Engineering the heterogeneous interfaces of inverse opals to boost charge transfer for efficient solar water splitting

Abstract

Herein, we report a three-dimensional porous TiO2/Fe2TiO5/Fe2O3 (TFF) inverse opal through in situ thermal solid reactions for photoelectrochemical water splitting. The Fe2TiO5 interfacial layer within TFF acting as a bridge to tightly connect to TiO2 and Fe2O3 reduces the interfacial charge transfer resistance, and suppresses the bulk carrier recombination. The optimized TFF displays a remarkable photocurrent density of 0.54 mA cm−2 at 1.23 V vs. reversible hydrogen electrode (RHE), which is 25 times higher than that of TiO2/Fe2O3 (TF) inverse opal (0.02 mA cm−2 at 1.23 V vs. RHE). The charge transfer rate in TFF inverse opal is 2–8 times higher than that of TF in the potential range of 0.7 −1.5 V vs. RHE. The effects of the Fe2TiO5 interfacial layer are further revealed by X-ray absorption spectroscopy and intensity-modulated photocurrent spectroscopy. This work offers an interfacial engineering protocol to improve charge separation and transfer for efficient solar water splitting.[Figure not available: see fulltext.]