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Developing highly effective and stable non‐precious bifunctional oxygen electrocatalysts is crucial and challenging. Herein, we report nano‐mediated straight bamboo‐shaped nitrogen‐doped carbon nanotubes modified with encapsulated NiCo2S4‐based nanoparticles (E‐NiCo2S4/SBS‐NCNTs) by electrodeposition and procedural calcination strategy, in which nitrogen‐doped carbon nanotubes with straight bamboo shape (SBS‐NCNTs) show more average diameter and encapsulated NiCo2S4‐based nanoparticles (E‐NiCo2S4) are coated by carbon, and what makes us even more excited is that they are evenly dispersed on SBS‐NCNTs surface, not just at the tip or inside. When applied for oxygen evolution reaction (OER) and oxygen reduction reaction (ORR), E‐NiCo2S4/SBS‐NCNTs show excellent catalytic activity, and onset potential (Eonset) in OER and ORR is only 1.52 V and 0.95 V (vs. RHE) in 0.1 M KOH, respectively. More importantly, the hybrids exhibit good methanol tolerance, with almost unchanged for ORR performance after adding 0.5 M methanol, and it has highly stability, the current density dropped by 22% after 7 h of reaction. The interaction of NiCo2S4 with the external carbon layer can greatly enhance the electrocatalytic activity toward the OER and it has a complete 4e– reaction process toward the ORR. The excellent electrocatalytic activity is mainly due to synergistic enhancement effect, in which SBS‐NCNTs with highly catalytic activity provide good conductivity, expose more active sites and promotes fast mass transfer; Carbon‐coated NiCo2S4‐based nanoparticles can improve the local work function of SBS‐NCNT through synergistic electronic interaction, promoting O2 adsorption, ensure rapid electron transport, and enable SBS‐NCNT to improve its electrocatalytic activity. Because of the weakness of Ostwald effect and synergistic enhancement, the stability and catalytic activity of NiCo2S4‐based nanoparticles can be greatly improved. All these advantages can synergistically improve the electrocatalytic efficiency and make it become one of the most promising bifunctional oxygen electrocatalysts. [ABSTRACT FROM AUTHOR]

Here, we successfully synthesized N‐doped carbon nanotubes embedded with nickel‐based nanoparticles on the top (N‐CNTs/E‐NNPs) by directly procedural calcination of melamine and nickel foam at 520 °C, 540 °C and 700 °C in Ar. When applied for oxygen reduction reaction (ORR), the onset potential and half‐wave potential are 0.96 V and 0.86 V in 0.1 M KOH, comparable to that of the commercial 10 wt% Pt/C. Moreover, the hybrids possess higher stability and better methanol tolerance. Additionally, the Tafel slope of N‐CNTs/E‐NNPs is 76 mV dec−1 in 0.1 M KOH, lower than 83 mV dec−1 of the commercial 10 wt% Pt/C, demonstrating a good kinetic process. The remarkable features are mainly ascribed to synergistic enhancement effect from N‐rich doped carbon nanotubes (N‐CNTs) and embedded Ni‐based nanoparticles on the top, promoting mass and electrons transport, enhancing the activity of active sites and making it a promising highly efficient non‐precious metal ORR catalyst. [ABSTRACT FROM AUTHOR]

Engineering favorable plasmonic-based catalytically active nanostructures has been an essential part of 2,4,6-trinitrotoluene (TNT) sensing due to their synergistically enhanced catalytic performance. However, how to increase the catalytically dynamic species and improve their electrocatalytic activity is still challenging. Herein, smart plasmonic AgPtPd porous nanoparticles anchored on reduced graphene oxide (AgPtPd NPs/rGO) have been developed as a novel material for TNT detection using a wet-chemical reduction strategy in which Ag nanoparticles were used as the starting template. The smart plasmonic AgPtPd nanoparticles show a porous 3D flower-like morphology, which contribute mainly to the high-performance electrochemical detection of TNT. Meanwhile, adsorbent-assisted reduced graphene oxide with a good adsorption capacity toward TNT was introduced. When used in electrochemical TNT detection, the AgPtPd NPs/rGO exhibits a wide linear range from 0.1 to 8 ppm with a limit of detcetion (LOD) of 0.95 ppb, which is much better than the previous study. The remarkable features are probably attributed to the integrated advantages of the plasmonic properties and the synergistic effect between the smart plasmonic AgPtPd porous nanoparticles (with highly micro-reactive sites) and rGO (with good adsorption capacity toward TNT). The results show that smart plasma nanocrystals supported by rGO have broad application prospects for high-performance electrochemical sensors. [ABSTRACT FROM AUTHOR]

