CCS Chemistry最新文献

Ruthenium (Ru) is a promising electrocatalyst for hydrogen oxidation reaction (HOR) due to the similar metal hydrogen bond energy to Pt. However, Ru is easily deactivated or dissolved under an oxidation potential, which makes it unavailable in proton exchange membrane fuel cells. In this work, ultrastable Ru-based electrocatalysts for HOR in high-temperature polymer electrolyte membrane fuel cells (HT-PEMFCs) were developed by Mo doping. Under the operation conditions of HT-PEMFCs, thermal reduction inhibited the production of amorphous Ru oxide (RuO₂) in the Ru-based electrocatalysts during the HOR. Mo doping significantly improved the stability of the electrocatalyst by decreasing the reduction temperature of RuO₂ and accelerating the HOR by reducing the adsorption of H*. RuMo/C exhibited excellent HOR activity at high temperatures due to thermal reduction inhibition of electrooxidation; the fabricated HT-PEMFCs exhibited long-term stability and a 1050 mW cm⁻² peak power density, comparable to the commercial Pt catalyst. This work provides a novel strategy for designing electrocatalysts by combining material intrinsic properties and work conditions, which could promote the development of advanced electrocatalysts for HT-PEMFCs.

The mass production of urea, the most widely used agricultural fertilizer, usually relies on energy- and carbon-intensive processes. The light-driven synthesis path has great potential for more sustainable techniques to produce urea from abundant naturally occurring resources, but this method suffers from the use of pure CO₂ and high-energy-driven forces (high temperature or ultraviolet light). Herein, we present a mild photocatalytic pathway for urea production from diverse nitrogenous species (such as NO₃⁻, NH₃, and N₂) and diluted CO₂ using visible light. We designed a palladium (Pd)-doped Schottky heterojunction, composed of graphene and titanium dioxide, as an effective photocatalyst to achieve on-farm urea generation. With the injection of visible-light-generated hot electrons from graphene to TiO₂, the as-integrated Pd(I) centers with a special oxidation state of +1.36 in the TiO₂ lattice can initiate the universal reaction path of cascade reduction of NO₃⁻/N₂ to NH₃ and resulting C–N coupling of CO₂ with as-formed or added NH₃ to transform diverse nitrogenous species and CO₂ into urea. The urea yield over the at.-Pd@TiO₂/Gr photocatalyst is 1.62 mmol g⁻¹ h⁻¹ under visible-light irradiation with an apparent quantum yield of 1.05% at 400 nm and 0.39% even at 700 nm.

Glassy thermosetting polymers, which possess excellent mechanical properties, structural stability, and solvent resistance, cannot be healed and recycled due to the irreversible crosslinking network. Covalent adaptive networks could address these drawbacks, as their chemical networks are able to shuffle dynamic covalent bonds through exchange reactions, which nevertheless need high temperature or solvent assistance. Here we report a room-temperature self-healing glassy thermoset enabled by designing a disulfide-bond and H-bond hybridized network carrying abundant dangling chains, which are commonly known as network “defects.” However, the “defects” do not plasticize the polymer, as they are bound to network chains through H-bonds. Therefore, the polymer possesses high modulus and strength at room temperature. Importantly, the “defects” can drive the metathesis reaction of disulfide bonds and the rearrangement of H-bonds in the glassy state, enabling the thermosetting network to self-heal at and even below room temperature.

Interactions between molecules and surfaces are crucial in modern surface science. In particular, surfaces catalyze molecular reactions and modulate molecular spin states. In this article, we investigate the adsorption behaviors and electronic structures of chloro-iron phthalocyanine (ClFePc) on Au(111). Combining ultrahigh vacuum scanning tunneling microscopy experiments with density functional theory calculations, we found indications of surface-catalyzed dechlorination. Our findings reveal that the adsorption behavior of ClFePc is determined by its adsorption direction. ClFePc in the Cl-up (Cl pointing to the vacuum) configuration exhibits stable adsorption on the Au(111) surface. Conversely, the Cl-down (Cl pointing to the substrate) configuration is unstable, resulting in the dissociation of the Cl–Fe bond due to interactions with the Au(111) surface. Through scanning tunneling spectroscopy analysis, we further investigate the Kondo resonance features and spin characteristics. Notably, following dechlorination, the spin-state transitions from S = 3/2 to 1. This study provides profound insights into the surface-molecule interaction and its application in modulating magnetic properties.

The installation of a trifluoromethyl group onto a nitrogen atom can effectively modulate the basicity of amines owing to the strong electron-withdrawing effect of fluorine. Nevertheless, efficient and operationally simple methods for N-trifluoromethylation of amines are yet to be developed. This protocol involves the use of readily available secondary amines as starting materials, along with CS₂ and AgF as the N-trifluoromethylation reagents, enabling the target molecules to be synthesized in a single step. The versatility of our method was demonstrated by successfully synthesizing N,N-dialkyl and N-(hetero)aromatic N-CF₃-containing compounds with various substituents. Moreover, this methodology has been successfully applied to the late-stage modification of complex bioactive molecules, facilitating the synthesis of N-CF₃ drug bioisosteres and N-CF₃-tailored amino acids, which would broadly stimulate the drug discovery of N-CF₃ containing molecules.

Two structurally analogous self-assembled bowl-shaped hosts were obtained in close to quantitative yields via hydrazone condensation in acidic aqueous media, where the dynamic nature of hydrazone bonds was activated. Each bowl bears nine positive charges, endowing it with good water solubility. The bowls can thus take advantage of the hydrophobic effect and/or electrostatic forces to recognize neutral or anionic guests. Upon being accommodated within the host cavity, an anthracene derivative was protected from UV-stimulated oxidation.