Ni-B非晶态合金纳米粒子的制备及电催化性能
发布时间：2018-08-06 21:08
【摘要】：直接甲醇燃料电池(DMFC)以其高能源效率和环境友好的优点,在迫切需求清洁能源的今天,成为了一个很有吸引力的选择。为了提高DMFC的性能,高活性的电催化剂显得十分重要。随着自然资源的逐渐枯竭,尤其是罕见的金属如铂、钯等,研究开发高效、廉价的催化剂已经成为了这一领域的焦点。 非晶态材料具有短程无序,长程有序的特殊结构,其高浓度的配位不饱和位点导致其优良的催化活性与选择性,可以很容易的进行反应。纳米材料具有大的比表面积,高表面活性中心密度与表面能,将非晶态与纳米结合在一起,可以导致更高的电化学容量和更强的电化学活性,可以作为提高催化剂电催化活性的有效手段。 在这篇论文中,通过化学还原法合成了不同Ni/B原子比的非晶态Ni-B合金纳米颗粒,采用HRTEM、SAED、XRD、DSC、XPS等手段对其进行表征。采用循环伏安法对非晶态合金纳米粒子的电化学性能进行测试。 物理表征结果表明：经过XRD检测,Ni-B合金未发现晶态金属的特征峰,通过SAED和HRTEM可以确定合金具有非晶态的长程无序、短程有序的结构特点,观察到制备的非晶态Ni-B合金纳米粒子为球形或者类球形,平均粒径为4-7纳米,团聚现象不明显。DSC的测试结果表明,非晶态Ni-B合金纳米颗粒最早在342.8℃处出现放热峰,随着Ni-B合金中B原子比例的增加,合金的放热峰的峰温先增大后减小,其中Ni1B4开始晶化的温度最高,说明其非晶态结构较其他催化剂有更好的热稳定性,较难晶化为金属Ni与B元素。XPS分析的结果表明,非晶态Ni-B合金中,B失去部分电子,而Ni则富余电子,Ni-B之间具有电子效应。颗粒表面Ni原子浓度随合金中B比例的增大先减小后增大,其中,Ni1B3的浓度最小。而氧化态镍的原子浓度也随合金中B比例的增加变化不明显。随反应物中Ni浓度的增加,氧化态Ni的浓度逐渐减小,而Ni原子的浓度则逐渐增大。 应用循环伏安法首次研究了碱性介质中非晶态Ni-B合金纳米颗粒对甲醇的电催化反应。结果表明,非晶态Ni-B合金纳米颗粒对甲醇有着较高的电催化氧化活性。对Ni-B非晶态合金纳米合金的对不同甲醇浓度的NaOH溶液中循环伏安曲线的分析,发现随甲醇浓度愈大,氧化峰电流密度也随之越大。随着非晶态合金中B含量的增加,其电催化氧化甲醇的能力先减弱后增强,其中,Ni1B4的氧化能力最弱。随反应物中Ni浓度的增加,非晶态Ni1B2纳米合金的电催化甲醇的性能逐渐增加。通过对催化剂进行50次扫描,非晶态合金的峰电流密度下降比例为26.8%。对比非晶态Ni1B4与晶态Ni1B4对甲醇的电催化氧化发现,非晶态合金具有较低的起始电位与峰电位,但是其氧化峰电流密度却低于晶态合金。
[Abstract]:Direct methanol fuel cell (DMFC) has become an attractive choice because of its advantages of high energy efficiency and environmental friendliness. In order to improve the performance of DMFC, high activity electrocatalyst is very important. With the gradual depletion of natural resources, especially rare metals such as platinum, palladium, research and development of efficient, cheap catalysts have become the focus of this field. The amorphous material has a special structure of short range disorder and long order. Its high concentration of coordination unsaturated site leads to its excellent catalytic activity and selectivity, so it can be easily reacted. Nanomaterials have large specific surface area, high surface active center density and surface energy, combine amorphous state with nanometer, can lead to higher electrochemical capacity and stronger electrochemical activity. It can be used as an effective means to improve the electrocatalytic activity of the catalyst. In this paper, amorphous Ni-B alloy nanoparticles with different Ni/B atomic ratios were synthesized by chemical reduction method. The electrochemical properties of amorphous alloy nanoparticles were measured by cyclic voltammetry. The results of physical characterization show that there is no characteristic peak of crystalline metal in Ni-B alloy by XRD. The structural characteristics of amorphous long range disorder and short range order can be determined by SAED and HRTEM. It was observed that the amorphous Ni-B alloy nanoparticles were spherical or spherical, with an average particle size of 4-7 nanometers. The agglomeration phenomenon was not obvious. The results showed that the exothermic peak of amorphous Ni-B alloy nanoparticles appeared at 342.8 鈩，
本文编号：2168993
[Abstract]:Direct methanol fuel cell (DMFC) has become an attractive choice because of its advantages of high energy efficiency and environmental friendliness. In order to improve the performance of DMFC, high activity electrocatalyst is very important. With the gradual depletion of natural resources, especially rare metals such as platinum, palladium, research and development of efficient, cheap catalysts have become the focus of this field. The amorphous material has a special structure of short range disorder and long order. Its high concentration of coordination unsaturated site leads to its excellent catalytic activity and selectivity, so it can be easily reacted. Nanomaterials have large specific surface area, high surface active center density and surface energy, combine amorphous state with nanometer, can lead to higher electrochemical capacity and stronger electrochemical activity. It can be used as an effective means to improve the electrocatalytic activity of the catalyst. In this paper, amorphous Ni-B alloy nanoparticles with different Ni/B atomic ratios were synthesized by chemical reduction method. The electrochemical properties of amorphous alloy nanoparticles were measured by cyclic voltammetry. The results of physical characterization show that there is no characteristic peak of crystalline metal in Ni-B alloy by XRD. The structural characteristics of amorphous long range disorder and short range order can be determined by SAED and HRTEM. It was observed that the amorphous Ni-B alloy nanoparticles were spherical or spherical, with an average particle size of 4-7 nanometers. The agglomeration phenomenon was not obvious. The results showed that the exothermic peak of amorphous Ni-B alloy nanoparticles appeared at 342.8 鈩，
本文编号：2168993
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