ISEP - Departamento de Física
Permanent URI for this community
Browse
Browsing ISEP - Departamento de Física by Field of Science and Technology (FOS) "Engenharia e Tecnologia::Engenharia Química"
Now showing 1 - 2 of 2
Results Per Page
Sort Options
- Covalent organic framework assisted low-content ultrafine ru on porous N-doped carbon for efficient hydrogen evolution reactionPublication . Kong-Gang Qu; Zhi-Fei Chen; Li-Hui Wang; Hai-Bo Li; Su-Yuan Zeng; Rui Li; Li-Jian Meng; Hong-Yan Chen; Qing-Xia Yao(Excerpt) Pt-based materials are the benchmarked catalysts in the cathodic hydrogen evolution reaction (HER) of water splitting; the prohibitive cost and scarcity of Pt immensely impede the commercialization of hydrogen energy. Ru has aroused significant concern because of its Pt-like activity and much lower price. However, it’s still a top priority to minimize the Ru loading and pursue the most superior cost performance. Herein, N-rich covalent organic framework (COF) was employed to assist the preparation of ultrafine Ru, including nanoclusters and single atoms loaded onto porous N-doped carbon by a simple impregnation-pyrolysis process with a low Ru content of 6.60 wt%, exhibiting superior HER activity with mass activity of 21.86 and 11.52 A mg-1 Ru (@100 mV) in alkaline and acidic conditions, separately 14.7 and 2.12 times higher than that of commercial Pt/C.
- Microwave-assisted synthesis of hierarchical BiOBr/BiOF Z-scheme heterojunction for activating peroxymonosulfate toward photodegradation of the recalcitrant levofloxacinPublication . Guohua Dong; Dongzhe Zhang; Xinjia Zhang; Zhuangfang Zhang; Dong-feng Chai; Lijian Meng; Jinlong Li; Ming Zhao; Wenzhi ZhangHerein, a novel Z-scheme BiOBr/BiOF heterojunction was synthesized via one-step microwave-assisted hydrothermal method, which was integrated with peroxymonosulfate (PMS) to design a sulfate radical (•SO4−) based advanced oxidation processes (AOPs) system through PMS activation (BiOBr/BiOF-PMS) toward Levofloxacin (LFX) photodegradation. In order to achieving an optimal degradation efficiency, the formed BiOBr/BiOF-PMS was systematically investigated and the operational parameters for LFX photodegradation were thoroughly optimized. Thereby, the optimal BiOBr/BiOF exhibits a higher photodegradation efficiency of 89.8 % toward LFX via PMS activation compared to others including PMS alone, BiOBr, BiOF and BiOBr/BiOF with varied ratios. Furthermore, the BiOBr/BiOF has superior stability for multiple cycles and universal applicability for degrading various contaminants. This can mainly be attributed that the formed heterojunction between BiOBr and BiOF and the enhanced concentration of oxygen vacancies (OVs) of BiOBr/BiOF heterojunction, which can synchronously promote the separation and transmission of the photogenerated charges (e−/h+) and thereby lead to more reactive oxygen species (ROS). As well, the expanded optical responsiveness and increased specific surface area of BiOBr/BiOF are also mainly responsible for the improved photodegradation capability. Free radical capture experiments and ESR technique verify that the •O2− is the primary ROS and •SO4− and •OH play subordinative role. The photodegradation pathways of LFX were unraveled based on the identified intermediates with a liquid-chromatography-mass (LC-MS) technique. Consequently, this study offers a novel route by developing Bi-based heterojunction photocatalyst to activate PMS for refractory antibiotic photodegradation.