| 1. |
- Bi, Zenghui, et al.
(författare)
-
Highly dispersed La−O/N−C sites anchored in hierarchically porous nitrogen-doped carbon as bifunctional catalysts for high-performance rechargeable Zn−air batteries
- 2023
-
Ingår i: Energy Storage Materials. - : Elsevier. - 2405-8289 .- 2405-8297. ; 54, s. 313-322
-
Tidskriftsartikel (refereegranskat)abstract
- Inexpensive, high-activity bifunctional catalysts for the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) are imperative for the development of energy storage and conversion systems. A nitrogen-doped carbon material with a micro−meso−macroporous structure doped with La (LaPNC) containing La−O/N−C active sites is prepared using SiO2 particle templating of carbon and a metal node exchange strategy. The coordination environment of La sites stabilized by two oxygen and four nitrogen atoms (LaO2N4), is further verified by X-ray absorption spectroscopy. The ORR half-wave potential reaches 0.852 V, and the OER overpotential reaches 263 mV at 10 mA cm−2. The Zn−air battery, with LaPNC as the air cathode, has a maximum power density of 202 mW cm−2 and achieves stable charge−discharge for at least 100 h without a significant increase or decrease in the charge or discharge voltages, respectively. Density functional theory calculations suggest that LaO2N4 sites exhibit the lowest activation free energy and the most easily desorbed oxygen capacity. This study provides new insights into the design of efficient, durable bifunctional catalysts as alternatives to precious-metal-based catalysts.
|
|
| 2. |
- Bi, Zenghui, et al.
(författare)
-
Three dimensional star-like mesoporous nitrogen-doped carbon anchored with highly dispersed Fe and Ce dual-sites for efficient oxygen reduction reaction in Zn-air battery
- 2022
-
Ingår i: Colloid and Interface Science Communications. - : Elsevier. - 2215-0382. ; 49
-
Tidskriftsartikel (refereegranskat)abstract
- Metal‑nitrogen‑carbon materials (M-N-C) have attracted much attention due to their low cost, high abundance, and efficient catalytic performance. Nevertheless, Fe-N-C materials are considered the most promising oxygen reduction reaction (ORR) catalysts for replacing noble metals. Ce is chemically active and has many metal valence states, and empty orbitals that can participate in coordination. On this basis, Fe, Ce-codoped catalyst was constructed in this study. The synergistic effect of the dual metal centers was verified, and a Fe, Ce-codoped nitrogen-doped carbon (FeCeNC) with six equal branch angles was proposed. The half-wave potential for the ORR catalyzed by FeCeNC is 0.855 V. As a rechargeable Zn-air battery cathode catalyst, FeCeNC exhibits excellent electrochemical performances, with an open-circuit voltage of 1.427 V, a maximum power density of 169.2 mW cm−2 and a stable cycling time of 80 h, demonstrating an excellent cycle performance.
|
|
| 3. |
- Jia, Xiuxiu, et al.
(författare)
-
Rod-shaped lanthanum oxychloride-decorated porous carbon material for efficient and ultra-fast removal of phosphorus from eutrophic water
- 2023
-
Ingår i: Separation and Purification Technology. - : Elsevier. - 1383-5866 .- 1873-3794. ; 306
-
Tidskriftsartikel (refereegranskat)abstract
- Removal of excess phosphorus (P) from water systems can effectively prevent eutrophication and maintain the ecological balance. In this study, we used a novel freeze-drying thermal oxidation process to prepare a rod-shaped lanthanum oxychloride decorated porous carbon material, polyvinylpyrrolidone /LaOCl (PL). PL showed excellent performance in removing P from water; the preparation method had not been reported previously. Specifically, the adsorption capacity of PL for P was as high as 90.9 mg P/g, and the removal rate was greater than 92.0 % over a wide pH range (2.5–11). Fast adsorption kinetics is an important feature for P removal. The high removal rate of PL for P could be achieved in a short time; that is, more than 97.8 % of the P species could be removed in only 25 min (initial concentration: 20 mg P/L). For water samples from the natural Laoyu River (24 μg P/L), 0.01 g of PL could reduce approximately 53 L of water to below the eutrophication threshold value (20 μg P/L). Furthermore, after five repetitions of the adsorption–desorption process, no significant decrease in the P removal efficiency was observed. The high adsorption capacity, fast adsorption kinetics, and persistent cyclic stability of PL for P in water were attributed to the advanced preparation process, in which freeze-drying ensured the porosity of the adsorbent and the uniformity of LaCl3 distribution; and the subsequent heat treatment created conditions for the generation of LaOCl species with stable adsorption activity. The adsorption mechanism mainly involved ion exchange, electrostatic attraction, and hydrogen bonding. This study provides a theoretical basis for preparing new adsorbing materials of P and technical support for preventing water eutrophication.
|
|
| 4. |
- Wang, Yuwen, et al.
