Rushuo Li,Tao Ban,Danfeng Zhao,Fajie Hu,Jing Lin,Xiubing Huang,Zhiping Tao,Ge Wang
Defect engineering improves the catalytic performance of metal-organic frameworks (MOFs) loaded metal nanoparticles (MNPs@MOFs), but there is still a challenge in defining the structure-activity relationships. Herein, the content of linker-missing defects in UiO-66(Ce) was systematically regulated via formic acid as the modulators, and defective UiO-66(Ce) loaded Ni nanoparticles (NPs) were constructed for dicyclopentadiene (DCPD) hydrogenation. The fine regulation of defect engineering and reduction conditions affected the structure properties of UiO-66(Ce) and the electronic metal-support interaction between MOFs and Ni NPs, thereby optimizing the microenvironment and electronic state of Ni NPs. The optimized U(Ce)-40eq with suitable defects, small size and structure stability effectively promoted the production of highly dispersed abundant electron-deficient Ni 0 active sites, enhancing the adsorption and activation of H 2 and C=C bonds, especially accelerating the rate-determining step. Therefore, U(Ce)-40eq loaded 5 wt% Ni NPs achieved DCPD saturated hydrogenation to tetrahydrodicyclopentadiene (70 °C, 2 MPa, 90 min), superior to most high-loading Ni-based catalysts. This work reveals the synergistic mechanism of MOFs defect engineering and electronic structure of Ni NPs, providing effective guidance for the precise preparation of highly efficient and stable MNPs@MOFs heterogeneous catalysts.
To address the high cost and limited electrochemical endurance of Pt-based electrocatalysts, the appropriate introduction of transition metal-based compounds as supports to disperse and anchor Pt species offers a promising approach for improving catalytic efficiency. In this study, sub-1 nm Pt nanoclusters were uniformly confined on NiO supports with a hierarchical nanotube/nanosheet structure (Pt/NiO/NF) through a combination of spatial domain confinement and annealing. The resulting catalyst exhibited excellent electrocatalytic activity and stability for hydrogen evolution (HER) and urea oxidation reactions (UOR) under alkaline conditions. Structural characterization and density functional theory calculations demonstrated that sub-1 nm Pt nanoclusters were immobilized on the NiO supports by Pt–O–Ni bonds at the interface. The strong metal-support interaction induced massive charge redistribution around the heterointerface, leading to the formation of multiple active sites. The Pt/NiO/NF catalyst only required an overpotential of 12 and 136 mV to actuate current densities of 10 and 100 mA cm −2 for the HER, respectively, and maintained a voltage retention of 96% for 260 h of continuous operation at a current density of 500 mA cm −2 . Notably, in energy-efficient hydrogen production systems coupled with the HER and UOR, the catalyst required cell voltages of 1.37 and 1.53 V to drive current densities of 10 and 50 mA cm −2 , respectively—approximately 300 mV lower than conventional water electrolysis systems. This study presents a novel pathway for designing highly efficient and robust sub-nanometer metal cluster catalysts.
Jiaxu Liu,Jiaxin Chen,Xiaoyan Zhang,Daidi Fan,Yunpeng Bai
Enzyme catalysis is a promising way to produce chiral products in a green and sustainable way. However, the high cost of cofactors and their relatively low recycling efficiency hinder the widespread application of enzyme catalysis in industry. In contrast, cofactor regeneration and recycling in cells is highly efficient, mainly due to physical effects caused by the ordered spatial organization of enzymes in vivo . The construction of similar catalytic systems with high cofactor recycling in vitro remains challenging. Here, we present a facile method to generate dual enzyme condensates in vitro based on intrinsically disordered region-mediated liquid-liquid phase separation. Typically, a carbonyl reductase from Serratia marcescens ( Sm CR V4 ) and a glucose dehydrogenase from Bacillus megaterium ( Bm GDH) were co-localized in the condensates. This resulted in an up to 20-fold increase in cofactor recycling efficiency (substrate converted per cofactor per unit time), and a 3.4-fold increase in space-time yield compared to the free enzyme system. The reaction enhancement was shown to be highly correlated with the degree of condensation of the dual enzymes. Fluorescence confocal microscopy showed that the cofactor, nicotinamide adenine dinucleotide phosphate (NADPH), was enriched between neighboring enzymes during the reaction due to the proximity effect, facilitating its regeneration and recycling within the condensate. In a scaled-up synthesis, the consumption of NADPH was reduced 50-fold compared to industrial biocatalytic standards, while the condensate still maintained efficient product synthesis. Concentrating multiple enzymes in a nano- and micro-condensate to increase the reaction rate may provide a general and inexpensive method for improving cofactor-involved enzymatic reactions.
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