ITO负载内凹AuPd合金纳米粒子形状的电化学调控

Electrochemically shape-controlled formation of concave AuPd alloy nanoparticles on ITO substrate

运用电化学方波电位法,在氧化铟锡(ITO)透明导电膜玻璃基底上实现AuPd纳米粒子的形状控制合成.当固定方波下限电位0.30 V,上限电位分别为0.64和0.70 V时,分别制备出内凹三八面体(TOH)和内凹六八面体(HOH)AuPd合金纳米粒子.运用扫描电镜(SEM)、X射线能量散射谱(EDX)和电化学循环伏安法表征所制备的纳米粒子,结果表明所制备的AuPd纳米粒子在ITO上分散均匀,具有清晰的内凹三八面体和内凹六八面体的形状,Au:Pd元素比均接近3:1.但由于Au比Pd的表面自由能低,导致Au在AuPd合金纳米粒子表面富集.发现从合成的TOH AuPd合金纳米粒子出发,对其施加下限电位0.30 V、上限电位0.70 V的方波电位处理,可实现由TOH向HOH形状转变;延长方波电位处理时间仅改变AuPd合金纳米粒子的尺寸,但HOH形状保持不变.

Shape-control of AuPd alloy nanoparticles （AuPd NPs） substrated on indium-tin oxide （ITO） was successfully achieved, for the first time, by using electrochemical square-wave-potential （SWP） method. Concave trisoctahedral AuPd alloy NPs （TOH AuPd NPs） and concave hexoctahedral AuPd alloy NPs （HOH AuPd NPs） were prepared under SWP conditions with lower potential of 0.3 V while different upper potentials of 0.64 and 0.70 V, respectively. Different techniques including SEM, EDX and electrochemical cyclic voltammetry were employed to characterize the morphology and composition of AuPd alloy NPs. The results demonstrated that the as-prepared TOH AuPd NPs and HOH AuPd NPs are uniform in shape of correspondingly concave TOH and concave HOH, and are well dispersed on the ITO substrate. The composition in terms of and Au：Pd atomic ratio of both TOH and HOH AuPd alloy NPs is determined by EDX around 3：1. However, a surface enrichment of Au on the AuPd NPs was observed, and is ascribed to the lower surface energy of Au in comparison with that of Pd. It has been found that, starting from the as-synthesized TOH AuPd NPs, shape transformation from TOH to HOH can be accomplished by applying a treatment of square wave with lower potential of 0.3 V and upper potential of 0.7 V. Prolonging the treatment time results in increasing the size of AuPd NPs, while the HOH shape is preserved.