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Constructing heterostructural photoanodes is attractive for elevating the photoelectrochemical (PEC) performance, however, it is a long‐standing challenge to achieve highly efficient interfacial charge transfer. Herein, a CoFe metal‐thiolate framework (CoFe MTF)/Fe2O3 photoanode connected by an interfacial Fe─O─N/S bond is designed to modulate the behavior of charge carriers and improve water oxidation performance. It is disclosed that this interfacial bond functions as a direct charge transfer bridge between shallow trap states of Fe2O3 and CoFe MTF, leading to prolonged carrier recombination lifetimes (85 ns for CoFe MTF/Fe2O3 compared to 37 ns for Fe2O3) and enhanced charge transfer efficiency. Alternatively, a robust interfacial electric field is established in the CoFe MTF/Fe2O3 p–n heterojunction, facilitating efficient charge transfer. As expected, the CoFe MTF/Fe2O3 photoanode exhibits significant enhancement in water oxidation, resulting in a three‐fold increase in photocurrent density compared to pristine Fe2O3. This study highlights the significance of designing interfacially bonded heterostructural photoelectrodes to regulate the transfer characters of charge carriers. [ABSTRACT FROM AUTHOR]

The NiCo(OH) x modified BCN/Fe 2 O 3 photoanode demonstrates much enhanced photocurrents and lowered onset potential for water splitting, which can be attributed to the efficient charge separation efficiency derived from the well-confined heterojunction structure together with the high catalytic activity of NiCo(OH) x for oxygen evolution. [Display omitted] • Well-designed NiCo(OH) x /BCN/Fe 2 O 3 photoande is constructed. • The photoanode exhibits highly enhanced current density. • An negative onset potential of 0.60 V RHE is recorded for PEC water oxidation. • Both surface and bulk charge separation efficiencies are all highly improved. The photoelectrochemical (PEC) performance of hematite (α -Fe 2 O 3)-based photoanodes is still far from its theoretical value because they are constrained by serious charge recombination and sluggish water oxidation kinetics. Herein, we developed a heterostructural photoanode by coating boron doped graphite carbon nitride nanolayers onto an Fe 2 O 3 nanoarray (BCN/Fe 2 O 3), followed by modification with NiCo(OH) x cocatalyst. The constructed NiCo(OH) x /BCN/Fe 2 O 3 demonstrates a significantly improved photocurrent density of 2.7 mA cm−2 at 1.23 V RHE (V versus reversible hydrogen electrode), which is 3.2 times higher than that of pristine Fe 2 O 3. Additionally, it exhibits an extremely negative onset potential of 0.60 V RHE. Detailed studies reveal that the BCN/Fe 2 O 3 heterojunction endows a driving force for charge separation and establishes a direct pathway for their transport, while NiCo(OH) x acts as a cocatalyst to accelerate the surface water oxidation reaction. [ABSTRACT FROM AUTHOR]

The well-designed FeCo-MOF/Fe 2 O 3 compound photoanode displays favorable PEC performances, which can be attributed to the coating of multifunctional FeCo MOF nanolayer that passivate the surface states, construct the p-n heterojunction and improve the water oxidation kinetics, all of these enable the substantially promoted charge separation and transport. [Display omitted] • Ultrathin FeCo MOF nanolayers coated on Fe 2 O 3 photoanode are in-situ formed. • Multifunctional roles of FeCo MOF on Fe 2 O 3 is disclosed. • This design endows photoanode with boosted charge separation/injection efficiency. • The catalytic mechanism for PEC water oxidation is unravelled. Owing to the high theoretical photocurrent density, the hematite (α -Fe 2 O 3) based photoanode has been intensively concerned in photoelectrochemical (PEC) water splitting, but its serious charge recombination and sluggish water oxidation kinetics are still the stumbling blocks. This work reports a high-performance Fe 2 O 3 -based photoanode achieved by coating multifunctional FeCo-bimetal organic framework (MOF) nanolayers (NLs) on Fe 2 O 3 nanoarrays via an in-situ solvothermal process. The FeCo MOF NLs introduced not only effectively passivate the surface states of Fe 2 O 3 photoanode and boost the water oxidation kinetics serving as the cocatalyst, but also construct p-n heterojunctions with Fe 2 O 3 to accelerate the directional migration and separation of photogenerated charge carriers. Expectedly, the as-obtained FeCo-MOF/Fe 2 O 3 photoanode exhibits an apparent negative shift of onset potential, an excellent long-term PEC stability, and highly improved photocurrent density. This finding provides a novel and effective strategy to introduce advanced multifunctional surface coating for enhancing the PEC performance of photoelectrodes. [ABSTRACT FROM AUTHOR]

