1：Experimental Design and Method Selection:

The study used oxygen plasma treatment to introduce oxygen species into carbon nanotubes (CNTs), combined with density functional theory (DFT) calculations to analyze electronic properties. Methods include plasma etching, material characterization, electrochemical tests, and DFT simulations.

2：Sample Selection and Data Sources:

Commercial CNTs (Shenzhen Nanotech Port Co., Ltd) were used. Samples were prepared with different plasma etching times (0, 1, 3, 5, 30 min) in oxygen atmosphere. Data from characterization techniques (XRD, SEM, TEM, XPS, Raman, BET) and electrochemical measurements (CV, EIS, Tafel, J-V curves).

3：List of Experimental Equipment and Materials:

Equipment includes plasma system (PCE-6), SEM (NOVA NanoSEM 450), TEM (FEI TF30), XRD (Rigaku D/Max 2400), XPS (Thermo ESCALAB 250), Raman microscope (DXR, Thermo Scientific), BET analyzer (Micromeritics 3Flex 3500), electrochemical workstation, solar simulator (Newport 94032A), IPCE spectrometer (Jasco SM-25). Materials include CNTs, carboxyethyl cellulose, FTO glasses, TiO2 photoanodes, N719 dye, redox electrolyte.

4：5). Materials include CNTs, carboxyethyl cellulose, FTO glasses, TiO2 photoanodes, N719 dye, redox electrolyte. Experimental Procedures and Operational Workflow:

4. Experimental Procedures and Operational Workflow: CNTs were plasma-treated, mixed with binder, coated on FTO, annealed. DSSCs were assembled with dye-sensitized TiO2 photoanodes and CEs, filled with electrolyte. Characterization and electrochemical tests were performed step by step as described.

5：Data Analysis Methods:

Data analyzed using equivalent circuits for EIS, peak analysis for CV, DFT calculations with Gaussian 09 for ionization energy, and statistical methods for photovoltaic parameters.