Amorphous Ta2OxNy-enwrapped TiO2 rutile nanorods for enhanced solar photoelectrochemical water splitting.

Graphical abstract A type-II core-shell nanostructure based on rutile TiO 2 nanorods was designed to enhance the PEC overall water splitting under solar light irradiation. The internal electric field formed at interface of Ta 2 O x N y /TiO 2 nanorods provides a huge driving force to efficiently separate charge carriers and reduce the exciton binding energy, achieving a solar-to-chemical energy conversion efficiency of ca. 1.49% at 1.23 V vs RHE. Highlights • 12 fold-enhanced solar water splitting was achieved over type-II core-shell nanostructured TiO 2 rutile photoanodes. • The formation of the Ta 2 O x N y layer extends the photo-response of TiO 2 to visible light region. • Constructing internal electric field to reduce the exciton binding energy and enhance the PEC overall water splitting. • The IPCE was increased from 2.2% to 22.6% in a two-electrode system under 390 nm light irradiation. • A solar-to-chemical energy conversion efficiency of ca. 1.49% was achieved at 1.23 V vs RHE. Abstract This work demonstrated the 12 fold-enhanced solar water splitting over the type-II core-shell nanostructured TiO 2 rutile photoanodes by orienting the charge flow and accelerating the hole transport to water-oxidation sites. Such nanoheterostructured photoanodes were designed rationally and prepared by a facile strategy to enwrapping an amorphous Ta 2 O x N y layer on surface of TiO 2 nanorods grown on the FTO glass substrates, consequently the incident photon-to-current conversion efficiency was increased from 2.2% to 22.6% in a two-electrode system under 390 nm light irradiation. The activity results showed that under AM 1.5 G illumination, the photocurrent output of TiO 2 @Ta 2 O x N y photoanodes reached a stable density of 1.32 mA cm−2 at 1.23 V vs RHE, and which is 12 times and ca. 4.3 times than that of the pristine TiO 2 and TiO 2 @Ta 2 O 5 counterparts, respectively. Correspondingly, the oxygen evolution rate was improved from 20.3 to 112.7 mmol m−2 h−1. A solar-to-chemical energy conversion efficiency of ca. 1.49% was achieved at 1.23 V vs RHE. [ABSTRACT FROM AUTHOR]