Shan Wang

Achieving a synergistic, rapid, and concentrated energy release process of ammonium perchlorate (AP) is of vital significance for boosting the thrust of composite solid propellants. However, conventional catalytic promoters often exhibit suboptimal catalytic kinetics due to inefficient utilization of active sites. Herein, atomically dispersed Cu‐coordinated covalent organic frameworks (COFs)‐based catalytic promoters are reported, decorating with energetic anion groups. The highly accessible single Cu sites confined in the COFs significantly contribute to the raid and concentrated energy release of AP, yielding a sharply narrowed decomposition peak at 341.3 °C with a peak width of only 9 °C. This performance is markedly superior to the dispersed exothermic process of raw AP (410.3 °C with a peak width of 30 °C). Additionally, the energetic COF promoter considerably increased the output energy via collaboratively promoting the chemical energy release of AP and its own decomposition. Correlating in situ spectroscopies and theoretical calculations reveals that the incorporated anionic groups effectively modulate the local electronic structure of the Cu sites. This alteration promotes the key step of cleavage of Cl─O bonds in AP intermediates to produce reactive oxygen species and also boosts the oxidation of NH ₃ to high‐valence nitrogen oxides, thereby accelerating the combustion reaction kinetic.

Near-infrared (NIR) photothermal materials efficiently convert low-energy near-infrared light into heat and have a significant role across various domains. Herein, a copper iodine cluster node (Cu₁₄I₁₄) featuring inorganic aromaticity was assembled with porphyrinic ligands characterized by classical π-aromaticity to create a dual-aromatic crystalline MOF (denoted as Cu₁₄I₁₄-CuTPyP). Cu₁₄I₁₄-CuTPyP with extensive electron delocalization exhibited broad NIR absorption and achieved a high NIR photothermal conversion efficiency of 63.77% under 1064 nm laser irradiation; this efficiency surpassed those of most reported porphyrin assembly materials. By combining in situ Raman spectroscopy, transient absorption spectroscopy, and control experiments, we revealed that the cooperation between aromatic Cu₁₄I₁₄ and porphyrin led to an active electron transfer pathway in Cu₁₄I₁₄-CuTPyP, which consumed a considerable amount of excited-state molecules (71.4%) through ultrafast nonradiative relaxation channels (2.1 ps). In this study, our thorough investigation of the photothermal properties of bis-aromatic MOFs could aid in setting a new standard for material design.

3D porous organic frameworks, which possess the advantages of high surface area and abundant exposed active sites, are considered ideal platforms to accommodate single atoms (SAs) and metal nanoclusters (NCs) in high‐performance catalysts; however, very little research has been conducted in this field. In the present work, a 3D porous organic framework containing Ni ₁ SAs and Ni _n NCs is prepared through the metal‐assisted one‐pot polycondensation of tetraaldehyde and hexaaminotriptycene. The single metal sites and metal clusters confined in the 3D space created a favorable micro‐environment that facilitated the activation of chemically inert CO ₂ molecules, thus promoting the overall photoconversion efficiency and selectivity of CO ₂ reduction. The 3D‐NiSAs/NiNCs‐POPs, as a CO ₂ photoreduction catalyst, demonstrated an exceptional CO production rate of 6.24 mmol g ⁻¹ h ⁻¹ , high selectivity of 98%, and excellent stability. The theoretical calculations uncovered that asymmetrical interaction between Ni ₁ SAs and Ni _n NCs not only favored the bending of CO ₂ molecules and reducing the CO ₂ reduction energy, but also regulated the electronic structure of the catalyst leading to the optimal binding strength of intermediates.