(författare)
-
Fast room-temperature hydrogenation of nitroaromatics on Pd nanocrystal-boron cluster/graphene oxide nanosheets
- 2022
-
Ingår i: Molecular Catalysis. - : Elsevier. - 2468-8231. ; 529
-
Tidskriftsartikel (refereegranskat)abstract
- The reduction of nitroaromatics to aminoaromatics is essential for fine chemical production and effective sewage treatment. However, the activity of an external catalyst is essential for the reaction. In this study, Pd nanocrystals were anchored in situ on two-dimensional graphene oxide (GO), which acted as a catalyst support with high specific surface area. The oxygen-containing groups on the surface of GO bonded to the functionally rich boron clusters through hydrogen bonding interactions. A mildly reducible closed-dodecahydrododecaboric acid anion cluster (closo‑[B12H12]2–) was employed as the target site. The mild reducibility of closo‑[B12H12]2– resulted in a wide dispersion of ultrafine Pd nanocrystals on GO. Under ambient conditions, Pd/BGO rapidly hydrogenated nitroaromatics, such as 4-nitrophenol, to aminoaromatics with approximately 100% efficiency. Moreover, Pd/BGO retained its high catalytic activity for the hydrogenation/reduction of 4-nitrophenol after five catalytic cycles. Therefore, Pd/BGO could be a promising and economically viable candidate for various practical applications. The proposed innovative preparation strategy and highly efficient catalytic activity suggested the effective performance of closo‑[B12H12]2– as nanometal nucleation target sites. In addition to providing an alternate route for preparing supported nanometals, this study presents a stable and efficient catalyst for the hydrogenation of nitroaromatics.
|
|
| 5. |
- Zhang, Hua, et al.
(författare)
-
Dense crystalline/amorphous phosphides/oxides interfacial sites for enhanced industrial-level large current density seawater oxidation
- 2023
-
Ingår i: ACS Nano. - : American Chemical Society (ACS). - 1936-0851 .- 1936-086X. ; 17:16, s. 16008-16019
-
Tidskriftsartikel (refereegranskat)abstract
- Designing high-efficiency and low-cost catalysts with high current densities for the oxygen evolution reaction (OER) is critical for commercial seawater electrolysis. Here, we present a heterophase synthetic strategy for constructing an electrocatalyst with dense heterogeneous interfacial sites among crystalline Ni2P, Fe2P, CeO2, and amorphous NiFeCe oxides on nickel foam (NF). The synergistic effect of high-density crystalline and amorphous heterogeneous interfaces effectively promotes the redistribution of the charge density and optimizes the adsorbed oxygen intermediates, lowering the energy barrier and promoting the O2 desorption, thus enhancing the OER performance. The obtained NiFeO-CeO2/NF catalyst exhibited outstanding OER catalytic activity, with low overpotentials of 338 and 408 mV required to attain high current densities of 500 and 1000 mA cm-2, respectively, in alkaline natural seawater electrolytes. The solar-driven seawater electrolysis system presents a record-setting and stable solar-to-hydrogen conversion efficiency of 20.10%. This work provides directives for developing highly effective and stable catalysts for large-scale clean energy production.
|
|
| 6. |
- Zhao, Xue, et al.
(författare)
-
Electron modulation and morphology engineering jointly accelerate oxygen reaction to enhance Zn-Air battery performance
- 2023
-
Ingår i: Advanced Science. - : John Wiley & Sons. - 2198-3844. ; 10:8
-
Tidskriftsartikel (refereegranskat)abstract
- Combining morphological control engineering and diatomic coupling strategies, heteronuclear Fe-Co bimetals are efficiently intercalated into nitrogen-doped carbon materials with star-like to simultaneously accelerate oxygen reduction reaction (ORR) and oxygen evolution reaction (OER). The half-wave potential and kinetic current density of the ORR driven by FeCoNC/SL surpass the commercial Pt/C catalyst. The overpotential of OER is as low as 316 mV (η10), and the mass activity is at least 3.2 and 9.4 times that of mononuclear CoNC/SL and FeNC/SL, respectively. The power density and specific capacity of the Zn-air battery with FeCoNC/SL as air cathode are as high as 224.8 mW cm−2 and 803 mAh g−1, respectively. Morphologically, FeCoNC/SL endows more reactive sites and accelerates the process of oxygen reaction. Density functional theory reveals the active site of the heteronuclear diatomic, and the formation of FeCoN5C configuration can effectively tune the d-band center and electronic structure. The redistribution of electrons provides conditions for fast electron exchange, and the change of the center of the d-band avoids the strong adsorption of intermediate species to simultaneously take into account both ORR and OER and thus achieve high-performance Zn-air batteries.
|
|
