Hydrogen-assisted one-pot synthesis of ultrasmall TiC nanoparticles enhancing hydrogen cycling of sodium alanate

Sodium alanate, NaAlH4, has great potential as a hydrogen carrier but suffers from sluggish kinetics and poor reversibility caused by high energy barriers. Transition metal-based catalysts are especially effective in reducing kinetic energy barriers for hydrogen cycling of NaAlH4. Herein, we demonstrate a facile fabrication of TiC nanoparticles with 2–4 nm in size supported on carbon ([email protected]). The resultant product consists of approximately 49.2 wt% of TiC and 50.8 wt% of C, and exhibits high and stable catalytic activity for hydrogen storage process of NaAlH4. The 7 wt% [email protected] NaAlH4 releases 5 wt% H2 starting from 65 °C and reabsorbs all released hydrogen at 30 °C under 100 bar H2, outperforming NaAlH4 modified by commercial TiC nanoparticles (∼50 nm in size). The enhancement is related to the ultrasmall size and high reactive activity of as-synthesized TiC nanoparticles. Moreover, the weak electronegativity of C prevents the formation of Na-based by-products, which are often observed in oxide and halide-containing systems. This finding sheds light on how to design and synthesize high-performance catalytic additives for light-metal hydride-based hydrogen storage materials.