Oil spills have become one of the most significant threats to the marine environment and coastal ecology. An efficient way of removing oil pollutants from the environment is urgently needed. To address this problem, Zhang Qianru, a research fellow from the Institute of Agricultural Resources and Regional Planning (IARRP) of the Chinese Academy of Agricultural Sciences (CAAS), and Liu Jianqiao, associate professor from Dalian Maritime University, have made new progress in researching photocatalytic degradation of oil pollutants by using new semiconductor quantum dots for water remediation.

In this work, the oxygen vacancy-rich SnO2 quantum dots (QDs) are prepared in aqueous solution via facile bottom-up self-assembly. The QDs are applied to the photocatalytic degradation of oil pollutants in water. The research shows that a high degradation efficiency of 91.9% for octane is obtained within 48 h under ultraviolet–visible irradiation and that the excellent performance can  be maintained for up to 90 days. Superoxide anion (O2•−) is the primary reactive radical in the degradation process, where the oxygen supply is essential to the photocatalytic removal of oil pollutants. The optical characterizations conclude that the QDs have 16.7% of oxygen vacancies and a band gap of 4.2 eV. Based on these characteristics, a computational model for the first principle-based simulation reveals the electrical properties and demonstrates a deep energy level of oxygen vacancies at 1.4 eV below the conduction band. The proficient photocatalytic degradation efficiency is ascribed to the inherent oxygen vacancies, which build an internal Z-scheme mechanism for the electron transition. A novel strategy in which the deep energy levels in low dimensional semiconductors are beneficial to the enhancement of photocatalytic activity is therefore proposed. The present oxygen vacancy-rich SnO2 QDs are prospective candidates for mass degradation of organic oil pollutants in water and are of great significance to the development of semiconductor photocatalysts as well as the remediation of marine environments.

The findings have been published in the top journal Chemical Engineering Journal (IF= 13.273) in an article titled “Highly Efficient Photocatalytic Degradation of Oil Pollutants by Oxygen Deficient SnO2 Quantum Dots for Water Remediation”. Associate professor Liu Jianqiao from Dalian Maritime University is the first author and IARRP research fellow Zhang Qianru is the co-corresponding author. This research was funded by the National Natural Science Foundation of China and the CAAS Innovation Project.

Figure 1 Characteristics of photocatalytic degradation of oil pollutants of SnO2 quantum dots

Figure 2 Schematic diagram of the photocatalytic mechanism of SnO2 quantum dots

https://doi.org/10.1016/j.cej.2020.127146