Efficient Charge Separation of In-Situ Nb-Doped TiO2 Nanowires for Photoelectrochemical Water-splitting

One-dimensional TiO2 nanowire is the top-performing semiconductor among photoanodes for photoelectrochemical water splitting, but still limited to a fraction of the theoretically photocurrent because of modest charge transport and low charge separation properties. Here, we demonstrate high-crystallized nanowires of Nb-doped rutile TiO2 for significantly increasing electron carrier density through a convenient method. The optimized Nb-doped TiO2 nanowires (0.5mol% in the Nb/Ti ratio) yield a high value of charge separation efficiency (eta(sep)) of 97.39% at 1.23 V-RHE, which is about 3 times as much as that of pristine sample (33.61% at 1.23 V-RHE). Moreover, the photoanode of Nb-doped TiO2 nanowires can achieve high charge transfer efficiency (eta(trans)) (91.07% at 1.23 V-RHE) without any oxygen evolution reaction catalysts. These results indicate that through appropriate amount of Nb doping can move the performance of TiO2 nanowires to their theoretical potential.