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Nitrogen-doped carbon materials with highly porous structures and interconnected ultrathin frameworks have shown outstanding features for electrocatalytic applications. Herein, we propose a self-assembly strategy to prepare nitrogen-doped carbon sponge (NCS) with high porosity, an ultrathin framework, and a high content of active nitrogen species for high performance oxygen reduction reaction (ORR) by direct pyrolysis of the polymeric precursor. Amphiphilic poly(amic acid) (PAA) can self-assemble into a highly porous sponge-like structure (donated as PAA sponge). After pyrolysis, the high porosity and ultrathin framework of the PAA sponge are well inherited. The nitrogen species in the PAA sponge convert to pyridinic and graphitic nitrogen when pyrolyzed at 800 °C to give NCS-800, corresponding to an atomic percent of 4.6%, which are believed to be the origin of ORR catalytic activity. The NCS-800 shows high catalytic performance toward the ORR and superior methanol tolerance and long-term stability in comparison to Pt/C. After 30 hours, the relative current density is still as high as 92.4%, which is much higher than that of Pt/C (73.7%). This strategy can be extended to facilely prepare doped carbon materials with tailored morphologies and heteroatom species by choosing appropriate monomers from the abundant library of diamines and dianhydrides. [ABSTRACT FROM AUTHOR]

Heteroatomic doping of porous carbon materials can give rise to variations in the electronic structure and properties, and has been used to enhance the adsorption and separation of CO 2. Herein, N and S doped zeolite-templated carbon (ZTC) are synthesized to study their CO 2 adsorption and selective from CO 2 /N 2. ZTC-N, ZTC-S and ZTC-NS exhibit comparatively high CO 2 adsorption of 6.12, 7.73 and 9.32 mmol g−1 at 0 °C, which are more than three times than that of ZTC (1.98 mmol g−1). The CO 2 adsorption capacity for ZTC-NS at 25 °C and 1 bar can reach as high as 6.03 mmol g−1, which can still occupy approximately 96% after 5 cycles. The obtained carbon materials ZTC-NS with the smallest BET surface area show the highest CO 2 adsorption capacity, which indicate an obvious synergistic enhancement effect between sulfur and nitrogen doping. The detailed theoretical calculations indicate N and S co-doping into porous carbon materials assists the change of electrostatic surface potential and local electronic density, thus enhanced the CO 2 adsorption. N and S co-doping into carbon structure are more beneficial to change internal electronic structure for enhancing the CO 2 adsorption and separation. [Display omitted] • N and S doped microporous zeolite-templated carbon (ZTC) are synthesized. • Microporous structure endow zeolite-templated carbon material with high specific surface areas. • DFT further elucidate the role of N and S co-doping for CO 2 adsorption. • The microporous carbon has application potentials in industrial CO 2 adsorption. [ABSTRACT FROM AUTHOR]

Refined architectures are of vital importance in determining the electrocatalytic activity of oxygen reduction reaction (ORR) and oxygen evolution reaction (OER). Herein, pyridinic N B pair doped carbon microspheres (NB-CMS) with hierarchical micropore-mesopore structure are prepared via a SiO 2 hard template assisted CO 2 activation strategy. The pyridinic N B pair accounts for ≈ 59.9 % of all N species in NB-CMS, accelerating the ORR process with onset potential (0.996 V) and half-wave potential (0.889 V). Meanwhile, the NB-CMS also exhibits high OER performance with overpotential of 384 mV at 10 mA cm−2. The assembled Zinc-air battery exhibits maximum power density of 134 mW cm−2 and long-term charging and discharging stability over 358 h. Density functional theory (DFT) simulations reveal that the pyridinic N B pair exhibits the highest electrocatalytic performance in dual-functional catalysis, owing to the highest charge density and readily accepts electrons from *OOH adsorbate of N active site neighboring B. Pyridinic N B pair doped carbon microspheres (NB-CMS) with hierarchical meso-microporous structure are prepared via a SiO 2 hard template assisted CO 2 activation strategy. The ORR and OER catalytic performance of NB-CMS outperforms most prior carbon-based electrocatalysts and comparable to commercial Pt/C (20 %) and RuO 2. [Display omitted] • Hard-templating assisted CO 2 activation yields hierarchical porous uniform carbon. • Thermally tailored graphitization and N/B configuration in carbon nanostructures. • Highly-active bifunctional NB-CMS catalyst for rechargeable zinc-air batteries. • DFT reveals Pyridinic N B optimizes ORR/OER through superior *OOH adsorption dynamics. [ABSTRACT FROM AUTHOR]

