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1.
Heterojunction design in a two-dimensional (2D) fashion has been deemed beneficial for improving the photocatalytic activity of g-C 3N 4 because of the promoted interfacial charge transfer, yet still facing challenges. Herein, we construct a novel 2D/2D Cu 3P nanosheet/P-doped g-C 3N 4 (PCN) nanosheet heterojunction photocatalyst (PCN/Cu 3P) through a simple in-situ phosphorization treatment of 2D/2D CuS/g-C 3N 4 composite for photocatalytic H 2 evolution. We demonstrate that the 2D lamellar structure of both CuS and g-C 3N 4 could be well reserved in the phosphorization process, while CuS and g-C 3N 4 in-situ transformed into Cu 3P and PCN, respectively, leading to the formation of PCN/Cu 3P tight 2D/2D heterojunction. Owing to the large contact area provided by intimate face-to-face 2D/2D structure, the PCN/Cu 3P photocatalyst exhibits significantly enhanced charge separation efficiency, thus achieving a boosted visible-light-driven photocatalytic behavior. The highest rate for H 2 evolution reaches 5.12 μmol·h –1, nearly 24 times and 368 times higher than that of pristine PCN and g-C 3N 4, respectively. This work represents an excellent example in elaborately constructing g-C 3N 4-based 2D/2D heterostructure and could be extended to other photocatalyst/co-catalyst system. 相似文献
2.
A series of Z-scheme TiO 2/g-C 3N 4/RGO ternary heterojunction photocatalysts are successfully constructed via a direct electrospinning technique coupled with an annealing process for the first time. They are investigated comprehensively in terms of crystal structure, morphology, composition, specific surface area, photoelectrochemical properties, photodegradation performance, etc. Compared with binary TiO 2/g-C 3N 4 and single-component photocatalysts, ternary heterojunction photocatalysts show the best photodegradation performance for RhB under stimulated sunlight. This can be attributed to the enlarged specific surface area (111.41 m 2/g), the formation of Z-scheme heterojunction, and the high separation migration efficiency of photoexcited charge carriers. A potential Z-scheme mechanism for ternary heterojunction photocatalysts is proposed to elucidate the remarkably ameliorated photocatalytic performance based on active species trapping experiments, PL detection test of hydroxyl radicals, and photoelectrochemical properties. 相似文献
3.
Graphitic carbon nitride (g-C 3N 4) photocatalysts were synthesized via a one-step pyrolysis process using melamine, dicyandiamide, thiourea, and urea as precursors. The obtained g-C 3N 4 materials exhibited a significantly different performance for the photocatalytic reduction of Cr(VI) under white light irradiation, which is attributed to the altered structure and occupancies surface groups. The urea-derived g-C 3N 4 with nanosheet morphology, large specific surface area, and high occupancies of surface amine groups exhibited superior photocatalytic activity. The nanosheet morphology and large surface area facilitated the separation and transmission of charge, while the high occupancies of surface amine groups promoted the formation of hydrogen adsorption atomic centers which were beneficial to Cr(VI) reduction. Moreover, the possible reduction pathway of Cr(VI) to Cr(III) over the urea-derived g-C 3N 4 was proposed and the reduction process was mainly initiated by a direct reduction of photogenerated electrons. 相似文献
4.
为了进一步提高聚合物半导体类石墨相氮化碳(g-C 3N 4)降解有机物的活性,通过简单的水热法复合得到碳化MoS 2/掺硫g-C 3N 4异质结(MoSC/S-CN),并在可见光下研究其罗丹明B (RhB)的降解性能。结果表明,相较于纯g-C 3N 4,最优化的MoSC/S-CN样品对可见光的吸收范围得到明显拓宽,并且在100 min内对RhB的降解效率为92.5%,比纯g-C 3N 4性能提高68.83%。一系列的结构和光学性质表明,掺硫后再进一步与碳化MoS 2耦合可以协同作用于g-C 3N 4,改善g-C 3N 4的能带结构,加速光生电子空穴对的分离,有效提高光催化活性。 相似文献
5.
