Cobalt-decorated defective carbon paper as a self-supported catalyst for oxygen electrocatalysis and rechargeable zinc-air battery

Carbon-supported transition-metal materials have been recognized as efficient bifunctional electrocatalysts for oxygen evolution/reduction reactions (OER/ORR) in rechargeable zinc-air batteries. While the pursuit of high-performance catalysts remains critical, the industrial applications of catalysts and their synthesis methods cannot be ignored. In this work, a self-supported hybrid catalyst is prepared by anchoring cobalt oxide particles on defective carbon papers. Commercial carbon papers were first treated by nitrogen plasma to introduce surface defects and increase their surface hydrophilicity, thereby facilitating the subsequent cobalt deposition. The resulting catalyst with abundant carbon defects and deposited Co oxide particles exhibits an increased number of active sites and improved surface conductivity compared to pristine carbon papers, leading to enhanced bifunctional electrocatalytic performance. When employed in a liquid zinc-air battery, this catalyst shows acceptable discharging and charging potentials, along with a higher durability than the battery utilizing a mixed noble metal-based catalyst. Our findings represent a novel and large-scale application strategy for synthesizing self-supported carbon-supported transition-metal materials for rechargeable zinc-air batteries and associated energy storage systems.

Novel design of hollow carbon nanocage modified with nanotubes as a bifunctional electrocatalyst for high performance Zn-air batteries

Microcavities play a crucial role as microreactors in the transport of molecular/ionic guests and the exposure of active sites, thus significantly influencing the electrocatalytic performance. This study prepares Co/N-codoped hollow carbon (HT-CoN/C) with surface-distributed carbon nanotubes by pyrolysis of PDA-coated Zn/Co bimetallic ZIF (BM-ZIF@PDA). Benefiting from the hierarchical porous structure, high specific surface area (307.17 m2 g-1) and abundant Co clusters, the HT-CoN/C exhibits remarkable bifunctional oxygen electrocatalytic activity with an overpotential of the ORR/OER processes (ΔE = 0.703 V). The density functional theory (DFT) calculations also verify that the configuration of C-coated N-coordinated Co clusters (Co4-Nx) affect the electrocatalytic activity of ORR and OER, illustrating the source of the excellent oxygen electrocatalytic activity of HT-CoN/C. The aqueous rechargeable zinc-air battery (RZAB) using HT-CoN/C as the air electrode is characterized by a superior peak power density (175 mW cm-2), a prolonged cycle life (1230 cycles/410 h at 5.0 mA cm-2) and a high open-circuit voltage (1.47 V). Meanwhile, the flexible solid-state RZAB assembled by the HT-CoN/C also exhibits a higher peak power density (117 mW cm-2) and an excellent bending performance. This work is extremely valuable for the design and synthesis of Co/N co-doped carbon electrocatalysts.

N-Doping Effects On Electrocatalytic Water Splitting of Non-Noble High-Entropy Alloy Nanoparticles Prepared by Inert Gas Condensation

The unique catalytic activities of high-entropy alloys (HEAs) emerge from the complex interaction among different elements in a single-phase solid solution. As a "green" nanofabrication technique, inert gas condensation (IGC) combined with laser source opens up a highly efficient avenue to develop HEA nanoparticles (NPs) for catalysis and energy storage. In this work, the novel N-doped non-noble HEA NPs are designed and successfully prepared by IGC. The N-doping effects of HEA NPs on oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) are systematically investigated. The results show that N-doping is conducive to improving the OER, but unfavorable for HER activity. The FeCoNiCrN NPs achieve an overpotential of 269.7 mV for OER at a current density of 10 mA cm-2 in 1.0 M KOH solution, which is among the best reported values for non-noble HEA catalysts. The effects of the differences in electronegativity, ionization energy and electron affinity energy among mixed elements in N-doped HEAs are discussed as inducing electron transfer efficiency. Combined with X-ray photoelectron spectroscopy and the extended X-ray absorption fine structure analysis, an element-design strategy in N-doped HEAs electrocatalysts is proposed to improve the intrinsic activity and ameliorate water splitting performance.

