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Enhanced photocatalytic hydrogen production activity of highly crystalline carbon nitride synthesized by hydrochloric acid treatment 被引量:3
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作者 Yang Li Dainan Zhang +1 位作者 Xionghan Feng Quanjun Xiang 《Chinese Journal of Catalysis》 SCIE EI CAS CSCD 北大核心 2020年第1期21-30,共10页
Crystalline carbon nitride(CCN)prepared by a molten-salt method is attracting increased attention because of its promising properties and excellent photocatalytic activity.In this work,we further improve the crystalli... Crystalline carbon nitride(CCN)prepared by a molten-salt method is attracting increased attention because of its promising properties and excellent photocatalytic activity.In this work,we further improve the crystallinity of CCN through synthesis by the molten-salt method under the action of aqueous hydrochloric acid(HCl)solution.Our results showed that the crystallinity of the as-prepared samples increased with increasing HCl concentration and reached the maximum value at 0.1 mol L^-1.This can be attributed to the removal of some potassium ions(K+)from the terminal amino groups of CCN by the aqueous HCl solution,which results in a release of the polymerization sites.As a result,the crystallinity of the as-prepared samples further increased.Moreover,the obtained 0.1 highly crystalline carbon nitride(0.1HCCN;treated with 0.1 mol L^-1 aqueous HCl solution)exhibited an excellent photocatalytic hydrogen evolution of 683.54μmol h^-1 g^-1 and a quantum efficiency of 6.6%at 420 nm with triethanolamine as the sacrificial agent.This photocatalytic hydrogen evolution was 2 and 10 times higher than those of CCN and bulk carbon nitride,respectively.The enhanced photocatalytic activity was attributed to the improved crystallinity and intercalation of K+into the xHCCN interlayer.The improved crystallinity can decrease the number of surface defects and hydrogen bonds in the as-prepared sample,thereby increasing the mobility of the photoinduced carriers and reducing the recombination sites of the electron-hole pairs.The K+intercalated into the xHCCN interlayer also promoted the transfer of the photoinduced electrons because these ions can increase the electronic delocalization and extend theπ-conjugated systems.This study may provide new insights into the further development of the molten-salt method. 展开更多
关键词 crystalline carbon nitride Molten-salt method Photocatalytic hydrogen evolution Potassium ions Aqueous hydrochloric acid solution
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S-scheme heterojunction of crystalline carbon nitride nanosheets and ultrafine WO_(3)nanoparticles for photocatalytic CO_(2)reduction 被引量:1
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作者 Gongjie Chen Ziruo Zhou +7 位作者 Bifang Li Xiahui Lin Can Yang Yuanxing Fang Wei Lin Yidong Hou Guigang Zhang Sibo Wang 《Journal of Environmental Sciences》 SCIE EI CAS CSCD 2024年第6期103-112,共10页
Highly crystalline carbon nitride polymers have shown great opportunities in overall water photosplitting;however,their mission in light-driven CO_(2)conversion remains to be explored.In this work,crystalline carbon n... Highly crystalline carbon nitride polymers have shown great opportunities in overall water photosplitting;however,their mission in light-driven CO_(2)conversion remains to be explored.In this work,crystalline carbon nitride(CCN)nanosheets of poly triazine imide(PTI)embedded with melon domains are fabricated by KCl/LiCl-mediated polycondensation of dicyandiamide,the surface of which is subsequently deposited with ultrafine WO_(3)nanoparticles to construct the CCN/WO_(3)heterostructure with a S-scheme interface.Systematic characterizations have been conducted to reveal the compositions and structures of the S-scheme CCN/WO_(3)hybrid,featuring strengthened optical capture,enhanced CO_(2)adsorption and activation,attractive textural properties,as well as spatial separation and directed movement of light-triggered charge carriers.Under mild conditions,the CCN/WO_(3)catalyst with optimized composition displays a high photocatalytic activity for reducing CO_(2)to CO in a rate of 23.0μmol/hr(i.e.,2300μmol/(hr·g)),which is about 7-fold that of pristine CCN,along with a high CO selectivity of 90.6%against H2formation.Moreover,it also manifests high stability and fine reusability for the CO_(2)conversion reaction.The CO_(2)adsorption and conversion processes on the catalyst are monitored by in-situ diffuse reflectance infrared Fourier transform spectroscopy(DRIFTS),identifying the crucial intermediates of CO_(2)^(*)-,COOH^(*)and CO^(*),which integrated with the results of performance evaluation proposes the possible CO_(2)reduction mechanism. 展开更多
关键词 crystalline carbon nitride Photocatalysis CO_(2)reduction S-scheme WO_(3)
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Crystalline carbon nitride with in-plane built-in electric field accelerates carrier separation for excellent photocatalytic hydrogen evolution 被引量:1
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作者 Wengao Zeng Yuchen Dong +4 位作者 Xiaoyuan Ye Ziying Zhang Tuo Zhang Xiangjiu Guan Liejin Guo 《Chinese Chemical Letters》 SCIE CAS CSCD 2024年第4期160-165,共6页
