硅酸盐学报2025，Vol.53Issue(3)：594-606,13.DOI:10.14062/j.issn.0454-5648.20240638
g-C3N4/NaNbO3复合材料降解混合染料的热释电光催化性能
Pyrophotocatalytic Performance of g-C3N4/NaNbO3 Composite Material for Degradation of Mixed Dyes
摘要
Abstract
Introduction With the rapid development of industry,the discharge of dye wastewater from the textile and printing industries poses a huge threat to aquatic ecosystems and human health.Exploring efficient catalytic technologies to reduce water pollution is highly anticipated.Photocatalysis,as an efficient and environmentally friendly advanced oxidation technology for decomposing organic dyes,has attracted considerable attention.However,the low utilization rate of solar energy and severe photogenerated carrier recombination restrict the practical application of photocatalysis.In addition to solar energy,the thermal energy generated by cold-hot alternation can be also used as a clean and renewable energy source to induce positive and negative charges and generate pyroelectric potential,thereby achieving pyrocatalysis.Combining pyrocatalysis with photocatalysis can simultaneously collect solar energy and alternating heat energy,and the pyroelectric potential can serve as an internal driving force for dissociating photo generated exciton.This work constructed g-C3N4/NaNbO3 composite materials for the absorption of g-C3N4 to visible light to enhance the utilization efficiency of sunlight.The Mott-Schottky curve was obtained by electrochemical workstation to analyze the conduction type and flat band potential of g-C3N4 and NaNbO. Methods A hydrated NaNbO3 sample was obtained via hydrothermal reaction at 160℃for 4 h with Nb2O5 and NaOH as raw materials.The hydrated NaNbO3 prepared was then mixed,ground with a certain mass of melamine powder(in a mass ratio of 1:2),and sintered at 500℃for 2 h to obtain g-C3N4/NaNbO3 composite material.The phase,morphology,and optical properties of the product was analyzed by X-ray diffraction(XRD),scanning electron microscopy(SEM),and ultraviolet-visible spectroscopy(UV-Vis).The pyrophotocatalytic performance of g-C3N4/NaNbO3 composite materials was evaluated via degrading mixed dyes(i.e.,methylene blue MB,methyl orange MO,rhodamine RhB,and acid orange AO7)under light irradiation and cold-hot cycling.The environmental adaptability of g-C3N4/NaNbO3 composite materials was analyzed by changing the concentration,pH value,and water source of the mixed dye solution.The stability of g-C3N4/NaNbO3 composite material was estimated through five repeated uses and the XRD patterns before and after use.The influence of g-C3N4/NaNbO3 on the degradation performance of the mixed dyes was analyzed via adding different active substance trapping agents,and the main active species in the catalytic reaction was determined.The work function was calculated based on density functional theory(DFT)to analyze the electron transfer after contacting g-C3N4 and NaNbO3. Results and discussion The g-C3N4/NaNbO3 composite material prepared by a two-step method of hydrothermal and mixed sintering is sheet-like g-C3N4 covering the surface of NaNbO3 nanorods with the diameters of 100-300 nm.The photocatalytic degradation efficiencies of g-C3N4,NaNbO3,and g-C3N4/NaNbO3 composite materials for RhB are 19%,71%,and 84%,respectively.Combined with the pyroelectric catalysis,the photocatalytic efficiency of g-C3N4/NaNbO3 increases to 97.3%.The results show that the formation of g-C3N4 and NaNbO3 composites can enhance the photocatalytic performance,and the pyroelectric potential generated by temperature fluctuations can further separate the photo-generated electron hole pairs,thus improving the photocatalytic degradation efficiency.Under illumination and cold-hot cycling,g-C3N4/NaNbO3 exhibits a pyrophotocatalytic degradation efficiency of 96.9%for mixed dyes,with a degradation reaction rate of 0.038 6 min-1.The degradation efficiency of g-C3N4/NaNbO3 decreases with the increase of initial concentrations of mixed dye solution(i.e.,2×10-5 mol/L,4×10-5 mol/L,6×10-5 mol/L and 8×10-5 mol/L).The pyro-photocatalytic degradation efficiency of the mixed dye is 96.9%,70.8%,and 54.3%when the pH value of the solution is 2.6,7.1 and 11,respectively,indicating that g-C3N4/NaNbO3 composite catalyst is suitable for working in acidic and neutral environments.Also,g-C3N4/NaNbO3 composite material has a better catalytic activity in deionized water and tap water,while its pyrophotocatalytic performance reduces in river water and lake water.The experimental results of adding sacrificial agents show that·O2-,·OH,and h+are all active substances in the thermal electric photocatalytic degradation,among which·O2-and·OH play a particularly significant role in the catalytic degradation.The results of UV-Vis spectra,the Mott-Schottky curve and DFT calculations indicate that g-C3N4/NaNbO3 composite material broadens the absorption range of the solar spectrum,forms an S-type heterojunction,and the pyroelectric potential generated by the pyroelectric effect promotes the dissociation of photo generated carriers,thus improving the pyrophotocatalytic performance. Conclusions The constructed g-C3N4/NaNbO3 composite material utilized a wide solar spectral absorption range and a photothermal effect of g-C3N4.The formation of S-type heterojunction between g-C3N4 and NaNbO3 was conducive to the separation and migration of photo generated carriers.Also,the pyroelectric potential induced by temperature fluctuation could result in band bending,and further promoted the separation of photo generated carriers in NaNbO3,demonstrating an enhanced pyrophotocatalytic performance.This work could provide an efficient catalyst that simultaneously utilized solar energy and environmental thermal energy to achieve sewage treatment and environmental remediation.关键词
石墨相氮化碳/铌酸钠/热释电光催化/热释电势/复合材料/内建电场Key words
graphitic carbon nitride/sodium niobate/pyrophotocatalysis/pyroelectric potential/composite material/build-in electric field分类
化学引用本文复制引用
徐利,邓树文,周小桔,王会峰,胡正龙..g-C3N4/NaNbO3复合材料降解混合染料的热释电光催化性能[J].硅酸盐学报,2025,53(3):594-606,13.基金项目
国家自然科学基金(12304539) （12304539）
湖北科技学院博士科研启动基金(BK202316) （BK202316）
湖北科技学院科研项目(2020-22GP08,2024-2025X08). （2020-22GP08,2024-2025X08）
