Carboxyl induced ultrahigh defects and boron/nitrogen active centers in cobalt-embedded hierarchically porous carbon nanofibers: The stable oxygen reduction reaction catalysis in acid

NaCl-Assisted electrospinning of bifunctional carbon fibers for High-Performance flexible zinc-air batteries

With the increasing demand for flexible, rechargeable zinc-air batteries (ZABs), developing efficient oxygen electrocatalysts is challenging. A large specific surface area and porous structure are critical for electrochemical performance but can compromise mechanical strength and flexibility. Herein, a novel strategy with NaCl-assisted electrospinning and pyrolysis has been proposed to fabricate self-supported carbon fibers with a solid core and mesoporous shell as bifunctional oxygen electrocatalysts for flexible ZABs. The fibers incorporate NaCl and ZnCo-ZIFs via coaxial electrospinning. NaCl enhances both the electrospinning process and ZIF carbonization, creating a porous surface on robust carbon fibers that balances surface exposure with structural stability. Experimental data and density functional theory calculations confirm that cobalt atoms anchored on the carbon surface are the primary active sites, boosting electrocatalytic performance. Zinc facilitates the formation of structural defects and porosity during volatilization at high temperatures, promoting NaCl molten salt infiltration, ZIF decomposition, and large pore formation. The resulting cross-linked porous structure increases active site exposure, enhancing catalytic efficiency. The synthesized ZN3-CNFs-900 exhibit remarkable catalytic activity, achieving an oxygen reduction reaction half-wave potential of 0.834 V and an oxygen evolution reaction overpotential of 1.695 V at 10 mA cm-2. ZABs assembled with these carbon fibers demonstrate an open-circuit voltage of 1.43 V, a peak power density of 111 mW cm-2, and cycling stability beyond 400 h. The carbon fiber-based solid-state ZABs show a high open circuit voltage of 1.39 V, a power density of 81.7 mW cm-2 and a cycle life of 33 h.

Development of the cobalt-modified boron-doped metal‑nitrogen‑carbon nanoparticles (co-BCN) for the chemiluminescent determination of the total antioxidant capacity of beverages and fruits

The development of novel detection methods is essential for total antioxidant capacity (TAC) assay in the quality of foods and dietary pharmaceuticals. Herein, a series of cobalt-modified boron-doped metal‑nitrogen‑carbon nanoparticles (Co-BCN) were prepared through high-temperature pyrolysis of the precursors. The Co-BCN shows an outstanding activity of oxidase mimics, and can activate dissolved oxygen to generate a large amount of reactive oxygen species (ROS). These ROS oxidize luminol anions rapidly and emits intense chemiluminescent (CL) radiation. The antioxidants, ascorbic acid, glutathione and cysteine can scavenge the generated ROS, thus sharply reducing the CL signal. The reduction in the CL signals show good linear relationships in the concentration range of 0.1-1.0 μmol·L-1 ascorbic acid, 1.0-10.0 μmol·L-1 glutathione, and 10.0-80.0 μmol·L-1 cysteine, respectively. The method was employed for the TAC determination in eight commercially available fruits and beverages, and the results show good agreement with those of the CUPRAC method.

Porous Materials for the Heterogeneously Catalyzed Synthesis of High Value-Added Products: Latest Trends and Future Prospects

Heterogeneous catalysis currently stands as a foundational area in materials synthesis and applied chemistry. In this context, emphasizing the significance of heterogeneous catalysis in expediting chemical reactions and controlling the formation of desired products using porous materials represents an intriguing approach in the current technological landscape. This work delves into the synthesis and design of a variety of porous materials, encompassing microporous, mesoporous and macroporous materials (e. g. carbonaceous materials, metal oxides, MOFs, zeolites and functionalized analogues), alongside their properties and characteristics pivotal in heterogeneous catalysis. among others, and their subsequent modification, underscoring the significance of tailoring porous materials for specific catalytic applications.

