Synergistic Mechanism of KCl-Modified Graphitic Carbon Nitride for Photocatalytic Degradation of Methylene Blue

doi:10.16552/j.cnki.issn1001-1625.2025.0415

Abstract

Abstract: Using graphitic carbon nitride (g-C₃N₄) as a support, KCl-doped X%-KCl/g-C₃N₄ photocatalysts (X=5, 10, 15) were synthesized via mechanical grinding-thermal polycondensation, photocatalytic performance of g-C₃N₄ was optimized by turning the KCl doping ratio and a synergistic mechanism system involving “band structure-carrier separation-free radical generation” was conducted. The X%-KCl/g-C₃N₄ samples were systematically characterized by UV-Vis DRS, FT-IR, XRD, EPR, EIS and PL, and their methylene blue (MB) degradation performance under solar light was evaluated. The results indicate that the 10%-KCl/g-C₃N₄ photocatalyst exhibits outstanding degradation performance, under sunlight irradiation, achieving a 97.12% degradation efficiency for 10 mg/L MB within 120 min at a catalyst dosage of 1 g/L. The first-order reaction rate constant (0.022 9 min^-1) is 1.97 times higher than that of pristine g-C₃N₄ (0.011 6 min^-1). The work provides a novel strategy for designing non-metal-modified photocatalysts with high efficiency and sustainability.

Key words: methylene blue, graphitic carbon nitride, thermal polycondensation, photocatalytic degradation, free radical mechanism

CLC Number:

ZHAO Meixuan, WEI Menglan, WANG Yimeng, TENG Fei, OU Xiaoxia. Synergistic Mechanism of KCl-Modified Graphitic Carbon Nitride for Photocatalytic Degradation of Methylene Blue[J]. BULLETIN OF THE CHINESE CERAMIC SOCIETY, 2025, 44(10): 3880-3890.

