Zhou Xiao, Yu Haoran, Liu Yang, Kong Yong, Tao Yongxin, Qin Yong
Jiangsu Key Laboratory of Advanced Catalytic Materials and Technology, School of Petrochemical Engineering, Changzhou University Changzhou Jiangsu 213164 China
RSC Adv. 2019 Oct 23;9(58):33997-34003. doi: 10.1039/c9ra07939d. eCollection 2019 Oct 18.
Co, Al and N tri-doped graphene (CANG) was successfully fabricated annealing N-doped graphene with Co and Al precursors. The material was characterized by scaning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), Raman spectroscopy, physical adsorption, and X-ray photoelectron spectroscopy (XPS). It was found that the as-prepared CANG features a robust three-dimensional hierarchically porous structure. The contents of Co and Al can achieve the maximum value of 2.18 at% and 0.51 at% at the annealing temperature of 950 °C. Upon using the electrocatalyst for the hydrogen evolution reaction (HER), the CANG exhibited remarkable electrocatalytic performance in both acidic ( = 105 mV) and alkaline media ( = 270 mV), and outperforms Co,N-codoped graphene and Al,N-codoped graphene, respectively. In combination with the density functional theory (DFT) calculations, it was revealed that the introduction of the Al heteroatom can decrease the absolute value of hydrogen adsorption free energy (Δ(H*)) of Co-N-C catalysts, thus greatly enhancing the HER activity. This discovery will provide new guidance to the design of advanced and inexpensive carbon materials for fuel cell, water-splitting and other electrochemical devices.
通过用钴和铝前驱体对氮掺杂石墨烯进行退火处理，成功制备了钴、铝和氮三掺杂石墨烯（CANG）。该材料通过扫描电子显微镜（SEM）、透射电子显微镜（TEM）、X射线衍射（XRD）、拉曼光谱、物理吸附和X射线光电子能谱（XPS）进行表征。结果发现，所制备的CANG具有坚固的三维分级多孔结构。在950℃的退火温度下，钴和铝的含量可分别达到最大值2.18原子%和0.51原子%。将该电催化剂用于析氢反应（HER）时，CANG在酸性（η = 105 mV）和碱性介质（η = 270 mV）中均表现出显著的电催化性能，并且分别优于钴、氮共掺杂石墨烯和铝、氮共掺杂石墨烯。结合密度泛函理论（DFT）计算表明，引入铝杂原子可降低Co-N-C催化剂氢吸附自由能（ΔG(H*)）的绝对值，从而大大提高HER活性。这一发现将为设计用于燃料电池、水分解和其他电化学装置的先进且廉价的碳材料提供新的指导。
