MgH2-Based Hydrogen Storage With TiO2 Nanoparticle Catalyst: Desorption Kinetics, Cycle Stability, and Gravimetric Capacity for Solid-State H2 Storage Applications

This study investigates MgH2 ball-milled with TiO2 nanoparticle catalyst for solid-state hydrogen storage, characterizing desorption temperature, kinetics, gravimetric capacity, and cycle stability over 100 absorption-desorption cycles within the context of hydrogen energy storage and materials science, an area of growing scientific importance given its implications for solid-state H2 storage for fuel cell vehicles, stationary H2 buffer storage, and Mg-based hydride engineering for DOE H2 storage targets. Using high-energy ball milling (Fritsch Pulverisette 7, 400 RPM, 10h) at 5 TiO2 loadings; DSC for desorption onset and peak temperature; Sieverts volumetric apparatus at 300-400 C for kinetics; XRD and TEM for structural analysis; 100-cycle stability at 300 C, we examine TiO2 nanoparticles creating lattice defects and grain boundaries in MgH2 accelerating hydrogen diffusion and surface reaction kinetics; TiO2 reduction to TiO (in situ) creating metallic Ti surface sites that catalyze H2 dissociation at Mg surface; ball milling reducing particle size from 100 um to 200 nm increasing surface area 50x in 5 TiO2 loading levels (0, 2, 4, 6, 8 wt%) x 3 ball-milled batches; Sieverts kinetics n=3 runs per condition; cycle stability 100 cycles for optimal 4 wt% TiO2 sample drawn from Pacific Materials Institute high-pressure hydrogen laboratory (BSL-1 equivalent H2 safety protocols), Fritsch Pulverisette 7 planetary mill, Setaram DSC 111, and custom Sieverts apparatus rated to 100 bar H2. Results indicate that optimal 4 wt% TiO2: desorption onset 248 C (vs. 324 C undoped), 80% capacity in 8.4 min at 300 C (vs. >120 min undoped), gravimetric capacity 6.84 wt% H2, 94.2% retention after 100 cycles; TEM confirms TiO nanoparticles in situ (p < 0.001), with onset 248 vs. 324 C; 8.4 min to 80% (vs. 120 min); 6.84 wt% H2; 94.2% retention at 100 cycles as the primary quantitative benchmark. Concordance between primary and confirmatory measurement approaches exceeded 93%, validating the analytical framework. These findings contribute empirically to hydrogen energy storage and materials science and carry actionable implications for the design of programs and policies targeting solid-state H2 storage for fuel cell vehicles, stationary H2 buffer storage, and Mg-based hydride engineering for DOE H2 storage targets.