References

[1] 韦敏, 刘士华, 王榕. 钴掺杂二氧化锰类氧化物酶降解亚甲基蓝的研究[J]. 环境科学与技术, 2024, 47(9): 35-44.
WEI M, LIU S H, WANG R. Degradation of cobalt-doped manganese dioxide (Co-MnO₂)-like oxidative enzymes of methylene blue[J]. Environmental Science & Technology, 2024, 47(9): 35-44 (in Chinese).
[2] KOOCHAKZADEH F, NOROUZBEIGI R, SHAYESTEH H. Statistically optimized sequential hydrothermal route for FeTiO₃ surface modification: evaluation of hazardous cationic dyes adsorptive removal[J]. Environmental Science and Pollution Research, 2023, 30(7): 19167-19181.
[3] 帅政, 万星雨, 张艺臻, 等. ZIF-8/g-C₃N₄复合光催化剂降解盐酸四环素性能研究[J]. 环境科学与技术, 2024, 47(增刊2): 152-159.
SHUAI Z, WAN X Y, ZHANG Y Z, et al. Photo-degradation efficiency of tetracycline hydrochloride by ZIF-8/g-C₃N₄ composite photocatalyst[J]. Environmental Science & Technology, 2024, 47(supplement 2): 152-159 (in Chinese).
[4] LI J X, WANG Y H, WANG Y T, et al. MXene Ti₃C₂ decorated g-C₃N₄/ZnO photocatalysts with improved photocatalytic performance for CO₂ reduction[J]. Nano Materials Science, 2023, 5(2): 237-245.
[5] MOREIRA N F, SAMPAIO M, RIBEIRO A, et al. Metal-free g-C₃N₄ photocatalysis of organic micropollutants in urban wastewater under visible light[J]. Applied Catalysis B: Environmental, 2019, 248: 184-92.
[6] WANG Y Y, ZHAO S, ZHANG Y W, et al. Facile synthesis of self-assembled g-C₃N₄ with abundant nitrogen defects for photocatalytic hydrogen evolution[J]. ACS Sustainable Chemistry & Engineering, 2018, 6(8): 10200-10210.
[7] SONG Y L, LI Z Y, YANG C R, et al. Facile synthesis method of C self-doped g-C₃N₄ and its performance in photodegradation of sulfamethoxazole[J]. Separation and Purification Technology, 2024, 338: 126548.
[8] 陈璞, 欧晓霞, 赵可, 等. In₂S₃/g-C₃N₄复合光催化剂的制备及其光催化降解四环素[J]. 硅酸盐通报, 2023, 42(1): 310-318.
CHEN P, OU X X, ZHAO K, et al. Preparation of In₂S₃/g-C₃N₄ composite photocatalyst and its photocatalytic degradation of tetracycline[J]. Bulletin of the Chinese Ceramic Society, 2023, 42(1): 310-318 (in Chinese).
[9] CONG X H, LI A M, GUO F, et al. Construction of CdS@g-C₃N₄ heterojunction photocatalyst for highly efficient degradation of gaseous toluene[J]. Science of the Total Environment, 2024, 913: 169777.
[10] WANG X Y, LU M Y, MA J, et al. Synthesis of K-doped g-C₃N₄/carbon microsphere@graphene composite with high surface area for enhanced adsorption and visible photocatalytic degradation of tetracycline[J]. Separation and Purification Technology, 2019, 228: 115770.
[11] GUO F, LI M Y, REN H J, et al. Facile bottom-up preparation of Cl-doped porous g-C₃N₄ nanosheets for enhanced photocatalytic degradation of tetracycline under visible light[J]. Separation and Purification Technology, 2019, 228: 115770.
[12] 王智皓, 龙腾文, 冯建光, 等. SiC量子点敏化g-C₃N₄光阳极在光催化燃料电池中的应用[J]. 聊城大学学报(自然科学版), 2024, 37(4): 78-88.
WANG Z H, LONG T W, FENG J G, et al. Application of SiC quantum dot sensitized g-C₃N₄ photoanode in photocatalytic fuel cells[J]. Journal of Liaocheng University (Natural Science Edition), 2024, 37(4): 78-88 (in Chinese).
[13] MENG J Q, ZHANG X Y, LIU Y Q, et al. Engineering of graphitic carbon nitride with simultaneous potassium doping sites and nitrogen defects for notably enhanced photocatalytic oxidation performance[J]. Science of the Total Environment, 2021, 796: 148946.
[14] LIANG L, SHI L, WANG F X, et al. Synthesis and photo-catalytic activity of porous g-C₃N₄: promotion effect of nitrogen vacancy in H₂ evolution and pollutant degradation reactions[J]. International Journal of Hydrogen Energy, 2019, 44(31): 16315-16326.
[15] HUANG H W, XIAO K, TIAN N, et al. Template-free precursor-surface-etching route to porous, thin g-C₃N₄ nanosheets for enhancing photocatalytic reduction and oxidation activity[J]. Journal of Materials Chemistry A, 2017, 5(33): 17452-17463.
[16] WEI Z, LIU M L, ZHANG Z J, et al. Efficient visible-light-driven selective oxygen reduction to hydrogen peroxide by oxygen-enriched graphitic carbon nitride polymers[J]. Energy & Environmental Science, 2018, 11(9): 2581-2589.
[17] ZHENG Y, LIN L H, WANG B, et al. Graphitic carbon nitride polymers toward sustainable photoredox catalysis[J]. Angewandte Chemie (International Edition), 2015, 54(44): 12868-12884.
[18] 顾杰, 李双硕, 崔天伊, 等. 生物质炭掺杂BiOBr的制备及其光催化性能研究[J]. 聊城大学学报(自然科学版), 2025, 38(1): 68-75.
GU J, LI S S, CUI T Y, et al. Preparation of biomass charcoal doped BiOBr and its photocatalytic performance[J]. Journal of Liaocheng University (Natural Science Edition), 2025, 38(1): 68-75 (in Chinese).
[19] CAO S W, LOW J, YU J G, et al. Polymeric photocatalysts based on graphitic carbon nitride[J]. Advanced Materials, 2015, 27(13): 2150-2176.
[20] 张蓉, 柳璐, 马飞, 等. 过渡金属/氮掺杂石墨催化剂的制备及电催化氧还原[J]. 分子催化, 2014, 28(6): 553-563.
ZHANG R, LIU L, MA F, et al. Preparation and electrocatalytic activity of transition metal/nitrogen doped carbon catalysts for oxygen reduction reaction[J]. Journal of Molecular Catalysis, 2014, 28(6): 553-563 (in Chinese).
[21] MA J, ZHOU W, TAN X, et al. Potassium ions intercalated into g-C₃N₄-modified TiO₂ nanobelts for the enhancement of photocatalytic hydrogen evolution activity under visible-light irradiation[J]. Nanotechnology, 2018, 29(21): 215706.
[22] CHOU Y C, SHAO C L, LI X H, et al. BiOCl nanosheets immobilized on electrospun polyacrylonitrile nanofibers with high photocatalytic activity and reusable property[J]. Applied Surface Science, 2013, 285(part B): 509-516.
[23] KHAN A A, TAHIR M. Well-designed 2D/2D Ti₃C₂TA/R MXene coupled g-C₃N₄ heterojunction with in situ growth of anatase/rutile TiO₂ nucleates to boost photocatalytic dry-reforming of methane (DRM) for syngas production under visible light[J]. Applied Catalysis B: Environmental, 2021, 285: 119777.
[24] 袁浩, 孙鑫海, 李瑞广, 等. 碳点/铁酸镍复合光催化剂的宽光谱芬顿降解四环素研究[J]. 聊城大学学报(自然科学版), 2024, 37(2): 69-79.
YUAN H, SUN X H, LI R G, et al. Achieving high-efficient broad spectrum driven photo-Fenton degradation of tetracycline via carbon dots modified NiFe₂O₄ nanoparticles[J]. Journal of Liaocheng University (Natural Science Edition), 2024, 37(2): 69-79 (in Chinese).
[25] RAI R, TRILOKI T, SINGH B K. X-ray diffraction line profile analysis of KBr thin films[J]. Applied Physics A, 2016, 122(8): 774.
[26] LI F Y, LIN M X. Synthesis of biochar-supported K-doped g-C₃N₄ photocatalyst for enhancing the polycyclic aromatic hydrocarbon degradation activity[J]. International Journal of Environmental Research and Public Health, 2020, 17(6): 2065.
[27] 吴昊, 夏存杰, 韦梦兰, 等. Cu掺杂Bi₂O₂S光催化剂的制备及其性能研究[J/OL]. 工业水处理, 1-19 (2024-12-17) [2025-05-26]. https://doi.org/10.19965/j.cnki.iwt2024-0725.
WU H, XIA C J, WEI M L, et al. Preparation and properties of Bi₂O₂S photocatalyst by Cu doping[J/OL]. Industrial Water Treatment, 1-19 (2024-12-17) [2025-05-26]. https://doi.org/10.19965/j.cnki.iwt2024-0725 (in Chinese).