Forming eco-friendly heterojunction photocatalysts is excellent method to accelerate the separation rate of photogenerated charge carriers, which is attracting more and more attention. In this study, a novel and stable disordered porous g-C 3N 4/SiO 2/SnO 2 (DOP-CSiSn) heterojunction composites was fabricated by a sol-gel hard template method, and the optimal g-C 3N 4 doped ratio was adjusted in DOP-CSiSn. The DOP-CSiSn photocatalyst had the much larger specific surface area and disordered porous structure, which exhibited strong photocatalytic effect to degrade Rhodamine B (RhB), Methylene blue (MB) and Methyl orange (MO) under visible light. When the g-C 3N 4 doping content was 30 wt%, the highest photocatalytic activities were obtained, and the degradation rate of MB and MO were 99.73% and 95.58% after 50 min, respectively. Degradation rate of RhB was 95.10% after 90 min. Photocatalytic degradation rate of organic pollutants were still more than 90% after six time consecutive cycles, the composite had wonderful stability and potential value in environmental purification. 相似文献
6.
通过焙烧-超声混合法成功地制备了BiOBr/g-C 3N 4S型异质结复合光催化剂。采用多种表征手段对样品物理属性进行了表征,包括X射线多晶粉末衍射仪(XRD)、扫描电子显微镜(SEM)、X射线光电子能谱(XPS)、紫外可见漫反射光谱(UV-Vis DRS)。研究了所制备样品有/无Fe 3+的光-自芬顿催化/光催化降解罗丹明B(RhB)性能。通过捕获实验确定了光催化反应中的主要活性物种,提出了光-自芬顿反应的降解机理。研究结果表明,BiOBr/g-C 3N 4S型异质结能原位生成H 2O 2,添加Fe 3+后,H 2O 2被原位活化成活性物种且光生电流和载流子分离效率获得显著提高。该光-自芬顿过程能高效降解RhB,其反应速率常数为0.208 min -1,约为无Fe 3+光催化反应速率常数的5.3倍,在光-自芬顿循环使用过程中表现出良好的稳定性。Fe... 相似文献
7.
通过焙烧-超声混合法成功地制备了BiOBr/g-C 3N 4 S型异质结复合光催化剂。采用多种表征手段对样品物理属性进行了表征,包括X射线多晶粉末衍射仪(XRD)、扫描电子显微镜(SEM)、X射线光电子能谱(XPS)、紫外可见漫反射光谱(UV-VisDRS)。研究了所制备样品有/无Fe 3+的光-自芬顿催化/光催化降解罗丹明B (RhB)性能。通过捕获实验确定了光催化反应中的主要活性物种,提出了光-自芬顿反应的降解机理。研究结果表明,BiOBr/g-C 3N 4 S型异质结能原位生成H 2O 2,添加Fe 3+后,H 2O 2被原位活化成活性物种且光生电流和载流子分离效率获得显著提高。该光-自芬顿过程能高效降解RhB,其反应速率常数为0.208 min -1,约为无Fe 3+光催化反应速率常数的5.3倍,在光-自芬顿循环使用过程中表现出良好的稳定性。Fe 3+的加入促进了光生电荷的分离和H 2O 2的活化,超氧阴离子自由基(·O 2-)、空穴和羟基是光-自芬顿催化过程中的主要活性物种,且·O 2-作用更大。 相似文献
8.
A novel GO modified g-C 3N 4 nanosheets/flower-like BiOBr hybrid photocatalyst is fabricated by a facile method. The characterization results reveal that wrinkled GO is deposited between g-C 3N 4 nanosheets and flower-like BiOBr forming a Z-scheme heterojunction. As a mediator, plicate GO plays a positive role in prompting photogenerated electrons transferring through its sizeable 2D/2D contact surface area. The g-C 3N 4/GO/BiOBr hybrid displays a superior photocatalytic ability to g-C 3N 4 and BiOBr in photodegrading tetracycline (TC), whose removal efficiency could reach 96% within 2 h. Besides, g-C 3N 4/GO/BiOBr composite can reduce Cr(VI), and simultaneously treat TC and Cr(VI) combination contaminant under the visible light. The g-C 3N 4/GO/BiOBr ternary composite also exhibits satisfactory stability and reusability after four cycling experiments. Further, a feasible mechanism related to the photocatalytic process of g-C 3N 4/GO/BiOBr is put forward. This study offers a ternary hybrid photocatalyst with eco-friendliness and hopeful application in water pollution. 相似文献
9.
