Stabilizing Ni²⁺ in Hollow Nano MOF/Polymetallic Phosphides Composites for Enhanced Electrochemical Performance in 3D‐Printed Micro‐Supercapacitors

Abstract Polymetallic phosphides exhibit favorable conductivities. A reasonable design of nano‐metal–organic frame (MOF) composite morphologies and in situ introduction of polymetallic phosphides into the framework can effectively improve electrolyte penetration and rapid electron transfer. To address existing challenges, Ni, with a strong coordination ability with N, is introduced to partially replace Co in nano‐Co–MOF composite. The hollow nanostructure is stabilized through CoNi bimetallic coordination and low‐temperature controllable polymetallic phosphide generation rate. The Ni, Co, and P atoms, generated during reduction, effectively enhance electron transfer rate within the framework. X‐ray absorption fine structure (XAFS) characterization results further confirm the existence of Ni–N, Ni–Ni, and Co–Co structures in the nanocomposite. The changes in each component during the charge–discharge process of the electrochemical reactions are investigated using in situ X‐ray diffraction (XRD). Theoretical calculations further confirm that P can effectively improve conductivity. VZNPGC//MXene MSCs, constructed with active materials derived from the hollow nano MOF composites synthesized through the Ni²⁺ stabilization strategy, demonstrate a specific capacitance of 1184 mF cm⁻², along with an energy density of 236.75 µWh cm⁻² (power density of 0.14 mW cm⁻²). This approach introduces a new direction for the synthesis of highly conductive nano‐MOF composites.