研究目的
To enhance the photocatalytic hydrogen production activity of graphitic carbon nitride (g-C3N4) by introducing nitrogen defects through selenium vapor treatment, addressing issues of high charge carrier recombination and limited visible-light absorption.
研究成果
The introduction of nitrogen defects into g-C3N4 via selenium vapor treatment significantly enhances photocatalytic hydrogen production by narrowing the bandgap, improving visible light absorption, and facilitating charge carrier separation. The optimized sample showed a 3.4-fold increase in H2 evolution rate compared to pristine g-C3N4, with good stability. This method offers a promising approach for defect engineering in photocatalysts, with potential for further optimization and application in sustainable energy technologies.
研究不足
The study is limited to laboratory-scale experiments; scalability and long-term stability in real-world applications are not addressed. The selenium vapor treatment method may have constraints in controlling defect density precisely, and the use of Pt co-catalyst adds cost. Environmental and safety aspects of selenium handling are not discussed.
1：Experimental Design and Method Selection:
The study involved synthesizing pristine g-C3N4 and nitrogen-deficient g-C3N4 via selenium vapor treatment to introduce nitrogen vacancies. Methods included calcination, vapor treatment, and various characterizations to analyze structural and photocatalytic properties.
2：Sample Selection and Data Sources:
Pristine g-C3N4 was synthesized from dicyandiamide precursor. Nitrogen-deficient samples were prepared by treating g-C3N4 with selenium vapor at 350°C for different durations (
3：5h, 1h, 2h). List of Experimental Equipment and Materials:
Equipment included a tube furnace, X-ray diffractometer (PANalytical with Cu Kα radiation), TEM microscope (HT7700, Hitachi), UV-vis spectrophotometer (Hita-chi-UH4150), FT-IR spectrometer (Nicolet 50, ThermoFisher), XPS system (Thermo escalab 250 Xi), photoreactor with Xe lamp and gas chromatograph (Agilent 7890B). Materials included dicyandiamide (
4：0%, AR, Sinopharm Chemical Reagent Co. Ltd.), selenium powder (0%, AR, Aladdin), triethanolamine, H2PtClExperimental Procedures and Operational Workflow:
Pristine g-C3N4 was calcined at 500°C for 4h. For nitrogen-deficient samples, g-C3N4 and selenium powder were heated in a tube furnace at 350°C under Ar/H2 flow. Photocatalytic H2 evolution tests were conducted with 20mg catalyst in 100ml 10% triethanolamine solution under visible light irradiation, with Pt co-catalyst.
5：4h. For nitrogen-deficient samples, g-C3N4 and selenium powder were heated in a tube furnace at 350°C under Ar/H2 flow. Photocatalytic H2 evolution tests were conducted with 20mg catalyst in 100ml 10% triethanolamine solution under visible light irradiation, with Pt co-catalyst. Data Analysis Methods:
5. Data Analysis Methods: XRD for crystal phase analysis, TEM for morphology, UV-vis DRS for bandgap calculation using Kubelka-Munk function, XPS for chemical composition, EPR for defect detection, photocurrent and EIS for charge separation efficiency, PL for recombination analysis, and DFT calculations for electronic structure.
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