TiN Bridged All‐Solid Z‐Scheme CNNS/TiN/TiO_2−x Heterojunction by a Facile In Situ Reduction Strategy for Enhanced Photocatalytic Hydrogen Evolution

Abstract

Proper interfacial electron mediators greatly influence the charge transfer efficiency of Z‐scheme photocatalytic system. TiN bridged all‐solid Z‐scheme CNNS/TiN/TiO2−x heterojunction composites are prepared by a facile in situ reduction strategy for highly promoted photocatalytic hydrogen evolution driven by visible light. The reduction process not only creates oxygen vacancies in TiO2 but also reduces partial TiO2 to TiN. Oxygen defected TiO2−x permits TiO2 visible light absorption capacity. Fermi level equilibrium forms internal electric fields at the interfaces to drive the charge transfer. Meanwhile, TiN electrons mediator connects the conduction band of TiO2−x and the valance band of CNNS, which is advantageous for the transfer of photoelectrons from the conduction band of TiO2−x to the valance band of CNNS. Compared with pure carbon nitride (CN), TiO2, and even composites CN/TiO2 without TiN, CNNS/TiN/TiO2−x shows a remarkably enhanced visible light catalytic hydrogen evolution performance of 1230 μmol g−1 h−1, about 95 times than that of pure CN. The dramatically boosted photocatalytic activity is attributed to the extra visible light absorption capacity of TiO2−x and convenient electron transfer between CNNS and TiO2−x through TiN electrons mediator.

Piezoelectric-Induced Internal Electric Field in Bi2WO6 Nanoplates for Boosting the Photocatalytic Degradation of Organic Pollutants

“…As shown in Figure S2, the bandgap energy ( E g ) of the as-prepared Bi 2 WO 6 was determined to be 2.43 eV according to the Tauc plot curve (the inset image of Figure S2a). VB XPS was further carried out to determine the VB potential of the Bi 2 WO 6 nanoplates, which is the energy gap between the VB of materials and Fermi level ( E f , vs vacuum) . The E f of Bi 2 WO 6 nanoplates was determined to be 1.87 eV (Figure S2b).…”

A Review on Oxygen-deficient Titanium Oxide for Photocatalytic Hydrogen Production

“…Among these limited reports, thermal treatment in hydrogen is the most widely used method of introducing oxygen defects in TiO 2 [22]. The introduced oxygen defects in TiO 2 are generally combined with other strategies, such as ion doping and composition with other semiconductors, to achieve high hydrogen evolution activity, which has been the focus of recent studies [47,[58][59][60][61].…”

Elucidating the Effect of Nitrogen Occupancy on the Hydrogen Evolution Reaction for a Series of Titanium Oxynitride Electrocatalysts

“…[8] Due to its unique electronic structure and conductivity, TiN was able to bridge oxygen defected TiO 2-x and carbon nitride within a heterojunction system for the photocatalytic generation of hydrogen. [9] The high conductivity of TiN comes from the closed-packed structure and excess d-band electrons of the metal atoms. [10,11] The electrical resistivity of the nitride (TiN) has been shown to be ~1.5×10 À 10 Ohm•cm, [12] whereas the electrical resistivity of the oxide (rutile TiO 2 ) is about 12 orders of magnitude higher (~7.2×10 2 Ohm•cm).…”

“…One increasingly popular strategy being explored is to use robust and conductive materials as supports for electrochemical water splitting reactions, [7] where it has been shown that TiN nanoparticles have shown a lower rate of electrochemical oxidation compared with conventional carbon black when supporting platinum under PEM fuel cell conditions [8] . Due to its unique electronic structure and conductivity, TiN was able to bridge oxygen defected TiO 2‐x and carbon nitride within a heterojunction system for the photocatalytic generation of hydrogen [9] . The high conductivity of TiN comes from the closed‐packed structure and excess d‐band electrons of the metal atoms [10,11] .…”