Cobalt Nanoparticles and Atomic Sites in Nitrogen‐Doped Carbon Frameworks for Highly Sensitive Sensing of Hydrogen Peroxide

Abstract

In situ monitoring of hydrogen peroxide (H2O2) during its production process is needed. Here, an electrochemical H2O2 sensor with a wide linear current response range (concentration: 5 × 10−8 to 5 × 10−2 m), a low detection limit (32.4 × 10−9 m), and a high sensitivity (568.47 µA mm−1 cm−2) is developed. The electrocatalyst of the sensor consists of cobalt nanoparticles and atomic Co‐Nx moieties anchored on nitrogen doped carbon nanotube arrays (Co‐N/CNT), which is obtained through the pyrolysis of the sandwich‐like urea@ZIF‐67 complex. More cobalt nanoparticles and atomic Co‐Nx as active sites are exposed during pyrolysis, contributing to higher electrocatalytic activity. Moreover, a portable screen‐printed electrode sensor is constructed and demonstrated for rapidly detecting (cost ≈40 s) H2O2 produced in microbial fuel cells with only 50 µL solution. Both the synthesis strategy and sensor design can be applied to other energy and environmental fields.

A flexible carbon nanotube@V2O5 film as a high-capacity and durable cathode for zinc ion batteries

“…In addition to the proper mechanical properties and excellent energy storage performance, safety has been imposed with a high priority for such devices [1][2][3][4][5][6], in which toxic and flammable components should be avoided as much as possible [7][8][9]. Recently, zinc, a much safer and cheaper alternative to lithium metal, has been used as the anode material for rechargeable zinc-ion batteries (ZIBs) [10][11][12]. Besides its own non-flammability, the utilization of aqueous and neutral electrolytes for ZIBs also brings extra benefits, including simple manufacture, low cost, and safe operation [13][14][15][16].…”

“…As a result, the strategy of directly integrating the high-capacity cathode materials for ZIBs with different types of flexible and conductive substrates has been often adopted. By far, a number of substrates, including metal foils, carbon fiber textiles, graphene, and carbon nanotubes (CNTs), have been used for this purpose [12,[18][19][20][21][22][23][24][25][26][27]. Among them, CNTs and their assemblies have distinct virtues in terms of lightweight, high conductivity, good mechanical flexibility [1,[28][29][30], and, more importantly, the matureness for continuous production at a low cost that matches well with the inexpensive feature of ZIBs [30].…”

Tailoring atomically dispersed cobalt–nitrogen active sites in wrinkled carbon nanosheets via “fence” isolation for highly sensitive detection of hydrogen peroxide

“…4b, both deconvoluted C 1s spectra can be fitted into four peaks at about 284.8, 286, 286.5, and 287.5 eV, which can be ascribed to C–C/CC, C–N, C–O–C, and CO, respectively. 13,35 The higher graphitization degree of Co (4%)–N/CNS can be further confirmed by the increase of the content of C–C/CC bonds from 54.25% to 55.57% compared with that of Co (4%)–N/C (Table S3†). Besides, the more pronounced C–N peak of Co (4%)–N/CNS than that of Co (4%)–N/C is consistent with its higher N content (5.34%).…”

“…12 Deriving TM-N/C electrocatalysts with abundant active sites and uniform micro/mesopores from rationally designed MOFs as self-sacrificing templates has been demonstrated to be one of the most effective ways. 13 Generally, sub-micron MOFs maintain their original structures after heat treatment. However, this uncontrolled heat treatment usually leads to the agglomeration of metals attached or enclosed in the graphitic carbon shell, forming metal particles with a wide ranging size distribution.…”

“…21 To increase the nitrogen content of the MOF-derived TM-N/C electrocatalysts, introducing other solid-phase carbon and nitrogen sources for auxiliary preparation during the pyrolysis process has been proven feasible. 22 Jiang et al 13 applied a urea-assisted pyrolysis of ZIF-67 to increase the amount of bonded nitrogen and successfully created more and uniformly dispersed metal active sites. Although previous studies have well addressed some of the challenges in the synthesis of MOF-derived TM-N/C electrocatalysts with metal atoms as active sites, the final electrocatalysts inherited the original polycell structure of MOFs, and the metal atoms present inside the structure could not be fully utilized.…”