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1.
Codoping of N and O in ultrathin graphitic carbon nitride (g‐C3N4) nanosheets leads to an inner electric field. This field restrains the recombination of photogenerated carriers and, thus, enhances hydrogen evolution. The layered structure of codoped g‐C3N4 nanosheets (N‐O‐CNNS) not only provides abundant sites of contact with the reaction medium, but also decreases the distance over which the photogenerated electron–hole pairs are transported to the reaction interface. Quantum confinement in the ultrathin structure results in an increased bandgap and makes the photocatalytic reaction more favorable than bulk g‐C3N4. Under visible light irradiation, N‐O‐CNNS with 3 wt% Pt achieves a hydrogen evolution rate of 9.2 mmol g?1 h?1 and a value of 46.9 mmol g?1 h?1 under AM1.5 with 5 wt% Pt. Thus, this work paves the way for designing efficient nanostructures with increased separation/transfer efficiency of photogenerated carriers and, hence, increased photocatalytic activities. 相似文献
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Sulfur‐Modified Graphitic Carbon Nitride Nanostructures as an Efficient Electrocatalyst for Water Oxidation 下载免费PDF全文
Vinayak S. Kale Uk Sim Jiwoong Yang Kyoungsuk Jin Sue In Chae Woo Je Chang Arun Kumar Sinha Heonjin Ha Chan‐Cuk Hwang Junghyun An Hyo‐Ki Hong Zonghoon Lee Ki Tae Nam Taeghwan Hyeon 《Small (Weinheim an der Bergstrasse, Germany)》2017,13(17)
There is an urgent need to develop metal‐free, low cost, durable, and highly efficient catalysts for industrially important oxygen evolution reactions. Inspired by natural geodes, unique melamine nanogeodes are successfully synthesized using hydrothermal process. Sulfur‐modified graphitic carbon nitride (S‐modified g‐CN x ) electrocatalysts are obtained by annealing these melamine nanogeodes in situ with sulfur. The sulfur modification in the g‐CN x structure leads to excellent oxygen evolution reaction activity by lowering the overpotential. Compared with the previously reported nonmetallic systems and well‐established metallic catalysts, the S‐modified g‐CN x nanostructures show superior performance, requiring a lower overpotential (290 mV) to achieve a current density of 10 mA cm?2 and a Tafel slope of 120 mV dec?1 with long‐term durability of 91.2% retention for 18 h. These inexpensive, environmentally friendly, and easy‐to‐synthesize catalysts with extraordinary performance will have a high impact in the field of oxygen evolution reaction electrocatalysis. 相似文献
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Alkali‐Assisted Synthesis of Nitrogen Deficient Graphitic Carbon Nitride with Tunable Band Structures for Efficient Visible‐Light‐Driven Hydrogen Evolution 下载免费PDF全文
Huijun Yu Run Shi Yunxuan Zhao Tong Bian Yufei Zhao Chao Zhou Geoffrey I. N. Waterhouse Li‐Zhu Wu Chen‐Ho Tung Tierui Zhang 《Advanced materials (Deerfield Beach, Fla.)》2017,29(16)
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Wenyao Zhang Qiong Peng Lingling Shi Qiushi Yao Xin Wang Aiping Yu Zhongwei Chen Yongsheng Fu 《Small (Weinheim an der Bergstrasse, Germany)》2019,15(50)
Scalable and sustainable solar hydrogen production via photocatalytic water splitting requires extremely active and stable light‐harvesting semiconductors to fulfill the stringent requirements of suitable energy band position and rapid interfacial charge transfer process. Motivated by this point, increasing attention has been given to the development of photocatalysts comprising intimately interfaced photoabsorbers and cocatalysts. Herein, a simple one‐step approach is reported to fabricate a high‐efficiency photocatalytic system, in which single‐site dispersed iron atoms are rationally integrated on the intrinsic structure of the porous crimped graphitic carbon nitride (g‐C3N4) polymer. A detailed analysis of the formation process shows that a stable complex is generated by spontaneously coordinating dicyandiamidine nitrate with iron ions in isopropanol, thus leading to a relatively complicated polycondensation reaction upon thermal treatment. The correlation of experimental and computational results confirms that optimized electronic structures of Fe@g‐C3N4 with an appropriate d‐band position and negatively shifting Fermi level can be achieved, which effectively gains the reducibility of electrons and creates more active sites for the photocatalytic reactions. As a result, the Fe@g‐C3N4 exhibits a highlighted intramolecular synergistic effect, performing greatly enhanced solar‐photon‐driven activities, including excellent photocatalytic hydrogen evolution rate (3390 µmol h?1 g?1, λ > 420 nm) and a reliable apparent quantum efficiency value of 6.89% at 420 nm. 相似文献