Water pollution has become a serious problem owing to the development of society. Photocatalysis is a promising approach to remove various pollutants in water, such as organic pollutants and antibiotic resistance bacteria. Meanwhile, the design of heterojunction between two semiconductors is an effective path to improve photocatalytic properties due to its potential in improving separation and transfer of photoinduced carriers. In this study, Nb 2O 5/g-C 3N 4 (NO/CN) composite materials were prepared through a one-step heating method. Characterizations confirmed successful preparation of NO/CN heterojunction structure and better optical properties than pure g-C 3N 4 and Nb 2O 5. NO/CN composite materials showed excellent photocatalytic efficiency for Escherichia coli ( E. coli) inactivation (95%) compared with the pure Nb 2O 5 (10%) and g-C 3N 4 (77%). Meanwhile, NO/CN exhibited better organic pollutants removal (RhB for 94%, methyl orange (MO) for 15% and methylene blue (MB) for 87%) under visible light, which is likely owing to the heterojunction structure between g-C 3N 4 and Nb 2O 5 that leads to the good separation of photogenerated electron-hole pair. Free radical scavenging and electron spin resonance (ESR) experiments demonstrated that superoxide radicals ( ?O 2?) and holes (h +) were the dominant radicals. Therefore, the NO/CN was proposed to be a promising material for effective disinfection and removal of organic contaminants in water treatment. 相似文献
10.
Melamine was added to the precursor of TiO2, then TiO2 prepared by hydrothermal, while melamine was modified. Subsequently, a series of Z-scheme TiO2/g-C3N4 heterojunction composites were successfully synthesized by simple calcination. The morphology and structure of samples were characterized by XRD, FT-IR, UV–vis DRS, SEM, TEM, PL and BET. The photocatalytic activity of these samples has been investigated by degradation of Rhodamine B (RhB), and results indicated that photocatalytic activity of the as-prepared samples was greatly influenced by the content of titanium tetrabutoxide in precursors and the hydrothermal time. The degradation rate of TiO2/g-C3N4-1 to RhB was the best, which was 5.05-fold of pure TiO2 (19.61%) and 2.25-fold of bulk g-C3N4 (44.06%), respectively. The trapping experiment results showed that ·O2? and h+ were main active species during degradation of RhB. The photocatalytic activity of the sample did not decrease significantly after 4 cycles. The unique Z-scheme heterojunction between TiO2 and g-C3N4 improved photocatalytic activity of the samples under visible light. 相似文献
11.
Graphene oxide modified porous g-C 3N 4 (porous g-C 3N 4/GO) had been synthesized by means of one-step calcination of cyanamide for efficient photocatalysis under visible light irradiation (λ > 400 nm). We expect that the photocatalytic activity of this hybrid photocatalyst could be enhanced by the efficient visible light absorption due to the porous structure and efficient photo generated charge separation at the heterojunction formed between porous g-C 3N 4 and GO. Scanning electron microscopy (SEM) images demonstrated that the as prepared photocatalyst is composed of GO and porous g-C 3N 4. The UV-vis diffuse reflectance spectrum shows that optical absorption of porous g-C 3N 4/GO is more intensive than for pristine g-C 3N 4. The enhanced generation of photocurrent under visible light irradiation (λ > 400 nm) is observed for the porous g-C 3N 4/GO. The results of photocatalytic experiments reveal that the pseudofirst-order kinetic constant of photocatalytic degradation of methylene blue (MB) using the porous g-C 3N 4/GO is 6 times higher than that of pristine g-C 3N 4. 相似文献
12.
AbstractA series of heterojunction catalysts (CuCN-X) were successfully fabricated by loading the different amounts of Keggin type Cu mono-substituted heteropoly acid (HPW 11Cu) on the surface of hollow nanospheres g-C 3N 4 (HSCN). The HSCNs were prepared by using SiO 2 as a hard template. The chemical structure, porosity, morphology and electronic property of the prepared catalysts were investigated using XRD, SEM, N 2-absorption isotherm and XPS. The results indicated that the modified HSCN show prominent absorption in the visible light range and decrease the band gap. The greatly enhanced photocatalytic activity of obtained CuCN-X have been shown by the degradation of Rhodamine B (RhB), reduction of CO 2 and production of photocatalytic hydrogen under visible light irradiation. More significantly, CuCN-15 has shown significantly improved photocatalytic performance at 4.5, 3.5 and 3.3 times higher that of than HSCN for the degradation of RhB, reduction of CO 2 and production of photocatalytic hydrogen, respectively. Furthermore, the mechanism for the enhanced photocatalytic activity of CuCN-X is proposed to be due to the formation of heterojunction. The electrons can be rapidly transferred from HSCN to HPW 11Cu, in which facilitate charge separation and charge transfer. 相似文献
13.
