Aging of plasma-activated carbon surfaces: Challenges and opportunities

Highlights: • Aging effect or reorientation phenomenon is a time-induced loss of surface activity. • Physicochemical properties of plasma-treated carbons change with time. • Aging impacts the performance of plasma-treated carbons in different applications. • Different characterization techniques can detect signs of aging on carbon platforms. • Plasma treatment parameters and storage conditions can alter aging and its speed. Plasma-activated carbon surfaces demonstrate an immediately enhanced surface energy, wettability, and roughness and perform considerably well in their intended applications. However, as the time progresses, plasma-treated carbon materials rapidly lose the generated features and functions as a result of aging. While plasma-generated surface functional groups reorient themselves in an attempt to occupy lower states of energy, the surface begins to also suffer from a brief shelf life that severely impacts its performance in various disciplines. This time-induced decay of the surface that manifests as the gradual loss of surface properties and functionalities is rarely mentioned or discussed in the literature. The main contribution of plasma treatment is to produce activated and functional platforms that can serve several applications including environmental monitoring, bio-diagnosis, food quality control, and extreme point-of-care. To reach the hands of final users at any of these destinations, plasma-activated carbon platforms have to remain active and stable over an acceptable period of time to fulfill their purpose. The current review article is an effort to garner the attention of the scientific community to this shortcoming and gather all the existing evidences on the aging of plasma-activated carbon platforms.