| 1. |
- 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.
|
|
| 2. |
- Zhang, Hua, et al.
(författare)
-
3D Melamine Sponge-Derived Cobalt Nanoparticle-Embedded N-Doped Carbon Nanocages as Efficient Electrocatalysts for the Oxygen Reduction Reaction
- 2021
-
Ingår i: ACS Omega. - : American Chemical Society (ACS). - 2470-1343. ; 6:31, s. 20130-20138
-
Tidskriftsartikel (refereegranskat)abstract
- The large-scale and controllable synthesis of novel N-doped three-dimensional (3D) carbon nanocage-decorated carbon skeleton sponges (Co-NCMS) is introduced. These Co-NCMS were highly active and durable non-noble metal catalysts for the oxygen reduction reaction (ORR). This hybrid electrocatalyst showed high ORR activity with a diffusion-limiting current of 5.237 mA·cm-2 in 0.1 M KOH solution through the highly efficient 4e- pathway, which was superior to that of the Pt/C catalyst (4.99 mA·cm-2), and the ORR Tafel slope is ca. 67.7 mV·dec-1 at a high potential region, close to that of Pt/C. Furthermore, Co-NCMS exhibited good ORR activity in acidic media with an onset potential comparable to that of the Pt/C catalyst. Most importantly, the prepared catalyst showed much higher stability and better methanol tolerance in both alkaline and acidic solutions. The power density obtained in a proton exchange membrane fuel cell was as high as 0.37 W·cm-2 at 0.19 V compared with 0.45 W·cm-2 at 0.56 V for the Pt/C catalyst. In Co-NCMS, the N-doped carbon nanocages facilitated the diffusion of the reactant, maximizing the exposure of active sites on the surface and protecting the active metallic core from oxidation. This made Co-NCMS one of the best non-noble metal catalysts and potentially offers an alternative approach for the efficient utilization of active transition metals in electrocatalyst applications.
|
|
| 3. |
- Sharifi, Tiva, et al.
(författare)
-
Oxygen Reduction Reactions on Single- or Few-Atom Discrete Active Sites for Heterogeneous Catalysis
- 2020
-
Ingår i: Advanced Energy Materials. - : John Wiley & Sons. - 1614-6832 .- 1614-6840. ; 10:11
-
Tidskriftsartikel (refereegranskat)abstract
- The oxygen reduction reaction (ORR) is of great importance in energy-converting processes such as fuel cells and in metal-air batteries and is vital to facilitate the transition toward a nonfossil dependent society. The ORR has been associated with expensive noble metal catalysts that facilitate the O-2 adsorption, dissociation, and subsequent electron transfer. Single- or few-atom motifs based on earth-abundant transition metals, such as Fe, Co, and Mo, combined with nonmetallic elements, such as P, S, and N, embedded in a carbon-based matrix represent one of the most promising alternatives. Often these are referred to as single atom catalysts; however, the coordination number of the metal atom as well as the type and nearest neighbor configuration has a strong influence on the function of the active sites, and a more adequate term to describe them is metal-coordinated motifs. Despite intense research, their function and catalytic mechanism still puzzle researchers. They are not molecular systems with discrete energy states; neither can they fully be described by theories that are adapted for heterogeneous bulk catalysts. Here, recent results on single- and few-atom electrocatalyst motifs are reviewed with an emphasis on reports discussing the function and the mechanism of the active sites.
|
|
| 4. |
- Zhang, Hua, et al.
