Two‐electron oxygen photoreduction to hydrogen peroxide (H2O2) is seriously inhibited by its sluggish charge kinetics. Herein, a polarization engineering strategy is demonstrated by grafting ...(thio)urea functional groups onto covalent triazine frameworks (CTFs), giving rise to significantly promoted charge separation/transport and obviously enhanced proton transfer. The thiourea‐functionalized CTF (Bpt‐CTF) presents a substantial improvement in the photocatalytic H2O2 production rate to 3268.1 µmol h−1 g−1 with no sacrificial agents or cocatalysts that is over an order of magnitude higher than unfunctionalized CTF (Dc‐CTF), and a remarkable quantum efficiency of 8.6% at 400 nm. Mechanistic studies reveal the photocatalytic performance is attributed to the prominently enhanced two‐electron oxygen reduction reaction by forming endoperoxide at the triazine unit and highly concentrated holes at the thiourea site. The generated O2 from water oxidation is subsequently consumed by the oxygen reduction reaction (ORR), thereby boosting overall reaction kinetics. The findings suggest a powerful functional‐groups‐mediated polarization engineering method for the development of highly efficient metal‐free polymer‐based photocatalysts.
(Thio)urea‐functionalized covalent triazine frameworks (CTFs) are rationally designed, showing an outstanding photocatalytic activity toward production of H2O2 in water (3268.1 μmol h−1 g−1 with a quantum yield of 8.6% at 400 nm for the thiourea‐functionalized CTF) via reducing molecular oxygen (O2). This is much higher than most of the reported metal‐free polymer‐based photocatalysts in nonsacrificial systems.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
Solar water disinfection catalyzed by metal-free photocatalyst has emerged as a promising approach for clean water production. By using the edge-functionalized graphitic carbon nitride (g-C3N4) as ...photocatalytic disinfectants, we find that the pathogen-rich water can be rapidly purified in 30 min with a disinfection efficiency of over 99.9999% under visible-light irradiation, which meets the requirement for drinking water. The edge-functionalized g-C3N4 shows a first-order disinfection rate that is five times higher than the previously reported best metal-free photocatalyst but only consumes 1/10 of the catalyst. The catalytic activity is also comparable to that of the best metal-based photocatalyst. Results of the highest occupied molecular orbitals and Mulliken charge distribution reveal that the exposed –COOH and C=O groups at the edges of g-C3N4 nanosheets not only significantly promote charge separation but also induce the upward bending of the surface band, facilitating the generation of hydrogen peroxide.
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•Selectively functionalize electron-withdrawing groups on the edges of g-C3N4 nanosheets•A record-high disinfection efficiency toward Escherichia coli-rich water is obtained•The first-order disinfection rate is comparable with that of the best metal-based photocatalyst
Discovering highly efficient metal-free catalysts for photocatalytic disinfection will be greatly beneficial for the alleviation of the issues of clean water scarcity and global energy shortage. In addition, secondary pollution resulting from the use of metal-based catalysts can be avoided. In our work, we prepared the edge-functionalized g-C3N4 by selectively introducing electron-withdrawing groups at the edges of g-C3N4 nanosheets by using a facile wet-chemical method. Among all the metal-free photocatalysts currently used in the disinfection of model Escherichia coli under visible-light irradiation, this method reaches a record efficiency. Notably, this edge functionalization generates an anisotropic built-in electric field that promotes the separation of photo-generated electron-hole pairs. This work provides a new strategy for controlling surface charge density, which could lead to the discovery of additional unique properties and promising applications in catalysis, electronics, and targeted therapy.