CP@NC-CoFe 2 O 4 /C as catalysts for OER: we covered a polyaniline nanowire array on carbon paper by a electrochemical polymerization method, directly grown MOF-74-Co/Fe on its surface and pyrolyzed to form the CoFe 2 O 4 /C supported on nitrogen-doped carbon nanoarray meterial, which is prepared a highly active and stable OER catalyst. High specific surface area, high utilization of the catalyst, enhanced electron transport characteristics and retention characteristics of the original carbon paper characteristics ensure excellent OER activity. Our results show great promise for developing OER catalysts as precious metal substitutes for PANI and MOFs complexes through a low-cost, scalable method. [Display omitted] • Polyaniline nanowire array was covered on carbon paper, directly grown MOF-74-Co/Fe on its surface. • The presence of PANI nanowire arrays also retains the original properties of carbon paper. • The unique 3D nano-array structure enhance the OER catalytic efficiency. • DFT reveals the main surface adsorbent is OH*, and surface Co atoms are the main active sites. Here, we covered a polyaniline nanowire array (denoted as PANI) on carbon paper (denoted as CP) by a electrochemical polymerization method, directly grown MOF-74-Co/Fe on its surface and pyrolyzed to form the CoFe 2 O 4 /C supported on nitrogen-doped carbon nanoarray materials (denoted as NC-CoFe 2 O 4 /C@CP), which is prepared a highly active and stable OER catalyst. PANI can not only be used as a "binder", grow MOF on its surface and cover the carbon paper, but also improve the conductivity and stability of the material by forming nitrogen-doped carbon after pyrolysis. And its unique 3D nano-array structure not only greatly increases the surface area, but also provides more attachment sites for CoFe 2 O 4 , thereby accelerating electron transport and improving OER performance. High specific surface area, high utilization of the catalyst, enhanced electron transport characteristics and retention characteristics of the original carbon paper characteristics ensure excellent OER activity. The final sample exhibits outstanding activity for OER in alkaline solution, accompanied by a low onset potential about 1.52 V (vs reversible hydrogen electrode), and the small Tafel slope of 70 mV dec−1. In particular, after 21600s, the current drop is negligible, which is means that the NC-CoFe 2 O 4 /C@CP catalyst has the high stability. Density Functional Theory (DFT) calculation reveals the main surface adsorbent of CoFe 2 O 4 is OH*, and the surface Co atoms are the main active sites. [ABSTRACT FROM AUTHOR]

3D HPN-GCNS/Co@CoO x as catalysts for ORR: The hybrids were fabricated by a controllable grading-pyrolysis strategy. The hybrids show 3D fluffy and hierarchically porous nanostructure in and out-of-plane, resulting in large accessible specific activity area, allowing the species to efficiently participate in ORR and facilitating the fast mass transfer; the graphene-like C nanosheets with N-rich dopant promote O 2 adsorption and assure fast electron transport; large numbers of Co@CoO x -based nanoparticles uniformly embedded on the C nanosheets and mesoporous active edge introduce more ORR active sites. The remarkable features synergistically enhance the ORR catalytic efficiency, making it a promising low-cost, highly efficient ORR catalyst. • The hybrids were successfully fabricated by a controllable grading pyrolysis strategy. • Graphene-like C nanosheets with N-rich dopant show in and out-of-plane nanostructure. • Co-based nanoparticles uniformly embedded on fluffy and hierarchically C nanosheets. • The remarkable features synergistically enhance the ORR catalytic efficiency. Here, Co@CoO x -based three-dimensional nitrogen-doped graphene-like carbon nanosheets (denoted as 3D HPN-GCNS/Co@CoO x) are fabricated by controllable grading-pyrolysis strategy, in which they show 3D fluffy and hierarchically porous nanostructure in and out-of-plane; large numbers of Co@CoO x -based nanoparticles uniformly embedded on graphene-like C nanosheets and mesoporous active edge introduce more ORR active sites. When applied for ORR, hybrids exhibit a half-wave potential (E 1/2) of 0.87 V and an onset potential (E onset) of 0.92 V in 0.1 M KOH, comparable to that of commercial 20% Pt/C. The hybrids display better methanol tolerance and stability, with almost no change of ORR performance before and after 5000 cycles. H 2 O 2 yield in ORR process is less than 5% and number of electron transfer is higher than 3.9. The remarkable features are mainly ascribed to synergistic enhancement effect, in which 3D fluffy and hierarchically porous nanostructure in and out-of-plane supplies large accessible specific activity area, allows species to efficiently participate in ORR and facilitates fast mass transfer; graphene-like C nanosheets with N-rich dopant promote O 2 adsorption and assure fast electron transport; large numbers of Co@CoO x -based nanoparticles introduce more ORR active sites. All the advantages synergistically enhance the ORR efficiency and make it a highly efficient ORR catalyst. [ABSTRACT FROM AUTHOR]