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Guanchao Wang Ying Ma Ting Zhang Yuefeng Liu Baojun Wang Riguang Zhang Zhongkui Zhao 《Small (Weinheim an der Bergstrasse, Germany)》2023,19(6):2205758
To develop a non-precious highly efficient cocatalyst to replace Pt on graphitic carbon nitride (g-C3N4) for solar H2 production is great significant, but still remains a huge challenge. The emerging single-atom catalyst presents a promising strategy for developing highly efficient non-precious cocatalyst owing to its unique adjustability of local coordination environment and electronic structure. Herein, this work presents a facile approach to achieve single Ni sites (Ni1-N2S) with unique local coordination structure featuring one Ni atom coordinated with two nitrogen atoms and one sulfur atom, confirmed by high-angle annular dark-field scanning transmission electron microscopy, X-ray absorption spectroscopy, and density functional theory calculation. Thanks to the unique electron structure of Ni1-N2S sites, the 1095 µmol g−1 h−1 of high H2 evolution rate with 4.1% of apparent quantum yield at 420 nm are achieved. This work paves a pathway for designing a highly efficient non-precious transition metal cocatalyst for photocatalytic H2 evolution. 相似文献
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Photocatalysis: Alkali‐Assisted Synthesis of Nitrogen Deficient Graphitic Carbon Nitride with Tunable Band Structures for Efficient Visible‐Light‐Driven Hydrogen Evolution (Adv. Mater. 16/2017) 下载免费PDF全文
Huijun Yu Run Shi Yunxuan Zhao Tong Bian Yufei Zhao Chao Zhou Geoffrey I. N. Waterhouse Li‐Zhu Wu Chen‐Ho Tung Tierui Zhang 《Advanced materials (Deerfield Beach, Fla.)》2017,29(16)
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石墨相氮化碳(Graphitic carbon nitride,g-C_3N_4)是一种由碳(C)和氮(N)元素组成的共轭聚合物材料,具有平面的三嗪聚合物(Poly(tri-s-triazine))网络结构。比起大部分其他碳材料,氮化碳是富电子体,因而赋予了其特殊的性质。然而目前对于g-C_3N_4的研究主要集中在其相关催化作用(光催化,电催化和光电催化),对于g-C_3N_4的吸附作用的研究相对很少涉及。本文探讨了g-C_3N_4材料在吸附领域中的应用,简要综述了G-C_3N_4的性质、制备方法及其作为吸附材料的应用现状,最后展望了石墨型氮化碳在吸附应用领域的未来发展方向。 相似文献
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Xueyan Zhang Guang Yang Jiaqi Meng Lang Qin Miao Ren Yue Pan Yuxin Yang Yihang Guo 《Small (Weinheim an der Bergstrasse, Germany)》2023,19(24):2208012
Acetamide- or formamide-assisted in situ strategy is designed to synthesize carbon atom self-doped g-C3N4 (AHCNx) or nitrogen vacancy-modified g-C3N4 (FHCNx). Different from the direct copolymerization route that suffers from the problem of mismatched physical properties of acetamide (or formamide) with urea, the synthesis of AHCNx (or FHCNx) starts from a crucial preorganization step of acetamide (or formamide) with urea via freeze drying-hydrothermal treatment so that the chemical structures as well as C-doping level in AHCNx and N-vacancy concentration in FHCNx can be precisely regulated. By using various structural characterization methods, well-defined AHCNx and FHCNx structures are proposed. At the optimal C-doping level in AHCNx or N-vacancy concentration in FHCNx, both AHCNx and FHCNx exhibit remarkably improved visible-light photocatalytic performance in oxidation of emerging organic pollutants (acetaminophen and methylparaben) and reduction of proton to H2 in comparison of unmodified g-C3N4. Combination of the experimental results with theoretical calculations, it is confirmed that AHCNx and FHCNx show different charge separation and transfer mechanisms, while the enhanced visible-light harvesting capacity and the localized charge distributions on HOMO and LUMO are responsible for this excellent photocatalytic redox performance of AHCNx and FHCNx. 相似文献
