Photo‐electrochemical (PEC) water splitting is a promising method for converting solar energy into clean energy, but the mechanism of improving PEC efficiency through the interfacial contact and defect strategy remains highly controversial. Herein, reduced graphene oxide (rGO) and oxygen vacancies are introduced into α‐Fe2O3 nanorod (NR) arrays using a simple spin‐coating method and acid treatment. The resultant oxygen vacancy–α‐Fe2O3/rGO‐integrated system exhibits a higher photocurrent, four times than the pristine α‐Fe2O3. It is well evidenced that the electronic interface interaction between α‐Fe2O3 and rGO is boosted with the oxygen vacancies, facilitating electron transfer from α‐Fe2O3 to rGO. Moreover, the oxygen vacancies not only create interband states in α‐Fe2O3 that can trap photogenerated holes and thus facilitate charge separation but significantly also strengthen the adsorption of oxidative intermediates and reduce the energy barrier of rate‐determining step during oxygen evolution reaction (OER). This study demonstrates an rGO–oxygen vacancy synergistic interfacial contact and defect modification approach to design semiconducting photocatalysts for high‐efficiency solar energy capture and conversion. The generated principle is expected to be extendable to another material system.

Plasmon-induced resonance energy transfer (PIRET) plays a key role in enhancing the photoelectrochemical (PEC) performance of metal oxide nanostructures. Herein, photoanodes consisting of α-Fe2O3 nanorod (NR) arrays decorated with Au nanoparticles (NPs) are prepared and optimized to study the PIRET effect. Both the experimental and calculated Ultraviolet-Visible (UV-Vis) spectra indicate that there is a significant near-field coupling between α-Fe2O3 NRs and Au NPs which enable cross-section absorption. The coupling greatly enhances the plasmonic energy transfer from Au NPs to α-Fe2O3 NRs array. The simulated field distribution indicates the Au NPs induce a strong electromagnetic field near the surface of α-Fe2O3 NRs through PIRET. Also, the transient absorption spectroscopy indicates that the direct recombination of photogenerated carriers is significantly limited by the near-field coupling interaction and amplification of the electromagnetic field. The co-catalysts, such as iron oxyhydroxide (FeOOH), are found to have an additional enhancement on the transfer kinetics of holes at the surface. As a result, the photocurrent density of Au/FeOOH-functionalized α-Fe2O3 arrays are about 3.5 times higher than that of pristine α-Fe2O3 NR arrays.

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