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Less defective, nitrogen-doped 3-dimensional graphene (N3DG) and defect-rich, nitrogen-doped 3-dimensional graphene (N3DG-D) were made by the thermal CVD (Chemical Vapor Deposition) process via varying the carbon precursors and synthesis temperature. These modified 3D graphene materials were compared with pristine 3-dimensional graphene (P3DG), which has fewer defects and no nitrogen in its structure. The different types of graphene obtained were characterized for morphological, structural, and compositional assessment through Scanning Electron Microscopy (SEM), Raman Spectroscopy, and X-ray Photoelectron Spectroscopy (XPS) techniques. Electrodes were fabricated, and electrochemical characterizations were conducted to evaluate the suitability of the three types of graphene for heavy metal sensing (lead) and Electric Double-Layer Capacitor (EDLC) applications. Initially, the various electrodes were treated with a mixture of 2.5 mM Ruhex (Ru (NH3)6Cl3 and 25 mM KCl to confirm that all the electrodes underwent a reversible and diffusion-controlled electrochemical process. Defect-rich graphene (N3DG-D) revealed the highest current density, followed by pristine (P3DG) and less-defect graphene (N3DG). Further, the three types of graphene were subjected to a sensing test by square wave anodic stripping voltammetry (SWASV) for lead detection. The obtained preliminary results showed that the N3DG material provided a great lead-sensing capability, detecting as little as 1 µM of lead in a water solution. The suitability of the electrodes to be employed in an Electric Double-Layer Capacitor (EDLC) was also comparatively assessed. Electrochemical characterization using 1 M sodium sulfate electrolyte was conducted through cyclic voltammetry and galvanostatic charge-discharge studies. The voltammogram and the galvanostatic charge-discharge (GCD) curves of the three types of graphene confirmed their suitability to be used as EDLC. The N3DG electrode proved superior with a gravimetric capacitance of 6.1 mF/g, followed by P3DG and N3DG, exhibiting 1.74 mF/g and 0.32 mF/g, respectively, at a current density of 2 A/g.
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Function Graded Carbon Micro‐Structures for Powerless Photon Sensing with Intriguing µm‐Scale Position Sensitivity
Abstract Partial laser treatment is introduced to carbon‐based microfibers to generate excellent photon sensing capability without bias. This treatment brings about a Seebeck coefficient distribution along the sample's length, out of which a photovoltage with no external bias is generated and sensed. Using a line‐shaped laser spot, carbon microfiber (CMF), graphene microfiber (GMF), and graphene aerogel fiber (GAF) are investigated for their response to µm‐scale photon irradiation. A higher sensitivity for the incident photon is found for the GAF with no position sensitivity. More Seebeck coefficient variation is also observed for the GAF considering the amount of laser power used for the laser treatment. A weaker Seebeck coefficient spatial variation is observed for the GMF compared with the GAF. However, its photovoltage shows an abrupt magnitude change from the laser‐treated region to the non‐treated one. Despite the low spatial variation of the Seebeck coefficient for the CMF, it features an excellent and accurate position‐sensitive photoresponse with polarization change over a distance of ≈100 µm. Such unique capability prompts novel applications in using partially annealed CMF for sensing the position of optical beams at the microscale.
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- PAR ID:
- 10641046
- Publisher / Repository:
- Wiley Blackwell (John Wiley & Sons)
- Date Published:
- Journal Name:
- Advanced Optical Materials
- Volume:
- 12
- Issue:
- 2
- ISSN:
- 2195-1071
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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