Visible-light-responsive g-C3N4/NaNbO3 nanowires photocatalysts were fabricated by introducing polymeric g-C3N4 on NaNbO3 nanowires. The microscopic mechanisms of interface interaction, charge transfer and separation, as well as the influence on the photocatalytic activity of g-C3N4/NaNbO3 composite were systematic investigated. The high-resolution transmission electron microscopy (HR-TEM) revealed that an intimate interface between C3N4 and NaNbO3 nanowires formed in the g-C3N4/NaNbO3 heterojunctions. The photocatalytic performance of photocatalysts was evaluated for CO2 reduction under visible-light illumination. Significantly, the activity of g-C3N4/NaNbO3 composite photocatalyst for photoreduction of CO2 was higher than that of either single-phase g-C3N4 or NaNbO3. Such a remarkable enhancement of photocatalytic activity was mainly ascribed to the improved separation and transfer of photogenerated electron–hole pairs at the intimate interface of g-C3N4/NaNbO3 heterojunctions, which originated from the well-aligned overlapping band structures of C3N4 and NaNbO3.

NaNbO 3 had been successfully developed as a new photocatalyst for CO 2 reduction. The catalysts were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and ultraviolet-visible spectroscopy (UV-Vis). The DFT calculations revealed that the top of VB consisted of the hybridized O 2p orbital, while the bottom of CB was constructed by Nb 3d orbital, respectively. In addition, the photocatalytic activities of the NaNbO 3 samples for reduction of CO 2 into methanol under UV light irradiation were investigated systematically. Compared with the bulk NaNbO 3 prepared by a solid state reaction method, the present NaNbO 3 nanowires exhibited a much higher photocatalytic activity for CH 4 production. This is the first example that CO 2 conversion into CH 4 proceeded on the semiconductor nanowire photocatalyst.