Browsing by Author "Ersöz, Mustafa"

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Enhanced Uptake Capacities and Isosteric Heats of Co2 and Ch4 Adsorption on Spent Coffee Ground Activated Carbons Loaded With Metal Ions
(2019) Kırbıyık, Çisem; Büyükbekar, Burak Zafer; Kuş, Mahmut; Ersöz, Mustafa
Low-cost activated carbon (AC) samples obtained from waste coffee grounds were used for CO2 and CH4 adsorption. ACs were prepared by chemical activation and carbonized at three different temperatures. AC carbonized at 800 ? C showed a relatively high surface area (582.92 m2 g ?1 ) and high adsorption capacities of 2.6 mmol g ?1 and 1.1 mmol g ?1 at 25 ? C for CO2 and CH4 , respectively. Adsorbent samples were prepared by loading of Fe 3+ metal ions onto ACs and their adsorption capacities were compared with those of nonloaded ACs. As expected, the loading of Fe 3+ metal ions increased the adsorption capacities at all temperatures and the adsorption capacity of Fe 3+ -loaded AC carbonized at 800 ? C was 3.1 mmol g ?1 for CO2 and 1.2 mmol g ?1 for CH4 at 25 ? C. The isosteric heats of adsorption were calculated at 0–35 ? C with the range of 20–35 kJ mol ?1 and 18–23 kJ mol ?1 for CO2 and CH4 , respectively. According to our findings, bio-based ACs can be used as an effective and alternative adsorbent for capturing different gas molecules.
Citation - WoS: 15
Citation - Scopus: 17
Improved Performance With Boron-Doped Carbon Quantum Dots in Perovskite Solar Cells
(Elsevier Ltd, 2022) Kırbıyık Kurukavak, Çisem; Yılmaz, Tuğbahan; Toprak, Ayşegül; Büyükbekar, Alihan; Kuş, Mahmut; Ersöz, Mustafa
This study reports the using of boron-doped carbon quantum dots (B-CQDs), which can convert ultraviolet to blue light, as an additive in MAPbI3 based perovskite solar cells (PSCs) for improved photovoltaic performance. After a successful facile synthesis of B-CQDs, our work showed that the appropriate addition of B-CQDs (5% vol.) into MAPbI3 absorber layer can passivate the grain boundaries of perovskite crystals, improve the crystallinity and the grain sizes. Additionally, optical, and photovoltaic characteristics showed that the addition of B-CQDs can efficiently improve the charge transport properties and the hole extraction, while decreasing the recombination losses. In comparison to control device, power conversion efficiency (PCE) of champion device was increased from 10.4% to 12.7%. This approach of constructing inverted p-i-n PSCs with B-CQDs additives offers a simple way for the preparation of efficient and stable perovskite photovoltaics for future application. © 2022 Elsevier B.V.
Citation - WoS: 26
Citation - Scopus: 30
Nitrogen -Doped Cqds To Enhance the Power Conversion Efficiency of Perovskite Solar Cells Via Surface Passivation
(ELSEVIER SCIENCE SA, 2020) Kırbıyık, Çisem; Toprak, Ayşegül; Başlak, Canan; Kuş, Mahmut; Ersöz, Mustafa
[Abstract Not Available]
Citation - WoS: 6
Citation - Scopus: 8
Pan-Based Activated Carbon Nanofiber/Metal Oxide Composites for Co2 and Ch4 Adsorption: Influence of Metal Oxide
(SCIENTIFIC TECHNICAL RESEARCH COUNCIL TURKEY-TUBITAK, 2021) Kırbıyık Kurukavak, Çisem; Büyükbekar, Burak Zafer; Ersöz, Mustafa
In the present study, we successfully prepared two different electrospun polyacrylonitrile (PAN) based-activated carbon nanofiber (ACNF) composites by incorporation of well-distributed Fe2O3 and Co3O4, nanoparticles (NPs). The influence of metal oxide on the structural, morphological, and textural properties of final composites was thoroughly investigated. The results showed that the morphological and textural properties could be easily tuned by changing the metal oxide NPs. Even though, the ACNE composites were not chemically activated by any activation agent, they presented relatively high surface areas (S-BET) calculated by Brunauer-Emmett-Thller (BET) equation as 212.21 and 185.12 m(2)/g for ACNE/Fe2O3 and ACNF/Co3O4 composites, respectively. Furthermore, the ACNE composites were utilized as candidate adsorbents for CO2 and CH4 adsorption. The ACNF/Fe2O3 and ACNF/Co3O4 composites resulted the highest CO2 adsorption capacities of 1.502 and 2.166 mmol/g at 0 degrees C, respectively, whereas the highest CH4 adsorption capacities were obtained to be 0.516 and 0.661 mmol/g at 0 degrees C by ACNF/Fe2O3 and ACNE/Co3O4 composites, respectively. The isosteric heats calculated lower than 80 kJ/mol showed that the adsorption processes of CO2 and CH4 were mainly dominated by physical adsorption for both ACNE composites. Our findings indicated that ACNF-metal oxide composites are useful materials for designing of CO2 and CH4 adsorption systems.
Citation - WoS: 6
Citation - Scopus: 12
Refractory-Metal Chalcogenides for Energy
(Wiley-V C H Verlag Gmbh, 2022) Özel, Faruk; Arkan, Emre; Coşkun, Halime; Deveci, İlyas; Yıldırım, Murat; Yıldırım, Mehmet; Ersöz, Mustafa; Kuş, Mahmut
When it is asked, where can refractory metals be used?, the possible shortest answer is, where cannot they be used? The uses of refractory-metal-based compounds in research and industry are too many to be enumerated; nevertheless, some outstanding examples are briefly mentioned here. Essentially, chalcogenide forms of refractory metals are preferred in the fabrication of high-performance structures. Therefore, expanding the current studies that usually focus on tungsten- and molybdenum-based structures to other materials may open new opportunities. Moreover, research on ternary and quaternary structures can also be a keystone in creating high-performance products. The rationale of the present review is to give a brief overview of the recent history of refractory-metal-based chalcogenides (RMCs). Initially, the framework is confined to the general design and approaches for the synthesis of refractory metal chalcogenides. The assay is continued by extending with characteristic features of materials from crystalline properties to thermoelectric attributes and examining device fabrication processes. Taken together, the device fabrication part where RMCs are mainly used is extensively focused upon. Finally, outlook and future perspectives are given on the design and construction of RMCs to enable future inspiration and innovation.