Rational construction of S-doped FeOOH onto Fe 2 O 3 nanorods for enhanced water oxidation Nguyen Duc Quang ⇑ , Phuoc Cao Van, Sutripto Majumder, Jong-Ryul Jeong, Dojin Kim, Chunjoong Kim ⇑ Department of Materials Science and Engineering, Chungnam National University, Daejeon 34134, Republic of Korea highlights  The S-FeOOH@Fe 2 O 3 core-shell nanorod array was firstly used for oxidation water splitting.  The S-FeOOH@Fe 2 O 3 photoanode showed a 2.42 times increase in photocurrent density.  A negative shift of the onset potential by 250 mV was observed for S- FeOOH@Fe 2 O 3.  The role of S-FeOOH catalyst layer was elaborated, which accelerated the charge transport at the interface of the photoanode. graphical abstract The new catalyst system, S-FeOOH, is immobilized onto the surface of Fe 2 O 3 nanorods for high- performance PEC water splitting. The S-FeOOH catalyst layer contributed to accelerating the water oxi- dation on the surface as well as facilitating the interface charge carrier separation and its transfer. article info Article history: Received 25 December 2021 Revised 22 February 2022 Accepted 24 February 2022 Available online 26 February 2022 Keywords: Fe 2 O 3 S-doped FeOOH Photocatalyst Photoelectrochemical Water oxidation abstract Hematite-based photoanode (a-Fe 2 O 3 ) is considered the promising candidate for photoelectrochemical (PEC) water splitting due to its relatively small optical bandgap. However, severe charge recombination in the bulk and poor surface water oxidation kinetics have limited the PEC performance of Fe 2 O 3 photo- electrodes, which is far below the theoretical value. Herein, a new catalyst, S-doped FeOOH (S-FeOOH), has been immobilized onto the surface of the Fe 2 O 3 nanorod (NR) array by a facile chemical bath depo- sition incorporated thermal sulfuration process. The grown S-FeOOH layer acts not only as an efficient catalyst layer to accelerate the water oxidation on the surface of photoelectrode but also constructs a heterojunction with the light absorption layer to facilitate the interface charge carrier separation and transfer. As expected, the modified S-FeOOH@Fe 2 O 3 photoanode achieves a remarkable increase in PEC performance of 2.30 mA cm 2 at 1.23 V versus the reversible hydrogen electrode (V RHE ) and an apparent negative shifted onset potential of 250 mV in comparison with pristine Fe 2 O 3 (0.95 mA cm 2 at 1.23 V RHE ). These results provide a simple and effective strategy to coupling oxygen evolution catalysts with photoanodes for practically high-performance PEC applications. Ó 2022 Elsevier Inc. All rights reserved. https://doi.org/10.1016/j.jcis.2022.02.117 0021-9797/Ó 2022 Elsevier Inc. All rights reserved. ⇑ Corresponding authors.at: Chungnam National University, Daejeon 34134, Republic of Korea. E-mail addresses: ndquang2092@cnu.ac.kr (N. Duc Quang), ckim0218@cnu.ac.kr (C. Kim). Journal of Colloid and Interface Science 616 (2022) 749–758 Contents lists available at ScienceDirect Journal of Colloid and Interface Science journal homepage: www.elsevier.com/locate/jcis