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• Ta 3 N 5 –LaTaON 2 heterojunction has been synthesized by ammonolysis of KLaTa 2 O 7. • The heterojunction has matched interfaces formed by Ta 3 N 5 (010) and LaTaON 2 (10 1 ¯) facets. • The matched interfaces greatly accelerate separation of photo-generated charges. • Ta 3 N 5 –LaTaON 2 heterojunction delivers high photocatalytic activity for water oxidation. • An AQE as high as 11.6% at 420 ± 20 nm has been achieved for O 2 production. Charge separation is generally considered as the most critical step to achieve efficient photocatalytic reactions. Although charge separation can be promoted by a semiconductor heterojunction, its efficacy is inherently restrained by the mismatched atomic arrangements across the heterojunction interfaces. Here, Ta 3 N 5 –LaTaON 2 heterojunction with matched interfaces has been fabricated by one-step ammonolysis treatment of KLaTa 2 O 7. The match interfaces are formed by nearly perfect adhesion of Ta 3 N 5 (010) and LaTaON 2 (10 1 ¯) facets whose interatomic distance is similar. Compared with conventional heterojunction, the so-formed Ta 3 N 5 –LaTaON 2 heterojunction are extremely efficient in accelerating charge separation which in turn enables a high photocatalytic activity. An apparent quantum efficiency as high as 11.6% at 420 ± 20 nm has been reached by Ta 3 N 5 –LaTaON 2 heterojunction, which is almost three times higher than Ta 3 N 5 /LaTaON 2 mixtures. These results signify the importance of matched heterojunction interfaces for charge separation and provide a paradigm in the design of efficient heterojunction-based semiconductor photocatalysts. Ta 3 N 5 -LaTaON 2 heterojunction with matched interfaces greatly accelerate separation of photo-generated charges, which in turn, enables a high photocatalytic activity for water oxidation reactions. [Display omitted] [ABSTRACT FROM AUTHOR]

• Two-dimensional SrNbO 2 N:Zr plates were nitrided from layered perovskite Sr 5 Nb 4 O 15. • Zr4+ was doped in Sr 5 Nb 4 O 15 during flux-assisted calcination. • The 2D SrNbO 2 N:Zr photoanode (λ<680 nm) exhibited high PEC activity. • The photoactivity mainly originated from the 2D surface morphology of SrNbO 2 N:Zr. • Controlling the surface morphology of SrNbO 2 N accelerates separation and transfer of charges. The superior ability of perovskite-type SrNbO 2 N to absorb intensive visible light makes it a potential semiconductor to produce hydrogen and oxygen by photoelectrochemical (PEC) water splitting under sunlight. The surface morphologies, such as shape and structure, of the oxynitride strongly affect its photoactivity, although the mechanism has been hardly studied. Herein, we report a two-dimensional (2D) porous SrNbO 2 N plate with Zr doping, nitrided from layered perovskite Sr 5 Nb 4 O 15 and also its largely enhanced PEC water splitting activity. Zr4+ was doped in Sr 5 Nb 4 O 15 during flux-assisted calcination using KCl, producing 2D-type truncated-octahedral Sr 5 Nb 4 O 15 :Zr plates approximately 50 nm in thickness. The nitridation completely transformed Sr 5 Nb 4 O 15 :Zr to 2D single-crystalline SrNbO 2 N:Zr with a large surface area, which was subsequently used to fabricate a thin and uniform photoanode by the spin coating method. As a result, the Co(OH) x /SrNbO 2 N:Zr/FTO photoanode capable of absorbing visible light of up to 680 nm exhibited an activity of 2.0 mA cm−2 at 1.23 V vs the reversible hydrogen electrode for water splitting under AM 1.5G simulated sunlight. This improvement in photoactivity mainly originated from the 2D surface morphology of SrNbO 2 N:Zr, which is clearly distinguishable from 3D-type oxynitrides. According to electrochemical analyses, the 2D structure of SrNbO 2 N:Zr boosted the separation and accelerated the transfer of charges photogenerated during the water splitting, thus driving the reaction further. Therefore, the result empirically demonstrates that controlling the surface morphology of SrNbO 2 N is an effective strategy to suppress the recombination of charges and minimize their diffusion pathway, eventually enhancing the PEC activity. [Display omitted] [ABSTRACT FROM AUTHOR]

• Introduce the electron transport layer SnO 2 between NiFe LDH and conductive substrate NF was first reported. • SnO 2 nanosheets are interwoven to form a sponge-like 3D structure, which promotes the formation of relatively smaller and thinner NiFe LDH nanosheets, thereby generating more active sites and reducing electron transmission resistance. • It was verified that the electronic structure of Ni and Fe was optimizing via the introduction of SnO 2. • NiFe LDH@SnO 2 /NF possesses a low overpotential of 234 mV at 10 mA cm−2 for OER and 1.396 V at 10 mA cm−2 for methanol oxidation reaction. In an electrocatalyst with a heterointerface structure, the different interfaces can efficiently adjust the catalyst's conductivity and electron arrangement, thereby enhancing the activity of the electrocatalyst. Ultrathin and smaller NiFe LDH was successfully constructed on the surface of SnO 2 nanosheet supported NF by layer by layer assembly, and exhibits lower overpotential of 234 mV at a current density of 10 mA cm−2, which only increases by 6.4% even at a high current density of 100 mA cm−2. The excellent OER activity of catalyst is attributed to the contribution of the semiconductor SnO 2 electron transport layer. Through experiments and characterization, 3d structure SnO 2 nanosheets control the growth of ultra-thin nickel-iron, the hierarchical interface between SnO 2 and NiFe LDH can change the electron arrangement around the iron and nickel active centers at the interface, resulting the valence states of iron slightly increased and Ni3+ content increased. The result will promote the oxidation of water. Meanwhile, the SnO 2 semiconductor as electron transport layer is conducive to trapping electrons generated in oxidation reaction, promoting electrons transferring from the NiFe LDH active center to the Ni substrate more quickly, and enhance the activity of NiFe LDH. It also shows excellent activity in an electrolyte solution containing 0.5 M methanol and 1 M KOH, and only 1.396 V (vs. RHE) is required to drive a current density of 10 mA cm−2. [ABSTRACT FROM AUTHOR]