Search query: , , , , ,  and , J. Am. Chem. Soc., 2010, 132, 11642–11648.

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abstract: Electronic structure intrinsically controls the light absorbance, redox potential, charge carrier mobility, and consequently, photoreactivity of semiconductor photocatalysts. The conventional approach of modifying the electronic structure of a semiconductor photocatalyst for a wider absorption range by anion doping operates at the cost of reduced redox potentials and/or charge carrier mobility, so that its photoreactivity is usually limited and some important reactions may not occur at all. Here, we report sulfur doped graphitic C(3)N(4) (C(3)N(4 x)S(x) with a unique electronic structure that displays an increased valence bandwidth in combination with an elevated conduction band minimum and a slightly reduced absorbance. The C(3)N(4 x)S(x) shows a photoreactivity of H(2) evolution 7.2 and 8.0 times higher than C(3)N(4) under lambda 300 and 420 nm, respectively. More strikingly, the complete oxidation process of phenol under lambda 400 nm can occur for sulfur doped C(3)N(4) which is impossible for C(3)N(4) even under lambda 300 nm. The homogeneous substitution of sulfur for lattice nitrogen and a concomitant quantum confinement effect are identified as the cause of this unique electronic structure and, consequently, the excellent photoreactivity of C(3)N(4 x)S(x) The results acquired may shed light on general doping strategies for designing potentially efficient photocatalysts.
author_names: Gang Liu

Ping Niu

Chenghua Sun

Sean C Smith

Zhigang Chen

Gao Q Lu

Hui-Ming Cheng
title: Unique electronic structure induced high photoreactivity of sulfur doped graphitic C3N4.
venue: Journal of the American Chemical Society
year: 2010

abstract: Phosphorus doped hexagonal tubular carbon nitride (P TCN) with the layered stacking structure was obtained from a hexagonal rod like single crystal supramolecular precursor (monoclinic, C2/m) The production process of P TCN involves two steps: 1) the precursor was prepared by self assembly of melamine with cyanuric acid from in situ hydrolysis of melamine under phosphorous acid assisted hydrothermal conditions; 2) the pyrolysis was initiated at the center of precursor under heating, thus giving the hexagonal P TCN. The tubular structure favors the enhancement of light scattering and active sites. Meanwhile, the introduction of phosphorus leads to a narrow band gap and increased electric conductivity. Thus, the P TCN exhibited a high hydrogen evolution rate of 67 mmol h( 1) (0.1 g catalyst, l >420 nm) in the presence of sacrificial agents, and an apparent quantum efficiency of 5.68 at 420 nm, which is better than most of bulk g C3 N4 reported.
author_names: Shien Guo

Zhao-Peng Deng

Mingxia Li

Baojiang Jiang

Chungui Tian

Qingjiang Pan

Honggang Fu
title: Phosphorus Doped Carbon Nitride Tubes with a Layered Micro nanostructure for Enhanced Visible Light Photocatalytic Hydrogen Evolution.
venue: Angewandte Chemie
year: 2016

abstract: Photocatalytic degradation by semiconductors is an ideal way to solve the environmental problem. Here, the porous Mn doped g C3N4 photocatalyst was synthesized by the calcination refluxing method. The as prepared g C3N4 exhibits the high activity of photocatalytic degradation under visible light irradiation 400nm) in the mixed system of Cr(VI) and organic pollutants. Especially, the photocatalytic activity of Cr(VI) reduction was increased from 9.5% to 76.5% while that of Rhodamine B(RhB) degradation was enhanced from 15.3% to 88.9% after 60min irradiation. The porous Mn doped g C3N4 still keeps the high degradation efficiency of mixed pollutants in the 7th running. Based on the computational modeling, the Mn doping and carboxyl modification affect the atomic arrangement and molecular orbital distribution of the g C3N4 semiconductor, leading to the enhancement of photo induced carrier separation. Additionally, the active oxygen species and intermediates in the photoreaction process were discovered by ESR measurement and UV vis test. The RhB degradation in synergistic photocatalysis not only inhibits the reverse reaction of Cr(VI) reduction, but also validly supply the photogenerated electrons by the photosensitization effect. This work may be useful for rationally designing photocatalysts and providing illuminating insights into the photocatalytic mechanism.
author_names: Ji-Chao Wang

