Synergic effects in Bi12MnO20/Nickel aluminum oxide hydrate nanocomposites as advanced electrode materials for electrochemical hydrogen storage

• Nanocomposites of Bi 12 MnO 20 and Ni 5 Al 4 O 11 ·18H 2 O were successfully synthesized via sol–gel and ultrasonic-assisted methods. • Bi 12 MnO 20 provides redox-active porous nanostructures, while NAO contributes a 2D lamellar framework with abundant adsorption sites. • Synergistic oxide–hydroxide interactions enhance hydrogen uptake and diffusion pathways. • Bi 12 MnO 20 /Ni 5 Al 4 O 11 ·18H 2 O nanocomposites exhibit a hydrogen storage capacity of 1673 mAhg -1 after 15 cycles, outperforming pristine Bi 12 MnO 20 (660 mAhg -1 ) and Ni 5 Al 4 O 11 ·18H 2 O (342 mAhg -1 ). • Cooperative hydrogen storage mechanisms include spillover, redox activity, and physisorption. The design of advanced materials for efficient hydrogen storage is crucial for the realization of sustainable energy technologies. In this work, nanocomposites based on bismuth manganese oxide (Bi 12 MnO 20 (BM)) and nickel aluminum oxide hydrate (Ni 5 Al 4 O 11 .18H 2 O (NAO)) were synthesized and investigated as potential hydrogen storage materials. The sol-gel synthesized porous nanostructured Bi 12 MnO 20 phase, known for its redox activity, was coupled with ultrasonic-assisted synthesized nickel aluminum oxide hydrate nanoparticles (particle size about 10 nm), which provide a two-dimensional lamellar structure with tunable surface chemistry and abundant adsorption sites. The resulting BMO/NAO nanocomposites exhibited enhanced hydrogen uptake compared to their pristine counterparts, owing to synergistic effects between the bismuth manganese oxide and the layered hydroxide host. Structural, morphological, and surface analyses confirmed the intimate interface interaction and improved textural properties, which facilitated hydrogen adsorption and diffusion pathways. Electrochemical measurements in 2.0 M KOH electrolyte by applying current of 1mA further demonstrated superior storage capacity, of the composites, highlighting their potential as promising candidates for solid-state hydrogen storage. Electrochemical hydrogen storage for BM/NAO nanocomposites shows 1673 mAhg -1 capacity after 15 cycles, while pristine BM and NAO present 660 and 342 mAhg -1 capacity after 15 cycles. This study provides new insights into combining mixed-metal oxides with layered double hydroxides to design efficient hydrogen storage systems because of cooperation of three mechanism of spillover, redox and physisorption.