敬曼曼, 张倩倩, 张安超, 芦涛, 倪飞翔, 栗敏, 杜海星. Ag3PO4改性g-C3N4复合材料增强光催化产氢性能[J]. 燃料化学学报(中英文). DOI: 10.3724/2097-213X.2024.JFCT.0018
引用本文: 敬曼曼, 张倩倩, 张安超, 芦涛, 倪飞翔, 栗敏, 杜海星. Ag3PO4改性g-C3N4复合材料增强光催化产氢性能[J]. 燃料化学学报(中英文). DOI: 10.3724/2097-213X.2024.JFCT.0018
JING Manman, ZHANG Qianqian, ZHANG Anchao, LU Tao, NI Feixiang, LI Min, DU Haixing. Enhanced photocatalytic performance of Ag3PO4 modified g-C3N4 composites for hydrogen production[J]. Journal of Fuel Chemistry and Technology. DOI: 10.3724/2097-213X.2024.JFCT.0018
Citation: JING Manman, ZHANG Qianqian, ZHANG Anchao, LU Tao, NI Feixiang, LI Min, DU Haixing. Enhanced photocatalytic performance of Ag3PO4 modified g-C3N4 composites for hydrogen production[J]. Journal of Fuel Chemistry and Technology. DOI: 10.3724/2097-213X.2024.JFCT.0018

Ag3PO4改性g-C3N4复合材料增强光催化产氢性能

Enhanced photocatalytic performance of Ag3PO4 modified g-C3N4 composites for hydrogen production

  • 摘要: 氢能作为无污染、高能量密度的清洁能源,被视为未来可持续发展的理想选择。光催化技术是缓解能源危机的绿色技术之一,寻找性能优异的光催化产氢材料成为当务之急。本文采用高温煅烧与原位沉积-沉淀法制备了磷酸银负载石墨相氮化碳(Ag3PO4/C3N4)二元复合光催化剂,并用于光催化制氢实验,研究了Ag3PO4负载量、牺牲剂种类、牺牲剂添加量对产氢性能的影响,采用XRD、FT-IR、XPS、SEM、UV-vis DRS、PL等多种技术对光催化剂进行物理化学特征分析。结果表明,Ag3PO4的负载量为4%时,Ag3PO4-4/C3N4产氢量最高,可达218.97 μmol,分别是C3N4和Ag3PO4的3.1倍和58.4倍。与甲醇、丙三醇和乳酸相比,三乙醇胺是Ag3PO4/C3N4光催化剂最佳的牺牲剂,然而过量的三乙醇胺不能进一步提升产氢量。随着Ag3PO4负载量的增加,C3N4(002)晶面的衍射峰逐渐减小,反映出Ag3PO4在C3N4表面良好的分散性和Ag3PO4/C3N4复合光催化剂的有效耦合。负载少量Ag3PO4后,C3N4的形貌发生变化,其比表面积增加,且Ag3PO4以纳米颗粒形式高度分散于C3N4表面。较大的比表面积、增强的光吸收特征、光生电子-空穴对的有效分离与转移是Ag3PO4/C3N4复合材料高效光催化产氢的重要因素。基于表征和实验结果,提出了Ag3PO4改性C3N4异质结光催化剂的产氢机理。

     

    Abstract: As a green and eco-friendly clean energy source, hydrogen energy has the advantages of high energy density and no pollution to the environment. Due to the direct utilization of solar energy, photocatalytic water splitting for hydrogen production is a promising technology. g-C3N4 could be utilized to achieve hydrogen through water splitting. However, g-C3N4 material has some disadvantages such as a small specific surface area, fast recombination of electron and hole pairs generated by photocatalysis, and insufficient photo-responsiveness, which greatly limits its photocatalytic performance. Ag3PO4, as one of the new silver-based photocatalysts, has the advantages of high quantum yield and narrow bandgap. Coupling polyhedral Ag3PO4 with two-dimensional g-C3N4 material to form a heterojunction to enhance photocatalytic stability should be feasible. In this paper, silver phosphate modified graphitic carbon nitride (Ag3PO4/C3N4) binary composite photocatalysts were prepared by a high-temperature calcination and in-situ deposition-precipitation method, which were employed for photocatalytic hydrogen production. The effects of Ag3PO4 loading, the type of sacrificial agents and the amount of sacrificial agent on hydrogen production were studied. Meanwhile, various techniques such as XRD, FI-TR, XPS, SEM, UV-vis DRS, PL, etc. were carried out to analyze the physical and chemical characteristics of the photocatalysts. The results show that when the Ag3PO4 mass loading is 4%, the hydrogen production rate of Ag3PO4-4/C3N4 is the highest, reaching 218.97 μmol, which is 3.1 times and 58.4 times higher than that of C3N4 and Ag3PO4, respectively. Compared with methanol, glycerol and lactic acid, triethanolamine is the best sacrificial agent for Ag3PO4/C3N4 photocatalyst, but an excessive triethanolamine cannot further improve the hydrogen production rate. No obvious absorption peak of Ag3PO4 is observed in the FT-IR spectra, which could be due to the low content of Ag3PO4. While with the increase of Ag3PO4 loading, the diffraction peak of C3N4 (002) crystal plane decreases gradually, reflecting an excellent dispersion of Ag3PO4 on C3N4 surface and an effective coupling of Ag3PO4 and C3N4. The shift in binding energies of the researched elements indicates a strong interaction between C3N4 and Ag3PO4. After loading a small amount of Ag3PO4, the morphology of C3N4 changes from the original rocky block shape to a multi angular flower shape, and its specific surface area increases. Moreover, Ag3PO4 is highly dispersed on the surface of C3N4 in the form of nanoparticles. Ag3PO4-4/C3N4 exhibits a high transient photocurrent intensity, confirming that C3N4 and Ag3PO4 form a heterojunction, effectively enhancing the separation of photo-generated electron-hole pairs in Ag3PO4-4/C3N4. The large specific surface area, enhanced light absorption characteristics and effective separation and transfer of photogenerated electron-hole pairs are important factors for efficient photocatalytic hydrogen production of Ag3PO4/C3N4 composites. Based on the characterization and experimental results, an S-type heterojunction photocatalytic hydrogen production mechanism is proposed. Under illumination, the cocatalyst H2PtCl6 in the reaction solution is reduced to Pt0. Due to the SPR effect of Pt metal, some e are transferred to Pt0, which combines with H+ to accelerate the photocatalytic hydrogen production reaction rate. At the same time, a small amount of Ag3PO4 is irradiated to precipitate Ag0 as a silver bridge, promoting the recombination of e generated by Ag3PO4 with h+ at the VB site of C3N4 photocatalyst. The h+ accumulated by Ag3PO4 photocatalyst at VB oxidizes triethanolamine to TEOA+. This S-shaped heterojunction charge transfer method helps to improve the separation speed of electron-hole pairs and enhance the photocatalytic hydrogen production performance.

     

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