(författare)
-
A high-performance transition-metal phosphide electrocatalyst for converting solar energy into hydrogen at 19.6% STH efficiency
- 2023
-
Ingår i: Carbon Energy. - : John Wiley & Sons. - 2637-9368. ; 5:1
-
Tidskriftsartikel (refereegranskat)abstract
- The construction of high-efficiency and low-cost non-noble metal bifunctional electrocatalysts for water electrolysis is crucial for commercial large-scale application of hydrogen energy. Here, we report a novel strategy with erbium-doped NiCoP nanowire arrays in situ grown on conductive nickel foam (Er-NiCoP/NF). Significantly, the developed electrode shows exceptional bifunctional catalytic activity, which only requires overpotentials of 46 and 225 mV to afford a current density of 10 mA cm−2 for the hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER), respectively. Density functional theory calculations reveal that the appropriate Er incorporation into the NiCoP lattice can significantly modulate the electronic structure with the d-band centers of Ni and Co atoms by shifting to lower energies with respect to the Fermi level, and optimize the Gibbs free energies of HER/OER intermediates, thereby accelerating water-splitting kinetics. When assembled as a solar-driven overall water-splitting electrolyzer, the as-prepared electrode shows a high and stable solar-to-hydrogen efficiency of 19.6%, indicating its potential for practical storage of intermittent energy.
|
|
| 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. |
- Zhang, Hua, et al.
(författare)
-
Interface engineering on amorphous/crystalline hydroxides/sulfides heterostructure nanoarrays for enhanced solar water splitting
- 2023
-
Ingår i: ACS Nano. - : American Chemical Society (ACS). - 1936-0851 .- 1936-086X. ; 17:1, s. 636-647
-
Tidskriftsartikel (refereegranskat)abstract
- Developing highly efficient and stable noble-metal-free electrocatalysts for water splitting is critical for producing clean and sustainable energy. Here, we design a hierarchical transition metal hydroxide/sulfide (NiFe(OH)x-Ni3S2/NF) electrode with dual heterointerface coexistence using a cation exchange-induced surface reconfiguration strategy. The electrode exhibits superior electrocatalytic activities, achieving low overpotentials of 55 mV for hydrogen evolution and 182 mV for oxygen evolution at 10 mA cm-2. Furthermore, the assembled two-electrode system requires voltages as low as 1.55 and 1.62 V to deliver industrially relevant current densities of 500 and 1000 mA cm-2, respectively, with excellent durability for over 200 h, which is comparable to commercial electrolysis. Theoretical calculations reveal that the hierarchical heterostructure increases the electronic delocalization of the Fe and Ni catalytic centers, lowering the energy barrier of the rate-limiting step and promoting O2 desorption. Finally, by implementing the catalysts in a solar-driven water electrolysis system, we demonstrate a record and durable solar-to-hydrogen (STH) conversion efficiency of up to 20.05%. This work provides a promising strategy for developing low-cost and high-efficiency bifunctional catalysts for a large-scale solar-to-hydrogen generation.
|
|
| 7. |
- Zhang, Yumeng, et al.
(författare)
-
Progress in molecular-simulation-based research on the effects of interface-induced fluid microstructures on flow resistance
- 2019
-
Ingår i: Chinese Journal of Chemical Engineering. - : Elsevier. - 1004-9541 .- 2210-321X. ; 27:6, s. 1403-1415
-
Tidskriftsartikel (refereegranskat)abstract
- In modern chemical engineering processes, solid interface involvement is the most important component of process intensification techniques, such as nanoporous membrane separation and heterogeneous catalysis. The fundamental mechanism underlying interfacial transport remains incompletely understood given the complexity of heterogeneous interfacial molecular interactions and the high nonideality of the fluid involved. Thus, understanding the effects of interface-induced fluid microstructures on flow resistance is the first step in further understanding interfacial transport. Molecular simulation has become an indispensable method for the investigation of fluid microstructure and flow resistance. Here, we reviewed the recent research progress of our group and the latest relevant works to elucidate the contribution of interface-induced fluid microstructures to flow resistance. We specifically focused on water, ionic aqueous solutions, and alcohol–water mixtures given the ubiquity of these fluid systems in modern chemical engineering processes. We discussed the effects of the interface-induced hydrogen bond networks of water molecules, the ionic hydration of ionic aqueous solutions, and the spatial distributions of alcohol and alcohol–water mixtures on flow resistance on the basis of the distinctive characteristics of different fluid systems.
|
|
