Atomically dispersed low-valent Au boosts photocatalytic hydroxyl radical production.

Providing affordable, safe drinking water and universal sanitation poses a grand societal challenge. Here we developed atomically dispersed Au on potassium-incorporated polymeric carbon nitride material that could simultaneously boost photocatalytic generation of ·OH and H2O2 with an apparent quantum efficiency over 85% at 420 nm. Potassium introduction into the poly(heptazine imide) matrix formed strong K-N bonds and rendered Au with an oxidation number close to 0. Extensive experimental characterization and computational simulations revealed that the low-valent Au altered the materials' band structure to trap highly localized holes produced under photoexcitation. These highly localized holes could boost the 1e- water oxidation reaction to form highly oxidative ·OH and simultaneously dissociate the hydrogen atom in H2O, which greatly promoted the reduction of oxygen to H2O2. The photogenerated ·OH led to an efficiency enhancement for visible-light-response superhydrophilicity. Furthermore, photo-illumination in an onsite fixed-bed reactor could disinfect water at a rate of 66 L H2O m-2 per day.

Atomically isolated Sb(CN)3 on sp2-c-COFs with balanced hydrophilic and oleophilic sites for photocatalytic C-H activation.

Activation of carbon-hydrogen (C-H) bonds is of utmost importance for the synthesis of vital molecules. Toward achieving efficient photocatalytic C-H activation, our investigation revealed that incorporating hydrophilic C≡N-Sb(CN)3 sites into hydrophobic sp2 carbon-conjugated covalent organic frameworks (sp2-c-COFs) had a dual effect: It simultaneously enhanced charge separation and improved generation of polar reactive oxygen species. Detailed spectroscopy measurements and simulations showed that C≡N-Sb(CN)3 primarily functioned as water capture sites, which were not directly involved in photocatalysis. However, the potent interaction between water molecules and the Sb(CN)3-modified framework notably enhanced charge dynamics in hydrophobic sp2-c-COFs. The reactive species ·O2- and ·OH (ad) subsequently combined with benzyl radical, leading to the formation of benzaldehyde, benzyl alcohol, and lastly benzyl benzoate. Notably, the Sb(CN)3-modified sp2-c-COFs exhibited a 54-fold improvement in reaction rate as compared to pristine sp2-c-COFs, which achieved a remarkable 68% conversion rate for toluene and an 80% selectivity for benzyl benzoate.

Developing Ni single-atom sites in carbon nitride for efficient photocatalytic H2O2 production.

Photocatalytic two-electron oxygen reduction to produce high-value hydrogen peroxide (H2O2) is gaining popularity as a promising avenue of research. However, structural evolution mechanisms of catalytically active sites in the entire photosynthetic H2O2 system remains unclear and seriously hinders the development of highly-active and stable H2O2 photocatalysts. Herein, we report a high-loading Ni single-atom photocatalyst for efficient H2O2 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-N3 sites dynamically transform into high-valent O1-Ni-N2 sites after O2 adsorption and further evolve to form a key *OOH intermediate before finally forming HOO-Ni-N2. 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 H2O2 production activity and selectivity.

A Ce-UiO-66 Metal-Organic Framework-Based Graphene-Embedded Photocatalyst with Controllable Activation for Solar Ammonia Fertilizer Production.

Currently, nitrogen fertilizers feed half of the global population, but their use is limited by energy consumption and transportation. Therefore, it is important to study photocatalysts for use in solar nitrogen fertilizers. Herein, a new type of graphene-embedded Ce-based UiO-66 (Ce-UiO-66) photocatalyst (GSCe) is investigated. Ce-UiO-66 is activated by the breakage of benzene-C bonds and the formation of active sites by ultraviolet light in water. Moreover, embedding graphene effectively controls activation and improves nitrogen fixation. GSCe exhibited a remarkable apparent quantum efficiency (AQE) of 9.25 % and stability under 365 nm light with solar-level intensity. GSCe also performed well as a solar ammonia fertilizer for crop cultivation. This investigation opens up opportunities for nitrogen fixation photocatalysts to be used as environmentally friendly solar nitrogen fertilizers.

Polarization Engineering of Covalent Triazine Frameworks for Highly Efficient Photosynthesis of Hydrogen Peroxide from Molecular Oxygen and Water.

Two-electron oxygen photoreduction to hydrogen peroxide (H2 O2 ) 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 H2 O2 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.

Intrinsic Defects in Polymeric Carbon Nitride for Photocatalysis Applications.

Introducing intrinsic defects in polymeric carbon nitride (PCN) without the addition of exotic atoms have been verified as an available strategy to boost the photocatalytic performance. This minireview focuses on the fundamental classifications and positive roles of intrinsic defects in PCN for photocatalysis applications. The intrinsic defects in PCN are classified into several types, such as nitrogen vacancy, carbon vacancy and derivative functional groups such as cyano, amino and cyanamide groups. The critical roles of these defects on the electronic configuration, charge transfer and surface properties of PCN are also carefully classified and elaborated. Furthermore, the photocatalysis applications of the defective PCN including photocatalytic water splitting, N2 fixation, H2 O2 production, CO2 reduction and NO removal are summarized. In the end, the challenges and opportunities of defect chemistry in PCN for photocatalysis field are presented.

Recent Progress in Two-Dimensional Antimicrobial Nanomaterials.

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.

Development of a Fluorescent Labeling Reagent for Determination of Proline and Hydroxyproline in Myeloma Patient Plasma by HPLC-FLD.

A fluorescent derivatization reagent, 3,6-dimethoxy-9-phenyl-9H-carbazole-1-sulfonyl chloride (DPCS-Cl), previously designed, synthesized and developed for amino acids labeling, is here employed. It was used as a pre-column derivatization reagent for the determination of proline (Pro) and hydroxyproline (Hyp) with high-performance liquid chromatography. Both of the analytes were labeled with DPCS-Cl at 60°C for 30 min. The optimized concentration of DPCS-Cl was 25 µg mL-1 and the molar ratio of analytes to DPCS-Cl was 1:6. Excitation wavelength of 318 nm and emission wavelength of 440 nm were selected for the fluorescence detection. For Pro and Hyp, the linear correlation coefficients were all >0.999; the linear ranges of calibration curve were all 5.0 nmol L-1 to 5.0 µmol L-1; the detection limits were 20.0 and 10.0 fmol, respectively; the intra-day and inter-day relative standard deviations were 2.6-3.3% and 3.5-4.6%, respectively. This reagent was applied to the determination of Pro and Hyp in plasma of myeloma patients with its merits of high efficiency of derivatization, stability of the derivatives and high sensitivity.

Glucose Sensors Based on Core@Shell Magnetic Nanomaterials and Their Application in Diabetes Management: A Review.

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.