Cheng-Xing Cui

Yucheng Li

Lu Liu

Yu-Ping Zhang

Weina Shi
title: Porous Mn doped g C3N4 photocatalysts for enhanced synergetic degradation under visible light illumination.
venue: Journal of hazardous materials
year: 2017

abstract: A heterogeneous WS2/g C3N4 composite photocatalyst was prepared by a facile ultrasound assisted hydrothermal method. The WS2/g C3N4 composite was used for photocatalytic regeneration of NAD+ to NADH, which were coupled with dehydrogenases for sustainable bioconversion of CO2 to methanol under visible light irradiation. Compared with pristine g C3N4 and the physical mixture of WS2 and g C3N4, the fabricated WS2/g C3N4 composite catalyst with 5 wt% of WS2 showed the highest activity for methanol synthesis. The methanol productivity reached 372.1 mmol h 1 gcat 1, which is approximately 7.5 times higher than that obtained using pure g C3N4. For further application demonstration, the activity of the WS2/g C3N4 composite catalyst toward photodegradation of Rhodamine B (RhB) was evaluated. RhB removal ratio approaching 100% was achieved in 1 hour by using the WS2/g C3N4 composite catalyst with 5 wt% of WS2, at an apparent degradation rate approximately 2.6 times higher than that of pure g C3N4. Based on detailed investigations on physiochemical properties of the photocatalysts, the significantly enhanced reaction efficiency of the WS2/g C3N4 composite was considered to be mainly benefiting from the formation of a heterojunction interface between WS2 and g C3N4. Upon visible light irradiation, the photo induced electrons can transfer from the conduction band of g C3N4 to WS2, thus recombination of electrons and holes was decreased and the photo harvesting efficiency was enhanced.
author_names: Peng Zeng

Xiaoyuan Ji

Zhi-guo Su

Songping Zhang
title: WS2/g C3N4 composite as an efficient heterojunction photocatalyst for biocatalyzed artificial photosynthesis
year: 2018

abstract: Novel photocatalysts CdSe quantum dots (QDs)/g C3N4 were successfully constructed. The structure, chemical composition, and optical properties of the prepared samples were investigated via a series of characterization techniques. The results indicated that CdSe QDs/g C3N4 photocatalysts exhibited remarkably enhanced photocatalytic activity for visible light induced H2 evolution compared to pristine g C3N4 and CdSe QDs and addition of 13.6 wt CdSe QDs into the composite photocatalyst generated the highest H2 production rate. The enhanced photocatalytic performance of CdSe QDs/g C3N4 can be attributed to the synergistic effects of excellent visible absorption and high charge separation efficiency from the heterostructure. This work could not only provide a facile method to fabricate semiconductor QDs modified g C3N4 photocatalysts but also contribute to the design for heterostructures.
author_names: Yunqian Zhong

Weiwei Chen

Shan Yu

Zhang-hui Xie

Shiqiang Wei

Ying Zhou
title: CdSe Quantum Dots/g C3N4 Heterostructure for Efficient H2 Production under Visible Light Irradiation
venue: ACS omega
year: 2018

abstract: Dicyanoacetylene (C4N2) is an unusual energetic molecule with alternating triple and single bonds (think miniature, nitrogen capped carbyne) which represents an interesting starting point for the transformation into extended carbon nitrogen solids. While pressure induced polymerization has been documented for a wide variety of related molecular solids, precise mechanistic details of reaction pathways are often poorly understood and the characterization of recovered products is typically incomplete. Here, we study the high pressure behavior of C4N2 and demonstrate polymerization into a disordered carbon nitrogen network that is recoverable to ambient conditions. The reaction proceeds via activation of linear molecules into buckled molecular chains, which spontaneously assemble into a polycyclic network that lacks long range order. The recovered product was characterized using a variety of optical spectroscopies, X ray methods, and theoretical simulations and is described as a predominately sp2 network com.
author_names: Huiyang Gou

