Electrocatalytic performances of phosphorus doped carbon supported Pd towards formic acid oxidation

Hydrogenative coupling of nitriles with diamines to benzimidazoles using lignin-derived Rh2P catalyst

Nitrile (C≡N bond) activation for direct organic synthesis has been less explored so far due to a high redox potential of nitrile and its low dissociation energy of C−CN bond. Herein, we demonstrate a direct reductive coupling of nitriles and 1,2-phenylenediamines to yield various benzimidazoles in excellent yields (95%–99%) by using rhodium phosphide (Rh₂P) catalyst supported on lignin-derived carbon (LC) using H₂ (or hydrazine hydrate) as a hydrogen source. The high catalytic performance of Rh₂P/LC is attributed to enhanced charge transfer to Rh and strong P−Rh interactions. Our isotope trace experiment confirms the presence of H/D exchange between H₂ and the inert –CD₃ group of CD₃CN via an intramolecular D-shift. Reusability of Rh₂P/LC is further demonstrated by a seven-time recycling without evident loss of activity. This research thus highlights a great potential in organic transformation with nitrile as a synthetic building block.

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Nitrile was developed as synthetic building block for organic synthesis

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Reductive coupling of nitriles to 1,2-phenylenediamines yielded benzimidazoles

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Strong P−Rh interaction and charge transfer to Rh enhanced Rh₂P activity

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H/D exchange between H₂ and –CD₃ in CD₃CN occurred via intramolecular D-shift

Cyclic voltammetry electrodeposition of well-dispersed Pd nanoparticles on carbon paper as a flow-through anode for microfluidic direct formate fuel cells

The preparation of low-loading and high-performance Pd-based electrodes is required for direct formate fuel cells. In this study, cyclic voltammetry electrodeposition is used to electrodeposit Pd nanoparticles on carbon paper (Pd/CP) and achieve excellent activity and promising stability toward the formate oxidation reaction (FOR). The prepared electrode shows a thin layer of hemispherical and well-dispersed Pd nanoparticles on the fibers of the carbon paper. The open structure and uniform catalyst distribution make the Pd/CP electrode show 2.56-fold higher active area and stability in the FOR as compared with those of commercial Pd/C catalysts. An air-breathing microfluidic direct formate fuel cell (μDFFC) with a Pd/CP electrode used as a flow-through anode is constructed to further assess electrode performance. The Pd/CP electrode with low Pd loading, 0.105 mg cm-2, delivers a peak power density and limiting current density of 46.6 mW cm-2 (443.8 mW mg-1Pd) and 288.4 mA cm-2, respectively. The performance of the μDFFC is superior to those of most others reported in the literature, further boosting the commercialization of this direct formate fuel cell to power next-generation portable electronics.

Highly Active and Durable Ultrasmall Pd Nanocatalyst Encapsulated in Ultrathin Silica Layers by Selective Deposition for Formic Acid Oxidation

The low performance of palladium (Pd) is a considerable challenge for direct formic acid fuel cells in practical applications. Herein, we develop a simple strategy to synthesize a highly active and durable Pd nanocatalyst encapsulated in ultrathin silica layers with vertically aligned nanochannels covered graphene oxides (Pd/rGO@pSiO₂) without blocking active sites by selective deposition. The Pd/rGO@pSiO₂ catalyst exhibits very high performance for a formic acid oxidation (FAO) reaction compared with the Pd/rGO without protective silica layers and commercial Pd/C catalysts. Pd/rGO@pSiO₂ shows an FAO activity 3.9 and 3.8 times better than those of Pd/rGO and Pd/C catalysts, respectively. The Pd/rGO@pSiO₂ catalysts are also almost 6-fold more stable than Pd/C and more than 3-fold more stable than Pd/rGO. The outstanding performance of our encapsulated Pd catalysts can be ascribed to the novel design of nanostructures by selective deposition fabricating ultrasmall Pd nanoparticles encapsulated in ultrathin silica layers with vertically aligned nanochannels, which not only avoid blocking the active sites but also facilitate the mass transfer in encapsulated catalysts. Our work indicates an important method to the rational design of high-performance catalysts for fuel cells in practical applications.

