零维/二维Bi_2S_3/g-C_3N_4异质结的原位构建及光催化性能

采用简单的一步溶剂热法,以硝酸铋为铋源,硫代硫酸钠为硫源,将Bi_2S_3纳米粒子原位修饰在g-C_3N_4纳米片上,成功制备了零维/二维Bi_2S_3/g-C_3N_4异质结。利用XRD、SEM、TEM、UV-Vis、荧光光谱以及电化学分析方法等手段对所制备的光催化材料进行了表征。在可见光照射下,以罗丹明B(RhB)为模型污染物,研究其光催化降解效率。结果表明,Bi_2S_3以纳米颗粒的形式分散于g-C_3N_4纳米片上,形成了零维/二维异质结结构,拓宽了g-C_3N_4在可见光区的吸收,降低了电子-空穴对的复合概率;与纯g-C_3N_4相比,Bi_2S_3/g-C_3N_4异质结表现出更高的光催化效率。同时,Bi_2S_3/g-C_3N_4催化剂具有良好的光催化稳定性,经过5次循环后其光催化活性基本稳定。     

高比表面积g-C_3N_4纳米片的制备及光解水制氢性能的研究

通过浓硫酸剥离块状类石墨相氮化碳(g-C_3N_4)制备了产率较高的g-C_3N_4纳米片;通过X射线衍射(XRD)、透射电镜(TEM)、红外光谱(FT-IR)、紫外-可见漫反射光谱(UV-Vis)、物理吸附仪(BET)、光电流等分析测试手段对g-C_3N_4纳米片和块状g-C_3N_4的结构、形貌、光学性质和光电性能进行了分析,并以光解水制氢性能评价了其可见光催化活性。结果表明,g-C_3N_4纳米片具有较大的比表面积(244.3m~2/g)和较小的片层厚度,带隙宽度增大到3.19eV,g-C_3N_4纳米片的光电流是块状g-C_3N_4的3.1倍,平均产氢速率为469μmol/(g·h),是块状g-C_3N_4的4.2倍。     

g-C3N4量子点修饰球形Bi2WO6及其光催化活性增强机制

采用水热法制备三维分级结构Bi_2WO_6,在此基础上采用浸渍-焙烧法将g-C_3N_4量子点成功沉积在Bi_2WO_6的表面,获得Z-型结构g-C_3N_4/Bi_2WO_6光催化剂。采用XRD,FE-SEM,TEM,UV-Vis-DRS测试手段对催化材料的组成、形貌和光吸收特性进行表征。以亚甲基蓝(MB)和对硝基苯酚(p-NPh)为模型污染物,考察g-C_3N_4量子点表面修饰对Bi_2WO_6光催化活性的影响。结果表明:所得Bi_2WO_6为三维分级多孔结构,孔尺寸约为10nm,浸渍-焙烧法可将尺寸约5nm的g-C_3N_4量子点沉积在其二级结构纳米片表面。Z-型结构g-C_3N_4/Bi_2WO_6光催化剂的催化活性优于纯Bi_2WO_6的,且10%g-C_3N_4/Bi_2WO_6(质量分数)异质光催化剂对MB的降解表观速率常数(k_(app))分别为纯Bi_2WO_6和g-C_3N_4的4.5倍和5.8倍,对p-NPh的k_(app)分别为纯Bi_2WO_6和g-C_3N_4的2.6倍和1.6倍。O■是光催化过程中的主要活性物种。g-C_3N_4量子点与Bi_2WO_6形成异质结,有利于拓宽光响应范围的同时有效抑制了Bi_2WO_6光生电子与空穴的复合,从而提高了催化剂的活性。     

Co_3O_4/g-C_3N_4复合材料的制备及光催化降解甲基橙

采用水热、煅烧制备Co_3O_4/g-C_3N_4复合催化剂。用IR、XRD、TEM、UV-Vis、电化学对复合材料分析结果表明,Co_3O_4均匀地附着在g-C_3N_4的表面,形成异质结。阻抗曲线表面异质结能够促进空穴和光生电子的转移和分离。在可见光照射下,当15%Co_3O_4/g-C_3N_4复合材料做为光催化剂,其光催化降解甲基橙的降解率可达90%,并拟合符合动力学一级方程,多次循环利用性能几乎不变。     

