Catalytically ultrathin titania coating to enhance energy storage and release of aluminum hydride via atomic layer deposition

Aluminum hydride (AlH3) has attracted much attention owing to its extraordinary hydrogen storage performance, yet AlH3 is prone to hydrogen release reaction during long-term storage, leading to a decrease in energy and hindering its practical application. Herein, AlH3 particles are stabilized by catalytically ultrathin TiO2 coating via atomic layer deposition (ALD), the hydrogen content of which is controllable and reduces only 0.0026 wt% per ALD cycle of TiO2 coating. 30 cycles of TiO2 (2.4 nm) coated AlH3 exhibits a peak decomposition temperature of 203.42 degrees C and decomposition activation energy of 112.21 kJ/mol, which are 7.83 degrees C and 22.64 kJ/mol higher than those of bare AlH3. The hydrogen content loss of TiO2 coated AlH3 under hydrothermal aging conditions is much lower than that of bare AlH3 due to the passivation of defects on native Al2O3 by forming inert Al2O3 and catalytic TiO2 double-shell coating structure. TiO2 coated AlH3 exhibits enhanced combustion performance with stronger flame radiation intensity compared to bare AlH3. The density functional theory calculations indicate that the contact between AlH3 and TiO2 can weaken the strength of Al-H ion bond and promote the release of hydrogen. Our work offers a feasible method for simultaneously improving the stability and energy release of AlH3.