Li Zhu

Haw-Tyng Huang

Arani Biswas

Derek W Keefer

Brian L Chaloux

Clemens Prescher

Liuxiang Yang

Duck Young Kim

Matthew D Ward

Jordan Oswald Lerach

Shengnan Wang

Artem R Oganov

Albert Epshteyn

John V Badding

Timothy A Strobel
title: From Linear Molecular Chains to Extended Polycyclic Networks: Polymerization of Dicyanoacetylene
year: 2017

author_names: Lihua Lin

Xinchen Wang
title: A s a promising two dimensional conjugated polymer graphitic carbon nitride
year: 2015

abstract: Polymeric photocatalysts have been identified as promising materials for H2 production from water due to their comparative low cost and facile modification of the electronic structure. However, the majority only respond to a limited wavelength region (l 420 nm) with an apparent quantum yield (AQY) of 10.3% at 420 nm and 2.1% at 500 nm, measured under ambient conditions, which is closer to the real environment (instead of vacuum conditions) The strategy used here thus paves a new avenue to dramatically tune both the light absorption and charge separation to increase the activity of polymeric photocatalysts.
author_names: Yiou Wang

Mustafa Kemal Bayazit

Savio J A Moniz

Qiushi Ruan

Chi Ching Lau

Natalia Martsinovich

Junwang Tang
title: Linker controlled polymeric photocatalyst for highly efficient hydrogen evolution from water
year: 2017

abstract: Defects are critically important for metal oxides in chemical and physical applications. Compared with the often studied oxygen vacancies, engineering metal vacancies in n type undoped metal oxides is still a great challenge, and the effect of metal vacancies on the physiochemical properties is seldom reported. Here, using anatase TiO2, the most important and widely studied semiconductor, we demonstrate that metal vacancies (VTi) can be introduced in undoped oxides easily, and the presence of VTi results in many novel physiochemical properties. Anatase Ti0.905O2 was synthesized using solvothermal treatment of tetrabutyl titanate in an ethanol glycerol mixture and then thermal calcination. Experimental measurements and DFT calculations on cell lattice parameters show the unstoichiometry is caused by the presence of VTi rather than oxygen interstitials. The presence of VTi changes the charge density and valence band edge of TiO2, and an unreported strong EPR signal at g 1.998 presents under room temperature. Contrary to normal n type and nonferromagnetic TiO2, Ti defected TiO2 shows inherent p type conductivity with high charge mobility, and room temperature ferromagnetism stronger than Co doped TiO2 nanocrystalline. Moreover, Ti defected TiO2 shows much better photocatalytic performance than normal TiO2 in H2 generation (4.4 fold) and organics degradation (7.0 fold for phenol) owing to the more efficient charge separation and transfer in bulk and at semiconductor/electrolyte interface. Metal defected undoped oxides represent a unique material; this work demonstrates the possibility to fabricate such material in easy and reliable way and thus provides new opportunities for multifunctional materials in chemical and physical devices.
author_names: Songbo Wang

Lun Pan

Jia Song

Wenbo Mi

Ji-Jun Zou

Li Wang

Xiangwen Zhang
title: Titanium defected undoped anatase TiO2 with p type conductivity, room temperature ferromagnetism, and remarkable photocatalytic performance.
venue: Journal of the American Chemical Society
year: 2015

abstract: In this report, we rationally designed and fabricated P C3N4/ZnIn2S4 nanocomposites by in situ immobilizing ZnIn2S4 nanosheets onto the surface of mesoporous P doped graphite carbon nitrogen (P C3N4) nanosheets in a mixed solvothermal environment; their application to the photoreduction of 4 nitroaniline was used to estimate the photocatalytic performance. Different to the template route, here the mesoporous P C3N4 nanosheets were prepared with a template free strategy. The as fabricated P C3N4/ZnIn2S4 nanocomposites were systematically characterized by analyzing the phase structure, chemical components, electronic and optical properties and separation of charge carrier pairs. More importantly, these P C3N4/ZnIn2S4 heterostructures have been proven to be highly efficient visible light responsive photocatalysts for photo reduction, and meanwhile exhibit excellent photo stability during recycling runs. The sufficient evidence reveals that the significantly improved photocatalytic performance is mainly attributed to the more efficient charge carrier separation based on the construction of a close heterogeneous interface. This work may provide new insights into the utilization of P C3N4/ZnIn2S4 nanocomposites as visible light driven photocatalysts for comprehensive organic transformations in the field of fine chemical engineering.
author_names: Weitao Chen

Tian-yu Liu

Tingbo Huang

Xiaoheng Liu

Xu-jie Yang
title: Novel mesoporous P doped graphitic carbon nitride nanosheets coupled with ZnIn2S4 nanosheets as efficient visible light driven heterostructures with remarkably enhanced photo reduction activity.
venue: Nanoscale
year: 2016