Copper oxides supported sulfur-doped porous carbon material as a remarkable catalyst for reduction of aromatic nitro compounds

Synthesis and manufacturing of metal-organic framework derived carbon/metal oxide nanomaterials with an advisable porous structure and composition are essential as catalysts in various organic transformation processes for the preparation of environmentally friendly catalysts. In this work, we report a scalable synthesis of sulfur-doped porous carbon-containing copper oxide nanoparticles (marked CuxO@CS-400) via direct pyrolysis of a mixture of metal-organic framework precursor called HKUST-1 and diphenyl disulfide for aromatic nitro compounds reduction. X-ray diffraction, surface area analysis (BET), X-ray energy diffraction (EDX) spectroscopy, thermal gravimetric analysis, elemental mapping, infrared spectroscopy (FT-IR), transmission electron microscope, and scanning electron microscope (FE-SEM) analysis were accomplished to acknowledge and investigate the effect of S and CuxO as active sites in heterogeneous catalyst to perform the reduction-nitro aromatic compounds reaction in the presence of CuxO@CS-400 as an effective heterogeneous catalyst. The studies showed that doping sulfur in the resulting carbon/metal oxide substrate increased the catalytic activity compared to the material without sulfur doping.

The low loading of metal in metal-organic framework-derived NiNx@NC promotes amide formation through C-N coupling

The pyrolysis of Ni-substituted zeolitic imidazolate framework-8 produces NiNx@NC with an ultra-low loading of Ni (7.4 × 10-6 mol%). The Ni-N coordination, subnanometer particle size, and uniform distribution of NiNx on the NC support lead to excellent catalytic activity (TON = 2702) and selectivity for the amination of aldehydes to produce amides.

Ball-milled prepared Fe3O4-FeSAs-NPs@NC catalyst synergistically facilitate the generation of reactive oxygen species for oxidative trifluoromethylation of alkenes

Heterogeneous catalysts have recently regarded as a promising chose for the thermally-driven generation of the reactive oxygen species (ROS) through catalytic reactions with molecular oxygen, which can facilitate this process by specific geometric and electronic structure. However, the oxidative trifluoromethylation of alkenes to α-trifluoromethylated ketones by CF3SO2Na is rarely reported in this system. In this work, we report a one-pot polymerization ball milling strategy to construct precursor, and then pyrolyze it to obtain specific carbon nanotubes matrix with Fe/Fe3O4 nanoparticles and single atoms Fe. Remarkably, the optimized catalyst (Fe3O4-FeSAs-NPs@NC-1) displays excellent catalytic performance, broad substrates and recyclability for this fluorination reaction via radical pathway. Based on characterizations and mechanistic studies, we discover that the coexistence of Fe/Fe3O4 and Fe-Nx not only synergistically facilitates the catalytic efficiency in altering the electronic structure of Fe sites, but also benefits the absorption of O2 and the ability of the thermally-driven generating ROS which can activate CF3SO2Na to CF3 radical. This work offers a method of designing Fe-based catalysts and also opens up a new thermal-heterogeneous catalysis way for the oxidative trifluoromethylation of alkenes.

4,6-Diamino-2-thiopyrimidine-based Cobalt Metal Organic Framework (Co-DAT-MOF): green, efficient, novel and reusable nanocatalyst for synthesis of multicomponent reactions

In this study, Co-DAT-MOF powder was prepared via the solvothermal method using 4, 6-diamino-2-thiopyrimidine as the organic linker and Co(NO₃)₂·6H₂O. The synthesized catalysts are characterized using XRD, FT-IR, TGA, SEM, BET, NH₃-TPD, and ICP-OES techniques. SEM analysis clearly indicated the formation of nanosheet microspheres. NH₃-TPD-MS was employed as a means of identifying the various strengths of acid sites and their relative abundance in an attempt to explain the effect of the catalyst surface acid sites. We identified a new acidic feature in Co-DAT-MOF catalyst, related to the presence of desorption peaks in the NH₃-TPD profiles. The activity of Co-DAT-MOF catalyst for the synthesis of multicomponent reactions correlates with lewis acidity. In addition, Co-DAT-MOF exhibited excellent performance for the synthesis of pyrroloacridine-1(2H)-one and chromeno [2, 3- d] pyrimidin-8-amines, as well as good reusability and recyclability.

N, S Co-Coordinated Zinc Single-Atom Catalysts for N-Alkylation of Aromatic Amines with Alcohols: The Role of S-Doping in the Reaction

S-doping emerged as a promising approach to further improve the catalytic performance of carbon-based materials for organic synthesis. Herein, a facile and gram-scale strategy was developed using zeolitic imidazole frameworks (ZIFs) as a precursor for the fabrication of the ZIF-derived N, S co-doped carbon-supported zinc single-atom catalyst (CNS@Zn₁-AA) via the pyrolysis of S-doped ZIF-8, which was modified by aniline, ammonia and thiourea and prepared by one-pot ball milling at room temperature. This catalyst, in which Zn is dispersed as the single atom, displays superior activity in N-alkylation via the hydrogen-borrowing strategy (120 °C, turnover frequency (TOF) up to 8.4 h^-1). S-doping significantly enhanced the catalytic activity of CNS@Zn₁-AA, as it increased the specific surface area and defects of this material and simultaneously increased the electron density of Zn sites in this catalyst. Furthermore, this catalyst had excellent stability and recyclability, and no obvious loss in activity after eight runs.

