Electroactive metal-organic frameworks enabling unidirectional electrochemical capacitors and logic gates (MOF-CAPode)

From concept to realization, the integration of porous redox-active metal-organic frameworks (MOFs) into asymmetric electrochemical capacitors for the assembly of electrochemical capacitor-diodes (CAPodes) is reported. CAPodes are innovative electrochemical capacitor analogues of diodes designed for unidirectional charge storage and logic gate applications. The novel devices deliberately utilize two distinct electroactive metal-organic frameworks with characteristic redox potentials acting as positively or negatively polarizable electrode materials, respectively. The first proof-of-concept devices presented here make use of the Chichibabin-like diradicaloid formation upon oxidation of the N,N,N',N'-benzidinetetrabenzoate linker in DUT-65/66 and N,N,N',N'-(1,4-phenylenebis-(azanetriyl))-tetrabenzoate in DUT-232/233 at high oxidation potentials as a positively polarizable electrode material paired with the highly reversible two-step reduction in [Zn(ndi)]n (ndi = 1,4-bis[(3,5-dimethyl)-pyrazol-4-yl]naphthalene-diimide). The novel porous MOF-CAPode achieves a remarkable figure of merit with rectification ratios (RR) up to RRI = 23 and RRII = 94 % at 10 mV s-1. The new MOF-based CAPodes operate efficiently in “AND” and “OR” logic gates, demonstrating logic operation under varying input voltages up to 3.0 V and frequencies of 40 mHz.