘要: Through incorporation of other metal elements like Li, K and Cu into the Co3O4 lattice, tuning electronic structures carbon-supported may be an effective way to improve electrochemical properties oxide as efficient catalyst for oxygen reduction reaction (ORR). In this paper, we have synthesized Li-doped (Li/Co = 0, 2.5%, 5%, 7.5%) solid solution nanocrystals through direct nucleation growth lithium-cobalt on a acid-treated carbon black. The supports LixCo3−xO4 spinel with average particle size approximately 4 nm, covered evenly surface in hybrid. electrocatalysis experiments alkaline reveal close correlation between ORR electrocatalytic activities doped Li contents these LixCo3−xO4/C catalysts. Interestingly, half-wave potential mass-specific activity catalysts show typical volcano plot function contents. Among all Co3−xO4/C samples, sample prepared at Li/Co atomic ratio 5% displays most positive largest respectively, which are 70 mV 3.3 times higher than undoped Co3O4/C. Compared that Co3O4/C, remarkly increased content covalent OC–O–CoIII–O bonds formed interfaces support is responsible improved electro-catalytic performances catalyst. Moreover, electron transfer from CoIII species electron-withdrawing OC–O can not only promote oxidation active sites CoIV but also facilitate hydroxide displacement, significantly contribute kinetics. Therefore, exact understanding unique interfacial hybrids very important develop oxides next-generation ORR.