Alotaibi Nusaybah, Hammud Hassan H, Al Otaibi Nasreen, Prakasam Thirumurugan
Department of Chemistry, College of Science, King Faisal University, Al-Ahsa 31982, Saudi Arabia.
Chemistry Program, New York University Abu Dhabi (NYUAD), Abu Dhabi, United Arab Emirates.
ACS Omega. 2020 Sep 29;5(40):26038-26048. doi: 10.1021/acsomega.0c03477. eCollection 2020 Oct 13.
A 3D hierarchical graphitic carbon nanostructure encapsulating cobalt(0)/cobalt oxide nanoparticles (CoGC) has been prepared by solid-state pyrolysis of a mixture of anthracene and cobalt 2,2'-bipyridine terephthalate complex at 850 °C. Based on the Brunauer-Emmett-Teller (BET) and Barrett-Joyner-Halenda (BJH) methods, the prepared material has high surface area (186.8 m g) with an average pore width of 205.5 Å. XPS reveals the functionalization of carbon with different oxygen-containing groups, such as carboxylic acid groups. The presence of metallic cobalt nanoparticles with cubic and hexagonal crystalline structures encapsulated in graphitized carbon is confirmed using XRD and TEM. Raman spectroscopy indicates a graphitization degree of / = 1.02. CoGC was cast onto a glassy carbon electrode and used for urea electrooxidation in an alkaline solution. The electrochemical investigation shows that the newly prepared CoGC has a promising electrocatalytic activity toward urea. The specific activity is 128 mA cm mg for the electrooxidation of 0.3 M urea in 1 M KOH at a relatively low onset potential (0.31 V vs Ag/AgCl). It can be mainly attributed to the morphological structure of carbon and the high reactivity of cobalt nanoparticles. The calculated charge-transfer resistance, , of the modified electrode in the presence of urea (10.95 Ω) is significantly lower than that in the absence of urea (113.5 Ω), which indicates electrocatalytic activity. The value of charge-transfer rate constant, , for the anodic reaction is 0.0058 s. Electrocatalytic durability in 1000 s chronoamperometry of the modified electrode suggests high structure stability. The modified electrode retained about 60% of its activity after 100 cycles as indicated by linear sweep voltammetry.
通过在850℃下对蒽与钴2,2'-联吡啶对苯二甲酸酯配合物的混合物进行固态热解，制备了一种封装钴(0)/氧化钴纳米颗粒的三维分层石墨碳纳米结构（CoGC）。基于布鲁诺尔-埃米特-泰勒（BET）和巴雷特-乔伊纳-哈伦达（BJH）方法，所制备的材料具有高表面积（186.8 m²/g），平均孔径为205.5 Å。X射线光电子能谱（XPS）揭示了碳与不同含氧基团（如羧酸基团）的功能化。使用X射线衍射（XRD）和透射电子显微镜（TEM）确认了封装在石墨化碳中的具有立方和六方晶体结构的金属钴纳米颗粒的存在。拉曼光谱表明石墨化程度I_D/I_G = 1.02。将CoGC浇铸在玻碳电极上，并用于碱性溶液中的尿素电氧化。电化学研究表明，新制备的CoGC对尿素具有良好的电催化活性。在1 M KOH中对0.3 M尿素进行电氧化时，相对较低的起始电位（相对于Ag/AgCl为0.31 V）下的比活性为128 mA cm²/mg。这主要归因于碳的形态结构和钴纳米颗粒的高反应活性。在存在尿素的情况下，修饰电极的计算电荷转移电阻Rct为10.95 Ω，明显低于不存在尿素时的113.5 Ω，这表明具有电催化活性。阳极反应的电荷转移速率常数k为0.0058 s⁻¹。修饰电极在1000 s计时电流法中的电催化耐久性表明其具有高结构稳定性。线性扫描伏安法表明，修饰电极在100次循环后保留了约60%的活性。
