查看更多>>摘要：Carbon nitride (C3N4) exhibits significant potential as a metal-free photocatalyst for H2 production using visible light. While the C3N4 network consists of tri-s-triazine building units linked by H bonds, it is still controversial how the H bonds affect the photocatalytic performance. In this study, we present a water-assisted method for production of polymeric carbon nitride to control intraplanar structures associated with H bonds and amine bridges. The C3N4 samples produced with a thermal treatment using water and humidified air gas (CN-H) exhibit excellent photocatalytic activities for the hydrogen evolution reaction. From structural and photophysical characterizations, it is found that CN-H samples contain fewer H bonds and more amine bridging groups as well as possess larger domains than C3N4 samples produced without using water (CN-A). These structural changes induced by the water treatment lead to efficient intraplanar migration of photoexcited charge carriers and thus are responsible for the enhanced photocatalytic performances.
查看更多>>摘要：Photocatalytic regeneration of the high-cost co-factor NADH is a promising method to couple photo-enzyme catalysis, however, the usage of homogeneous electron mediator ([Cp*Rh(bpy)H2O]~(2+)) which deactivates enzymes deteriorates the whole process efficiency. Herein, we report the immobilization of electron mediator ([Cp*Rh(bpy)H2O]~(2+)) on covalent organic frameworks (COFs) by the sequential assembly method. The resultant bi-functional photocatalyst with controlled cascade electron transfer afforded NADH production rate of 9.8 mmol·g_(COF)~(-1)· h~(-1) , much higher than previously reported ones with integrated electron mediator. The photo-enzyme coupling system with the photocatalyst and alcohol dehydrogenase could continuously produce butanol for at least 180 min under visible light irradiation, implying the potential application of bi-functional photocatalyst in artificial photosynthesis.
查看更多>>摘要：The authors regret, the heading of 2.6 and 3.6 in the manuscript "Synthesis experiment of β-amino alcohol (1-phenyl-2-(phenylamino) ethanol)" should be corrected as "Synthesis experiment of β-amino alcohol (2-phenyl-2- (phenylamino)ethanol)".
查看更多>>摘要：Renewable energy-powered water electrolysis and photocatalytic water splitting are two promising approaches to green hydrogen production. Electrocatalysts and photocatalysts are essential components determining the performance of water electrolyzers and photocatalytic reactors, respectively. Currently, there is a pressing need to develop efficient and stable electrocatalysts and photocatalysts for large-scale deployment of these devices to reach carbon neutrality. Herein, we report the synthesis of single-atom Ir and Ru anchored on mesoporous graphitic carbon nitride (Ir-g-CN and Ru-g-CN), which can be used as electrocatalysts and photocatalysts for the hydrogen evolution reaction (HER). Remarkably, Ru-g-CN shows a high turnover frequency (TOF) of 12.9 and 5.1 s~(-1) at an overpotential (η) of 100 mV in 0.5 M H2SO4 and 1.0 M KOH, respectively, outperforming Ir-g-CN, commercial Pt/C benchmark and many other advanced HER catalysts reported recently. Moreover, Ru-g-CN can deliver an exceptionally high mass activity of 24.55 and 8.78 A mg~(-1) at η = 100 mV in acidic and alkaline solutions, meanwhile exhibiting a high apparent current density, which is favorable for practical applications. Additionally, both Ru-g-CN and Ir-g-CN show outstanding catalytic stability, continuously catalyzing the HER in acidic and alkaline conditions for 120 h with minimal degradation. Besides, when used for photocatalytic water splitting, Ru-g-CN can achieve a high hydrogen production rate of 489.7 mmol H2 g_(Ru)~(-1) h~(-1), and shows good photocatalytic stability. Our density functional theory (DFT) calculations demonstrate that loading Ir and Ru single-atoms on g-CN alters the electronic structure, resulting in a reduced bandgap and improved electrical conductivity, facilitating electron transfer during the catalysis. Moreover, the Gibbs free energy of hydrogen adsorption on Ru-g-CN and Ir-g-CN is also substantially lowered, enhancing HER performance.
查看更多>>摘要：The oxygen vacancy (Ov) in photocatalysts plays a significant role for N2 fixation, but effective and simple means for creation of Ov are in urgent demand. Herein, surface-layer Br doping was confirmed to create massive surface Ov in Bi2MoO6 in a solvothermal process, with the product (BMO-Br-Ov) exhibiting remarkably enhanced N2 chemisorption and activation, photoinduced charge separation, and thus photocatalytic N2 fixation, compared with bulk Bi2MoO6, with an apparent quantum yield at 420 nm reaching 0.52% in pure water and 2.56% in the methanol aqueous solution. The charge separation enhancement benefits from the Ov introduced defect level and Br doping and surface Ov modification induced band-level difference between the surface and the inside in BMO-Br-Ov that leads to fabrication of the surface/inside homojunction. This work provides a simple way to create surface Ov in Bi2MoO6 and may direct Ov creation in other Bi-based photocatalysts for efficient N2 fixation.
