硅藻土/g-C3N4复合材料的制备及其可见光增强活性

doi:10.15541/jim20160015

摘要/Abstract

摘要：

采用浸渍-焙烧法制备了具有可见光响应活性的硅藻土/g-C₃N₄复合光催化材料。利用TG、XRD、FE-SEM、HR-TEM、FT-IR、XPS、UV-Vis-DRS 和 PL谱等手段对其物相组成、形貌和光吸收特性进行表征。以RhB的光催化降解为探针反应评价催化剂的活性。光催化结果表明, 2.32wt%硅藻土/g-C₃N₄复合材料对RhB有较高的催化活性, 光催化降解的速率常数是纯g-C₃N₄的1.9倍。自由基捕获实验表明, ·O₂^-是RhB在硅藻土/g-C₃N₄复合材料上光催化降解的主要活性物种。光催化活性提高的主要原因在于硅藻土和g-C₃N₄之间静电作用有利于光生电子-空穴在g-C₃N₄表面的迁移, 进而提高g-C₃N₄的光催化活性。

关键词: 硅藻土/g-C3N4复合材料, 浸渍-焙烧法, 可见光照射, 静电作用

Abstract:

Novel visible-light-responsive diatomite/g-C₃N₄ composite was successfully synthesized via a facile impregnation-calcination method. The sample was characterized by TG, XRD, FE-SEM, HR-TEM, FT-IR, XPS, UV-Vis-DRS, and PL spectra. The photocatalytic activities of samples were evaluated by degradation of RhB under visible light irradiation. Experimental results indicated that 2.32wt% diatomite/g-C₃N₄ composite exhibits high efficiency for the degradation of RhB. The photoreaction kinetics constant value is about 1.9 times as high as that of g-C₃N₄ under visible light irradiation. The radical trap experiments indicate that ·O₂^- serves as the main active species for the photodegradation of RhB over 2.32wt% diatomite/g-C₃N₄ under visible light irradiation. The enhanced photoactivity is mainly attributed to the electrostatic interaction between g-C₃N₄ and negatively charged diatomite, synergistic effect lead to the efficient migration of the photogenerated electrons and holes of g-C₃N₄.

Key words: diatomite/g-C3N4 composite, impregnation-calcination method, visible-light-irradiation, electrostatic interaction

中图分类号:

TB321

王丹军, 申会东, 郭莉, 何小梅, 张洁, 付峰. 硅藻土/g-C₃N₄复合材料的制备及其可见光增强活性[J]. 无机材料学报, 2016, 31(8): 881-889.

WANG Dan-Jun, SHEN Hui-Dong, GUO Li, HE Xiao-Mei, ZHANG Jie, FU Feng. Synthesis of Diatomite/g-C₃N₄ Composite with Enhanced Visible-light-responsive Photocatalytic Activity[J]. Journal of Inorganic Materials, 2016, 31(8): 881-889.

图/表 10

Fig. 1 XRD patterns of samples(a) XRD patterns of diatomite, g-C3N4 and diatomite/g-C3N4 composite; (b) Enlarged XRD pattern of diatomite g-C3N4 and diatomite/g-C3N4 composites from 25° to 30° The peaks marked by (●) in (a) are the characteristic of the Quartz impurity in the diatomite sample

Fig. 2 XPS spectra of g-C3N4 and diatomite/g-C3N4(2.32wt%)(a) Survey spectra; (b) C1s; (c) N1s

Table 1 Content in diatomite/g-C3N4 by TG curves analysis

Samples	Diatomite theoretical content /wt%	Diatomite experimental/wt%
Diatomite/g-C₃N₄ (1.22wt%)	1.79	1.22
Diatomite/g-C₃N₄(2.32wt%)	3.56	2.32
Diatomite/g-C₃N₄(5.46wt%)	6.78	5.46
Diatomite/g-C₃N₄(13.88wt%)	15.38	13.88
Diatomite/g-C₃N₄(25.21wt%)	26.67	25.21

Fig. 3 TG curves for heating diatomite, g-C3N4 and diatomite/g-C3N4 composites

Fig. 4 FE-SEM and TEM images of samples(a) FE-SEM image of diatomite; (b) FE-SEM image of alkali washed diatomite; (c) FE-SEM image of diatomite/g-C3N4 composite; (d) TEM of diatomite/g-C3N4 composite; (e) SEAD pattern of g-C3N4; (f) Conjunction edge between flake-like g-C3N4 and diatomite particles

Fig. 5 FT-IR spectra of diatomite, g-C3N4 and diatomite/g- C3N4 composites

Fig. 6 (a) UV-Vis spectra and (b) plot of (αhν)1/2 vs energy (hν) for the band gap energy of g-C3N4 and diatomite/g-C3N4 composites

Fig. 7 Photocatalytic activity of the samples(A) Photocatalytic degradation efficiency of RhB by g-C3N4 and diatomite/g-C3N4 composites; (B) Comparison of mixted, treated and untreated diatomite/g-C3N4(2.32wt%); (C) Kinetic fit for the degradation of RhB with g-C3N4 and diatomite/g-C3N4 composites (a, blank; b, g-C3N4; c, diatomite/g-C3N4 (1.22wt%); d, diatomite/g-C3N4 (2.32wt%); e, diatomite/g-C3N4 (5.46wt%); f, diatomite/g-C3N4 (13.88wt%); g, diatomite/g-C3N4 (25.21wt%); h, diatomite/g- C3N4 mixture (2.32wt%); i, diatomite); (D) Adsorption percentage and rate constants; (E) Absorption spectral changes of RhB under visible light irradiation using diatomite/g-C3N4 (2.32wt%) as photocatalyst; (F) XRD patterns of diatomite/g-C3N4 before and after being used

Fig. 8 PL spectra of g-C3N4 and diatomite/ g-C3N4 composites

Fig. 9 Trapping experiment of active species during photocatalytic degradation of RhB over diatomite/g-C3N4 (2.32wt%) under visible light irradiation

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硅藻土/g-C₃N₄复合材料的制备及其可见光增强活性

Synthesis of Diatomite/g-C₃N₄ Composite with Enhanced Visible-light-responsive Photocatalytic Activity

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