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Mesoporous carbon aerogel supported PtCu bimetallic nanoparticles via supercritical deposition and their dealloying and electrocatalytic behaviour
Catalysis Today ( IF 5.3 ) Pub Date : 2017-09-13 , DOI: 10.1016/j.cattod.2017.09.023
Sansim Bengisu Barim , Selmi Erim Bozbag , Haibo Yu , Rıza Kızılel , Mark Aindow , Can Erkey

Mesoporous carbon aerogel (CA) supported PtCu bimetallic nanoparticles were prepared via a sequential supercritical deposition (SCD) method using supercritical carbon dioxide (scCO2). The effects of deposition order of the metal, annealing temperature and metal composition on the average PtCu particle size, size distribution and dispersion were investigated. Four sets of PtCu/CA samples were prepared with two Pt:Cu molar ratios (1:1 and 1:3) and with two different deposition orders (i.e. either Pt or Cu first). X-ray diffraction and electron microscopy data showed that all of the as-prepared samples formed homogeneously distributed disordered PtCu alloy nanoparticles with narrow particle size distributions on the CA support. Increasing annealing temperature in the range 600–950 °C increased the average particle size from 1.8 nm to 4.5 nm and resulted in the elimination of separate Cu nanoparticles on the CA surface. The dealloying of the supported PtCu nanoparticles were carried out by cyclic voltammetry and the activity of the dealloyed nanoparticles (after 300 potential cycles) towards the oxygen reduction reaction (ORR) was investigated using rotating disc electrode (RDE) experiments. During dealloying, peaks associated with bulk dissolution and deposition of Cu and dissolution and re-deposition of Cu from the alloyed PtCu nanoparticles were observed at initial cycles along with peaks associated with creation of new Pt sites. Supported nanoparticles with Pt:Cu molar ratios of 1:1 and 1:3 which were prepared by deposition of Cu first had low activities towards ORR after dealloying. On the contrary, nanoparticles prepared by depositing Pt first exhibited promising electrocatalytic activities after dealloying. Samples with a Pt:Cu molar ratio of 1:3 showed higher activities than those with a molar ratio of 1:1. An enhanced ESA of 137 m2/g and dealloying induced enhanced mass activity of 0.123 A/mgPt was obtained using the sample with a Pt:Cu molar ratio of 1:3, which was annealed at 800 °C. On the other hand, the same sample annealed at 950 °C had the highest specific activity of 0.165 mA/cm2.



中文翻译:

介孔碳气凝胶通过超临界沉积及其负载脱金属和电催化行为负载PtCu双金属纳米颗粒

介孔碳气凝胶(CA)负载的PtCu双金属纳米颗粒是通过使用超临界二氧化碳(scCO 2)。研究了金属的沉积顺序,退火温度和金属组成对PtCu平均粒径,粒径分布和分散度的影响。用两种Pt:Cu摩尔比(1:1和1:3)和两种不同的沉积顺序(即Pt或Cu首先)制备了四组PtCu / CA样品。X射线衍射和电子显微镜数据表明,所有制备的样品在CA载体上均形成具有窄粒度分布的均匀分布的无序PtCu合金纳米颗粒。将退火温度提高到600–950°C范围内,可使平均粒径从1.8 nm增加到4.5 nm,并消除了CA表面上单独的Cu纳米颗粒。通过循环伏安法进行负载的PtCu纳米粒子的脱合金,并使用旋转盘电极(RDE)实验研究了脱合金的纳米粒子(在300个电位循环后)对氧还原反应(ORR)的活性。在脱合金过程中,在初始循环中观察到与合金的PtCu纳米粒子的大量溶解和沉积以及铜的溶解和再沉积相关的峰,以及与新的Pt位点产生相关的峰。首先通过沉积Cu制备的Pt:Cu摩尔比为1:1和1:3的负载型纳米颗粒在脱合金后对ORR的活性较低。相反,通过沉积Pt制备的纳米颗粒在脱合金后首先表现出有希望的电催化活性。Pt:Cu摩尔比为1:的样品 3显示出比具有1:1摩尔比的那些更高的活性。增强的ESA达137 mPt:Cu摩尔比为1:3的样品在800°C退火后,获得了2 / g的脱合金诱导的质量活性为0.123 A / mg Pt。另一方面,在950℃下退火的相同样品的最高比活度为0.165mA / cm 2

更新日期:2017-09-13
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