Interfacial Electron Modulation in a Mixed-Valence Cu(II)/Cu(III) Energetic MOF for Dual-Functional Catalysis: Enhanced Ammonium Perchlorate Thermolysis and Efficient CO2 Electroreduction

The development of multifunctional catalytic platforms that reconcile high energy density with environmental sustainability presents a significant challenge in materials science. Herein, we report a rare mixed-valence Cu(II)/Cu(III) energetic metal–organic framework (EMOF), {[Cu(II)Cu(III)2(HBTT)(BTT)Cl3(H2O)4]·H2O}n (denoted as CuBTT), as a dual-functional catalyst for both ammonium perchlorate (AP) thermolysis and electrochemical CO2 reduction (ECO2R). CuBTT exhibits remarkable structural robustness, thermal safety, and low sensitivity, enabling practical deployment. The dual catalytic prowess originates from its special mixed-valence Cu(II)/Cu(III) interfaces, which enable efficient interfacial electron modulation and stepwise electron transfer tailored to the specific demands of each reaction. This unique mechanism, unequivocally validated by X-ray photoelectron spectroscopy (XPS) analysis, demonstrates distinct redox behaviors: in AP thermolysis, CuBTT acts as a multielectron redox shuttle, dramatically lowering the high-temperature decomposition (HTD) peak by 127.2 °C and boosting the total heat release by 81.6%; in ECO2R, its dynamic valence cycling facilitates C–C coupling, achieving high Faradaic efficiencies for CO (42.4%), C2H5OH (23.4%), and CH4 (3.3%) at −0.6 V vs RHE. CuBTT also demonstrates excellent stability (>60 h) and rapid kinetics (Tafel slope: 69 mV dec–1). This work highlights valence engineering via interfacial electron modulation as a powerful strategy for designing multifunctional materials and positioning CuBTT as a promising platform for sustainable energy and environmental applications.