Achieving a high carrier migration efficiency by constructing built-in electric field is one of the promising approaches for promoting photocatalytic activity. Herein, we have designed a donor-acceptor(D-A) crystallin... Achieving a high carrier migration efficiency by constructing built-in electric field is one of the promising approaches for promoting photocatalytic activity. Herein, we have designed a donor-acceptor(D-A) crystalline carbon nitride(APMCN) with 4-amino-2,6-dihydroxypyrimidine(AP) as electron donor, in which the pyrimidine ring was well embedded in the heptazine ring via hydrogen-bonding effect during hydrothermal process. The APMCN shows superior charge-transfer due to giant built-in electric field(5.94times higher than pristine carbon nitride), thereby exhibiting excellent photocatalytic H_(2) evolution rate(1350 μmol/h) with a high AQY(62.8%) at 400 nm. Mechanistic analysis based on detailed experimental investigation together with theoretical analysis reveals that the excellent photocatalytic activity is attributed to the promoted charge separation by the giant internal electric field originated from the D–A structure. 展开更多
关键词 crystalline carbon nitride Built-in electric field Donor-acceptor structure PHOTOCATALYSIS Hydrogen production
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High-efficiency crystalline carbon nitride photocatalysts:Status and perspectives
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作者 Wenji Pu Yunqiao Zhou +4 位作者 Lingfeng Yang Haifeng Gong Yuhan Li Qingyu Yang Dieqing Zhang 《Nano Research》 SCIE EI CSCD 2024年第9期7840-7863,共24页
Crystallinity and crystal structure greatly influence the photocatalytic behavior of photocatalysts.Pristine g-C3N4 produced by traditional thermal-induced polycondensation reaction bears low crystallinity and thus po... Crystallinity and crystal structure greatly influence the photocatalytic behavior of photocatalysts.Pristine g-C3N4 produced by traditional thermal-induced polycondensation reaction bears low crystallinity and thus poor photoactivity,which originates from the incomplete polymerization of the precursor containing amine groups,abundant hydrogen bonds,and unreacted amino,as well as cyanide functional groups in the skeleton.During photocatalytic process,these residual functional groups often work as electron trap sites,which may hinder the transfer of electrons on the plane,resulting in low photoactivity.Fortunately,crystalline carbon nitride(CCN)was reported as a promising photocatalyst because its increased crystallinity not only reduces the number of carriers recombination centers,but also increases charge conductivity and improves light utilization due to extendedπ-conjugated systems and delocalizedπ-electrons.As such,we summarize the recent studies on CCN-based photocatalysts for the photoactivity enhancement.Firstly,the unique structure and properties of CCN materials are presented.Next,the preparation methods and modification strategies are well outlined.We also sum up the applications of CCN-based materials in the environmental purification and energy fields.Finally,this review concerning CNN materials ends with prospects and challenges in the obtainment of high crystallinity by effective techniques,and the deep understanding of photocatalytic mechanism. 展开更多
关键词 crystalline carbon nitride preparation method modification strategy photocatalytic application
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Room-temperature ferromagnetism and piezoelectricity in metalfree 2D semiconductor crystalline carbon nitride
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作者 Yong Wang Dingyi Yang +9 位作者 Wei Xu Yongjie Xu Yu Zhang Zixuan Cheng Yizhang Wu Xuetao Gan Wei Zhong Yan Liu Genquan Han Yue Hao 《Nano Research》 SCIE EI CSCD 2024年第6期5670-5679,共10页
Two-dimensional(2D)materials that combine ferromagnetic,semiconductor,and piezoelectric properties hold significant potential for both fundamental research and spin electronic devices.However,the majority of reported ... Two-dimensional(2D)materials that combine ferromagnetic,semiconductor,and piezoelectric properties hold significant potential for both fundamental research and spin electronic devices.However,the majority of reported 2D ferromagnetic-semiconductor-piezoelectric materials rely on d-electron systems,which limits their practical applications due to a Curie temperature lower than room temperature(RT).Here,we report a high-crystallinity carbon nitride(CCN)material based on sp-electrons using a chemical vapor deposition strategy.CCN exhibits a band gap of 1.8 eV and has been confirmed to possess substantial in-plane and out-of-plane piezoelectricity.Moreover,we acquired clear evidences of ferromagnetic behavior at room temperature.Extensive structural characterizations combined with theoretical calculations reveal that incorporating structural oxygen into the highly ordered heptazine structure causes partial substitution of nitrogen sites,which is primarily responsible for generating room-temperature ferromagnetism and piezoelectricity.As a result,the strain in wrinkles can effectively modulate the domain behavior and piezoelectric potential at room temperature.The addition of RT ferromagnetic-semiconductor-piezoelectric material based on sp-electrons to the family of two-dimensional materials opens up numerous possibilities for novel applications in fundamental research and spin electronic devices. 展开更多
