Excimer Laser Patterned Holey Graphene Oxide Films for Nonenzymatic Electrochemical Sensing

Abstract

The existence of point defects, holes, and corrugations (macroscopic defects) induces high catalytic potential in graphene and its derivatives. We report a systematic approach for microscopic and macroscopic defect density optimization in excimer laser-induced reduced graphene oxide by varying the laser energy density and pulse number to achieve a record detection limit of 7.15 nM for peroxide sensing. A quantitative estimation of point defect densities was obtained using Raman spectroscopy and confirmed with electrochemical sensing measurements. Laser annealing (LA) at 0.6 J cm–2 led to the formation of highly reduced graphene oxide (GO) by liquid-phase regrowth of molten carbon with the presence of dangling bonds, making it catalytically active. Hall-effect measurements yielded a mobility of ∼200 cm2 V–1 s–1. An additional increase in the number of pulses at 0.6 J cm–2 resulted in deoxygenation through the solid-state route, leading to the formation of holey graphene structure. The average hole size showed a hierarchical increase, with the number of pulses characterized with multiple microscopy techniques, including scanning electron microscopy, atomic force microscopy, and transmission electron microscopy. The exposure of edge sites due to high hole density after 10 pulses supported the formation of proximal diffusion layers, which led to facile mass transfer and improvement in the detection limit from 25.4 mM to 7.15 nM for peroxide sensing. However, LA at 1 J cm–2 with 1 pulse resulted in a high melt lifetime of molten carbon and the formation of GO characterized by a high resistivity of 3 × 10–2 Ω-cm, which was not ideal for sensing applications. The rapid thermal annealing technique using a batch furnace to generate holey graphene results in structure with uneven hole sizes. However, holey graphene formation using the LA technique is scalable with better control over hole size and density. This study will pave the path for cost-efficient and high-performance holey graphene sensors for advanced sensing applications.

Fabricating Graphene Oxide/h-BN Metal Insulator Semiconductor Diodes by Nanosecond Laser Irradiation

“…Furthermore, this technique utilizes excimer lasers. Excimer lasers have the smallest wavelength compared with other candidate lasers and thus possess the advantage of higher resolution, making feasible the miniaturization and complex patterning process for bulk manufacturing of these devices [ 7 ].…”

“…The main novelty of these devices is the tunable Schottky barrier height, a feature that makes the graphene–semiconductor junction an excellent platform for the study of the interface transport mechanisms and applications in photo-detection, high-speed communications, solar cells, chemical and biological sensing, etc. [ 6 , 7 , 8 ]. Bartolomeo et al fabricated this device by transferring commercial graphene on a low-doped n-type Si substrate [ 9 ].…”

“…Notably, the limit of the resolution of the patterning is directly proportional to the wavelength of the laser used. Excimer lasers have the smallest wavelength compared with what other candidate lasers possess, and they thus possess the advantage of a higher resolution making feasible the miniaturization and complex patterning process necessary for the synthesis of 2D graphene and h-BN films [ 7 ].…”

Density-Induced Joule-Heating Characteristics of Nanocarbon Aerogels: Implications for Tunable Electrothermal Behaviors

“…Nanocarbon materials are becoming increasingly popular due to their remarkable physicochemical attributes, such as high surface area, good aspect ratio, superlative conductivity, impressive mechanical strength, outstanding thermal stability, and chemical inertness. − With these exceptional functional capabilities, this class of materials also showcases a wide range of dimensional variations, including fullerene, carbon nanohorn, , carbon nanotube, , graphene, − and graphitized nanofiber (GNF), , making them versatile for a broad spectrum of applications in emerging fields such as sensing, catalysis, environmental remediation, water generation, energy storage, and superconductors . An especially exciting attribute of nanocarbon materials is their ability to be assembled into three-dimensional (3D) nanocarbon aerogels through a variety of methods (e.g., hydrothermal method and polymer-assisted cross-linking method) to create highly porous and ultralight-weight bulk materials …”

Microneedle‐Integrated Device for Transdermal Sampling and Analyses of Targeted Biomarkers

“…The integrated system, which contained three fiber electrodes with distinct components, was assembled after modification with appropriate receptors. Owing to the excellent adsorption properties of activated CFs, [14][15][16] they were functionalized with Pd@Au core shell nanoparticle dispersions along with specific catalytic bioreceptors glucose oxidase (GO x ), lactate oxidase (LO x ), and 4-aminobenzo-18-Crown-6-ether (AOCE-6). This integrated portable microscale device enabled the parallel electrochemical detection of three clinically relevant analytes.…”