Reused images are observed on the article [1].
The SEM images on Figure 2 (a), (b), and (c) were described to be taken from different samples, (a) and (b) were taken from "mesoporous inorganic silica", but (d) were taken from "organic ligand-modified composite adsorbent", however, the images on Figure 2 (a), (b), and (c) are identical to each other.
Reference
The 5GH Team analyzed the 50 most recently published articles on PLoS ONE using "RetractionRisk Scanner", a tool developed by Mr ZHENG Erte and his colleagues, and identified problematic references in 48 out of these 50 articles.
An undergraduate students (HONG Yanggang / 洪扬刚) at Wenzhou Medical University (温州医科大学) has edited three articles on an U.S. based journal "PLoS ONE".
These cases reflect the fact that China has a long history of loose ethics management. Although in recent years, authorities have applied several regulations on this matter, the enforcement is not as strengthened as it is expected.