The electron-withdrawing groups were selectively introduced onto the edge of g-C3N4 nanosheets. The edge functionalization not only induces an upward bending that improves the adsorption of oxygen molecules but also promotes the separation of photo-generated electron-hole pairs. By using these nanosheets as the photocatalyst for water disinfection, Dan Wang and colleauges achieved a record-high efficiency toward the photo-disinfection of Escherichia coli under visible-light irradiation among all metal-free catalysts.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Carrier dynamics and surface reaction are two critical processes for determining the performance of photocatalytic reaction. Highly designable polymer-based photocatalysts have shown promising ...protectives in energetic and environmental applications. In this prospective, we first distinguished the differences of physiochemical properties between polymer-based semiconductors and traditional inorganic semiconductors. Then, the effects of single-atom sites on the charge dynamics and reaction kinetics of polymer-based photocatalysts are further elaborated. Time(excitation)-space(wavefunction) population analysis, which can provide relevant information to clarify the structure-excitation relationships after introducing the single atom sites was also reviewed. In the future, with the further development of artificial intelligence, the establishment of an energy function with a regression accuracy close to or reaching the level of density functional theory is highly desired to infer the energetic diagram of the photocatalytic systems at the excited states. Furthermore, coordination structures, interaction with inorganic semiconductors, photocatalytic stability and solvent effects should also be carefully considered in the future studies of polymer-based photocatalyst.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
Abstract
Photocatalytic two-electron oxygen reduction to produce high-value hydrogen peroxide (H
2
O
2
) is gaining popularity as a promising avenue of research. However, structural evolution ...mechanisms of catalytically active sites in the entire photosynthetic H
2
O
2
system remains unclear and seriously hinders the development of highly-active and stable H
2
O
2
photocatalysts. Herein, we report a high-loading Ni single-atom photocatalyst for efficient H
2
O
2
synthesis in pure water, achieving an apparent quantum yield of 10.9% at 420 nm and a solar-to-chemical conversion efficiency of 0.82%. Importantly, using in situ synchrotron X-ray absorption spectroscopy and Raman spectroscopy we directly observe that initial Ni-N
3
sites dynamically transform into high-valent O
1
-Ni-N
2
sites after O
2
adsorption and further evolve to form a key *OOH intermediate before finally forming HOO-Ni-N
2
. Theoretical calculations and experiments further reveal that the evolution of the active sites structure reduces the formation energy barrier of *OOH and suppresses the O=O bond dissociation, leading to improved H
2
O
2
production activity and selectivity.
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•The preparation process of spray pyrolysis was discussed in detail.•The heterojunction of Cu3BiS3 and In2S3 effectively promotes charge separation.•Pt worked as a co-catalyst for ...hydrogen evolution.•H2 was generated at a rate of 1.4 μmol·h−1 with an excellent Faraday efficiency of 94% under 0 VRHE.
Spray pyrolysis technology for a uniform and high conductive Cu3BiS3 (CBS) electrode was developed in order to carry out the water splitting reaction. A heterojunction photocathode consisting of a p-type Cu3BiS3 and an n-type In2S3 semiconductor was successfully fabricated and further modified by Pt particles for hydrogen generation in a PEC cell. Modification of the n-type semiconductor In2S3 significantly improved the electron-hole separation efficiency, leading to a photocurrent of –223 μA·cm−2 under an applied bias of 0 VRHE. Pt particles were used as effective cocatalysts in water reduction. Under visible light irradiation, H2 was generated with an excellent Faraday efficiency of 94% using Pt/In2S3/Cu3BiS3 as a photocathode under the applied bias of 0 VRHE.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
In recent years, single-atom catalysts(SACs) have attracted increasing attention in catalysis. However, their stability is considerably challenging. As a result, fine-tuning the interaction of metal ...single atoms(SA) with different types of supports has emerged as an effective strategy for improving their thermal and chemical stabilities. Owing to its non-toxicity, cost-effectiveness, high abundance, and excellent stability, as well as presence of rich, tunable, and reliable anchor sites for metal SA, TiO
2
has been extensively explored as a superior support for SACs. In this review, recent advances of TiO
2
-supported SACs(M
1
/TiO
2
) are discussed, and synthetic strategies, structure elucidation, and catalytic applications are summarized. First, the recently developed synthetic strategies for M
1
/TiO
2
are highlighted and summarized, identifying the major challenges for the precise fabrication of M
1
/TiO
2
. Subsequently, key characterization techniques for the structure identification of M
1
/TiO
2
are discussed. Next, catalytic applications of M
1
/TiO
2
are highlighted,
viz.
photocatalysis, electrocatalysis, and thermocatalysis. In addition, the mechanism
via
geometric structures and electronic states of metal centers facilitate catalytic reactions is outlined. Finally, opportunities and challenges of M
1
/TiO
2
in catalysis are discussed, which may inspire the future development of M
1
/TiO
2
for multifunctional catalytic applications.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
Morphology‐controlled rutile titanium(IV) oxide (TiO2) and anatase TiO2 were prepared by a hydrothermal method and their surfaces were selectively loaded with Au, Ag and AuAg bimetallic nanoparticles ...(NPs) by photo‐deposition in order to obtain visible‐light responsive photocatalysts. With the help of local surface plasmon resonance (LSPR) of noble metal NPs, the photocatalytic activity of noble metal‐loaded TiO2 under visible‐light irradiation was improved compared to that of bare TiO2. The enhancement of LSPR on the photocatalytic activity of rutile TiO2 was larger than that of anatase TiO2 with optimum amount of Au or AuAg. In addition, the reusability (stability) of AuAg‐loaded TiO2 was much better than that of Ag‐loaded TiO2. Double‐beam photoacoustic results confirmed different trap energy level distribution lead to different electron transfer ways, resulting in different oxidizing capabilities and they gave one of important strategies for designing visible‐light responsive TiO2.
