Department of Physics, Pennsylvania State University, University Park, PA 16802, USA.
J Phys Condens Matter. 2010 Aug 25;22(33):334208. doi: 10.1088/0953-8984/22/33/334208. Epub 2010 Aug 4.
The adsorption/desorption processes of oxygen are investigated in nanoporous carbon (activated carbon fiber (ACF)) consisting of a disordered network of nanographene sheets. The heat-induced desorption at 200 °C shows the decomposition of oxygen-including functional groups weakly bonded to nanographene edges. The removal of these oxygen-including negatively charged functional groups brings about a change in the type of majority carriers, from holes to electrons, through charge transfer from the functional groups to the interior of nanographene sheets. The oxygen adsorption brings ACF back to the electronic state with holes being majority carriers. In this process, a large concentration of negatively charged O(2)(δ-) molecules with δ ∼ 0.1 are created through charge transfer from nanographene sheets to the adsorbed oxygen molecules. The changes in the thermoelectric power and the electrical resistance in the oxygen desorption process is steeper than that in the oxygen adsorption process. This suggests the irreversibility between the two processes.
研究了由无序纳米石墨片网络组成的纳米多孔碳（活性碳纤维（ACF））中氧的吸附/解吸过程。在 200°C 下的热诱导解吸显示了与纳米石墨边缘弱结合的含氧官能团的分解。这些含氧带负电荷官能团的去除导致多数载流子的类型从空穴变为电子，通过从官能团到纳米石墨片内部的电荷转移。氧的吸附使 ACF 通过空穴成为多数载流子回到电子态。在这个过程中，通过纳米石墨片向吸附氧分子的电荷转移，形成了具有约 0.1 的 δ 的大量带负电荷的 O(2)(δ-)分子。在氧脱附过程中，温差电动势和电阻的变化比氧吸附过程更陡峭。这表明这两个过程之间存在不可逆性。
