Photoluminescence and hydrogen storage properties of gallium nitride hexagonal micro-bricks

A novel morphology of gallium nitride (GaN) hexagonal micro-bricks has been synthesized at 1250 °C by chemical vapor deposition (CVD) method. Photoluminescence (PL) and hydrogen storage capabilities of hexagonal micro-bricks have been investigated. The PL spectrum exhibits strong near-band-edge emission at 369 nm (3.36 eV). Defect related broad yellow band emission at 556 nm (2.23 eV) has also been observed, which plays significant role in the hydrogen absorption. Maximum hydrogen storage capacity of 1.68 wt.% has been achieved under the pressure of 5 MPa and at 373 K. During desorption process under ambient pressure, about 76% releasing of the stored hydrogen has been noted. Highly reversible absorption/desorption results exhibited by GaN hexagonal micro-bricks are encouraging and promising for hydrogen storage.

► GaN hexagonal micro-bricks have been synthesized by CVD method at 1250 °C.
► The PL spectrum exhibited strong near-band-edge emission at 369 nm (3.36 eV).
► Defects related broad yellow band emission at 556 nm has also been observed.
► Hydrogen storage capacity of 1.68 wt.% has been achieved under the pressure of 5 MPa.
► During the desorption process, about 76% of absorbed hydrogen has been released.