固混法制备BiVO_4/石墨相氮化碳复合物及其光催化性能表征

通过固混法制备不同BiVO_4含量的BiVO_4/石墨相氮化碳(BiVO_4/g-C_3N_4)复合光催化材料。采用粉末X射线衍射仪、傅里叶变换红外光谱仪和扫描电子显微镜分别对BiVO_4/g-C_3N_4复合催化剂的晶相组成、官能团和微观形貌进行了表征;通过可见光照射下罗丹明B的降解来评价纳米复合材料的光催化活性。结果表明:在可见光照射3h后,30%(质量分数)BiVO_4/g-C_3N_4复合物的降解率最高,达到87%。BiVO_4/g-C_3N_4良好的光催化性能可以归因于在BiVO_4和g-C_3N_4的界面形成的异质结。     

常压条件下NaOH剥离g-C3N4及其光催化性能研究

通过热聚合法制备了块状g-C_3N_4,并利用不同浓度的NaOH对块状g-C_3N_4进行常压剥离处理,获得了大比表面积、疏松多孔的g-C_3N_4。对样品进行了XRD、SEM、TEM、BET、PL、FT-IR、UV-Vis光谱多项表征,并进行了降解罗丹明B光催化性能测试。结果显示,随着NaOH溶液浓度的增加,g-C_3N_4疏松程度增加,经过浓度为0.3 mol/L的NaOH处理的g-C_3N_4层间氢键破坏程度大,层内的结构也遭到一定程度的破坏,比表面积明显增大,是块状g-C_3N_4的5.5倍。较大的比表面积有效地增加了对罗丹明B的吸附性,同时经过0.3 mol/L的NaOH处理的g-C_3N_4电子与空穴的复合速率降低,吸附和光催化协同效应使0.3 mol/L NaOH处理过的g-C_3N_4光催化降解罗丹明B的效率较块状的g-C_3N_4有较大程度的提高。     

Z型BiVO_4/GO/g-C_3N_4复合材料的制备及其可见光下催化性能（英文）

Z-型光催化剂可以有效增强电荷分离,从而改善光催化剂的活性。采用浸渍–煅烧和水热法两步制备Z型BiVO_4/GO/g-C_3N_4光催化剂,并用不同手段对其进行表征。在BiVO_4/GO/g-C_3N_4的光催化过程中,GO纳米片作为BiVO_4和g-C_3N_4之间的快速传输通道,可以抑制电子–空穴复合,显著促进电荷分离,提高三元异质结的氧化还原能力。与单组分或二元复合物相比,该催化剂具有良好的光降解罗丹明B(RhB)的能力。在可见光照射下,它能够在120 min内降解85%RhB,空穴(h~+)在反应中起主要作用。该工作为三元光催化剂体系提供了简单的制备方法,其中g-C_3N_4通过GO与BiVO_4偶联,光催化活性显著提高。     

g-C_3N_4/MnO_2复合光催化剂的制备及可见光下降解四环素性能

通过原位生长法制备了g-C_3N_4/MnO_2复合光催化剂,利用XRD,FTIR和UV-vis DRS等方法表征材料的结构和光学性质,并考察在可见光照射下降解四环素的性能。结果表明,MnO_2的引入增强了g-C_3N_4对可见光的吸收;g-C_3N_4/MnO_2复合材料的光催化活性较单体得到提升,在可见光照射90 min内对TC降解率可达77.1%,经过5次循环实验后,对TC的降解率仅下降4%,复合材料具有良好的稳定性;机理研究表明,·O~(2-)是反应体系中的主要活性物质,g-C_3N_4与MnO_2之间形成了Z型异质结,促进了光生电子-空穴的转移,提高了光催化活性。     

具有三维网状结构的石墨相氮化碳/还原氧化石墨烯/钯复合材料的合成及可见光催化性能

石墨相氮化碳(g-C_3N_4)已经被认为是一种高效的非金属半导体光催化剂。为进一步优化其光催化性能,通过热解-水热两步法制备了三维网状结构的g-C_3N_4/还原氧化石墨烯(rGO)/钯纳米颗粒(Pd NPs)复合材料。该复合材料由大量超薄片组成,而且薄片上有大量直径约为10nm的Pd NPs。g-C_3N_4/rGO/Pd NPs复合材料展现了一个宽的可见光吸收(边~460nm),其在460~800nm波长范围内还有一个随波长增加的光吸收。经可见光(λ400nm)照射140 min后,g-C_3N_4/rGO/Pd NPs复合材料可降解90%罗丹明B(RhB)。此外,循环实验表明g-C_3N_4/rGO/Pd NPs复合材料具有良好的稳定性。因此,g-C_3N_4/rGO/Pd NPs复合材料有望成为一种高效稳定的光催化剂,在水污染处理领域具有潜在的应用价值。     