关键词 crystallinity carbon nitride room-temperature ferromagnetism PIEZOELECTRICITY magnetic force microscopy density functional theory(DFT)calculations
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Pyrimidine donor induced built-in electric field between melon chains in crystalline carbon nitride to facilitate excitons dissociation
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作者 Guoqiang Zhang Yangsen Xu +5 位作者 Guoshuai Liu Yongliang Li Chuanxin He Xiangzhong Ren Peixin Zhang Hongwei Mi 《Chinese Chemical Letters》 SCIE CAS CSCD 2023年第3期546-552,共7页
The strong intrinsic Coulomb interactions of Frenkel excitons in crystalline carbon nitride(CCN) greatly limits their dissociation into electrons and holes, resulting in unsatisfactory charges separation and photocata... The strong intrinsic Coulomb interactions of Frenkel excitons in crystalline carbon nitride(CCN) greatly limits their dissociation into electrons and holes, resulting in unsatisfactory charges separation and photocatalytic efficiency. Herein, we propose a strategy to facilitate excitons dissociation by molecular regulation induced built-in electric field(BIEF). The electron-rich pyrimidine-ring into CCN changes the charge density distribution over heptazine-rings to induce BIEF between melon chains. Such BIEF is sufficient to overcome the considerable exciton binding energy(EBE) and reduce it from 38.4 meV to 16.4 meV,increasing the excitons dissociation efficiency(EDE) from 21.5% to 51.9%. Our results establish a strategy to facilitate excitons dissociation through molecular regulation induced BIEF, targeting the intrinsic high EBE and low EDE of polymer photocatalysts. 展开更多
关键词 crystalline carbon nitride Exciton binding energy Built-in electric field Pyrimidine donor Excitons dissociation
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Copper and platinum dual-single-atoms supported on crystalline graphitic carbon nitride for enhanced photocatalytic CO_(2) reduction 被引量:15
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作者 Lei Cheng Peng Zhang +2 位作者 Qiye Wen Jiajie Fan Quanjun Xiang 《Chinese Journal of Catalysis》 SCIE EI CAS CSCD 2022年第2期451-460,共10页
Single-atom Pt catalysts are designed to promote efficient atom utilization,whereas effective decrease of Pt loading and improvement of photocatalytic activity in monoatomic Pt-deposited systems is still ongoing.Atomi... Single-atom Pt catalysts are designed to promote efficient atom utilization,whereas effective decrease of Pt loading and improvement of photocatalytic activity in monoatomic Pt-deposited systems is still ongoing.Atomically dispersed metal species in crystalline carbon nitride are still challenging owing to their high crystallization and structural stability.In this study,we developed a novel single-atomic Pt-Cu catalyst for reducing noble metal loading by combining Pt with earth-abundant Cu atoms and enhancing photocatalytic CO_(2)reduction.N-vacancy-rich crystalline carbon nitride was used as a fine-tuning ligand for isolated Pt-Cu atom dispersion based on its accessible functional N vacancies as the seeded centers.The synthesized dimetal Pt-Cu atoms on crystalline carbon nitride(Pt Cu-cr CN)exhibited high selectivity and activity for CO_(2)conversion without the addition of any cocatalyst or sacrificial agent.In particular,we demonstrated that the diatomic Pt-Cu exhibited high mass activity with only 0.32 wt% Pt loading and showed excellent photocatalytic selectivity toward CH_(4)generation.The mechanism of CO_(2)photoreduction for Pt Cu-cr CN was proposed based on the observations and analysis of aberration-corrected high-angle annular dark-field scanning transmission electron microscopy images,in situ irradiated X-ray photoelectron spectroscopy,and in situ diffuse reflectance infrared Fourier transform spectroscopy.The findings of this work provide insights for abrogating specific bifunctional atomic metal sites in noble metal-based photocatalysts by reducing noble metal loading and maximizing their effective mass activity. 展开更多
关键词 Dimetal Pt-Cu atom crystalline carbon nitride Photocatalytic CO_(2)reduction Low loading Synergistic photocatalysis
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Recent advances in crystalline carbon nitride for photocatalysis 被引量:5
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作者 Jingjun Liu Wei Fu +2 位作者 Yulong Liao Jiajie Fan Quanjun Xiang 《Journal of Materials Science & Technology》 SCIE EI CAS CSCD 2021年第32期224-240,共17页
