Science China Chemistry最新文献

Electrocatalytic conversion of biomass-derived compounds and nitrate pollutants offers a promising route toward sustainable chemical synthesis and environmental remediation. In this work, a bifunctional NiO-NiCoP catalyst with a well-defined heterogeneous interface is synthesized via a low-temperature co-precipitation, annealing and phosphidation process to enable the coupled electrocatalytic 5-hydroxymethylfurfural oxidation reaction (HMFOR) and nitrate reduction reaction (NO₃⁻RR). X-ray photoelectron spectroscopy (XPS), high-resolution transmission electron microscopy (HRTEM), open-circuit potential (OCP), and in-situ electrochemical impedance spectroscopy (in-situ EIS) confirm the formation of the heterogeneous interface, which facilitates electron redistribution, enhances charge transfer, and optimizes reactant adsorption. The catalyst exhibits excellent HMFOR activity, achieving 99.46% HMF conversion, 97.23% 2,5-furandicarboxylic acid (FDCA) yield, and 97.62% Faradaic efficiency (FE) at 1.40 V vs. RHE. For NO₃⁻RR, nearly 100% FE and an NH₃ yield of 8.82 mg h⁻¹ cm⁻² are obtained at −0.40 V vs. RHE. In a paired HMFOR//NO₃⁻RR electrolyzer, the NiO-NiCoP catalyst demonstrates superior current density, product selectivity, and long-term stability compared to conventional oxygen evolution reaction//hydrogen evolution reaction (OER// HER) systems. At 1.60 V, the HMFOR//NO₃⁻RR system achieved a maximum HMF conversion of 95.84%, an FDCA yield of 94.83%, and a FE of 89.53%, while at 1.90 V, it reached a maximum NH₃ yield of 32.50 mg h⁻¹ cm⁻² with an FE of 94.63%. This study underscores the catalytic advantages of heterogeneous interface engineering and provides a viable strategy for integrated biomass valorization and nitrogen-cycle remediation.

Anchoring a molecular metal complex on a solid support is becoming the most fascinating field of catalysis, as it bridges homogeneous and heterogeneous catalysis. However, owing to the spatial confinement of surface chemistry in supported catalysts, they display an inevitable loss of activity and selectivity compared to the homogeneous counterparts. Here, we propose a strategy to construct swellable supported catalysts where active metal centers are located on a swellable support for enhanced performance, where the occurrence of spontaneous swelling in the reaction medium facilitates active site exposure and reactant diffusion. The key to the strategy involves simultaneous immobilization of Al-porphyrins and quaternary ammonium salts on swellable Merrifield resin, forming swellable bifunctional supported catalysts (SBSCs), which were characterized in the swollen state by polarization microscopy and X-ray photoelectron spectroscopy. Surprisingly, SBSCs displayed a record-high activity of 2540 g g⁻¹ h⁻¹ for the cycloaddition of CO₂/propylene oxide even under low catalyst loading (1.28 × 10⁻³ mol%, based on Al), significantly outperforming the non-swellable counterpart (~0 g g⁻¹ h⁻¹). Moreover, because of the heterogeneous attribute, the repeatable synthesis of colorless cyclic carbonate was realized for over 6 cycles without significant loss of activity. An in-depth understanding of reaction kinetics and mechanisms in SBSCs can be rationally analyzed owing to the high accessibility of active sites. This swellable-supported catalyst strategy is expected to pave the way for the design of next-generation heterogeneous catalysts.

Enantioselective C-H functionalization has emerged as an efficient and transformative tool for constructing complex chiral molecules with exceptional step- and atom-economy. While this field was historically dominated by 4d and 5d transition metal catalysts, recent attention has shifted toward cobalt—an earth-abundant, cost-effective 3d transition metal with unique reactivity. Over the past few years, remarkable progress has been achieved in cobalt-catalyzed enantioselective C-H functionalization, primarily through three catalytic systems: (1) low-valent cobalt(I) catalysis, (2) cyclopentadienyl cobalt(III) catalysis, and (3) in situ generated cobalt(III) catalysis. This review provides a comprehensive survey of all reported asymmetric cobalt-catalyzed C-H activations proceeding through inner-sphere mechanisms, providing a systematic analysis of synthetic methodologies, reactivity patterns, origins of stereocontrol, mechanistic insights, and future opportunities.

The low phase-transition temperatures (T_pts) of structurally defined small molecules impose fundamental limitations on thermal stability in all-small-molecule (all-SM) systems. To overcome this, we designed and synthesized a dimeric donor, DM-2Cl, interconnected by a benzo[1,2-b:4,5-b′]dithiophene central unit side chain, and combined it with the giant molecule acceptor, BDY-β, to construct a conceptual all-giant-molecule (all-GM) system with enhanced solid-state T_pt. The DM-2Cl:BDY-β system suppressed morphology evolution under continuous thermal-annealing and demonstrated superior stability relative to the BDT-1S1Cl:Y6 reference. Crucially, optimized blend morphology and improved charge transport/extraction properties enabled the binary all-GM system to achieve a 15.56% PCE, which increased to 16.24% upon incorporating giant-molecule acceptor Se-giant-2F. This work paves the way to design dimeric donors, introducing new all-giant-molecule systems with high device efficiency and excellent thermal stability.

Palladium (Pd) has exceptional H₂ adsorption capacity and has been used as an adsorptive filler in mixed matrix membranes (MMMs) to enhance H₂ separation performance. However, a high Pd loading (20 wt%–60 wt%) is impractical due to cost. In this study, highly dispersed Pd nanoclusters are confined within the channels of mesoporous silica nanoparticles (MSNs), largely improving Pd atom utilization for facilitating H₂ transport while greatly reducing Pd loading content. MMMs prepared by mixing Pd@MSN with polybenzimidazole matrix, corresponding to a very low Pd loading of 0.6 wt%–3.0 wt%, exhibit much improved H₂/CO₂ separation performance. Specifically, an MMM containing only 2.5 wt% Pd shows mixed-gas separation performance of 302.6 barrer of H₂ permeability and 16.3 of H₂/CO₂ selectivity at 120 °C, largely surpassing the latest 150 °C upper bound. Our work demonstrates the enormous potential for applying Pd-based MMMs in gas separation by reducing noble metal loading by nearly two orders of magnitude.

Conventional gel polymer electrolytes based on polymers such as poly(ethylene oxide) face inherent limitations in enhancing ionic conductivity and electrochemical stability. Introducing diverse functional groups into the polymer framework enables the precise modulation of its physicochemical properties, thereby influencing the performance of lithium metal batteries. Herein, an in situ dual-crosslinked gel polymer electrolyte based on polyester and polyamide is proposed. This design enables synergistic cation-anion regulation, facilitating continuous Li⁺ transport by abundant ester groups while anchoring the anions by N–H groups. The resulting gel polymer electrolyte exhibits a high ionic conductivity of 0.58 mS cm⁻¹ and an elevated Li⁺ transference number of 0.6. The assembled Li∥LiNi_0.8Mn_0.1Co_0.1O₂ coin cells achieve 400 cycles at 0.5 C and 300 cycles at 1 C. Furthermore, a 4-layer stacked Li∥LiNi_0.8Mn_0.1Co_0.1O₂ (active material mass loading of 26.7 mg cm⁻²) pouch cell in lean electrolyte conditions (1.7 g Ah⁻¹) is assembled and sustains 45 cycles without obvious decay. This study provides a strategy of synergistic cation-anion regulation in gel polymer electrolytes, offering insights for stable lithium metal batteries.