Self-supporting multi-channel Janus carbon fibers: A new strategy to achieve an efficient bifunctional electrocatalyst for overall water splitting

A new type of self-supporting multi-channel Janus carbon fibers with efficient water splitting has been successfully manufactured using a specially designed parallel spinneret through electrospinning technology and subsequent carbonization technique. Every single Janus fiber composes of a half side of Mo2C and the other half side of Ni components as Mo2C, Ni embedded in N-doped multi-channel Janus carbon fibers ([Mo2C/C]//[Ni/C]-NMCFs) for overall water splitting. Under optimized condition, the hydrogen evolution reaction overpotential of [Mo2C/C]//[Ni/C]-NMCFs (62 mV) is just 24 mV higher than 20 wt% Pt/C (38 mV) at a current density of 10 mA cm-2. Furthermore, it achieves current density of 10 mA cm-2 to require an overpotential of 324 mV for oxygen evolution reaction. Additionally, the cell assembled by the identical [Mo2C/C]//[Ni/C]-NMCFs catalyst as both the cathode and anode needs only 1.607 V at a current density of 10 mA cm-2, which is only 0.022 V higher than that of Pt/C-IrO2 electrodes. Moreover, [Mo2C/C]//[Ni/C]-NMCFs catalyst also exhibits a long-term stability. The synergistic effect and unique heterostructure of Mo2C and Ni enhance the catalytic activity.

Recycling cobalt in spent lithium ion batteries to design CoN/HPCF/CoN electrocatalysts for advanced zinc-air batteries

Cobalt (Co) in spent lithium ion batteries was recycled to design a hollow and porous CoN/HPCF/CoN bifunctional electrocatalyst. It reveals superior rechargeable zinc-air battery performance (peak power density is 161.6 mW cm-2) with excellent stability.

B-Doping-Induced Lattice Expansion of Pd Metallene Nanoribbons for Oxygen Reduction Reaction

Pd-based metallene is regarded as an efficient catalyst in the field of oxygen reduction reaction (ORR) because of its fantastic physicochemical features. The morphological structure control, lattice strain engineering, and electronic structure modulation of Pd-based metallene are effective tactics to enhance its electrocatalytic performance. In this work, we fabricate atomically thin B-doped Pd metallene nanoribbons (B-Pd MNRs) for efficient alkaline ORR. The atomically thin nanoribbon structure of B-Pd MNRs can expose many surface atoms as catalytically active sites. Moreover, the incorporation of boron effectively induces the lattice expansion and modulates the electronic structure of Pd, which can synergistically weaken the adsorption of intermediate species on B-Pd MNRs. Therefore, the B-Pd MNRs display excellent activity and durability for ORR. This work opens an avenue to the synthesis of atomically thin heteroatom-doped metallene nanoribbons for energy electrocatalytic applications.

Nitrogen doped CoP on ammoniated black phosphorus nanosheets enabling highly efficient hydrogen evolution electrocatalysis

Developing a rational and cost-effective approach for designing highly-efficient and sustainable electrocatalysts is essential for clean and renewable hydrogen energy. Herein, we report nitrogen-doped CoP on two-dimensional ammoniated black phosphorus (BP) nanosheets (N-CoP/NH2-BP) as novel and highly-active heterostructure electrocatalysts for the hydrogen evolution reaction (HER). Using the reactive defects on the BP nanosheets as the original sites under NH3 gas, N-doped CoP nanocrystals were grown on the surface of the BP nanosheets that were functionalized with NH2 groups at their edge. The N-CoP/NH2-BP heterostructure exhibits low overpotentials of 90 and 246 mV at 10 and 200 mA cm-2, respectively, in an alkaline electrolyte. The excellent HER activity should be attributed to the synergistic effect between N-doped CoP and NH2-functionalized BP, in which NH2-BP, with its high electron mobility and hydrophilicity, accelerates the charge transfer and offers more active sites, moreover, N-doped CoP modulates the electronic structure of CoP for enhanced HER activity. This work not only provides a novel and effective electrocatalyst, but also opens up a straightforward strategy for the design of phosphorene-based electrocatalysts for highly efficient hydrogen evolution and beyond.