[Display omitted] • Nitrogen-doped carbon-supported Fe 7 C 3 clusters with hierarchical pore structure were synthesized. • A two-step method of liquid-phase impregnation combined with physical activation. • N-doped carbon and Fe 7 C 3 synergistically reduce potential-limiting step free energy. • The excellent performance of which the overpotential reached 181 mV. As the crucial step of electrolytic water, oxygen evolution reaction (OER) is urgent to be enhanced by developing the most efficient electrocatalysts to accelerate the sluggish OER kinetics. Herein, nitrogen-doped carbon-based Fe 7 C 3 clusters with hierarchical pore structure (NHAC@Fe 7 C 3) were synthesized via a two-step method of FeCl 3 and seaweed liquid-phase impregnation combined with physical activation. The optimum NHAC@Fe 7 C 3 = 3:1 catalyst (with a mass ratio of Sargassum Horneri to FeCl 3 of 3:1) demonstrated much better catalytic activity and durability towards OER in alkaline electrolyte than the most noble-metal-free catalysts, of which the overpotential reached 181 mV at 10 mA cm−2. Long-term discharging stability of over 33 h at 10 mA cm−2 current density. The excellent performance is attributed to the synergistic effect of graphitic carbon and Fe 7 C 3 clusters, hierarchical pore structure and good electrical conductivity. Density functional theory calculations confirm that the free energy for the potential-limiting step is reduced by the synergistic effect of N-doped carbon and Fe 7 C 3 substrance. This study employs a simple and effective method to synthesize iron carbide embedded in algae-derived biochar, providing an opportunity for the rational design of robust performance electrocatalysts for oxygen evolution reaction. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • The mesoporous Ni x Co 1-x Fe 2 O 4 nanostructured microspheres with tunable composite were synthesized by a solvothermal method. • The Ni-doping into CoFe 2 O 4 could lead to an increase in the concentration of oxygen vacancies and specific surface area. • The gas-sensing tests to toluene showed that the Ni 0.33 Co 0.67 Fe 2 O 4 microspheres showed highest gas-sensing sensitivity. • The suitable Ni-doping was good for the sensing properties of Ni x Co 1-x Fe 2 O 4 , which were suppressed with the more Ni doping. Abstract The mesoporous Ni x Co 1-x Fe 2 O 4 (x = 0, 0.33, 0.50, 0.67) nanostructured microspheres with tunable composite were successfully controllable synthesized by a simple solvothermal method. The results of XRD, XPS and FT-IR demonstrated that the Ni, taking the place of Co, were successfully doped into CoFe 2 O 4. The gas sensing results demonstrated that the Ni 0.33 Co 0.67 Fe 2 O 4 nanostructured microspheres showed higher gas-sensing response and better selectivity to harmful toluene than that of other samples. Moreover, the influences of Ni-doping amount on the structure, morphology and gas-sensing property of Ni x Co 1-x Fe 2 O 4 were investigated. The enhanced gas-sensing properties of gas sensor based on Ni 0.33 Co 0.67 Fe 2 O 4 to toluene may be due to appropriate Ni-doping into cobalt ferrite which resulted in the increased concentration of oxygen vacancies, large specific surface area (77.2 m2 g−1) and suitable catalytic activity. Therefore, the Ni x Co 1-x Fe 2 O 4 will be a promising candidate for gas-sensing material for detecting toluene. [ABSTRACT FROM AUTHOR]