Systematic Material Study Reveals TiNb₂O₇ as a Model Wide‐Bandgap Photoanode Material for Solar Water Splitting

Abstract

This work reveals that photoanodes based on TiNb 2 O 7 (TNO)p owder show remarkablew ater-oxidation properties including nearly ideal charge-transfer and chargeinjectione fficiencies. Furthermore, using as implified photoanode construction and carefully surveying the structural and morphological characteristics of oriented and polycrystalline thin films and powder-based samples revealedt hat the water-splitting kinetics of TNO is negligibly effected by surface morphology; instead, internal grain boundaries likely play ad riving role. The current powder-based TNO photoanodes exhibit ideal water-oxidation kinetics and oxidize water at minimal applied biases under illumination; consequently, TNO exhibits an early onset photocurrent voltage (0.4 Vv s. RHE) that rivals that of other state-of-the-art photoanode materials. Figure 10. Linear voltage sweep comparison of a) TNO-powder-based photoanodes and 400 nm polycrystalline TNO film and b) thick (400 nm) and thin (100 nm) TNO film photoanodes (the 100 nm TNO photoanode is shownwith chopped-lightillumination for easy dark-current comparison).

Heteroepitaxial Hexagonal (00.1) CuFeO2 Thin Film Grown on Cubic (001) SrTiO3 Substrate Through Translational and Rotational Domain Matching

“…Particularly, important is for example, the role of the crystallographic surface and bulk orientation which can affect the charge transfer at the solid/liquid interface and the external quantum efficiency. [17][18][19] Crystalline, epitaxial thin films, of CuFeO 2 grown on conducting substrates, is an alternative device design that would allow us to gain complementary insights into the PEC properties of this promising material.…”