结构化学最新文献

The sp² carbon-conjugated covalent organic frameworks (COFs) with fully π-conjugated lattice and high chemical stability are promising heterogeneous photocatalysts. Herein, we report the design and synthesis of a novel palladium (Pd) porphyrin-based sp² carbon-conjugated COF (PdPor-sp²c-COF) with an eclipsed AA stacking 2D structure. Interestingly, PdPor-sp²c-COF showed high crystallinity, good chemical stability, and a broad absorption of visible light. Moreover, compared to our previously reported metal-free Por-sp²c-COF, PdPor-sp²c-COF displays an improved photocatalytic performance in the selective aerobic oxidation of sulfides under green light irradiation. The systematic mechanistic studies testified that the enhanced photocatalytic activity can be ascribed to promoting energy transfer pathway over PdPor-sp²c-COF. Our study clearly demonstrates that it is favorable to promote the energy transfer pathway in sp² carbon-conjugated COFs by using metalloporphyrin-based molecular building blocks. This work will inspire us to design and synthesize novel photocatalysts based on COFs for the selective aerobic oxidation.

Lithium-sulfur (Li–S) batteries are one of the promising energy storage systems. However, rapid capacity attenuation caused by shuttle effect of soluble polysulfides is a major challenge in practical application. The separator modification is one complementary countermeasure besides the construction of sulfur host materials in cathode. MXene is one type of outstanding candidates for promoting redox kinetics of sulfur species. Herein, recent advances of MXene-based materials as separator modifiers are summarized. The importance of high conductivity and catalytic effects in promoting catalytic conversion of polysulfides and suppressing shuttle effect of polysulfides has been highlighted, and the superiority of MXene for improving reversible capacity and cycling stability has been demonstrated. New strategies for the design of MXene-based separator modifiers are proposed to improve energy density and lifetime. The review provides new perspectives for future development of high-performance Li–S batteries.

Developing efficient bifunctional catalysts for urea oxidation reaction (UOR)/hydrogen evolution reaction (HER) is important for energy-saving hydrogen production. Herein, a catalyst with crystalline-amorphous heterostructure supported by NiCo alloy on nickel foam (NiCoO-MoO_x/NC) is reported for the first time. Through simple molybdenum salt etching, 2D NiCo alloy nanosheets are transformed into a unique 3D cycad-leaf-like structure with a super-hydrophilic surface. Simultaneously, the synergistic effect between crystalline NiCoO and amorphous MoO_x improves the UOR and HER activity, merely requiring 1.28 V and −45 mV potentials to reach ±10 mA cm⁻², respectively. Particularly, the UOR kinetics of NiCoO-MoO_x/NC is enhanced significantly compared to that of NiCoO/NC. The electronic structure of NiCoO is modified by MoO_x, enabling the rapid generation of NiOOH and CoOOH active species, which would accelerate the synergistic electrocatalytic oxidation of urea molecules. This work inspires the design of highly active and stable bifunctional catalysts for urea assisted H₂ production.

Flexible zinc-air batteries (FZABs) are featured with safety and high theoretical capacity and become one of the ideal energy supply devices for flexible electronics. However, the lack of cost-effective electrocatalysts remains a major obstacle to their commercialization. Herein, we synthesized a porous dodecahedral nitrogen-doped carbon (NC) material with Co and Mn bimetallic co-embedding (Co_xMn_1−x@NC) as a highly efficient oxygen reduction reaction (ORR) catalyst for ZABs. The incorporation of Mn effectively modulates the electronic structure of Co sites, which may lead to optimized energetics with oxygen-containing intermediates thereby significantly enhancing catalytic performance. Notably, the optimized Co₄Mn₁@NC catalyst exhibits superior E_1/2 (0.86 V) and j_L (limiting current density, 5.96 mA cm⁻²) compared to Pt/C and other recent reports. Moreover, aqueous ZAB using Co₄Mn₁@NC as a cathodic catalyst demonstrates a high peak power density of 163.9 mW cm⁻² and maintains stable charging and discharging for over 650 h. Furthermore, FZAB based on Co₄Mn₁@NC can steadily operate within the temperature range of −10 to 40 °C, demonstrating the potential for practical applications in complex climatic conditions.