The development of facile tailoring approach to adjust the intrinsic activity and stability of atomically-precise metal nanoclusters catalysts is of great interest but remians challenging. Herein, the well-defined Au₈ nanoclusters modified by single-atom sites are rationally synthesized via a co-eletropolymerization strategy, in which uniformly dispersed metal nanocluster and single-atom co-entrenched on the poly-carbazole matrix. Systematic characterization and theoretical modeling reveal that functionalizing single-atoms enable altering the electronic structures of Au₈ clusters, which amplifies their electrocatalytic reduction of CO₂ to CO activity by ~18.07 fold compared to isolated Au₈ metal clusters. The rearrangements of the electronic structure not only strengthen the adsorption of the key intermediates *COOH, but also establish a favorable reaction pathway for the CO₂ reduction reaction. Moreover, this strategy fixing nanoclusters and single-atoms on cross-linked polymer networks efficiently deduce the performance deactivation caused by agglomeration during the catalytic process. This work contribute to explore the intrinsic activity and stability improvement of metal clusters.

A bimetallic phthalocyanine–porphyrin covalent organic framework with benzimidazole linkage was developed as an efficient CO₂electrocatalyst. Mechanistic studies clarified that a synergistic effect in the CO₂reduction thermodynamic pathway.

Exploring novel hypergolic fuels for modern space propulsion is highly desired. However, the analysis and understanding of the structure and hypergolic performance at the molecular level are still insufficient. To understand the factors that dictate hypergolicity, we conducted a comparative study on a series of metal-organic frameworks (MOFs) characterized by the same topology but with varied ligand structures. The ignition delay (ID) time trend was found to be imidazole < triazole < tetrazole, and the rapid ID time was 8 ms. By combining experimental studies and density functional theory (DFT) calculations, we found that propargyl and cyanoborohydride groups that functioned as dual hypergolic triggers contributed to the hypergolicity, and a distinct electronic structure was detrimental to ID time. The structure-performance relationships presented herein can potentially provide some fundamental insights into the field of developing high-performance hypergolic fuels.

Atomically precise metal clusters are attractive as highly efficient catalysts, but suffer from continuous efficiency deactivation in the catalytic process. Here, we report the development of an efficient strategy that enhances catalytic performance by electropolymerization (EP) of metal clusters into hybrid materials. Based on carbazole ligand protection, three polymerized metal‐cluster hybrid materials, namely Poly‐Cu₁₄cba, Poly‐Cu₆Au₆cbz and Poly‐Cu₆Ag₄cbz, were prepared. Compared with isolated metal clusters, metal clusters immobilizing on a biscarbazole network after EP significantly improved their electron‐transfer ability and long‐term recyclability, resulting in higher catalytic performance. As a proof‐of‐concept, Poly‐Cu₁₄cba was evaluated as an electrocatalyst for reducing nitrate (NO₃⁻) to ammonia (NH₃), which exhibited ≈4‐fold NH₃ yield rate and ≈2‐fold Faraday efficiency enhancement compared to that of Cu₁₄cba with good durability. Similarly, Poly‐Cu₆Au₆cbz showed 10 times higher photocatalytic efficiency towards chemical warfare simulants degradation than the cluster counterpart.

Atomically precise metal clusters are attractive as highly efficient catalysts, but suffer from continuous efficiency deactivation in the catalytic process. Here, we report the development of an efficient strategy that enhances catalytic performance by electropolymerization (EP) of metal clusters into hybrid materials. Based on carbazole ligand protection, three polymerized metal‐cluster hybrid materials, namely Poly‐Cu₁₄cba, Poly‐Cu₆Au₆cbz and Poly‐Cu₆Ag₄cbz, were prepared. Compared with isolated metal clusters, metal clusters immobilizing on a biscarbazole network after EP significantly improved their electron‐transfer ability and long‐term recyclability, resulting in higher catalytic performance. As a proof‐of‐concept, Poly‐Cu₁₄cba was evaluated as an electrocatalyst for reducing nitrate (NO₃⁻) to ammonia (NH₃), which exhibited ≈4‐fold NH₃ yield rate and ≈2‐fold Faraday efficiency enhancement compared to that of Cu₁₄cba with good durability. Similarly, Poly‐Cu₆Au₆cbz showed 10 times higher photocatalytic efficiency towards chemical warfare simulants degradation than the cluster counterpart.

A novel H-COP was synthesized through Schiff-base condensation reaction, which shows high sensitivity (K_sv ∼ 10⁶ M⁻¹) and selectivity (μM level) towards nitro-explosives.