Heterostructure-induced light absorption and charge-transfer optimization of a TiO₂ photoanode for photoelectrochemical water splitting

Rutile titanium dioxide (TiO2) exhibits excellent photoelectrochemical properties but limited photocatalytic performance due to its large band gap and fast electron-hole recombination. Here, we report a composite catalyst of NiTiO3 nanoparticle-coated TiO2 nanorod arrays (NiTiO3/TiO2 NRAs) via an electrostatic assembly strategy. The NiTiO3/TiO2 heterostructure endows an enlarged absorption range and enhanced electron-hole separation efficiency. When being used as an electrode in photoelectrochemical water splitting, it achieves the highest photocurrent density of 1.94 mA cm-2 at 1.0 V versus reversible hydrogen electrode, which is 3.74 times higher than the photocurrent density of pristine rutile TiO2 NRAs (0.51 mA cm-2). The heterostructure engineering strategy is demonstrated to enhance the photoelectrochemical performance, which can be extended to optimize various semiconductor photocatalysts.This research was supported by the National Natural Science Foundation of China (Grant No. 62005027, 62074019, 62174016, and K121402819), the Natural Science Foundation of Jiangsu Province (Grant No. BK20181037), the Natural Science Foundation of the Jiangsu Higher Education Institutions of China (Grant No. 20KJB510016), and the Suzhou Science and Technology Project (Grant No. SZS2020313)