Integration of Atomically Dispersed Cu–N₄ Sites with C₃N₄ for Enhanced Photo-Fenton Degradation over a Nonradical Mechanism

Photo-Fenton degradation as a promising strategy for antibiotic wastewater treatment attracted extensive attention, while the unsatisfactory catalytic performance vitally limits its industrial application. Herein, we demonstrate that confining atomically dispersed Cu into C3N4 (Cu–C3N4) enables fast H2O2 activation and efficient separation of photogenerated electron–hole pairs, resulting in a dramatic improvement of the degradation efficiency of the Photo-Fenton reaction. Photo-Fenton degradation of ciprofloxacin (CIP) was close to 99% within 30 min over optimized Cu–C3N4, corresponding to a pseudo-first-order rate constant of ∼0.0978 min–1, almost 4.5 times higher than pure C3N4 counterpart. The electron paramagnetic resonance, quenching experiments, and X-ray absorption fine structure results reveal that the superior Photo-Fenton catalytic performance is attributed to a nonradical reaction pathway, where the H2O2 is activated by the formation of the OCu–N4O intermediate. The advanced catalyst as well as the refreshing H2O2 activation mechanism are of profound significance for the materials design in the wastewater treatment field

Hollow Metal–Organic Framework Nanospheres via Emulsion-Based Interfacial Synthesis and Their Application in Size-Selective Catalysis

Metal–organic frameworks (MOFs) represent an emerging class of crystalline materials with well-defined pore structures and hold great potentials in a wide range of important applications. The functionality of MOFs can be further extended by integration with other functional materials, e.g., encapsulating metal nanoparticles, to form hybrid materials with novel properties. In spite of various synthetic approaches that have been developed recently, a facile method to prepare hierarchical hollow MOF nanostructures still remains a challenge. Here we describe a facile emulsion-based interfacial reaction method for the large-scale synthesis of hollow zeolitic imidazolate framework 8 (ZIF-8) nanospheres with controllable shell thickness. We further demonstrate that functional metal nanoparticles such as Pd nanocubes can be encapsulated during the emulsification process and used for heterogeneous catalysis. The inherently porous structure of ZIF-8 shells enables encapsulated catalysts to show size-selective hydrogenation reactions

Atomically Dispersed Dual Metal Sites Boost the Efficiency of Olefins Epoxidation in Tandem with CO₂ Cycloaddition

Tandem catalysis provides an economical and energy-efficient process for the production of fine chemicals. In this work, we demonstrate that a rationally synthesized carbon-based catalyst with atomically dispersed dual Fe–Al sites (ADD-Fe-Al) achieves superior catalytic activity for the one-pot oxidative carboxylation of olefins (conversion ∼97%, selectivity ∼91%), where the yield of target product over ADD-Fe-Al is at least 62% higher than that of monometallic counterparts. The kinetic results reveal that the excellent catalytic performance arises from the synergistic effect between Fe (oxidation site) and Al sites (cycloaddition site), where the efficient CO2 cycloaddition with epoxides in the presence of Al sites (3.91 wt %) positively shifts the oxidation equilibrium to olefin epoxidation over Fe sites (0.89 wt %). This work not only offers an advanced catalyst for oxidative carboxylation of olefins but also opens up an avenue for the rational design of multifunctional catalysts for tandem catalytic reactions in the future