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Author: search.filters.author.Kunbuala, Neeraphat

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    Remodelling hierarchical NiCo2O4@ZnS nanorods with multi-walled carbon nanotubes as a counter electrode for dye-sensitized solar cell applications
    (2026-12-01)
    Nukunudompanich, Methawee
    ;
    Nachaithong, Theeranuch
    ;
    Phumuen, Phatcharin
    ;
    Wannabut, Wassana
    ;
    Kunbuala, Neeraphat
    A hierarchical NiCo<inf>2</inf>O<inf>4</inf>@ZnS/MWCNT (NCO@Z-MWCNTs) nanocomposite was synthesized to serve as a platinum-free counter electrode for dye-sensitized solar cells (DSSCs). The nanocomposite comprised spinel NiCo<inf>2</inf>O<inf>4</inf> nanorods, ZnS associated with the surface of the nanorods, and an interconnected multi-walled carbon nanotube (MWCNT) network, and it was synthesized via a low-temperature solution-based hydrothermal method. XRD confirmed the presence of cubic NiCo<inf>2</inf>O<inf>4</inf> and zinc blende ZnS phases, while FESEM–EDS and XPS analyses verified the incorporation of ZnS and the formation of a conductive carbon framework interconnecting adjacent nanorods. ZnS, rather than acting as an isolated catalytic component, was considered to contribute additional sulfide-related surface sites and to modulate the interfacial electronic environment of the NiCo<inf>2</inf>O<inf>4</inf> nanorods, which likely facilitated redox reactions involving the I<sup>−</sup>/I<inf>3</inf><sup>−</sup> couple. Meanwhile, the MWCNT network established continuous electron transport pathways, effectively reducing interfacial resistance and enhancing charge-transfer efficiency. Thermogravimetric and electrochemical analyses revealed enhanced thermal stability, improved redox kinetics, and a significant reduction in charge-transfer resistance compared with pristine NiCo<inf>2</inf>O<inf>4</inf>.The optimized NCO@Z–MWCNT 9wt% counter electrode achieved a power conversion efficiency of 10.03% under AM 1.5 G illumination, exceeding that of the Pt reference device (9.6%). Overall, the improved performance was attributed to the combined contributions of ZnS surface modification and the conductive MWCNT network, which together enhanced charge transport and electrocatalytic activity. This work demonstrates a scalable strategy for developing cost-effective, durable, and high-performance counter electrodes for dye-sensitized solar cells.
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    Comparative study of vacuum arc-remelting and spark plasma sintering processes on microstructure and corrosion behavior of Cp-Ti for biomedical implant applications
    (2025-11-01)
    Kunbuala, Neeraphat
    ;
    Srirussamee, Kasama
    ;
    Phamornnak, Chinnawich
    ;
    Tunthawiroon, Phacharaphon
    ;
    Hankoy, Montree
    Titanium (Ti) and its alloys are widely used for biomedical applications due to their excellent mechanical properties and biocompatibility. However, the selection of an appropriate manufacturing process is critical to ensuring the optimal performance of Ti-based implants. This study investigates the effects of two fabrication methods –vacuum arc remelting (VAR) and spark plasma sintering (SPS) – on the microstructure and corrosion behavior of commercially pure titanium (Cp-Ti). VAR-Ti ingots were fabricated using arc-melting with multiple remelting cycles, whereas SPS-Ti specimens were sintered from Ti powders under pressure and pulsed current in a high-vacuum environment. Both specimens were subsequently heat-treated at 800 °C and furnace cooled. Microstructural characterization revealed coarser grains and porosity in VAR-Ti, while SPS-Ti showed refined, uniform α-phase structures. Electrochemical tests, including OCP, polarization, EIS, and ICP-MS, indicated slightly enhanced corrosion resistance in SPS-Ti, attributed to its defect-free microstructure. XPS analysis confirmed TiO<inf>2</inf> surface formation on both samples. Additionally, both materials exhibited high ductility and excellent biocompatibility, with cell viability exceeding ISO 10993-5 thresholds. These findings highlight the advantage of SPS in producing defect-minimized Cp-Ti with improved corrosion behavior for biomedical applications.
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    Integrated Assessment of Rooftop Photovoltaic Systems and Carbon Footprint for Organization: A Case Study of an Educational Facility in Thailand
    (2025-05-01)
    Leeabai, Nattapon
    ;
    Sakaraphantip, Natthakarn
    ;
    Kunbuala, Neeraphat
    ;
    Roongrueng, Kamonchanok
    ;
    Nukunudompanich, Methawee
    This study presents an integrated methodology to assess and reduce greenhouse gas (GHG) emissions in institutional buildings by combining organizational carbon footprint (CFO) analysis with rooftop photovoltaic (PV) system simulation. The HM Building at King Mongkut’s Institute of Technology Ladkrabang (KMITL), Thailand, was selected as a case study to evaluate carbon emissions and the feasibility of solar-based mitigation strategies. The CFO assessment, conducted in accordance with ISO 14064-1:2018 and the Thailand Greenhouse Gas Management Organization (TGO) guidelines, identified total emissions of 1841.04 tCO<inf>2</inf>e/year, with Scope 2 electricity-related emissions accounting for 442.00 tCO<inf>2</inf>e/year. Appliance-level audits revealed that classroom activities represent 36.7% of the building’s electricity demand. These findings were validated using utility data totaling 850,000 kWh/year. A rooftop PV system with a capacity of 207 kWp was simulated using PVsyst software (version 7.1), incorporating site-specific solar irradiance and technical loss parameters. Monocrystalline modules produced the highest energy output of 292,000 kWh/year, capable of offsetting 151.84 tCO<inf>2</inf>e/year, equivalent to 34.4% of Scope 2 emissions. Economic evaluation indicated a 7.4-year payback period, with a net present value (NPV) of THB 12.49 million and an internal rate of return (IRR) of 12.79%. The integration of verified CFO data with empirical load modeling and derated PV performance projections provides a robust, scalable framework for institutional carbon mitigation. This approach supports data-driven Net Zero campus planning aligned with Thailand’s Nationally Determined Contributions (NDCs) and carbon neutrality policies.