Hierarchical TiO₂ Photoanodes with Spatial Charge Separation for Efficient Oxygen Evolution Reaction

Abstract

Charge separation and transfer are crucial to determine photoelectrochemical (PEC) water splitting performance. Herein, a hierarchical bottom‐up approach for fabricating TiO2 nanorod arrays with an Au nanolayer and Sn3O4 cocatalysts is demonstrated. The hierarchical Sn3O4/TiO2/Au photoanode exhibits a significantly enhanced photocurrent density of 2.5 mA cm−2 at 1.23 VRHE under AM 1.5G irradiation, which is about 5 times higher than that of pristine TiO2 (0.5 mA cm−2 at 1.23 VRHE). The significantly enhanced PEC properties are attributed to the spatial charge separation among Au nanolayer and Sn3O4 cocatalysts. More specifically, the bottom Au nanolayer can accelerate the electron transfer from TiO2 to fluorine doped tin dioxide (FTO) substrate, and the surface Sn3O4 nanoflakes can effectively capture holes and provide abundant active sites for oxygen‐evolution reaction. These demonstrations may offer a new insight for rational design and construction of highly efficient TiO2‐based PEC devices for solar water splitting.

Advanced oxygen evolution reaction catalysts for solar-driven photoelectrochemical water splitting

“…Under suitable conditions, both large surface area and good charge transport properties could be achieved. 119 Moreover, 3-D OER catalysts could also address the shortcomings of insufficient light absorption, limited loading and severe carrier recombination in light-harvesting semiconductors. Yang and co-workers displayed a decoupling strategy for constructing 3-D OER catalysts of a pore-spanning crisscross conducting polymer (CP) by the in situ cogrowth of FeO x nanoparticles and a CP network (CP-FeO x ).…”

Stabilized Brookite Nanotube Array Films Grown on Transparent Substrates for Photoelectrochemical Water Splitting

“…However, fabricating homogeneously distributed and well-adhered TiO 2 nanotubular structures on FTO substrate is still a grand challenge. On the other hand, the fabrication of titania nanotubes without any clumping or debris using organic-based electrolytes in which the rate of chemical dissolution of TiO 2 is very low is another challenge that needs to be addressed. − …”

Ni Foam Supported TiO2 Nanorod Arrays with CdS Branches: Type II and Z‐Scheme Mechanisms Coexisted Monolithic Catalyst Film for Improved Photocatalytic H2 Production

“…[ 22–24 ] Up to now, almost all the reported TiO 2 nanoarrays are grown on these two types of substrates: metal foil or conductive glass. Based on these, various improvement strategies have been carried out to pursue their desired energy storage and conversion properties such as doping foreign elements, [ 25 ] formulating hybrid composited structure, [ 17,26,27 ] loading efficient cocatalysts, [ 28,29 ] constructing advantaged structures and morphologies, [ 4,30 ] adjusting the exposing crystalline surface, surface sensitization, etc. However, the 2D plane structure of metal foil or glass substrate limits the content and mass transfer performance of monolayer 1D TiO 2 catalysts, which may fundamentally reduce the energy collection and conversion efficiency of such materials.…”