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New fabrication method for producing reduced graphene oxide flexible electrodes by using low-power visible laser diode engraving system
摘要： The fabrication of bendable electronic devices is being a scientific-technological area of very rapid advance in which new materials and fabrication techniques are being continuously developed. In this kind of devices, the fabrication of flexible conductive electrodes adherent to the substrate is a key factor. Besides, eco-friendliness, low cost and fast production are essential requirements for the successful progress of new technologies. In this work, a novel method for obtaining graphene-based flexible electrodes is presented. Conductive films were obtained by means of visible laser irradiation of graphene oxide layers deposited on polyethylene terephthalate substrates besides self-standing membranes sandwiched between glass slides. Despite the low power of the laser system, numerical simulations indicate the development of temperatures over 1000 K throughout the irradiated material. The laser-induced spatially confined heating leads to the reduction of the graphene oxide material whereas the glass-based sandwich assembly avoids reoxidation from surrounding air. By scanning and pixelated modes, reduced graphene oxide electrodes, up to 100 μm in thickness, and with resistivity as low as 6×10-4 ?m were obtained in an easy and versatile way. Proof-of-concept microsupercapacitors and electrochemical sensors were fabricated with this technique, showing promising performance.
关键词： laser fabrication,flexible electrode,laser-reduced graphene oxide,graphene electrode
更新于2025-09-23 15:21:01
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Origin of the Overpotential for the Oxygen Evolution Reaction on a Well-defined Graphene Electrode Probed by in situ Sum Frequency Generation Vibrational Spectroscopy
摘要： To develop an efficient material for the cathode of the lithium-oxygen (Li-O2) secondary battery, the oxygen reduction and evolution reactions (ORR and OER) on a well-defined graphene monolayer have been investigated in a typical organic solvent, dimethyl sulfoxide (DMSO). The adsorption and desorption behaviors of the solvents on the graphene electrode surface were evaluated by an intrinsically surface-selective vibrational spectroscopy of sum frequency generation (SFG) during the ORR and OER. After the initial ORR depositing lithium peroxide (Li2O2) on the graphene electrode surface in a LiClO4/DMSO solution, the SFG spectroscopy revealed that the subsequent OER oxidizing the Li2O2 preferentially proceeds at the interface between the Li2O2 and graphene rather than that between the Li2O2 and bulk solution. Therefore, the OER tends to reduce the electric conductivity between the Li2O2 and graphene by decreasing their contact area before a large part of the deposited Li2O2 was oxidized, which elucidates the origin of the high overpotential for the OER.
关键词： oxygen reduction reaction,lithium-oxygen battery,oxygen evolution reaction,sum frequency generation vibrational spectroscopy,graphene electrode
更新于2025-09-23 15:21:01
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Structure-activity relationships of hierarchical three-dimensional electrodes with photosystem II for semi-artificial photosynthesis
摘要： Semi-artificial photosynthesis integrates photosynthetic enzymes with artificial electronics, which is an emerging approach to reroute the natural photoelectrogenetic pathways for sustainable fuel and chemical synthesis. However, the reduced catalytic activity of enzymes in bioelectrodes limits the overall performance and further applications in fuel production. Here, we show new insights into factors that govern the photoelectrogenesis in a model system consisting of photosystem II and three-dimensional indium tin oxide and graphene electrodes. Fluorescence microscopy and in situ surface-sensitive infrared spectroscopy are employed to probe the enzyme distribution and penetration within electrode scaffolds of different structures, which is further correlated with protein film-photoelectrochemistry to establish relationships between the electrode structure and enzyme activity. We find that the hierarchical structure of electrodes mainly affects the protein integration, but not the enzyme activity. Photoactivity is more limited by light intensity and electronic communication at the biointerface. This study provides guidelines for maximizing the performance of semi-artificial photosynthesis and also presents a set of methodologies to probe the photoactive biofilms in three-dimensional electrodes.
关键词： semi-artificial photosynthesis,Photosystem II,inverse opal,graphene electrode,indium tin oxide electrode
更新于2025-09-19 17:15:36
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Design of zinc oxide-based surface acoustic wave sensors using a graphene electrode
摘要： Continuous monitoring of skin moisture by using a wearable moisture sensor consisting of the materials that have no risk of skin sensitization, such as zinc oxide (ZnO), is essential to optimize the healing process in wound care. Here we tackled the investigation of the optimum electrode for ZnO-based surface acoustic wave (SAW) sensors to achieve this goal. Al and Au electrodes commonly used were compared with a graphene electrode by simulation in terms of the frequency characteristics of the SAW device. Graphene and Al showed the same tendency in frequency characteristics as the 0 thickness electrode (ideal electrode). Since graphene is suitable for flexible devices due to its stretchability and for the long-term stability due to its chemical innerness, it was concluded that graphene is more suitable than the conventional Al and Au electrodes for flexible SAW sensor devices.
关键词： flexible devices,surface acoustic wave sensors,wearable moisture sensor,zinc oxide,graphene electrode
更新于2025-09-04 15:30:14