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Enhanced Singlet Oxygen Generation in Oxidized Graphitic Carbon Nitride for Organic Synthesis 下载免费PDF全文
Hui Wang Shenlong Jiang Shichuan Chen Dandan Li Xiaodong Zhang Wei Shao Xianshun Sun Junfeng Xie Zhi Zhao Qun Zhang Yupeng Tian Yi Xie 《Advanced materials (Deerfield Beach, Fla.)》2016,28(32):6940-6945
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Imran Khan Salman Khan Shiuan-Yau Wu Hsin-Tsung Chen Amir Zada Liu Linlin Ahmed Ismail Sharafat Ali Fazal Raziq Mustafa Haider Javid Khan Sami Ullah Shin-pon Ju Shiliang Wang 《Small (Weinheim an der Bergstrasse, Germany)》2023,19(25):2208179
The realization of solar-light-driven CO2 reduction reactions (CO2 RR) is essential for the commercial development of renewable energy modules and the reduction of global CO2 emissions. Combining experimental measurements and theoretical calculations, to introduce boron dopants and nitrogen defects in graphitic carbon nitride (g-C3N4), sodium borohydride is simply calcined with the mixture of g-C3N4 (CN), followed by the introduction of ultrathin Co phthalocyanine through phosphate groups. By strengthening H-bonding interactions, the resultant CoPc/P-BNDCN nanocomposite showed excellent photocatalytic CO2 reduction activity, releasing 197.76 and 130.32 µmol h−1 g−1 CO and CH4, respectively, and conveying an unprecedented 10-26-time improvement under visible-light irradiation. The substantial tuning is performed towards the conduction and valance band locations by B-dopants and N-defects to modulate the band structure for significantly accelerated CO2 RR. Through the use of ultrathin metal phthalocyanine assemblies that have a lot of single-atom sites, this work demonstrates a sustainable approach for achieving effective photocatalytic CO2 activation. More importantly, the excellent photoactivity is attributed to the fast charge separation via Z-scheme transfer mechanism formed by the universally facile strategy of dimension-matched ultrathin (≈4 nm) metal phthalocyanine-assisted nanocomposites. 相似文献
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3D Aerogel of Graphitic Carbon Nitride Modified with Perylene Imide and Graphene Oxide for Highly Efficient Nitric Oxide Removal under Visible Light 下载免费PDF全文
Jundie Hu Dongyun Chen Najun Li Qingfeng Xu Hua Li Jinghui He Jianmei Lu 《Small (Weinheim an der Bergstrasse, Germany)》2018,14(19)
3D materials are considered promising for photocatalytic applications in air purification because of their large surface areas, controllability, and recyclability. Here, a series of aerogels consisting of graphitic‐carbon nitride (g‐C3N4) modified with a perylene imide (PI) and graphene oxide (GO) are prepared for nitric oxide (NO) removal under visible‐light irradiation. All of the photocatalysts exhibit excellent activity in NO removal because of the strong light absorption and good planarity of PI–g‐C3N4 coupled with the favorable charge transport properties of GO, which slow the recombination of electron–hole pairs. The aerogel containing thiophene displays the most efficient NO removal of the aerogel series, with a removal ratio of up to 66%. Density functional theory calculations are conducted to explain this result and recycling experiments are carried out to verify the stability and recyclability of these photocatalysts. 相似文献
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Yunyan Wu Pan Xiong Jianchun Wu Zengliang Huang Jingwen Sun Qinqin Liu Xiaonong Cheng Juan Yang Junwu Zhu Yazhou Zhou 《纳微快报(英文)》2021,(3):95-106
Graphitic carbon nitride(g-C3N4)-based photocatalysts have shown great potential in the splitting of water.However,the intrinsic drawbacks of g-C3N4,such as low surface area,poor diffusion,and charge separation efficiency,remain as the bottleneck to achieve highly efficient hydrogen evolution.Here,a hollow oxygen-incorporated g-C3N4 nanosheet(OCN)with an improved surface area of 148.5 m2 g^−1 is fabricated by the multiple thermal treatments under the N2/O2 atmosphere,wherein the C–O bonds are formed through two ways of physical adsorption and doping.The physical characterization and theoretical calculation indicate that the O-adsorption can promote the generation of defects,leading to the formation of hollow morphology,while the O-doping results in reduced band gap of g-C3N4.The optimized OCN shows an excellent photocatalytic hydrogen evolution activity of 3519.6μmol g^−1 h^−1 for~20 h,which is over four times higher than that of g-C3N4(850.1μmol g^−1 h^−1)and outperforms most of the reported g-C3N4 catalysts. 相似文献