Mesoporous Carbon and Ceria Nanoparticles Composite Modified Electrode for the Simultaneous Determination of Hydroquinone and Catechol

In this work, a novel material that was based on mesoporous carbon and ceria nanoparticles composite (MC–CeNPs) was synthesized, and a modified electrode was fabricated. When compared with a bare glass electrode, the modified electrode exhibited enhanced electrocatalytic activity towards the simultaneous determination of hydroquinone (HQ) and catechol (CC), which is attributed to the large specific area and fast electron transfer ability of MC–CeNPs. Additionally, it exhibited linear response ranges in the concentrations of 0.5–500 µM and 0.4–320 µM for HQ and CC, with detection limits (S/N = 3) of 0.24 µM and 0.13 µM, respectively. This method also displayed good stability and reproducibility. Furthermore, the modified electrode was applied to the simultaneous determination of HQ and CC in tap and lake water samples, and it exhibited satisfactory recovery levels of 98.5–103.2% and 98–103.4% for HQ and CC, respectively. All of these results indicate that a MC–CeNPs modified electrode could be a candidate for the determination of HQ and CC.

Controllable Synthesis of Multiheteroatoms Co-Doped Hierarchical Porous Carbon Spheres as an Ideal Catalysis Platform

The synthesis of porous carbon spheres with hierarchical porous structures coupled with the doping of heteroatoms is particularly important for advanced applications. In this research, a new route for efficient and controllable synthesis of hierarchical porous carbon spheres co-doped with nitrogen, phosphorus, and sulfur (denoted as NPS-HPCs) was reported. This new approach combines in situ polymerization of hexachlorocyclophosphazene and 4,4'-sulfonyldiphenol with the self-assembly of colloidal silica nanoparticles (SiO₂ NPs). After pyrolysis and subsequent removal of the SiO₂ NPs, the resulting NPS-HPCs possess a high surface area (960 m²/g) as well as homogeneously distributed N, P, and S heteroatoms. The NPS-HPCs are shown to be an ideal support for anchoring highly dispersed and uniformly sized noble metal NPs for heterogeneous catalysis. As a proof of concept, Pd NPs are loaded onto the NPS-HPCs using only methanol as a reductant at room temperature. The prepared Pd/NPS-HPCs are shown to exhibit high activity, excellent stability, and recyclability for hydrogenation of nitroarenes.

Mediator- and co-catalyst-free direct Z-scheme composites of Bi2WO6-Cu3P for solar-water splitting

Exploring new single, active photocatalysts for solar-water splitting is highly desirable to expedite current research on solar-chemical energy conversion. In particular, Z-scheme-based composites (ZBCs) have attracted extensive attention due to their unique charge transfer pathway, broader redox range, and stronger redox power compared to conventional heterostructures. In the present report, we have for the first time explored Cu₃P, a new, single photocatalyst for solar-water splitting applications. Moreover, a novel ZBC system composed of Bi₂WO₆-Cu₃P was designed employing a simple method of ball-milling complexation. The synthesized materials were examined and further investigated through various microscopic, spectroscopic, and surface area characterization methods, which have confirmed the successful hybridization between Bi₂WO₆ and Cu₃P and the formation of a ZBC system that shows the ideal position of energy levels for solar-water splitting. Notably, the ZBC composed of Bi₂WO₆-Cu₃P is a mediator- and co-catalyst-free photocatalyst system. The improved photocatalytic efficiency obtained with this system compared to other ZBC systems assisted by mediators and co-catalysts establishes the critical importance of interfacial solid-solid contact and the well-balanced position of energy levels for solar-water splitting. The promising solar-water splitting under optimum composition conditions highlighted the relationship between effective charge separation and composition.