Jiangshan Gao,Huanhuan Wang,Yang Zhou,Zhiming Liu,Yan He
The combination of magnetic nanoparticles and transition metal oxides has attracted much attention in microwave absorption applications. Herein, the MnO 2 /Mn 3 O 4 @Ni-Co/graphite carbon (GC) nanocubes with porous structure and ultrathin nanosheets was constructed by self-template strategy and in-situ synthesis. The composites not only synergize the magnetic loss of magnetic Ni-Co nanoparticles with the dielectric losses of GC and MnO 2 /Mn 3 O 4 , but also enhance the multiple interface polarization and improve impedance matching. As a result, the MnO 2 /Mn 3 O 4 @Ni-Co/GC nanocubes present outstanding electromagnetic wave (EMW) absorption performances, in which a RL min of −26 dB at 6.4 GHz with a thickness of 4 mm and an effective absorption bandwidth covering from 5.3 GHz to 6.4 GHz are achieved. Meanwhile, the widest effective absorption bandwidth with the value of 3.7 GHz can be achieved at a matching thickness of 2.0 mm. More importantly, this work provides a new strategy for the synthesis of EMW absorbing materials.
The utilization of bio-wastes, such as shaddock peels, is of great significance for sustainable development. Combined with the potential of peroxymonosulfate (PMS) based advanced oxidation process (AOP) in wastewater treatment , a highly efficient functional catalyst, derived from shaddock peels biochar (SPC) and embedded with CoO@Co nanoparticles , i.e. Co-SPC-x(y), was prepared using a facile impregnation-calcination method and used for refractory organics degradation with PMS. The decoration amount of Co and annealing temperature were optimized, and the effects of various reaction factors were investigated. The results indicated that the optimized sample of Co-SPC-10 (900) consisted of multilayer biochar with curly edges and highly dispersed CoO@Co nanoparticles in the range of 20–200 nm, which is in cubic metallic Co and CoO. Moreover, it also possessed a specific surface area of 248.6 m 2 /g, and exhibited excellent PMS activation ability with ∼100% chlortetracycline hydrochloride (CTC) removal ratio within only 12 min of operation. The Co-SPC-10 (900)/PMS system showed relatively high tolerance for HPO 4 2− , NO 3 − and SO 4 2− , while the Cl − and HA had considerable effects on it. Mechanism exploration results revealed that both radical and non-radical pathways existed in the Co-SPC-10 (900)/PMS system, in which the multilayered biochar functioned as an electron transfer carrier to facilitate the continuous cycle of Co 2+ /Co 3+ in the CoO@Co nanoparticles by reacting with the absorbed CTC and PMS, resulting in the production of •OH, SO 4 •− , O 2 •− and 1 O 2 . Additionally, the Co-SPC-10 (900) also showed good stability and catalytic oxidation performance for various refractory organics.
Huijie Cao,Tianran Wei,Qian Liu,Shusheng Zhang,Yongji Qin,Hao Wang,Jun Luo,Xijun Liu
Graphical Nano-structured materials for glycerol/glucose oxidation reaction : Herein, hollow-structured PW-NiCo-NC was synthesized from a POMOF precursor as a highly efficient and stable electrocatalyst for HER and glycerol/glucose oxidation reaction. Furthermore, it exhibits energy-efficient catalytic hydrogen production activity in an OWS cell assisted by glycerol/glucose oxidation reaction. The electrocatalytic conversion of water-to-hydrogen powered by renewable energy is one of the promising strategies to unravel the energy and environment crises. However, a such process usually costs large energy consumption owing to the low efficiency of anodic oxygen evolution reaction (OER), which is another vital half reaction of the overall water splitting (OWS) system. Herein, we designed and fabricated hollow nitrogen-doped carbon nanocages loaded with Ni 3 N and Co nanoparticles derived from polyoxometalate-encapsuled metal-organic frameworks. The catalyst exhibited appealing dual functions for both OER and hydrogen evolution reaction (HER), outperforming the Ni-free and solid samples. Notably, the designed catalyst also showed much enhanced electrochemical performance for glycerol/glucose oxidation reaction when compared with OER. The home-made two-electrode electrolyzer, coupled HER with polyalcohol or glucose oxidation reaction, only needs cell voltages of 1.125 and 1.557 V to reach 10 mA cm −2 , respectively, which are much smaller than that in 1 M KOH (2.087 V), demonstrating a large amount of energy saving for hydrogen production.
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