High mobility and photocatalytic properties of NaXO2(X = Co, Rh, Ir)

The transition metal oxide NaCoO2 and NaRhO2 is proved to be good thermoelectric materials although neither experimental nor theoretical investigation on homologous derivatives NaIrO2 is available in the literature. However, the photocatalytic properties are not explored up to date. In the present paper, the feasibility of NaXO2 photocatalytic hydrogen production from water splitting with the irradiation of the visible light is examined through band structure, the density of state, optical absorption and mobility based on the first principles calculations. The results show that the band edges of NaXO2 match to the conditions of the redox potentials of water splitting reaction. The high mobility of the electron and hole as well as the obvious difference between the mobilities of the hole and electron are identified. The strong optical absorption in the visible light range is also observed. All the obtained results suggest that NaXO2 is a promising candidate for the photocatalytic water splitting to produce hydrogen with the irradiation of the visible light.