Different electron transfer ways of Au‐ or AuAg‐ modified rutile TiO2 and anatase TiO2 for photocatalytic reaction under visible light were revealed. The distribution of trapped energy level determines the transfer and consumption ways of photo‐generated electrons and determines the oxidization for photocatalytic reaction.
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FZAB, GIS, IJS, IZUM, KILJ, NLZOH, NUK, OILJ, PILJ, PNG, SAZU, SBCE, SBMB, UL, UM, UPUK
By breaking structural symmetry of the single atomic active site, the photocatalytic water oxidation pathway is tuned for highly selective oxidation of CH4 to CH3OH in an aqueous solution. The water ...oxidation ability and its influence on photocatalytic oxidation of CH4 over symmetrically coordinated cobalt single atom (Co-4N) on carbon nitride (SC-Co1/PCN) and asymmetrically coordinated cobalt single atom (Co-C2N2) on carbon nitride (AC-Co1/PCNKOH) photocatalysts are systematically investigated. A super selectivity of 87.22% for photocatalytic oxidation of CH4 to CH3OH is realized on AC-Co1/PCNKOH, which is only 45% on SC-Co1/PCN. Moreover, a CH4 conversion of 2.42% and a CH3OH yield of 2.11% are achieved over AC-Co1/PCNKOH (200 mg). Combining multiple in-situ characterizations and time-dependent density functional theory calculations, it is revealed that AC-Co1/PCNKOH possesses a desired electronic configuration for single-electron transfer water oxidation reaction during photocatalysis, leading to a notably promoted selectivity for CH4 oxidation to CH3OH under illumination.
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•Asymmetrically coordinated cobalt single atom on C3N4 photocatalyst is designed•A record-high selectivity for CH4 oxidation to CH3OH under visible light irradiation•The chemical adsorption of CH4 on PCN through the C–H/π interaction•Single-electron transfer controls selectivity for CH4 photooxidation to CH3OH
The photocatalytic water oxidation pathway can be modified for highly selective oxidation of CH4 to CH3OH using H2O as a green oxidant under visible light irradiation at room temperature. The ∗OH is generated from photooxidation of H2O, which can be regulated by the coordination structure of the cobalt atomic site, thus inhibiting overoxidation of CH4. This work highlights the importance of controlling coordination structure for boosting photocatalytic reactions. The understanding gained here shall provide a vista for the design of advanced photocatalytic systems for energy conversion and chemical transformation. Our design strategy proposed in this work can be extendable to other organic semiconductor photocatalyst systems (e.g., supramolecular coordination complexes SCCs, coordination polymers CPs, metal-organic frameworks, covalent organic frameworks COFs, etc.), as well as for other photocatalytic reactions.
Asymmetrically coordinated cobalt single atom on carbon nitride (AC-Co1/PCNKOH) photocatalyst realizes a record-high selectivity of 87.22% for photocatalytic CH4 oxidation to CH3OH by tuning the single-electron transfer process of water oxidation.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
This review presents a comprehensive attempt to conclude and discuss various glucose biosensors based on core@shell magnetic nanomaterials. Owing to good biocompatibility and stability, the ...core@shell magnetic nanomaterials have found widespread applications in many fields and draw extensive attention. Most magnetic nanoparticles possess an intrinsic enzyme mimetic activity like natural peroxidases, which invests magnetic nanomaterials with great potential in the construction of glucose sensors. We summarize the synthesis of core@shell magnetic nanomaterials, fundamental theory of glucose sensor and the advances in glucose sensors based on core@shell magnetic nanomaterials. The aim of the review is to provide an overview of the exploitation of the core@shell magnetic nanomaterials for glucose sensors construction.
Nowadays, microorganisms, including bacteria and viruses, are regarded as new environmental pollutants and pose serious threats to public health. Yet, traditional disinfection approaches for bacteria ...and viruses are generally ineffective. Furthermore, they exhibit the disadvantages of high‐energy consumption, environmental pollution, high cost, and toxic byproduct generation. In this respect, nanomaterials display promising antimicrobial capabilities due to their unique properties and provide solutions to the abovementioned issues. Herein, recent progress in the development of 2D nanomaterials displaying antimicrobial capabilities is highlighted. The structures, morphologies, and performances of essential metal, graphene, and nitride‐based 2D antibacterial nanomaterials are summarized in detail. In addition, possible antimicrobial mechanisms and the relationship between structure and antimicrobial efficiency are elaborated.
Banishing bacteria: Recent progress in the development of 2D nanomaterials that display antimicrobial capabilities is reviewed. The structures, morphologies, and performances of essential metal, graphene, and nitride‐based 2D antibacterial nanomaterials are summarized in detail. In particular, the photocatalytic properties of antimicrobial nanomaterials are discussed (see figure).
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