Aluminum is emerging as an alternative plasmonic material to traditional novel material like Au and has shown great potentials in plasmonic photocatalysis. Here I have performed comprehensive theoretical investigations on Al nanoparticles with various shapes which have been chemically synthesized by collaborators. We find that nanoparticles with sharp corners such as Al nanocubes and Al octopods possess much larger localized electric field enhancement around the corners than traditional spherical-like nanocrystals. As result, substantially increased near-field coupling of Al nanocube with metal substrate can provide more tunability of plasmonic resonant wavelength and further field enhancements. We demonstrate theoretically and experimentally that Al nanocubes can significantly improve the photocatalytic reactivity of poor plasmonic Pd deposited on nanocube corners. Pristine Al nanocrystals also show morphology-dependent photocatalytic reactivity in H2 dissociation experiments. I develop new Al hot-carriers (HC) generation model to explain the experimental results. The theory shows HC generation rates of Al octopods is 5 times higher than Al spherical-like nanocrystal and 2 times higher than Al nanocubes.