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• The bifunctional electrocatalyst, Ni(OH) 2 -CNT-Co 3 O 4 /NC, with good ORR and OER performance was prepared by thermal processes of ZIF-67@ZIF-8 and CBD. • The synergistic effect of the Ni(OH) 2 , Co 3 O 4 , N-doping in the catalyst showed high activities compared to the Pt/C and Ir/C catalyst. • The porous and graphitized carbon framework and CNTs in the catalyst are important for the electron conductivity and ion diffusion. • The Zn-air battery with the electrocatalyst demonstrated a high specific capacity of 805.4 mAh g−1 and energy density of 1021.7 Wh Kg−1. • The charge-discharge tests showed a very stable potential gap (0.65 V) with an excellent retention of 94.5% after 4500 cycles at 10 mA cm−2. A rechargeable zinc-air battery (RZAB) is a hopeful alternative battery solution to meet the world's ever-increasing energy storage need. Developing a high-performance electrocatalyst is one of the most critical challenges that need to be addressed for the RZAB to fulfill that role. A Ni(OH) 2 -CNT-Co 3 O 4 /NC catalyst consisting of carbon nanotube (CNT), cobalt oxide, and nitrogen-doped functionalities embedded in a porous carbon framework with two-dimensional Ni(OH) 2 nanosheets is reported. The prepared catalytic material, Ni(OH) 2 -CNT-Co 3 O 4 /NC, showed a high limit current density of -6.409 mA cm−2 during the oxygen reduction reaction (ORR), surpassing that of the commercial Pt/C (-5.625 mA cm−2). The oxygen evolution reaction (OER) potential for this electrocatalyst also reached 1.653 V at a current density of 10 mA cm−2, which is close to that of the commercial RuO 2 and thus showed excellent catalytic activity for the OER. As a bifunctional catalyst in the RZAB, the Ni(OH) 2 -CNT-Co 3 O 4 /NC electrocatalyst exhibited a high power density of 244.5 mW cm−2, and cycled 4500 times at a current density of 10 mA cm−2 while displaying good charge and discharge stability. Based upon these performances, we believe that the Ni(OH) 2 -CNT-Co 3 O 4 /NC catalyst can serve as an excellent bifunctional catalyst in the next-generation RZAB. [Display omitted] [ABSTRACT FROM AUTHOR]

We report on a 20–40 s process for growing aligned, uniformed, high purity multi-walled carbon nanotubes (MWNTs) using an alcohol lamp burner. With an appropriate catalyst precursor concentration, MWNTs can be grown on a Co-coated 304 stainless steel mesh under incomplete combustion conditions at 680–700°C. The process provides a rapid, easy, economic and safe method for the formation of carbon nanotubes. We suggest that the proposed method be considered as an educational kit for college or high school level experiments. [ABSTRACT FROM AUTHOR]

The commercialization of Proton Exchange Membrane Fuel Cells (PEMFCs) is hindering by the cost of noble metal catalysts. We are introducing A-Fe SAC -NC DS /rGO, a novel catalyst derived from metal-organic framework through carbonization and ammonia treatment. This catalyst is incorporating single iron atoms (Fe SAC) within dual-sized porous nitrogen-carbon frameworks (NC DS , 30 nm and 100 nm), supporting on reduced graphene oxide (rGO). The catalyst is providing abundant active sites, with NC DS increasing active site density and rGO enhancing material conductivity. Consequently, catalyst is exceling in the oxygen reduction reaction, boasting an onset potential of 0.807 V and a half-wave potential of 0.779 V, near benchmark Pt/C catalyst. PEMFC tests employing A-Fe SAC -NC DS /rGO achieved a power density of 780.7 mWcm−2 at 1.6 A cm−2 in an H 2 –O 2 system. In durability tests at 0.6 Acm−2 in H 2 -air, voltage loss was 28.68 % after 50 h. These results position the catalyst as a promising choice for PEMFC. [Display omitted] • A-Fe SAC -NC DS /rGO is derived from carbonization and ammonia treatment of MOFs. • Catalyst has abundant Fe SAC within dual-sized porous N-carbon supported on rGO. • Catalyst exhibits ORR LSV E onset and E 1/2 values close to the benchmark Pt/carbon. • PEMFC demonstrates a power density of 780.7 mWcm−2 at 1.62 Acm−2 in H 2 –O 2 system. • Durability test of PEMFC shows a voltage loss is 28.68 % at 0.6 Acm−2 after 50 h. [ABSTRACT FROM AUTHOR]

