石墨烯基气体传感器响应延迟的原因
What retards the response of graphene based gaseous sensor
摘要：
由于石墨烯的单原子厚度，基于石墨烯的气体分子传感器应该是超灵敏和超快的，而响应并不快。通常，对于许多分子，例如CO、NH3、SO2、CO2和NO2等，测量的响应时间在分钟或更长的尺度上。在目前的工作中，我们通过\emph{ab initio}计算发现，存在大于0.7 eV的势垒，该势垒阻碍气体分子直接降落在石墨烯的缺陷位置并延迟响应。提出了一种有效的方法来解决这个问题，即用其他分子修饰石墨烯片以降低势垒，并通过用Fe2O3分子修饰的石墨烯片来证明，该石墨烯片显示出对H2S分子的快速响应，并且计算的响应时间接近于测量的响应时间，500 $μ$ s。
英文摘要：
Graphene based sensor to gas molecules should be ultrasensitive and ultrafast because of the single-atomic thickness of graphene, while the response is not fast. Usually, the measured response time for many molecules, such as CO, NH3, SO2, CO2 and NO2 and so on, is on the scale of minutes or longer. In the present work, we found via \emph{ab initio} calculations there exists a potential barrier larger than 0.7 eV that hinders the gas molecule to land directly at the defective sites of graphene and retards the response. An efficient approach to the problem is suggested as modifying the graphene sheet with other molecules to reduce the potential barrier and was demonstrated by a graphene sheet modified by Fe2O3 molecules that shows fast response to H2S molecule, and the calculated response time is close to the measured one, 500 $μ$s.
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