查看更多>>摘要：Obtaining high-value-added products like C_(2+) hydrocarbons from CO2 reduction in a photocatalytic system has always remained a great challenge. Herein we fabricated a π-π stacking hybrid photocatalyst by combining two two-dimensional (2D) materials of g-C3N4 and Cu-porphyrin metal-organic framework (MOF). This hybrid photocatalyst exhibited the excellent capability to reduce CO2 into C2H6 in a selectivity of 44% and the selectivity of total hydrocarbons (C2H6 and CH4) was as high as 71%, as one of the best performances among the reported photocatalytic systems. The node sites of 2D-MOF were identified to be critical for the generation of C2H6, and a self-reconstruction during photocatalysis was clarified: the initial paddle-wheel Cu~(II)2(COO)4 node was reconstructed to the partially reduced Cu~(1+δ)_2(COO)3. Such reconstruction strengthened the trapping of in-situ generated CO and the synergistic action of the dual-Cu-site, therefore, achieved the efficient C-C coupling to form C2H6.
查看更多>>摘要：Although Schottky barriers at the interface of metal/semiconductor help electron/hole separation in photo-catalysis, they also limit the migration of electrons across the interface. Herein, we tune Schottky barriers over Ni/S vacancy-rich Mn_(0.3)Cd_(0.7)S (Ni/MCS-s) composites prepared by self-assembly and photochemical method. The Ni/MCS-s heterostructures exhibits superior hydrogen production activity up to 164.1 mmol/h/g in simulated seawater (3.5 wt% NaCl), which is 68 and 5 times higher than MCS-s and 1 wt% Pt/MCS-s, respectively. The apparent quantum yield reached 60.4% at 420 nm. The excellent photocatalytic performance of Ni/MCS-s results from the coupling of plasmonic Ni and S vacancies, which can effectively lower Schottky barrier and enhance hot electrons across the interface for photocatalytic process. Moreover, the Ni layer effectively prevents the catalyst from being corroded in seawater. This work provides a feasible strategy for designing efficient photocatalysts for solar energy conversion in seawater.
查看更多>>摘要：Highly efficient photocatalytic water reduction to evolve hydrogen can be achieved by the construction of Z-scheme systems that mimics natural photosynthesis. However, coupling appropriate semiconductors with suitable water reduction potential still remains challenging. Herein, we report a novel Z-scheme system, based on the Au decorated 5,10,15,20-tetxalus(4-trimethylammoniophenyl) porphyrin tetra(p-toluene sulfonate) functional-ized iron-doped carbon nitride. We prepared carbon nitride by varying the amount of iron dopant and then functionalized with porphyrin to obtain heterostructure photocatalyst. Owing to the strong interfacial contact and proper band alignment, a Z-scheme system is fabricated. Finally, we deposited Au nanoparticles over the surface of the as-fabricated Z-scheme system to promote the surface redox properties via efficient charge carrier's separation and transfer. The 3Au-3 P/30Fe-CN photocatalyst achieved excellent H2 evolution activity by producing 3172.20 μmol h~(-1) g~(-1) under UV-visible irradiation. The calculated quantum efficiencies for 3Au-3 P/ 30Fe-CN photocatalyst at 365 and 420 nm irradiation wavelengths are 7.2% and 3.26%, respectively. The experimentally observed efficiency of our photocatalyst is supported by the density functional theory simulations in terms of the lowest work function and strong electrostatic interaction among the constituents of Z-scheme system.
查看更多>>摘要：Few-layered polymeric carbon nitride (PCN) nanosheets with large specific surface area and effective charge/ electron transport pathway have emerged as promising photocatalysts. However, PCN nanosheets normally exhibit enlarged bandgap, structural defects, and easy agglomeration. Herein, we report an intermediate-induced strategy for synthesizing red PCN nanosheets with a crystalline free self-assembly (CFSA) architecture, exhibiting a three-dimensional (3D) structure, minimum structural defects, small curved nanosheet subunits, and abundant reactive sites. The careful tuning of the condensation degree and repolymerization ability of intermediates affords CFSA PCN with an optimal 3D structure and optical properties, enabling the synergistic optimization of light absorption, charge mobility, and surface reactions during photocatalysis. The catalyst shows a superior H2 evolution rate of 14665 μmol g~(-1) h~(-1) (Pt 1.1 wt%), outperforming those of pristine bulk and nanosheet-structured PCN. This work provides a facile intermediate-induced strategy for guiding the design and synthesis of novel PCN-based photocatalysts.
查看更多>>摘要：The heterogenized metallomacrocycles with atomically dispersed active sites are identified as the promising candidates for electrocatalytic CO2 reduction reaction (CO2RR), where their unique heterointerface with interaction between sp~2 carbon and macrocyclic molecules is important but remains vague. Herein, based on well-structured nickel phthalocyanine and porphyrin with the same functional groups (MeNiPc and MeNiPp), the influences of heterointerfacial effect on catalytic performances are systematically disclosed. Through the molecular structure-induced self-adaptive adsorption with optimized heterointerfacial distance, MeNiPc/graphene reveals a high CO Faradaic efficiency of -99% in a wide potential window, greatly outperforming the MeNiPp/ graphene counterpart (≤29.6%). Detailed measurements and theoretical calculations decipher that the higher CO2RR activity of MeNiPc/graphene is attributed to the unique electronic structures of the Ni-N4 configurations suitable for well-suited heterointerfacial charge transfer and rapid CO desorption. Additionally, the extended research confirms the universality of heterointerface engineering on boosting the catalytic performances.
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