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Rational design of high-efficiency and cost-effective nonprecious metal-based catalysts with outstanding oxygen reduction reaction (ORR) performance, is of great importance to replace platinum-based electrocatalysts in fuel cell. Herein, a novel N, B and Fe co-doped carbon materials (Fe-NBC) electrocatalyst is designed through the pyrolysis of a metal-organic coordination polymer precursor, which is formed from the coordination between dendrimer-like terpyridinic monomer and Fe3+. The as-prepared Fe-NBC catalyst exhibits superior ORR activity with an onset potential of 0.98 V and a half-wave potential of 0.86 V, which are comparable to that of the Pt/C catalyst. The formation of Fe-Nx moieties is considered to be the most important factor for the improved ORR activity of Fe-NBC. Besides, Fe-NBC catalyst displays a better methanol tolerance as well as durability (5 mV negative shift of E1/2, after 1000 cycles) in comparison with Pt/C (12 mV negative shift of E1/2, after 1000 cycles). This work provides a facile protocol for the design and fabrication of multi-element co-doped carbon materials. Moreover, the excellent ORR performance of these N, B and Fe co-doped carbon materials may be a potential candidate to replace Pt-based catalyst in fuel cells.

In this report, we show that a facile and highly adaptable route based on the Schiff-base formation reaction can generate crosslinked polymer precursors for the fabrication of hierarchical porous nitrogen-doped carbon materials. The optimized sample with a moderate surface wettability, Brunauer–Emmett–Teller (BET) surface area, and heteroatom content displays outstanding supercapacitance performances in both acidic and alkaline electrolytes. Capacitances of 362 F g−1 in 1 M H2SO4 and 374.5 F g−1 in 6 M KOH at 0.5 A g−1 as well as an excellent rate capability (75% and 79.5% capacitance retention at 30 A g−1 in 1 M H2SO4 and 6 M KOH, respectively) are achieved, which are much better than those of the sample fabricated via a conventional synthetic route (acetic acid as the catalyst). Moreover, according to the differing slopes of the discharge portion, the overall specific capacitance is divided into electric double layer capacitor (EDLC) and faradaic capacitance, and EDLC and faradaic capacitance contributions to the overall specific capacitance are analyzed. It is found that the faradaic capacitance is mainly associated with the heteroatom content and the utilization of available heteroatoms. The EDLC capacitance is related to the BET surface area, surface wettability, and the concentration and ionic size of the electrolyte. This simple synthetic strategy may be of interest in the design of crosslinked polymer precursors, thus enabling the fabrication of carbon materials with unique electrochemical properties. Moreover, our finding on EDLC and faradaic capacitance contributions to the overall specific capacitance is crucial for the future fabrication of nitrogen-doped carbons for supercapacitors.

In order to improve thermal and flame-retardant as well as mechanical properties of epoxy resins efficiently, a new P/N/Si-containing nano-filler called 2,4-(bis-polyhedral-oligomeric-silsesquioxane)-6-[(bis-9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-yl)amine]-(p-4-hydroxyphenyl)-1,3,5-triazine (abbrev. PDT) was synthesized by nucleophilic aromatic substitution reaction and was combined with curing-agent to prepare epoxy resin composites, incorporating both nanocaged framework of Si O and rigid phenyl-rings from triazine and DOPO into the epoxy matrix at molecular level. The prepared EP-PDT composites were characterized by means of techniques such as TGA-IR, Raman, SEM, EDX analysis, Py-GC/MS and XPS etc. It showed that all samples had a single Tg, indicating that these epoxy composites were homogeneous phase for long-term use. Both the LOI value and char yield increased with the increasing of PDT content, while the corresponding PHRR and THR data of EP composites dropped. SEM revealed that PDT in EP composites self-assembled into nano-sized particles, resulting in an enhanced mechanical property. Py-GC/MS and XPS characterizations showed that PDT could release free radicals and promote the char formation deriving from the synergic effect of phosphorus, nitrogen and silicon during combustion, which resulted in the formation of quenching and barrier effects to endow the EP composites with excellent thermal stability and flame retardancy for potential applications in many fields.

A novel strategy has been developed to generate B, N co-doped carbon materials (CNBs) through the pyrolysis of boronate polymer nanoparticles (BPNs) derived from the condensation reaction between catechol and boronic monomers. The morphology, surface area and heteroatom ( viz . B and N) content of the CNBs can be easily adjusted by altering the molar ratio between catechol and boronic monomers. The supercapacitor and oxygen reduction reaction (ORR) performance of the CNBs are optimized. CNBs derived from equal molar ratio of catechol and boronic monomers exhibit favorable performance for supercapacitor, featuring a specific capacitance of up to 299.4 F/g at 0.2 A/g, an improved rate capability and excellent cycle stability. Notably, CNBs prepared using 1/2 molar ratio of catechol to boronic monomers show excellent ORR performance, as they demonstrate good electrocatalytic activity, high tolerance for methanol and long durability. Our findings may be of interest in the design of carbon materials with optimized electrochemical properties through the control over surface area and the content of heteroatom.