两种g-C_3N_4的异质结的第一性原理计算

运用第一性原理方法计算了两种新型的g-C_3N_4的异质结g-C_3N_4/TiO_2和g-C_3N_4/MoS_2,其带隙分别为1.281和0.344eV,两者的带隙相比单层g-C_3N_4有所减小。两者的VBM主要由N2p电子构成,CBM主要由Ti或Mo3d电子构成,并且两者的HOMO和LUMO都出现了层分离,使得电子空穴复合速度下降,提高了光催化效率。     

A novel Z-scheme CeO2/g-C3N4 heterojunction photocatalyst for degradation of Bisphenol A and hydrogen evolution and insight of the photocatalysis mechanism

CeO2/g-C3N4 heterojunction photocatalyst had been successfully fabricated through a one-step in-situ pyrolysis formation of 3D hollow CeO2 mesoporous nanospheres and 2D g-C3N4 nanosheets together with simultaneous removal of carbon sphere templates after heat treatment.The sample shows high catalytic performances for photocatalytic hydrogen generation and photocatalytic oxidation of Bisphe-nol A(BPA)under visible light irradiation,and the catalytic degradation route of BPA was suggested by the degradation products determined by GC-MS.The enhancing catalytic activity was attributed to the effective interfacial charge migration and separation.Finally,it was proposed that the CeO2/g-C3N4 het-erojunction photocatalyst could follow a more appropriate Z-scheme charge transfer mechanism,which was confirmed by the analysis of experiment and theoretical calculation results.     

三维大孔g-C3N4吸附和光催化还原U(VI)性能研究

将易溶的U(VI)还原为微溶的U(IV)是治理放射性铀污染的有效方法。本研究以SiO₂纳米球作为硬模板, 通过热聚合-刻蚀制备具有连续贯通的三维大孔g-C₃N₄光催化剂, 用于吸附-光催化还原U(VI)。材料表征结果显示: 三维大孔g-C₃N₄比表面积显著增加, 对可见光的吸收明显增强; 同时具有三维有序大孔结构, 并呈规则的紧密堆积结构, 孔壁完整多孔, 整个结构具有良好的三维连通性。吸附实验表明: 三维大孔g-C₃N₄对U(VI)最大吸附容量可达~30.5 mg/g, 该过程更符合Langmuir吸附模型, 与块体g-C₃N₄相比吸附容量提高了~1.83倍。光催化还原实验表明: 三维大孔g-C₃N₄具有高的光催化活性和良好的稳定性, 其还原反应速率常数为~0.0142 min ^-1, 是块体g-C₃N₄ (~0.0024 min ^-1)的~5.9倍。鉴于三维大孔g-C₃N₄具有较优异的吸附-催化还原性能, 该材料有望应用于放射性废水中U(VI)的快速高效清除。     

Increasingπ-electron availability in benzene ring incorporated graphitic carbon nitride for increased photocatalytic hydrogen generation

Increasing the availability ofπ-electron in graphitic carbon nitride(g-C₃N₄)can reduce the band gap and thus enhance the photocatalytic hydrogen(H₂)generation activity upon exposure to visible light,However,such strategy has not yet been largely applied to increase the H₂generation of g-C₃N₄.Herein,we succes s fully increased the amount ofπ-electron in g-C₃N₄by incorporatingπ-electron-rich benzene rings through copolymerization of melamine and trimesic acid in air.The incorporation of benzene rings not only extends the light absorption of g-C₃N₄to 650 nm,but also improves the electrical conductivity due to delocalization ofπelectrons in benzene rings.As a result,a 3.4 times enhancement of photocatalytic H₂generation was achieved from the g-C₃N₄with benzene ring incorporation in comparing with that of pristine g-C₃N₄.More interestingly,H₂generation still occurs under irradiation of the light ofλ≥490 nm,above the absorption edge of pristine g-C₃N₄(~460 nm),illustrating the positive effectiveness of incorporated benzene rings on enhancing the H₂generation capacity of g-C₃N₄.The present work manifests the advantages of increasingπ-conjugated electrons on designing highly active g-C₃N₄photocatalysts.     

Facile synthesis of BiOCl/g-C3N4 heterojunction via in situ hydrolysis of Bi nanospheres: a high-efficiency visible-light-driven photocatalyst

Journal of Materials Science: Materials in Electronics - BiOCl/g-C3N4 (BC) heterojunctions were constructed successfully through a novel in situ hydrolysis method by taking metallic Bi nanospheres...     

