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Öğe The Mo catalyzed graphitization of amorphous carbon: an in situ TEM study(Royal Soc Chemistry, 2019) Sharma, Subash; Jaisi, Balaram Paudel; Araby, Mona Ibrahim; Elnobi, Sahar; Ayhan, Muhammed Emre; Kalita, Golap; Tanemura, MasakiFor the fabrication of graphene-based nano-scale interconnects, precise control over their position and proper nanoscale soldering are essential. In this work, we report the Joule heat-induced conversion of amorphous carbon to graphene in an in situ TEM setup, using Mo as a catalyst. The catalytic role of Mo during graphene formation has been less explored compared to other metals like Cu or Ni. Compared to metals like Cu, Mo is less subject to electromigration and brittleness, making it suitable for high-temperature electronics. We found that during the electromigration of Mo, amorphous carbon nanofibers (CNFs) can be converted to highly crystalline few-layered graphene. It was also found that during the graphene formation process, agglomerated Mo particles can be effectively channeled to the end of graphene by voltage-driven electromigration. An agglomerated Mo particle between the probe and graphene acted as a soldering agent, providing the prospect of the further exploration of Mo as a nanoscale soldering material. This work explores the double role of Mo: as a catalyst for graphene synthesis and as a soldering material.Öğe Silver nanoparticle doped graphene-based impedimetric biosensor towards sensitive detection of procalcitonin(Elsevier, 2023) Selimoğlu, Faysal; Gür, Bahri; Ayhan, Muhammed Emre; Gür, Fatma; Kalita, Golap; Tanemura, Masaki; Alma, Mehmet HakkıIn the early detection of sepsis, procalcitonin (PCT) appears to be a highly sensitive biomarker for severe inflammation and infection. A significant interaction between the electrode material to be used in the design of the biosensor and the material to be attached to the surface is of great importance. Here, we demonstrated a silver nanoparticle (AgNp) doped graphene-based sensitive PCT biosensor with low-cost, environmentally friendly materials. Cyclic voltammetry curves showing the reusability of the electrodes obtained were obtained and showed antibody-protein adhesion on the AgNp/SLG@ITO surface. The anodic and cathodic peak currents values after 20 cycles show that these values are suitable even after 20 measurements. Electrochemical impedance spectroscopy (EIS) studies confirmed the effects of PCT on binding events due to increasing con-centration at a constant PCT-antibody concentration. The limit of detection (LOD) value of the fabricated PCT/ Ab/AgNp/SLG@ITO impedimetric biosensor was determined as 0.55 ngmL-1. The low LOD value can be attributed to the uniform and large surface area of single-layer graphene (SLG) and noble AgNp. The LOD value based on the EIS studies has revealed that the PCT/Ab/AgNp/SLG@ITO impedimetric biosensor can be employed in real samples.Öğe Ultraviolet radiation-induced photovoltaic action in ?-CuI/?-Ga2O3 heterojunction(Elsevier, 2020) Ayhan, Muhammed Emre; Shinde, Mandar; Todankar, Bhagyashri; Desai, Pradeep; Ranade, Ajinkya K.; Tanemura, Masaki; Kalita, GolapWe report on the fabrication of gamma-phase copper iodide (gamma-Cul) and beta-gallium oxide (beta-Ga2O3) heterostructure device and obtaining the ultraviolet (UV) radiation responsive photovoltaic action. The crystalline gamma-Cul with predominant (1 1 1) plane orientation was deposited on the beta-Ga2O3 by thermal evaporation process under vacuum condition. The electrical analysis revealed that the gamma-Cul/gamma-Ga2O3 heterojunction possess an excellent rectifying diode characteristic with high rectification ratio and turn-on voltage. The fabricated heterojunction device showed a photovoltaic action under solar-blind UV irradiation (254 nm) with outstanding photovoltage of 0.706 V and photocurrent of 2.49 mA/W. The device also showed a photovoltaic action under illumination of 365 nm and 300-400 nm wavelength of UV light, corresponding to absorption due to the gamma-Cul layer. The UV irradiation-induced photovoltaic action in the gamma-Cul/beta-Ga2O3 with outstanding photovoltage and excellent diode characteristics can be significant for self-powered UV photodetector applications. (C) 2019 Elsevier B.V. All rights reserved.