Direct methanol fuel cell with enhanced oxygen reduction performance enabled by CoFe alloys embedded into N-doped carbon nanofiber and bamboo-like carbon nanotube.

The exploration of cost-effective electrocatalysts with high catalytic activity and methanol tolerance to replace precious metal catalysts in the oxygen reduction reaction (ORR) is highly desirable for direct methanol fuel cells (DMFCs). Herein, we report a novel complex composed of a CoFe alloy with a modulated electronic structure confined to nitrogen-doped carbon nanofiber (NCNF) and bamboo-like carbon nanotube (BCNT) by tuning the molar ratio of Co and Fe (CoFe@NCNF/BCNT). The synthetized catalysts possess one-dimensional (1D) mesoporous structure, high specific surface area, and rich pyridinic-N content. Notably, the Co1Fe1@NCNF/BCNT and Co1Fe3@NCNF/BCNT (Co:Fe ≈ 1:1 and 1:3) exhibited enhanced oxygen reduction activity and methanol tolerance, compared to unmodified samples. In addition, alkaline DMFCs containing Co1Fe1@NCNF/BCNT and Co1Fe3@NCNF/BCNT presented high power density (29.10 and 31.11 mW cm-2), exceeding that of Pt/C-modified DMFC (27.23 mW cm-2). Furthermore, the Co1Fe1@NCNF/BCNT-catalyzed DMFC exhibited high stability. This improved catalytic activity can be attributed to the rich surface area, controllable alloy composition, optimized N configuration, and favorable electronic interaction. The as-developed CoFe@NCNF/BCNT with multifunctional components may open a new avenue for designing highly active cathode catalysts for various fuel cells.

Enhanced oxygen reduction upon Ag-Fe-doped polyacrylonitrile@UiO-66-NH2 nanofibers to improve power-generation performance of microbial fuel cells.

Microbial fuel cells (MFCs) have great potential as a new energy technology that utilizes microorganisms to produce electrical energy by decomposing organic matter. A cathode catalyst is key to achieving an accelerated cathodic oxygen reduction reaction (ORR) in MFCs. We prepared a Zr-based metal organic-framework-derived silver-iron co-doped bimetallic material based on electrospun nanofibers by promoting the in situ growth of UiO-66-NH2 on polyacrylonitrile (PAN) nanofibers and named it as CNFs-Ag/Fe-m:n doped catalyst (m:n were 0, 1:1, 1:2, 1:3, and 2:1, respectively). Experimental results combined with density functional theory (DFT) calculations reveal that a moderate amount of Fe doped in CNFs-Ag-1:1 reduces the Gibbs free energy in the last step of the ORR. This indicates that Fe doping improves the performance of the catalytic ORR, and MFCs equipped with CNFs-Ag/Fe-1:1 exhibit a maximum power density of 737. 45 mW m-2, significantly higher than that obtained for MFCs using commercial Pt/C (457.99 mW m-2).

Hierarchical N-doped carbon nanofiber-loaded NiCo alloy nanocrystals with enhanced methanol electrooxidation for alkaline direct methanol fuel cells.

The high catalytic activity of non-precious metals in alkaline media opens a new direction for the development of alkaline direct methanol fuel cell (ADMFC) electrocatalysts. Herein, a highly dispersed N-doped carbon nanofibers (CNFs) -loaded NiCo non-precious metal alloy electrocatalyst based on metal-organic frameworks (MOFs) was prepared, which conferred excellent methanol oxidation activity and resistance to carbon monoxide (CO) poisoning through a surface electronic structure modulation strategy. The porous electrospun polyacrylonitrile (PAN) nanofibers and the P-electron conjugated structure of polyaniline chains provide fast charge transfer channels, enabling electrocatalysts with abundant active sites and efficient electron transfer. The optimized NiCo/N-CNFs@800 was tested as an anode catalyst for ADMFC single cell and exhibited a power density of 29.15 mW cm-2. Due to the fast charge transfer and mass transfer brought by its one-dimensional porous structure and the synergistic effect between NiCo alloy, NiCo/N-CNFs@800 is expected to be an economical, efficient and CO-resistant methanol oxidation reaction (MOR) electrocatalyst.

Heterostructure-induced enhanced oxygen catalysis behavior based on metal cobalt coupled with compound anchored on N-doped carbon nanofiber for microbial fuel cell.

