Interfacial Electron Modulation in a Mixed-Valence Cu(II)/Cu(III) Energetic MOF for Dual-Functional Catalysis: Enhanced Ammonium Perchlorate Thermolysis and Efficient CO ₂ 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)Cl 3 (H 2 O) 4 ]·H 2 O} n (denoted as CuBTT), as a dual-functional catalyst for both ammonium perchlorate (AP) thermolysis and electrochemical CO 2 reduction (ECO 2 R). 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 ECO 2 R, its dynamic valence cycling facilitates C–C coupling, achieving high Faradaic efficiencies for CO (42.4%), C 2 H 5 OH (23.4%), and CH 4 (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.