Ultrathin TiC nanosheets served as a highly efficient hole transport layer on a FeO photoanode for photoelectrochemical water oxidation

Surface modification of oxygen evolution reaction (OER) cocatalysts is a promising approach to improve PEC water oxidation activity by accelerating the surface charge injection efficiency and catalytic reaction kinetics. However, the PEC performance is still restricted by inefficient charge transfer at the semiconductor/cocatalyst interface. In this study, ultrathin Ti 3 C 2 nanosheets, serving as a highly efficient hole transport layer, were introduced into the Fe 2 O 3 /CoAl-layered double hydroxide (LDH) interface. The obtained Fe 2 O 3 -Ti 3 C 2 -CoAl photoanodes exhibited a significantly improved photocurrent density of 2.1 mA cm −2 at 1.23 V versus the reversible hydrogen electrode (RHE) under AM 1.5G illumination. In this system, the Ti 3 C 2 nanolayer not only suppresses the interfacial recombination of photogenerated carriers but also facilitates efficient hole transfer from Fe 2 O 3 to the OER cocatalyst, thus promoting the PEC performance. This study provides a new guideline for optimizing the charge transfer at the semiconductor/cocatalyst interface. Ultrathin Ti 3 C 2 nanosheets, serving as a highly efficient hole transport layer, are introduced into the Fe 2 O 3 /CoAl layered double hydroxide (LDH) interface, for highly efficient PEC water oxidation.