One-pot synthesis and Nb₄N₅ surface modification of Nb⁴⁺ self-doped KNbO₃ nanorods for enhanced visible-light-driven hydrogen production

Abstract

Herein, rhombohedral self-doped KNbO3 (S-KN) nanorods were fabricated via a one pot, solvothermal method without using any surfactant. The presence of Nb(4+) in S-KN greatly narrows its band gap and thus extends its photoresponse from UV to the visible light region. Moreover, S-KN/Nb4N5 nanorod heterostructures were obtained by nitriding S-KN nanorods for different times, which exhibited significantly enhanced photocatalytic activity for hydrogen production under visible light irradiation. The junction formed between S-KN and Nb4N5 and the Nb(4+) self-doping of KN are supposed to be responsible for the enhanced photocatalytic activity of S-KN/Nb4N5. This study also paves the way for the synthesis of other similar photocatalysts.

Ordered Mesoporous TiO2 Gyroids: Effects of Pore Architecture and Nb‐Doping on Photocatalytic Hydrogen Evolution under UV and Visible Irradiation

“…However, G A ‐TNO3 showed a significant decrease in binding energy of the Nb 3d by around 0.7 eV with respect to an identically prepared gyroidal Nb 2 O 5 reference (Table S3, Supporting Information). A lower binding energy corresponds to a lower oxidation state of Nb due to a higher local electron density, such as provided by interstitial O″ i species, which may be present to charge compensate for Nb 5+ doping …”

Niobium Nitride Nb4N5 as a New High‐Performance Electrode Material for Supercapacitors

“…The reason why only Nb 4 N 5 phase is found might be that the formation of Nb 4 N 5 via the reaction of Nb 2 O 5 and NH 3 is thermodynamically and kinetically beneficial. The fabrication of Nb 4 N 5 via different methods has also been reported in previous literatures …”

“…The nanochannels appear ordered, straight but unsmooth feature, comprising many disintegrated particles. Well‐resolved lattice fringes of 0.216 nm are observed from the HR‐TEM image of Nb 4 N 5 nanoparticles derived from the wall of Nb 4 N 5 nanochannels, coincide with the (310) plane of tetragonal Nb 4 N 5 , demonstrating the presence of Nb 4 N 5 phase. The ring structure of the selected area electron diffraction (SAED) pattern indicates the polycrystalline structure of the Nb 4 N 5 nanochannels.…”

Covalently Connected Nb4N5–xOx–MoS2 Heterocatalysts with Desired Electron Density to Boost Hydrogen Evolution

“…Also, the EPR signal at g = 2.01 is observed in Nb 4 N 5−x O x /NG and Nb 4 N 5−x O x −MoS 2 /NG, demonstrating the presence of Nb 4+ . 37 The +4 oxidation state of Nb has a d-orbital filling of 4d 1 , indicating an increased affinity for H. Taken together, covalently connected Nb 4 N 5−x O x −MoS 2 heterostructures with lattice distortion possess adequate electron density, which is beneficial to promote adsorption of H and water, promoting HER kinetics. 20 The nitridation with the CVD process is a general strategy for converting Nb oxides to corresponding oxynitrides and nitrides.…”