Solar photocatalytic technology is of great significance for adjusting energy structure and environmental improvement. Developing an efficient and low-cost photocatalyst is key to realizing the conversion of solar to chemical energy. In this study, α-Fe 2O 3-modified few-layer g-C 3N 4 hybrids (α-Fe 2O 3/FL g-C 3N 4) were successfully prepared by a two-step calcination route with a mixture of α-Fe 2O 3 and melamine. The samples were characterized by Thermogravimetric analysis, X-ray diffraction, Fourier transform infrared, scanning electron microscope, transmission electron microscope, High-resolution transmission electron microscopy, X-ray photoelectron spectroscopy, Brunauer–Emmett–Teller, UV–Vis absorption spectrum, photoluminescence, and Time-resolved photoluminescence spectroscopy; furthermore, their photoelectrochemical measurements and their photocatalytic performances were evaluated by visible light-driven hydrogen evolution and degradation of RhB. The results showed that the hydrogen production activity and degradation ability of α-Fe 2O 3/FL g-C 3N 4 were significantly enhanced compared with those of α-Fe 2O 3 / multilayer g-C 3N 4 (α-Fe 2O 3/ML g-C 3N 4) and FL g-C 3N 4. The enhanced photoactivities were mainly attributed to the synergistic effect between the increased visible-light absorption, enhanced surface area, and highly efficient electron transfer and separation on the Z-type heterojunction interface. This work not only provides evidence for the formation of FL g-C 3N 4 nanosheets using a thermal exfoliation method but also provides new insights into the interfacial charge carrier dynamics of Z-scheme α-Fe 2O 3/FL g-C 3N 4 heterostructures for photocatalytic H 2 generation and pollutant degradation. 相似文献
14.
通过水热法合成具有协同机制的三元复合材料Bi 2Fe 4O 9/g-C 3N 4/UiO-66,研究表明三元复合光催化剂的催化活性要高于二元材料和纯材料。这主要是由于Bi 2Fe 4O 9更易于和g-C 3N 4结合形成稳定的Z-scheme异质结结构,使三元复合材料增强了可见光响应能力,提高了电子-空穴分离能力,增强了空穴和电子的氧化还原能力。 相似文献
15.
通过水热法合成具有协同机制的三元复合材料Bi 2Fe 4O 9/g-C 3N 4/UiO-66,研究表明三元复合光催化剂的催化活性要高于二元材料和纯材料。这主要是由于Bi 2Fe 4O 9更易于和g-C 3N 4结合形成稳定的Z-scheme异质结结构,使三元复合材料增强了可见光响应能力,提高了电子-空穴分离能力,增强了空穴和电子的氧化还原能力。 相似文献
16.
The graphitic carbon nitride (g-C 3N 4) materials with many intriguing properties have attracted much attention in photocatalysis. The photocatalytic activity of g-C 3N 4 is hindered by serious aggregation and limited exposed active sites. Herein is shown that nanosized g-C 3N 4 can be simply obtained by a superfast high-pressure homogenization approach. The high-pressure homogenization treatment can provide strong force to cut and/or to exfoliate the bulk g-C 3N 4 into nanosized g-C 3N 4 with good dispersion. Moreover, choosing different solvents during treatment can cause a different surface structure of as-prepared nanosized g-C 3N 4. In addition, the narrow bandgap properties, the high photogenerated charge carrier separation, and the transport abilities are achieved in as-prepared nanosized g-C 3N 4 because of the retaining conjugated C 3N 4 system. Specifically, the photocatalytic activities of as-prepared nanosized g-C 3N 4 have been significantly enhanced in terms of degradation of organic dye Rhodamine B (RhB) under visible light irradiation (10 times higher than that of bulk g-C 3N 4). These findings can provide a promising and simple approach to the exfoliation, nanonization, and surface functionalization of 2D layered materials. 相似文献
17.
通过在三聚氰胺热分解过程中加入NaHCO 3制备出具有氮缺陷的石墨相氮化碳(g-C 3N 4),利用X射线衍射(XRD)、傅里叶变换红外光谱(FT-IR)、N 2吸附-脱附、X射线光电子能谱(XPS)、紫外-可见漫反射光谱(UV-vis DRS)和固体荧光光谱(PL)等方法对其进行表征,并在可见光(λ> 420nm)照射下,以水相中罗丹明B(RhB)的降解为模型反应,研究了该氮缺陷g-C 3N 4对有机污染物降解的光催化活性。结果表明,引入氮缺陷可以提高g-C 3N 4对可见光的吸收以及电子-空穴对的分离效率,进而提高g-C 3N 4的可见光催化活性。催化剂CNK0.005、CNK0.01和CNK0.05在30min内对RhB的降解率分别为79.8%、100.0%和87.6%;而在相同条件下,没有氮缺陷的g-C 3N 4对RhB的降解率仅为59.8%。 相似文献
18.