Simultaneous introduction of both transition metal and other inorganic elements into the carbon matrix has attracted great attention in the fabrication of carbon materials with high electrochemical properties. Herein, rational design of ligand-iron coordinative supramolecular precursors is achieved for the fabrication of Fe-N/C catalysts, which possess high oxygen reduction reaction (ORR) performance. A series of precursors are prepared by a simple coordination reaction between a three armed catechol monomer and iron ions. Particular interest is focused on tuning the doping species, surface area and morphology of the Fe-N/C catalysts through a simple selection of iron resources. We show that an Fe-N/C catalyst derived from Fe2(SO4)3 at a carbonization temperature of 800 °C, has the optimized ORR performance with an onset potential of 0.930 V and half-wave potential of 0.801 V. Detailed investigation indicates that the synergistic effect among doping elements of nitrogen and sulfur and the unique carbon structure determines the performance of the Fe-N/C catalysts. Our findings may be of significance for the fabrication of doped carbon materials using coordinative supramolecular polymers as precursors.

Introduction of both nitrogen and transition metal elements into the carbon materials has demonstrated to be a promising strategy to construct highly active electrode materials for energy shortage. In this work, through the coordination reaction between Fe3+ and 1,3,5&ndash, tris(4&ndash, aminophenyl)benzene, metallosupramolecular polymer precursors are designed for the preparation of carbon flakes co-doped with both Fe and N elements. The asprepared carbon flakes display wrinkled edges and comprise Fe3C nanoparticle and active site of Fe&ndash, Nx. These carbon materials exhibit excellent electrocatalytic performance. Towards oxygen reduction reaction (ORR), the optimized sample has Eonset and Ehalf-wave of 0.93 V and 0.83 V in alkaline system, respectively, which are very close to that of Pt/C. This approach may offer a new way to high performance and lowcost electrochemical catalysts.

Incorporation of two or more types of metallic atoms into carbon matrix is of particular interest in the fabrication of high performance electrode materials. This normally requires complex synthetic routes or intricate post-processing process. Moreover, the composition and morphology of the resultant carbon materials are uncontrollable. Herein, we show the first time that a bimetal ions (Sn4+ and Fe3+) etching method based on Kirkendall effect can transform boronate polymer assemblies into metallosupramolecular polymer hollow spheres, which can be carbonized into carbon shells comprising FeSn2 alloy. The carbon shells display evidently improved activity towards oxygen reduction reaction with onset potential 0.94 V and half-wave potential 0.84 V vs. RHE, which are comparable to that of Pt/C. The as formed FeSn2 alloy in the carbon matrix possesses characteristics of rich in electrons, excellent conductivity and high chemical activity. Our supramolecular approach is simple, and able to control both the composition and morphology of the carbon materials, which may afford a new strategy for the design of higher performance electrochemical catalysts.

A new type of recyclable flexible solid-state supercapacitor with good electrochemical performance and folder ability is produced through a facile method. Polyvinylidene fluoride - acetylene black - polyethylene glycol - polyaniline (PVDF-AB-PEG-PANI) film electrode with excellent processability and tailorability is prepared by casting strategy, which uses large amount of PVDF as film former. The new electrode has good performance with excellent flexibility (dr

Heteroatom-doped carbon materials have been extensively studied in the field of electrochemical catalysis to solve the challenges of energy shortage. In particular, there is vigorous research activity in the design of multi-element co-doped carbon materials for the improvement of electrochemical performance. Herein, we developed a supramolecular approach to construct metallosupramolecular polymer hollow spheres, which could be used as precursors for the generation of carbon shells co-doped with B, N, F and Fe elements. The metallosupramolecular polymer hollow spheres were fabricated through a simple route based on the Kirkendall effect. The in situ reaction between the boronate polymer spheres and Fe3+ could easily control the component and shell thickness of the precursors. The as-prepared multi-element co-doped carbon shells showed excellent catalytic activity in an oxygen reduction reaction, with onset potential (Eonset) 0.91 V and half-wave (Ehalf-wave) 0.82 V vs reversible hydrogen electrode (RHE). The fluorine element in the carbon matrix was important for the improvement of oxygen reduction reaction (ORR) activity performance through designing the control experiment. This supramolecular approach may afford a new route to explore good activity and a low-cost catalyst for ORR.