One step method of structure engineering porous graphitic carbon nitride for efficient visible-light photocatalytic reduction of Cr(Ⅵ)

Porous g-C3N4 nanosheets (PCN) were prepared by the nickel-assisted one-step thermal polymerization method.Hydrogen (H2) which was produced by the reaction between nickel (Ni) foam and ammonia (NH3) defined the structure and properties of PCN.During the formation of PCN,the participation of H2 not only enhanced the spacing between layers but also boosted the specific surface area that more active sites were exposed.Additionally,H2 promoted pores formation in the nanosheets,which was beneficial to the transfer of photons through lamellar structure and improved the absorption efficiency of visible light.Remarkably,the obtained PCN possessed better Cr(Ⅵ) photocatalytic reduction efficiency than pure g-C3N4.The reaction rate constant (k) of PCN (0.013 min-1) was approximately twice that of bare g-C3N4 (0.007 min-1).Furthermore,the effects of original pH and concentration of Cr(Ⅵ)-containing solution on removal efficiency of Cr(Ⅵ) were explored.A possible photocatalytic mechanism was proposed based on the experiments of radical scavengers and photoelectrochemical characterizations.     

高能微波辐照合成类石墨烯氮化碳纳米片的结构特征

以碳纤维为微波吸收剂,基于微波辐照法直接处理三聚氰胺,快速高效地合成类石墨烯结构的氮化碳纳米片。借助于场发射扫描电子显微镜、透射电子显微镜、原子力显微镜、X射线衍射和傅里叶变换红外光谱等分析手段,对微波合成产物进行表征。结果表明:与常规热缩聚合成的石墨相氮化碳相比,高能微波技术合成产物具有明显的纳米片特征,即成功地制备得到类石墨烯结构的氮化碳纳米片。同时,与超声剥离或氧化刻蚀得到的类石墨烯氮化碳纳米片相比,高能微波技术合成产物表面光滑平整,且可发现脆性断裂的现象,呈现出一定的刚性。     

Platinum-coordinated graphitic carbon nitride nanosheet used for targeted inhibition of amyloid β-peptide aggregation

Amyloid β-peptide (Aβ) aggregation is a critical step in the pathogenesis of Alzheimer's disease (AD).Inhibition of Aβ production,dissolution of existing aggregates and clearance of Aβ represent valid therapeutic strategies against AD.Herein,a novel platinum(Ⅱ)-coordinated graphitic carbon nitride (g-C3N4)nanosheet (g-C3N4@Pt) has been designed to covalently bind to Aβ and modulate the peptide's aggregation and toxicity.Furthermore,g-C3N4@Pt nanosheets possess high photocatalytic activity and can oxygenate Aβ upon visible light irradiation,remarkably attenuating both the aggregation potency and neurotoxidty of Aβ.Due to its ability to cross the blood-brain barrier (BBB) and its good biocompatibility,g-C3N4@Pt nanosheet is a promising inhibitor of Aβ aggregation.This study may serve as a model for the engineering of novel multifunctional nanomaterials used for the treatment of AD.     

Confined reaction inside nanotubes: New approach to mesoporous g-C3N4 photocatalysts

Mesoporous g-C3N4 nanorods (NRs) are synthesized through the nano-confined thermal condensation of cyanamide in silica nanotubes (NTs) with porous shells.The gas bubbles retained during condensation and the limited cyanamide precursor inside the silica NTs lead to the formation of mesoporous g-C3N4.This nano-confined reaction is an alternative method to the traditional templating process for the synthesis of mesoporous materials.The as-prepared mesoporous g-C3N4 NRs exhibit remarkably improved photocatalytic activity and high stability in water splitting and degradation of Rhodamine B compared with bulk g-C3N4.     

Constructing CdSe QDs modified porous g-C3N4 heterostructures for visible light photocatalytic hydrogen production

Constructing heterostructures with narrow-band-gap semiconductors is a promising strategy to extend light absorption range of graphitic carbon nitride (g-C3N4) and simultaneously promote charge separa-tion for its photocatalytic activity improvement.However,its highly localized electronic states of g-C3N4 hinder photo-carrier migration through bulk towards heterostructure interfaces,resulting in low charge carrier separation effidency of solid bulk g-C3N4-based heterostructures.Herein,porous g-C3N4 (PCN)material with greatly shortened migration distance of photo-carriers from bulk to surface was used as an effective substrate to host CdSe quantum dots to construct type Ⅱ heterostructure of CdSe/PCN for pho-tocatalytic hydrogen production.The homogeneous modification of the CdSe quantum dots throughout the whole bulk of PCN together with proper band alignments between CdSe and PCN enables the ef-fective separation of photo-generated charge carriers in the heterostructure.Consequently,the CdSe/PCN heterostructure photocatalyst gives the greatly enhanced photocatalytic hydrogen production activity of 192.3 μmol h-1,which is 4.4 and 8.1 times that of CdSe andPCN,respectively.This work provides a fea-sible strategy to construct carbon nitride-based heterostructure photocatalysts for boosting visible light driven water splitting performance.