A novel CaCO 3/graphitic carbon nitride (g-C 3N 4) photocatalyst was synthesized for the first time via a facile calcination method using CaCO 3 and melamine as precursors. The as-prepared samples were characterized using various techniques, such as scanning and transmission electron microscopy, X-ray diffraction, Brunauer-Emmett-Teller analysis, as well as Fourier-transform infrared, X-ray photoelectron, photoluminescence, and UV–vis diffuse reflectance spectroscopy. The results of the experiments confirm the successful coupling of CaCO 3 to g-C 3N 4. The photocatalytic activity of the synthesized CaCO 3/g-C 3N 4 composites was evaluated by assessing their performance in the photocatalytic degradation of crystal violet (CV) in water under visible light irradiation. The analysis shows that CaCO 3/g-C 3N 4 exhibits higher photocatalytic activity towards CV degradation (76.0%) than pristine g-C 3N 4 (21.6%) and CaCO 3 (23.2%). Radical trapping and electron spin resonance experiments show that hydroxyl radicals (OH) and holes (h +) are the key reactive species in the photocatalytic process. The enhanced photocatalytic activity of the composite is mainly attributed to the efficient separation rate of electron-hole pairs achieved through the incorporation of CaCO 3. 相似文献
19.
以硝酸铁和三聚氰胺为原料制备不同含铁量的Fe 掺杂石墨氮化碳(g-C 3N 4). 采用X 射线衍射光谱(XRD)、紫外-可见(UV-Vis)光谱、傅里叶变换红外(FT-IR)光谱、电感耦合等离子体-原子发射光谱(ICP-AES)、荧光(PL)光谱、X光电子能谱(XPS)等分析手段对制备的催化剂进行了表征. 结果表明,铁以离子形式镶嵌在g-C 3N 4的结构单元中,影响了g-C 3N 4的能带结构,增加了g-C 3N 4对可见光的吸收,降低了光生电子-空穴对的复合几率. 以染料罗丹明B的降解为探针反应系统研究了不同含铁量对g-C 3N 4在可见光下催化性能的影响. 结果表明,m(Fe)/m(g-C 3N 4)=0.14%时,制备的Fe 掺杂g-C 3N 4表现出最佳的光催化性能,120 min 内罗丹明B的降解率高达99.7%,速率常数达到0.026 min -1,是纯g-C 3N 4的3.2 倍. 以叔丁醇、对苯醌、乙二胺四乙酸二钠为自由基(·OH)、自由基(O 2-·)和空穴(h VB+)的捕获剂,研究了光催化反应机理. 相似文献
20.
As the main component of syngas, reducing CO 2 to CO with high selectivity through photocatalysis could provide a sustainable way to alleviate energy shortage issues. Developing a photocatalytic system with low cost and high performance that is environmentally friendly is the ultimate goal towards CO 2 photoreduction. Herein, an efficient and economic three-component heterojunction photocatalyst is designed and fabricated for converting CO 2 to CO in the absence of organic sacrificial agents. The heterojunction is made of Cu 2−xS nanotubes coated with a carbon layer (C-Cu 2−xS) and g-C 3N 4. By using the classical MOF material HKUST-1 as a precursor, hollow tubular-like metal sulfides (C-Cu 2−xS) with carbon coating were synthesized and further loaded on g-C 3N 4, forming a three-component heterojunction C-Cu 2−xS@g-C 3N 4. The carbon coat in C-Cu 2−xS@g-C 3N 4 acts as an electron reservoir, which facilitates electron–hole pair separation. The optimized C-Cu 2−xS@g-C 3N 4 acted as a photocatalyst in CO 2 reduction with a high reactivity of 1062.6 μmol g −1 and selectivity of 97 %. Compared with bare g-C 3N 4 (158.4 μmol g −1) and C-Cu 2−xS, the reactivity is nearly 7 and 23-fold enhanced and this CO generation rate is higher than most of the reported Cu 2S or g-C 3N 4 composites under similar conditions. The prominent activity may result from enhanced light adsorption and effective charge separation. This work might open up an alternative method for the design and fabrication of high-performance and low-cost photocatalysts for efficiently and durably converting CO 2 to CO with high selectivity. 相似文献
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