Development of an advanced porphyrin-based organic–inorganic nanohybrid for electrochemical hydrogen storage

The aim of this study was to design and construct an advanced nanohybrid to overcome the challenges of electrochemical hydrogen storage through the creation of a synergistic architecture. To achieve this goal, trans-dialdehyde porphyrin was successfully synthesized via a four-step pathway. Subsequently, TiO 2 and Ni nanoparticles were immobilized onto amine-functionalized multi-walled carbon nanotubes (MWCNT–NH 2 ) to provide catalytic sites and improve charge transfer. Finally, the synthesized porphyrin was covalently anchored to the amine groups of the nanotubes via imine (C=N) bond formation, acting as a molecular bridge to construct an integrated and stable framework, yielding the final nanohybrid (MWCNT–NH 2 /TiO 2 /Ni@Por). This hybrid, owing to the extended π–π conjugated structure and the presence of pyrrolic nitrogen atoms in porphyrin, provides reversible redox-active centers and accelerates charge transport. Structural and morphological characterizations confirmed the successful synthesis and integrity of the hybrid. Hydrogen storage evaluations demonstrated that MWCNT–NH 2 /TiO 2 /Ni@Por achieved an impressive desorption capacity of 7925 mAh g⁻ 1 (equivalent to 30.1 wt%) after 12 cycles. This represents an ~ 11.1-fold improvement compared with pristine nanotubes and a twofold enhancement compared with the porphyrin-free sample (MWCNT–NH 2 /TiO 2 /Ni), along with superior cycling stability. Such outstanding performance arises from the synergistic contributions of the components: CNTs provide a conductive 3D network, Ni acts as a catalyst for hydrogen dissociation and facilitates the spillover mechanism, TiO 2 enhances structural stability and physical storage sites, while porphyrin introduces additional redox-active centers, promotes electron transfer, and increases the density of active sites. This hybrid architecture offers an innovative strategy for the development of efficient hydrogen storage materials under near-ambient conditions.