Semiconductor photocatalytic technology has become one of the most important means to solve the current energy shortage and environmental pollution. Compared with the traditional photocatalysts, graphite carbon nitrid... Semiconductor photocatalytic technology has become one of the most important means to solve the current energy shortage and environmental pollution. Compared with the traditional photocatalysts, graphite carbon nitride has a wider range of light-harvesting and more stable physical and chemical properties. However, traditional thermally induced polymerization of nitrogen-containing precursors produces the melon-based carbon nitride solids with an amorphous or semi-crystalline structure, resulting in low conductivity and moderate photocatalytic activity. Recently, crystalline carbon nitride has attracted more and more attention in improving photocatalytic performance. Some significant progress regarding crystalline carbon nitride for the preparation of solar-fuel and environmental purification has also been made.This review describes the recent advances in the design and synthesis of crystalline carbon nitride photocatalysts. A brief description of the unique physical and chemical properties of crystalline carbon nitride was given. Later, the synthetic and modification strategies are being introduced. Then, the photocatalytic application of crystalline carbon nitride was discussed, mainly including photocatalytic H2 production,photocatalytic CO2 reduction, and photocatalytic degradation of pollutants. Finally, the challenges and future directions of crystalline carbon nitride photocatalysts are briefly introduced. 展开更多
关键词 crystalline carbon nitride Design and synthesis Photocatalytic H_(2)production CO_(2)reduction Photocatalytic degradation
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Crystallinity engineering of carbon nitride protective coating for ultra-stable Zn metal anodes
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作者 Chen Liu Yuxin Zhu +6 位作者 Shuanlong Di Jiarui He Ping Niu Antonios Kelarakis Marta Krysmann Shulan Wang Li Li 《Electron》 2024年第1期177-187,共11页
Ineffective control of dendrite growth and side reactions on Zn anodes significantly retards commercialization of aqueous Zn-ion batteries.Unlike conventional interfacial modification strategies that are primarily foc... Ineffective control of dendrite growth and side reactions on Zn anodes significantly retards commercialization of aqueous Zn-ion batteries.Unlike conventional interfacial modification strategies that are primarily focused on component optimization or microstructural tuning,herein,we propose a crystallinity engineering strategy by developing highly crystalline carbon nitride protective layers for Zn anodes through molten salt treatment.Interestingly,the highly ordered structure along with sufficient functional polar groups and pre-intercalated Kþendows the coating with high ionic conductivity,strong hydrophilicity,and accelerated ion diffusion kinetics.Theoretical calculations also confirm its enhanced Zn adsorption capability compared to commonly reported carbon nitride with amorphous or semi-crystalline structure and bare Zn.Benefiting from the aforementioned features,the as-synthesized protective layer enables a calendar lifespan of symmetric cells for 1100 h and outstanding stability of full cells with capacity retention of 91.5%after 1500 cycles.This work proposes a new conceptual strategy for Zn anode protection. 展开更多
关键词 crystalline carbon nitride crystallinity engineering long cycling life uniform Zn deposition Zn metal anode
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Boosting photocatalytic hydrogen production by creating isotype heterojunctions and single-atom active sites in highly-crystallized carbon nitride 被引量:6
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作者 Shaohua Shen Jie Chen +9 位作者 Yiqing Wang Chung-Li Dong Fanqi Meng Qinghua Zhang Yiliang Huangfu Zhi Lin Yu-Cheng Huang Yanrui Li Mingtao Li Lin Gu 《Science Bulletin》 SCIE EI CSCD 2022年第5期520-528,M0004,共10页
Carbon nitride-based photocatalysts hold an enormous potential in producing hydrogen.A strategy to simultaneously create isotype heterojunctions and active sites in highly-crystallized carbon nitride is anticipated to... Carbon nitride-based photocatalysts hold an enormous potential in producing hydrogen.A strategy to simultaneously create isotype heterojunctions and active sites in highly-crystallized carbon nitride is anticipated to significantly boost the photocatalytic activity,but is yet to be realized.Herein,we find that cobalt salt added in the ionothermal synthesis can promote the phase transition of heptazine-based crystalline carbon nitride(CCN)to triazine-based poly(triazine imide)(PTI),rendering the creation of singleatom cobalt coordinated isotype CCN/PTI heterojunction.Co-CCN/PTI exhibits an appreciable apparent quantum yield of 20.88%at 425 nm for photocatalytic hydrogen production with a rate achieving3538μmol h^(-1)g^(-1)(λ>420 nm),which is 4.8 times that of CCN and 27.6 times that of PTI.The high photocatalytic activity is attributed to the Type II isotype highly-crystallized CCN/PTI heterojunction for promoting charge carrier migration,and the single-atom Co sites for accelerating surface oxidation reaction. 展开更多
关键词 Photocatalytic hydrogen production Single-atom cobalt crystalline carbon nitride Poly(triazine imide) Isotype heterojunctions
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