CoN x -based helically coiled nitrogen-doped carbon nanotubes (CoN x /HCN-CNTs) for electrochemical oxygen reduction: The hybrids were fabricated by two-step pyrolysis strategy, in which the helically coiled nitrogen-doped carbon nanotubes (HCN-CNTs) show a uniform diameter of approximately 50 nm and CoN x -based nanoparticles are not only distributed either at the tip or inside of HCN-CNTs, but excitingly, they are uniformly dispersed on the surface of HCN-CNTs. The remarkable features have greatly assured higher ORR catalytic efficiency, better methanol tolerance and stability than commercial 20% Pt/C, making it a promising low-cost, highly efficient ORR catalyst. • Hybrid electrocatalysts are successfully fabricated by two-step pyrolysis strategy. • N-CNTs show uniform diameter of about 50 nm and helically coiled nanostructure. • CoN x -based nanoparticles can be uniformly dispersed on the surface of HCN-CNTs. • The hybrids possess higher ORR activity, stability and better methanol tolerance. Here, CoN x -based helically coiled nitrogen-doped carbon nanotubes (CoN x /HCN-CNTs) are reported based on two-step pyrolysis strategy, in which the helically coiled nitrogen-doped carbon nanotubes (HCN-CNTs) show uniform diameter of approximately 50 nm and CoN x -based nanoparticles are not only distributed either at the tip or inside of HCN-CNTs, but excitingly, they are uniformly dispersed on the surface of HCN-CNTs. When applied for ORR, CoN x /HCN-CNTs show excellent ORR activity, with good onset potential and higher current density, comparable to that of the commercial 20% Pt/C. The half-wave potential is 0.92 V (vs reversible hydrogen electrode, RHE) in 0.1 M KOH, 20 mV higher than that of 20% Pt/C. Most importantly, CoN x /HCN-CNTs display better methanol tolerance and higher stability. After 28,800 s, the current density only decreased by 1.4%. The high ORR performance maybe related with synergistic enhancement effect, in which CoN x -based nanoparticles can induce a host-guest electronic interaction and according improve the local work function of the HCN-CNTs, making carbon layer have higher ORR activity; meanwhile, the ORR activity of embedded CoN x -based nanoparticles can be greatly improved, mainly attributing to the protection of HCN-CNTs and weakness of the Ostwald-ripening-like effect in ORR progress. The features make it one of the best non-noble-metal catalysts for ORR. [ABSTRACT FROM AUTHOR]

• CoP 3 /FeP on nitrogen-doped carbon nanoarrays for HER was prepared. • The hybrids were produced by a low-temperature phosphating reaction. • The hybrids possess good HER activity and higher stability. • The features are ascribed to synergistic enhancement. With the gradual exhaustion of fossil energy and the increasingly serious climate problem, hydrogen, as a clean and sustainable energy source, has become the focus of new energy development due to its high energy density. Here, we reported a stable performance nitrogen-doped carbon material coated with CoP 3 /FeP nanoarrays (N C@CoP 3 /FeP) which is produced by a low-temperature phosphating reaction. The experiment proves that combining the phosphide with the nitrogen-doped carbon material increases the electron mobility of the catalyst and improves the slow kinetics of the electrochemical reaction. The obtained N C@CoP 3 /FeP had excellent electrocatalytic performance in 0.5 M H 2 SO 4 electrolyte, the initial overpotential of N C@CoP 3 /FeP was only 50.04 mV with a low Tafel slope (70 mV dec−1) and impedance. Additionally, this electrode offers excellent durability whose current density remains 96.3% after 6 h. [ABSTRACT FROM AUTHOR]