Ultrathin HNb3O8 nanosheet: an efficient photocatalyst for the hydrogen production

A ultrathin HNb3O8 nanosheet was successfully prepared through a top-down approach. Atomic force microscopy (AFM) further confirmed that the thickness of the nanosheet was about 1.30 nm. The structure and the surface chemical state of the HNb3O8 nanosheet were well-characterized using X-ray diffraction (XRD), high-resolution transmission electron microscopy (HRTEM), X-ray absorption fine structure (XAFS), Raman and X-ray photoelectron spectroscopy (XPS). The photocatalytic hydrogen evolution activity of the HNb3O8 nanosheet was about 4 times higher than that of layered HNb3O8 under ultraviolet irradiation. The enhanced activity was ascribed to the unique two-dimensional structure with a molecular thickness that leads to the effective separation of the photogenerated carriers. Moreover, a considerable variation in the photocatalytic hydrogen evolution activity of the HNb3O8 nanosheet was observed when suitable metals were loaded on the nanosheet via in situ photodeposition.