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Herein we demonstrate that adding single-atoms of selected transition metals to graphitic carbon nitrides allow the tailoring of their electronic and chemical properties of these 2D nanomaterials, directly impacting their...

Carbon nitride single-atom based catalysts: supporting the transition from the fossil past to the green future.

Photocatalysis provides a sustainable pathway to produce the consumer chemical H2O2 from atmospheric O2 via an oxygen reduction reaction (ORR). Such an alternative is attractive to replace the cumbersome traditional anthraquinone method for H2O2 synthesis on a large scale. Carbon nitrides have shown very interesting results as heterogeneous photocatalysts in ORR because their covalent two-dimensional (2D) structure is believed to increase selectivity toward the two-electron process. However, an efficient and scalable application of carbon nitrides for this reaction is far from being achieved. Poly­(heptazine imides) (PHIs) are a more powerful subgroup of carbon nitrides whose structure provides high crystallinity and a scaffold to host transition-metal single atoms. Herein, we show that PHIs functionalized with sodium and the recently reported fully protonated PHI exhibit high activity in two-electron ORR under visible light. The latter converted O2 to up to 1556 mmol L–1 h–1 g–1 H2O2 under 410 nm irradiation using inexpensive but otherwise chemically demanding glycerin as a sacrificial electron donor. We also prove that functionalization with transition metals is not beneficial for H2O2 synthesis, as the metal also catalyzes its decomposition. Transient photoluminescence spectroscopy suggests that H-PHIs exhibit higher activity due to their longer excited-state lifetime. Overall, this work highlights the high photocatalytic activity of the rarely examined fully protonated PHI and represents a step forward in the application of inexpensive covalent materials for photocatalytic H2O2 synthesis.

Here we report a photocatalytic system based on crystalline carbon nitrides (PHI) and highly dispersed transition metals (Fe, Co and Cu) for controlled methane photooxidation to methanol under mild conditions....

In this work, a new morphology was obtained for bismuth tungstate (Bi 2 WO 6 -glyc) using a hydrothermal method with the addition of glycerol as a surfactant. In order to compare, the bismuth tungstate without glycerol as the surfactant, i.e., Bi 2 WO 6 , was synthesized. Structural characterization by XRD and Rietveld refinement confirmed the orthorhombic structure as a single phase for all samples with high crystallinity. All active modes in Raman spectroscopy for the orthorhombic phase of bismuth tungstate were confirmed in agreement with XRD analysis. N 2 adsorption/desorption and size pore distribution confirmed the high surface area (85.7 m 2 /g) for Bi 2 WO 6 -glyc when compared with Bi 2 WO 6 (8.5 m 2 /g). The optical band gap by diffuse reflectance was 2.78 eV and 2.88 eV for Bi 2 WO 6 -glyc and Bi 2 WO 6 , respectively. SEM images confirmed the different morphology for these materials, and microstructures with cheese crisp were observed for Bi 2 WO 6 -glyc (cheese crisp). On the other hand, flower-like microcrystals were confirmed for Bi 2 WO 6 sample. The photocatalytic performance of Bi 2 WO 6 -glyc (94.2%) in the photodegradation of rhodamine B (RhB) dye solutions at 60 min was more expressive than Bi 2 WO 6 (81.3%) and photolysis (8.2%) at 90 min.

Herein, we describe a simple laboratory experiment to address nanomaterial synthesis, plasmon resonance, and its application to detect Cu2+ in ultralow concentrations. The proposed experiment is very visual and appealing for chemistry students, especially the undergraduate-level chemistry major. In this experiment, the aggregation of silver nanoparticles (Ag NPs) promoted by interactions between the NPs and cations in solution induces a color change in the Ag NP suspension. This visual color change can be explained by concepts of plasmon resonance and nanomaterial properties which can be addressed in this laboratory course. The experiment comprises three main parts: (1) synthesis of Ag NPs using a well-established method reported in the literature; (2) functionalization of the Ag NP surface by l-cysteine; and (3) application of the Ag NPs to detect Cu2+ ions in ultralow concentrations. This experiment can be performed with a relatively simple laboratory infrastructure and with instrumentation that is generally widely available.

C–H activation of hydrocarbons is extremely challenging, especially in short-chain hydrocarbons like propane. In industry, propane is first converted to propylene mostly by steam cracking, which is only oxidized to acetone in the cumene process, yielding acetone and phenol. In this work, we show that the simple FeCl3 salt in acetonitrile photocatalyzes the oxidation of propane to acetone at room temperature under aerobic conditions and visible-light irradiation. We achieved 100% conversion of propane with 67% selectivity in acetone after 4 h of irradiation and TON up to 600. Mechanistic studies, including electrospray ionization mass spectrometry, Mössbauer, and electroparamagnetic resonance spectroscopy, concluded that the reaction is driven by chlorine radicals generated by Fe–Cl bond photolysis. These results not only hold promise for the development of solar-based oxidation of hydrocarbons but more importantly also disclose deeper insights into the largely overlooked photochemistry of FeCl3.