A facile and green process was developed for the synthesis of pyrochlore H4 Nb2 O7 hollow microspheres by using hydrothermal treatment of Sn2 Nb2 O7 hollow microspheres in aqueous 2 m HCl at 100-180 °C. The facile transformation of Sn2 Nb2 O7 into H4 Nb2 O7 is facilitated by the intrinsic ion-exchange capability of Sn2 Nb2 O7 . The resulting H4 Nb2 O7 hollow microspheres (diameter 1-2 μm, shell thickness 100-200 nm) displayed excellent photocatalytic performance for overall water splitting under UV irradiation, affording H2 and O2 evolution rates of 240 and 116 μmol h-1 g-1 , respectively. Following decoration with 0.5 wt % Pt, the H4 Nb2 O7 hollow microspheres demonstrated remarkably high H2 and O2 evolution rates of 1240 and 600 μmol h-1 g-1 , respectively. To our knowledge, this work is the first reported study examining the photocatalytic performance of H4 Nb2 O7 for water splitting. The hydrothermal synthesis method described here is also applicable to the synthesis of pyrochlore H4 Ta2 O7 from Sn2 Ta2 O7 , highlighting the versatility of the approach.
Keywords: hydrothermal synthesis; ion exchange; photocatalysis; water splitting.
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