Nitrogen and Phosphorus Dual-Coordinated Single-Atom Mn: MnN2P Active Sites for Catalytic Transfer Hydrogenation of Nitroarenes

The coordination environment of atomically metal sites can modulate the electronic states and geometric structure of single-atom catalysts, which determine their catalytic performance. In this work, the porous carbon-supported N, P dual-coordinated Mn single-atom catalyst was successfully prepared via the phosphatization of zeolitic imidazolate frameworks and followed by pyrolysis at 900 °C. The optimal Mn₁-N/P-C catalyst with atomic MnN₂P structure has displayed better catalytic activity than the related catalyst with Mn-N_x structure in catalytic transfer hydrogenation of nitroarenes using formic acid as the hydrogen donor. We find that the doping of P source plays a crucial role in improving the catalytic performance, which affects the morphology and electronic properties of catalyst. This is the first Mn heterogeneous catalyst example for the reduction of nitroarenes, and it also revealed that the MnN₂P configuration is a more promising alternative in heterogeneous catalysis.

Hydrogenation of pyrolysis gasoline by novel Ni-doped MOF derived catalysts from ZIF-8 and ZIF-67

Pyrolysis gasoline is the valuable byproduct of the thermal breakdown of heavier oil fractions in an olefin unit with high aromatic content. To separate such aromatic components, firstly, this product should be hydrogenated. In this contribution, new nanostructure catalysts derived from the zeolitic metal–organic framework, namely ZIF-8 and ZIF-67, were used to investigate their hydrogenation capability. Owing to its great hydrogenation capability of Nickle, the structures of the ZIF-8 and ZIF-67 were improved by Nickle through in situ synthesis. Moreover, to enhance the pore size of catalysts and their electronic properties, the synthesized catalysts were pyrolyzed under nitrogen media at 450 °C, and five catalysts, namely Co/NC, ZnCo/NC, ZnNi/NC, CoNi/NC, and ZnCoNi/NC were created. Results indicated that the CoNi/NC showed a superior hydrogenation performance (69.5% conversion of total olefins) to others. In addition, the synthesized catalysts without the carbonization process had no conversion in the hydrogenation process because there is no active site in these structures. The current synthesized catalysts can compete with the costly Pt or Pd-based hydrogenation catalysts due to their high surface area and great electronic properties.

Recent Advances in Carbon-Based Iron Catalysts for Organic Synthesis

Carbon-based iron catalysts combining the advantages of iron and carbon material are efficient and sustainable catalysts for green organic synthesis. The present review summarizes the recent examples of carbon-based iron catalysts for organic reactions, including reduction, oxidation, tandem and other reactions. In addition, the introduction strategies of iron into carbon materials and the structure and activity relationship (SAR) between these catalysts and organic reactions are also highlighted. Moreover, the challenges and opportunities of organic synthesis over carbon-based iron catalysts have also been addressed. This review will stimulate more systematic and in-depth investigations on carbon-based iron catalysts for exploring sustainable organic chemistry.

Concave octopus-like PtCu nanoframe mediated photo-electro Fenton catalysis for fast organic dyestuff elimination

In this work, a photo-electro Fenton catalytic nanoplatform based on concave octopus-like PtCu nanoframes was fabricated for organic dyestuff degradation. The electrochemical oxidation reaction was performed to generate hydrogen peroxide (H2O2) on the interface of PtCu nanoframes via a promising electro-Fenton process for on-demand aqueous remediation.

Fe–FeOx nanoparticles encapsulated in N-doped carbon material: a facile catalyst for selective synthesis of quinazolines from alcohols in water

A Fe–FeOx@NC catalyst with N-doped carbon encapsulated Fe–FeOx nanoparticles has excellent performance in the synthesis of quinazolines.

A heterogeneous cobalt catalyst for C–C bond formation by a borrowing hydrogen strategy

Co–MgO/TiO2 exhibited high activity for α-alkylation of ketones with alcohols through a borrowing hydrogen strategy without the addition of bases which were utilized in reported heterogeneous catalytic systems.