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以石墨相氮化碳(g-C3N4)和六水合硝酸钴为原料制备Co@CNT复合电磁波吸收剂,调节Co元素含量以提高其电磁波吸收性能。采用X射线衍射(XRD)、X射线光电子能谱(XPS)、拉曼光谱、扫描电镜(SEM)、能谱分析(EDS)和透射电镜(TEM)等手段表征其微结构和物相组成,使用矢量网络分析仪测量复合物电磁参数并进行Matlab模拟得到反射损耗图。结果表明,Co@CNT-1与石蜡质量比为1:3的材料,其吸波性能最优,厚度为4.1 mm时对电磁波的吸收最强,最小反射损耗(RLmin)为-45.5 dB;厚度仅为1.5 mm的材料,有效吸收带宽(RL<-10 dB)最大为4.42 GHz。 相似文献
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Guangming Cheng Shanshan Yao Xiahan Sang Boyi Hao Dongyan Zhang Yoke Khin Yap Yong Zhu 《Small (Weinheim an der Bergstrasse, Germany)》2016,12(6):818-824
Irradiation‐induced vacancy defects in multiwalled (MW) boron nitride nanotubes (BNNTs) are investigated via in situ high‐resolution transmission electron microscope operated at 80 kV, with a homogeneous distribution of electron beam intensity. During the irradiation triangle‐shaped vacancy defects are gradually generated in MW BNNTs under a mediate electron current density (30 A cm?2), by knocking the B atoms out. The vacancy defects grow along a well‐defined direction within a wall at the early stage as a result of the curvature induced lattice strain, and then develop wall by wall. The orientation or the growth direction of the vacancy defects can be used to identify the chirality of an individual wall. With increasing electron current density, the shape of the irradiation‐induced vacancy defects changes from regular triangle to irregular polygon. 相似文献
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Cobalt Sulfide Nanowires Core Encapsulated by a N,S Codoped Graphitic Carbon Shell for Efficient Oxygen Reduction Reaction 下载免费PDF全文
Ce Han Qun Li Dewen Wang Qingqing Lu Zhicai Xing Xiurong Yang 《Small (Weinheim an der Bergstrasse, Germany)》2018,14(17)
Exploration of economical electrocatalysts for highly efficient and stable oxygen reduction reaction (ORR) is believed to be essential for diverse future renewable energy applications. Herein, cobalt sulfide nanowire core encapsulated in a N, S codoped graphitic carbon shell (CoS NWs@NSC) is successfully fabricated via the calcination of polydopamine‐coated Co(CO3)0.5(OH)0.11H2O NWs with sulfur powder under argon atmosphere. The uniform encapsulation of CoS core by N, S codoped graphitic carbon shell favors the interaction of the core–shell structure for generating stable and numerous ORR active sites homogeneously dispersed throughout the materials. Meanwhile, the wire‐like CoS NWs@NSC stacks to form 3D mesoporous conductive networks, which improves the mass and charge transport capability of catalyst. Accordingly, the resultant CoS NWs@NSC electrocatalysts possess excellent ORR activity through the four‐electron pathway with superior stability and methanol tolerance over the Pt/C in 0.1 m KOH. This strategy can offer inspiration for designing and fabricating novel core–shell‐structured nanomaterials with active sites derived from uniform morphology as potential electrocatalysts for various vital renewable energy devices. 相似文献
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Microcontact‐Printing‐Assisted Access of Graphitic Carbon Nitride Films with Favorable Textures toward Photoelectrochemical Application 下载免费PDF全文
Jian Liu Hongqiang Wang Zu Peng Chen Helmuth Moehwald Sebastian Fiechter Roel van de Krol Liping Wen Lei Jiang Markus Antonietti 《Advanced materials (Deerfield Beach, Fla.)》2015,27(4):712-718
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Hadiseh Taheri Mehmet Altay Unal Melike Sevim Cansu Gurcan Okan Ekim Ahmet Ceylan Zois Syrgiannis Konstantinos C. Christoforidis Susanna Bosi Ozge Ozgen Manuel Jos Gmez Mine Turktas Erken igdem Soydal Zafer Erolu Ceylan Verda Bitirim Umut Cagin Fikret Ar Asuman Ozen Ozlem Kuuk Lucia Gemma Delogu Maurizio Prato
nder Metin Aelya Yilmazer 《Small (Weinheim an der Bergstrasse, Germany)》2020,16(10)