Libeert Guillaume, Murugesan Ramasamy, Guba Márton, Keijers Wout, Collienne Simon, Raes Bart, Brems Steven, De Gendt Stefan, Silhanek Alejandro V, Höltzl Tibor, Houssa Michel, Van de Vondel Joris, Janssens Ewald
Quantum Solid-State Physics, Department of Physics and Astronomy, KU Leuven, Leuven, Belgium.
Semiconductor Physics Laboratory, Department of Physics and Astronomy, KU Leuven, Leuven, Belgium.
Nanoscale. 2022 Sep 2;14(34):12437-12446. doi: 10.1039/d2nr03076d.
The adsorption and desorption kinetics of molecules is of significant fundamental and applied interest. In this paper, we present a new method to quantify the energy barriers for the adsorption and desorption of gas molecules on few-atom clusters, by exploiting reaction induced changes of the doping level of a graphene substrate. The method is illustrated for oxygen adsorption on Au clusters. The gold clusters were deposited on a graphene field effect transistor and exposed to O. From the change in graphene's electronic properties during adsorption, the energy barrier for the adsorption of O on Au is estimated to be 0.45 eV. Electric current pulses increase the temperature of the graphene strip in a controlled way and provide the required thermal energy for oxygen desorption. The oxygen binding energy on Au/graphene is found to be 1.03 eV and the activation entropy is 1.4 meV K. The experimental values are compared and interpreted on the basis of density functional theory calculations of the adsorption barrier, the binding energy and the activation entropy. The large value of the activation entropy is explained by the hindering effect that the adsorbed O has on the fluxional motion of the Au cluster.
分子的吸附和解吸动力学具有重要的基础和应用价值。在本文中，我们提出了一种新方法，通过利用反应诱导的石墨烯基底掺杂水平变化，来量化气体分子在少原子团簇上吸附和解吸的能垒。该方法通过氧在金团簇上的吸附进行了说明。金团簇沉积在石墨烯场效应晶体管上并暴露于氧气中。根据吸附过程中石墨烯电子性质的变化，估计氧在金上吸附的能垒为0.45电子伏特。电流脉冲以可控方式提高石墨烯条带的温度，并为氧的解吸提供所需的热能。发现氧在金/石墨烯上的结合能为1.03电子伏特，活化熵为1.4毫电子伏特/开尔文。基于吸附能垒、结合能和活化熵的密度泛函理论计算，对实验值进行了比较和解释。活化熵的较大值是由吸附的氧对金团簇的流动运动的阻碍作用所解释的。
