Ab initio simulation of laser-induced water decomposition close to carbon nanotubes

First-principles simulations were used to investigate water (H2O) decomposition induced by a femtosecond laser with high flux similar to 1 x 10(20) photons/(sec cm(2)). One goal of our research is to find metamaterials that locally enhance the laser field to reduce the threshold laser intensity required to decompose H2O molecules. In this work, small-diameter (6.3 angstrom) single-walled carbon nanotubes were found to reduce the threshold power by 90% compared with the power required to decompose H2O in the gas phase. The present results suggest a strategy for the design of materials with high energy efficiency for H2O decomposition based on polarizability and morphology (curvature) to enhance the local field. We demonstrate that carbon nanotubes enhance the local field resulting in a power enhancement of approximately eight times.