【摘要】 高度支化的树枝状铂(Pt)基纳米晶在氧还原催化反应(ORR)中具有很大的研究价值,但由于其较差的热稳定性和电化学稳定性而遇到性能瓶颈.本文提出了一种与传统一维(1D)纳米线构建的纳米枝晶(NDs)不同的Pt Fe纳米枝晶新结构.该结构主要由二维(2D)孪晶纳米片构建,并且通过适当热处理过程所形成的Pt表面形态打破了支状Pt基催化剂的活性上限.进一步将其与氨基功能化的离子液体(ILs)结合,在相对于可逆氢电极的0.9 V电位下,获得了Pt Fe基ORR电催化剂的超高质量活性(3.15 A/mgPt).在循环20,000个周期后,该催化剂呈现出可以忽略不计的活性衰减和结构变化,表现出对ORR电催化反应的卓越耐久性,与由纳米线构建而成的Pt Fe NDs形成了鲜明对比.这种优异的电催化性能是几种独特的结构特征共同导致的,主要包括2D形态、孪晶界面、部分有序结构以及与氨基的强配位.本研究强调了通过形貌调控和进一步的表界面调控获得稳定的电催化剂结构的重要性,最终实现了ORR电催化剂的性能突破.更多还原

【Abstract】 Highly-branched dendritic Pt-based nanocrystals possess great potential in catalyzing the oxygen reduction reaction(ORR),but encounter performance ceiling due to their poor thermal and electrochemical stability.Here,we present a novel Pt Fe nanodendrites(NDs) branched with two-dimensional(2 D)twinned nanoplates rather than conventional 1 D nanowires,which breaks the ORR performance ceiling of dendritic catalysts by inducing the unique Pt-skin configuration via rationally thermal treatment.By further hybridizing the Pt-skin Pt Fe NDs/C with amino-functionalized ionic liquids(ILs),we achieve an unprecedented mass activity of 3.15 A/mgPtat 0.9 V versus reversible hydrogen electrode(RHE) in the Pt Fe-based ORR electrocatalytic system.They also show excellent electrocatalytic durability for ORR with negligible activity decay and no apparent structural change after 20,000 cycles,in sharp contrast to the nanowires branched Pt Fe NDs counterpart.The remarkable catalytic performance is attributed to a combination of several structural features,including 2 D morphology,twin boundary,partially ordered phase and strong coordination with amino group.This work highlights the significance of stabilizing electrocatalytic structures via morphology tuning,which thus enables further surface and interface modification for performance breakthrough in ORR electrocatalysis.更多还原