[Display omitted] • A Fe-Ni-Zn triple single atom catalyst is an excellent bifunctional catalyst for ORR and OER. • XAS and TEM studies confirm Fe, Ni and Zn SAC atomically dispersed in the matrix. • The SAC(Fe,Ni,Zn) with an optimal Fe/Ni ratio of 5:5 is used for ZAB. • The battery has good specific capacity(809 mAh/g @ 50 mA cm−2) and excellent power density of 300 mW cm−2 @ 406 mA cm−2. • A rechargeable Zn-air battery has superior cycle stability with 2150 cycles (358.3 h). The rechargeable Zn-air battery (ZAB) is a promising device for energy storage. A good bifunctional catalyst for oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) plays a decisive role in the ZAB. Here, we prepare a Fe-Ni-Zn triple single-atom catalyst (SAC) anchored in the nitrogen-doped porous carbon framework (NC) denoted as SAC(Fe, Ni, Zn)/NC or A-SAC(Fe, Ni, Zn)/NC (ammonia-treated) for the ZAB study. We found that not only Fe-N x , Ni-N x , and Zn-N x act as excellent catalytic sites for ORR and OER, but the synergetic effect by the three adjacent SAC(Fe, Ni, Zn) in the NC enhances the catalytic performance. As a result, the voltage difference (ΔE) of 0.75 V is achieved (half-wave potential of ORR: 0.88 V and the potential of OER at 10 mA cm−2: 1.63 V). In the rechargeable ZAB study, the battery with the A-SAC(Fe, Ni, Zn)/NC has a good specific capacity of 809 mAh/g @ 50 mA cm−2, the excellent power density of 300 mW cm−2 @ 406 mA cm−2 and superior cycle stability (2150 cycles, 358.3 h @ 10 mA cm−2) while the all-soild-state ZAB showed promising power density of 64.5 mW cm−2 and acceptable cycling durability over 25 h@1 mA cm−2. Triple SAC(Fe, Ni, Zn) in the hierarchical porous NC possesses the bifunctional catalytic capability, high ionic diffusivity, and electron conductivity. [ABSTRACT FROM AUTHOR]

Abstract: Turbostratic carbon nanofibers (CNFs), platelet graphite nanofibers (PGNFs) and tubular graphite nanofibers (TGNFs, also called multi-walled carbon nanotubes) were synthesized using thermal decomposition from a mixture of poly(ethylene glycol) and NiCl2. A detailed study found that the synthesis temperature dramatically affected the morphology and topography of the catalysts, which play an important role in the synthesis of the various CNFs. At the temperature of 600°C, irregular shape nanocatalysts with very rough surfaces were formed for the synthesis of turbostratic CNFs. Cubic-like nanocatalysts were formed at 750°C for PGNFs and truncated cone-like nanocatalysts were formed at 850°C for TGNFs. The surface roughness and the shape of the catalysts determined the stacking order of the graphene layers so that different types of CNF were formed. The growth direction of the graphene layers was from the Ni(111) plane for PGNFs and from the Ni(110) plane for TGNFs. Characterizations and field emission properties of these materials were also studied and compared. [Copyright &y& Elsevier]

In this study, carbon-nanotube (CNT)-grafted and nano Co 3 O 4 -doped porous carbon was prepared by the carbonization of a synthesized zeolitic imidazolate framework compound (ZIF-67/ZIF-8) followed by an oxidation treatment. The novel catalyst demonstrated excellent ORR and OER because of the Co 3 O 4 nanoparticles and nitrogen-doped in the carbon framework (NC). In addition, the carbon nanotube grafted on the framework provided a good electrical conductivity while the carbon framework matrix provided a porous skeleton which is beneficial for the mass transfer of electrolyte. In the ORR study, the novel catalyst, CNT-Co 3 O 4 /NC, showed a half-wave potential of −0.124 V at 0.1 M KOH (Pt/carbon: −0.152 V) while the limited current density is 4.84 mA/cm2 (Pt/carbon: 4.9 mA/cm2). In terms of OER performance, the potential is 0.819 V at current density of 10 mA/cm2 (Ir/carbon: 0.771 V). The CNT-Co 3 O 4 /NC catalyst shows a specific capacitance of 814 mAh/g (1.19 V at 50 mA/cm2), which is very close to the theoretical capacitance (820 mAh/g) and the maximum power density was 267 mW/cm2 (0.746 V at 385 mA/cm2) while 255 mW/cm2 (0.711 V at 360 mA/cm2) was obtained using Pt/carbon catalyst. We believe that the novel CNT-Co 3 O 4 /NC can be used as an excellent catalyst in the zinc-air battery. Image 1 • A 3D-network of Co 3 O 4 , NC and CNT show efficient activity in ORR/OER. • The CNT-Co 3 O 4 /NC is as a promising catalyst with specific capacitance of 814 mAh/g. • The ZABs revealed a high peak power density of 267 mW cm2 (0.746 V at 385 mA/cm2). • A better cycling performance of the ZAB using CNT-Co 3 O 4 /NC catalyst than Pt/Carbon. [ABSTRACT FROM AUTHOR]