The well-designed MoO 3- x /Fe 2 O 3- x photoanode exhibits superior PEC water oxidation performance due to the efficient charge separation and transport derived from the introduced MoO 3 surface passivation layer and oxygen vacancy. • Establishing passivation effect of MoO 3 on Fe 2 O 3 photoanode. • Collaboration of passivation layer and oxygen vacancy on Fe 2 O 3 was designed. • The boosted charge separation and transport are achieved on modified photoanode. • Exhibiting superior water oxidation performance on MoO 3- x /Fe 2 O 3- x photoanode. To seek effective strategies that improve the photoelectrochemical water oxidation performance of hematite (α -Fe 2 O 3) photoanodes is still challenging owning to their abundant surface states and low charge transfer efficiency. Herein, a facile impregnation method with an annealing process was developed to synthesize MoO 3 modified Fe 2 O 3 photoanodes using the MoO 3 layer as an effective passivation component to decrease surface states and thus to improve the charge separation and transfer process at the electrode/electrolyte interfaces. The oxygen vacancies were subsequently introduced to steer the electrical conductivity, and further to boost the charge separation and transfer. The optimized MoO 3- x /Fe 2 O 3- x photoanode displays a photocurrent density of 2.6 mA cm–2 at 1.23 V versus the reversible hydrogen electrode under AM 1.5 G irradiation, 2.2 times that of the Fe 2 O 3 (1.2 mA cm–2). The synergetic integration of passivation layer and oxygen vacancies on photoelectrodes heralds an efficient paradigm for solar energy conversion. [ABSTRACT FROM AUTHOR]

The decoration of In 2 O 3 nanolayers on hematite nanoarray photoanode are successfully synthesized to reduce the surface recombination of charge carriers and prolong their lifetimes. The coupling effects of surface passivation and interface electric field enhancement for In 2 O 3 endows the Fe 2 O 3 photoanode with significantly enhanced PEC performance for water oxidation. • In 2 O 3 effectively passivated surface states and enhanced interface electric field of Fe 2 O 3 photoanode. • High charge separation and transportation are achieved both in bulk and surface. • The catalytic mechanism of In 2 O 3 /Fe 2 O 3 nanoarray photoanode is fully excavated. • The high IPCE of 80 % is recorded at 400 nm. Hematite (α -Fe 2 O 3) based nanomaterials are considered as the most promising photoelectrodes for solar water splitting. However, some inherent shortcomings like high density of surface states is still the critically challengeable issue. This paper reports the integration of In 2 O 3 nanolayers (NLs) on the surface of worm-like Fe 2 O 3 films to significantly improve the photoelectrochemical (PEC) water oxidation activity. The In 2 O 3 NLs on the modified α -Fe 2 O 3 photoelectrodes exhibit dual positive effects on PEC performance: i) acting as the passivation material to decrease surface electron-hole recombination losses; ii) constructing heterojunctions with Fe 2 O 3 to facilitate efficient separation of surface charges and spatial transfer with extended lifetimes. The resulting treated Fe 2 O 3 photoanode yields a current density of 3.4 mA cm―2 at 1.23 V vs. reversible hydrogen electrode and high incident photon-to-current efficiency of 80 % at 400 nm. These results may bring inspiration to introduce multifunctional modifiers on photoelectrodes that offer practically high-performance PEC applications. [ABSTRACT FROM AUTHOR]