High-efficiency oxygen reduction reaction (ORR) electrocatalyst in microbial fuel cells (MFCs) is important to boost the power production efficiency and reduce overall cost. Herein, we demonstrate a novel nitrogen (N)-doped carbon nanofiber (N-CNF) supported metal and metal compound heterostructure derived from metal-organic frameworks (MOFs), which endows superior electrocatalytic activity by optimizing the coupling modulation effect. The resulting cobalt/cobalt phosphide and cobalt/cobalt sulfide nanoparticles embedded in N-doped carbon nanofiber (Co/CoP/Co2P@N-CNF, Co/CoS2@N-CNF) present superior ORR activity and methanol tolerance. Moreover, the assembled MFCs modified with Co/CoP/Co2P@N-CNF and Co/CoS2@N-CNF composite also achieve higher power density (375.16 and 400.06 mW m-2) as well as coulombic efficiency (11.2 %, 12.4 %), superior than that of Pt/C electrode (333.70 mW m-2, 10.4 %). Impressively, the Co/CoS2@N-CNF electrode exhibits long-term stability and durability in dual-chamber MFCs. A high-performance heterostructure cathode with an effective strategy for bridging nanocatalysis and practical MFCs is reported and presented.

Carbon nanotubes encapsulating FeS2 micropolyhedrons as an anode electrocatalyst for improving the power generation of microbial fuel cells.

The low power density originating from poor electroactive bacteria (EAB) adhesion and sluggish extracellular electron transfer (EET) at the anode interface, is a major impediment preventing the practical implementation of microbial fuel cells (MFCs). Tailoring the surface properties of anodes is an effective and powerful strategy for addressing this issue. In this study, we successfully fabricated an efficient anode electrocatalyst, consisting of carbon nanotubes encapsulating iron disulfide (FeS2@CNT) micropolyhedrons, using simple hydrothermal and freeze-drying methods, which not only strengthened the anode interaction with EAB but also promoted the EET process at the anode interface. As expected, the MFCs with a FeS2@CNT anode yielded an outstanding power density of 1914 mWm-2 at a current density of 4350 mA m-2, which significantly exceeded those of pure CNT (1096.2mW m-2, 2703.3 mA m-2) and carbon cloth (426.8mWm-2, 965.6 mA m-2) anodes. The high-power output can be attributed to the synergistic effect between FeS2 and CNTs, endowing the anode with biocompatibility for biofilm adhesion and colonization, nutrient diffusion, and the presence of abundant Fe and S active sites for EET mediation. Owing to the low cost, facile fabrication process, and excellent electrocatalytic performance toward the redox reactions in biofilms, the synthesized FeS2@CNT electrocatalyst is a promising material for high-performance and cost-effective MFCs with commercial applications.

UiO-66-NH2 Fabrics: Role of Trifluoroacetic Acid as a Modulator on MOF Uniform Coating on Electrospun Nanofibers and Efficient Decontamination of Chemical Warfare Agent Simulants.

Protective fabrics with air-permeable and flexible features are crucial for practical application in the detoxification of chemical warfare agents (CWAs). Zr-based metal-organic frameworks (Zr-MOFs) are desirable to exhibit outstanding degradation toward CWAs. However, generally, MOFs with powders cannot afford the utilization as a protective layer directly; meanwhile, it is still a puzzling challenge to integrate MOFs with textiles efficiently. Herein, we develop a scalable and controllable strategy to fabricate UiO-66-NH2 on electrospun polyacrylonitrile nanofibers (UiO-66-NH2 fabrics) firmly and uniformly to capture and catalyze 2-chloroethyl ethyl sulfide (CEES) effectively for self-detoxification. The obtained UiO-66-NH2 fabrics are greatly capable of specific surface area, ample porosity, excellent crystallinity, and abundant catalytic active sites. Consequently, CEES can be removed efficiently up to 97.7% after 48 h by reaction and adsorption. The degradation products mainly including ethyl-2-hydroxyethyl sulfide, ether, bis[2-(ethylthio)ethyl], and 2-(2-(ethylthio)ethylamino) terephthalic acid are detected. Moreover, the obtained nanofibrous fabrics possess air-permeable, washable, and flexible as well as lightweight merits, totally ensuring their promising engineering applications for protective clothing.

Development of 29 microsatellite markers for Osmanthus fragrans (Oleaceae), a traditional fragrant flowering tree of China.

PREMISE OF THE STUDY: Microsatellite markers were developed for a traditional fragrant flowering tree of China, Osmanthus fragrans, to investigate the genetic diversity of its wild populations and to facilitate the classification and identification of O. fragrans cultivars. METHODS AND RESULTS: Using the fast isolation by AFLP of sequences containing repeats (FIASCO) protocol, 29 primer sets were identified in two wild populations. All primer pairs displayed polymorphism. The number of alleles per locus ranged from two to eight, with a mean of 3.9. The expected and observed heterozygosities ranged from 0.125 to 0.932 and from 0.083 to 0.917, respectively. The transferability of the 29 primer pairs was tested on O. serrulatus, O. delavayi, and O. yunnanensis (three individuals for each species). Eighteen (62.1%), 16 (55.2%), and 21 (72.4%) of them were successfully amplified in O. serrulatus, O. delavayi, and O. yunnanensis, respectively. CONCLUSIONS: These markers will facilitate further studies on the population genetics of O. fragrans and the classification and identification of O. fragrans cultivars.