Exceptional Hydrogen Storage Performance of Ti-Decorated C3B2 Quantum Dot: A Comprehensive First-Principles Study

The development of lightweight materials with high and reversible hydrogen storage capacity remains a key materials design challenge. Here, we investigate pristine and Ti-decorated C3B2 quantum dots using DFT, DLPNO-CCSD(T), and statistical thermodynamics. Pristine C3B2 strongly chemisorbs H2 (Eads = −0.93 eV), while Ti decoration moderates the interaction to a reversible regime (Eads = −0.39 eV) through a balanced Kubas-type mechanism. Structural analysis shows that the Ti center becomes saturated at approximately five H2 molecules via Kubas-type coordination, while additional hydrogen molecules are stabilized in the vicinity of the Ti–C3B2 framework through cooperative interactions. Sequential adsorption shows that up to 20 H2 molecules can be stored per Ti–C3B2 unit. Thermodynamic and kinetic analyses reveal moderate desorption temperatures (≈322–366 K) and ultrafast release times, ensuring efficient cycling. Under realistic operating conditions (30/3 atm; 298/373 K), Ti–C3B2 achieves a reversible capacity of 20.10 wt%, surpassing DOE targets. These results highlight Ti-decorated C3B2 quantum dots as a promising, design-tunable platform for next-generation solid-state hydrogen storage.