ISEP - Departamento de Física
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Browsing ISEP - Departamento de Física by Field of Science and Technology (FOS) "Engenharia e Tecnologia"
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- Atomic Dispersion of Scandium in Electrochemically Reduced Copper Oxide Nanosheets for Efficient Electrocatalytic CO2 Reduction to C2+ ProductsPublication . Zhao, Yang; Zeng, Binwen; Huang, Haoliang; Yang, Huanhuan; Yu, Zhipeng; Song, Chao; Wang, Jingwei; Xu, Kaiyang; Xiang, Xinyi; Wang, Wei; Lin, Fei; Meng, Sheng; Meng, Lijian; Cui, Zhiming; Liu, LifengConverting CO2 into value-added chemicals and fuels through electrochemical CO2 reduction reaction (CO2RR) has been acknowledged as a disruptive technology for chemical industry and an important means to realizing carbon neutrality. However, it remains challenging to achieve high selectivity for C2+ products at a large current density with a low overpotential. Herein, we report a scandium (Sc) single-atom-doped CuO nanosheet (Sc1CuO NS) electrocatalyst for efficient and durable CO2-to-C2+ conversion. The optimal Sc1CuO NS catalyst achieves a maximal C2+ Faradaic efficiency of 73 ± 1.8 % at 475.2 mA cm−2 under an ultralow potential of −0.6 V versus the reversible hydrogen electrode (RHE) and maintains stable CO2-to-C2+ conversion at ∼206 mA cm−2 with a > 60 % Faradaic efficiency for 47 h without degradation. In-situ spectroscopy measurements combined with density functional theory (DFT) calculations reveal that the electron transfer from Sc to Cu enhances the activation of CO2 to *CO. Moreover, the in-situ electrochemical reduction of CuO generates abundant undercoordinated Cu0 sites, featuring tensile-strained Sc-(O)-Cu motifs, which serve as active centers that reduce the reaction barrier for Csingle bondC coupling. This work highlights the importance of rare-earth doping combined with in-situ electrochemical surface reconstruction of CuO as an effective catalyst design strategy to boost CO2-to-C2+ conversion performance.
- Gold Single Atom Doped Defective Nanoporous Copper Octahedrons for Electrocatalytic Reduction of Carbon Dioxide to EthylenePublication . Zhao, Yang; Wang, Yanan; Yu, Zhipeng; Song, Chao; Wang, Jingwei; Huang, Haoliang; Meng, Lijian; Liu, Miao; Liu, LifengElectrocatalytic CO2 reduction into high-value multicarbon products offers a sustainable approach to closing the anthropogenic carbon cycle and contributing to carbon neutrality, particularly when renewable electricity is used to power the reaction. However, the lack of efficient and durable electrocatalysts with high selectivity for multicarbons severely hinders the practical application of this promising technology. Herein, a nanoporous defective Au1Cu single-atom alloy (DeAu1Cu SAA) catalyst is developed through facile low-temperature thermal reduction in hydrogen and a subsequent dealloying process, which shows high selectivity toward ethylene (C2H4), with a Faradaic efficiency of 52% at the current density of 252 mA cm−2 under a potential of −1.1 V versus reversible hydrogen electrode (RHE). In situ spectroscopy measurements and density functional theory (DFT) calculations reveal that the high C2H4 product selectivity results from the synergistic effect between Au single atoms and defective Cu sites on the surface of catalysts, where Au single atoms promote *CO generation and Cu defects stabilize the key intermediate *OCCO, which altogether enhances C−C coupling kinetics. This work provides important insights into the catalyst design for electrochemical CO2 reduction to multicarbon products.
- Ir Nanoparticles Synergistically Regulated by B, N Co-Doping in Carbon for pH-Universal Bifunctional Electrocatalysts towards Energy-Efficient Hydrogen ProductionPublication . Huang, Hongli; Meng, Lijian; li, Haibo; Li, Rui; Zeng, Suyuan; Yao, Qingxia; Chen, Hongyan; Qu, Kong-GangThe ultralow-potential hydrazine oxidation reaction (HzOR) can be integrated with hydrogen evolution reaction (HER) to construct the overall hydrazine splitting (OHzS) system, thus realizing energy-saving hydrogen production. Meanwhile, the real electrocatalytic processes normally involve the constantly changed pH and also need to operate under different pH conditions. Therefore, designing advanced pH-universal electrocatalysts with high compatibility for HER and HzOR is of greatly practical significance. Herein, ultrafine Ir nanoparticles embedding in B, N-codoped carbon (Ir/BNC) were facilely synthesized with one Ir-based complex and boric acid by simple mixing and pyrolysis. To reach the current density of 10 mA cm−2, the bifunctional Ir/BNC merely demands the low potentials of −4.8/-6.3/-38.5 mV for HER, 7.5/157.8/330.1 mV for HzOR, and 19/236/358 mV for OHzS in the alkaline, neutral and acidic electrolytes, respectively, all greatly outperforming commercial Pt/C and displaying the huge energy-saving advantage for pH-universal hydrogen generation over the conventional water splitting. Underlyingly, the codoping of abundant B and N heteroatoms with different electronic modulation effects can play synergistical roles to Ir active sites, endowing with the pH-universal multifunctionality as well as the boosted intrinsic unit activity. Additionally, the large surface area, rich pores and highly graphitized carbon also collectively ensure the remarkable apparent performance for bifunctional HER and HzOR. This work supplies a promising strategy for exploiting pH-universal HER and HzOR bifunctional electrocatalysts, greatly potential to the practical energy-efficient hydrogen generation.
- A novel ternary Z-scheme g-C3N4/CQDs/FeVO4 heterojunction for photodegradation of levofloxacin via peroxymonosulfate activationPublication . Li, Yunuo; Han, Pengda; Zhang, Dongzhe; Zhang, Wenzhi; Chai, Dong-feng; Meng, Lijian; Meng, Lijian; Liming, Bai; Zhao, Ming; Dong, GuohuaCurrently, it is still a significant challenge for photodegradation of the emerging pollutants using g-C3N4 (CN) due to their interior visible light responsibility and rapid recombination of e-/h+. Herein, a novel Z-scheme g-C3N4/CQDs/FeVO4 (CCF) photocatalyst was synthesized by initially preparing hollow tubular g-C3N4/CQDs (CC) and then anchoring FeVO4 on CC. The morphology, structural composition and photoelectrochemical performance of the CCF were investigated by comprehensive characterization such as FT-IR, XPS, XRD, SEM and photoelectrochemical performance tests. The CCF shows superior photodegradation capability toward LFX via activation of peroxymonosulfate (PMS), resulting in a photodegradation efficiency ∼ 97.3 % in the optimal conditions. Apart from the strengthened light responsibility, improved BET specific surface area and porous texture of CCF, the improved photodegradation properties can be ascribed to the formed Z-scheme heterojunction between CC and FeVO4, which can ameliorate the separation efficiency of e-/h+ and accelerate their transfer rate. The addition of CQDs can also serve as a channel for promoting the rapid transfer of photogenerated e-/h+. The photodegradation processes of LFX including generation of reactive oxygen species (ROS) and removal pathways were systematically explored by using radical capturing assays, electron spin resonance (ESR) tests and liquid chromatography-mass spectrometry (LC-MS) techniques. To sum up, this study provides an innovative method for regulating the photocatalytic activity of g-C3N4 via constructing Z-scheme heterostructures and incorporating CQD to degrade emerging contaminants.