Acid–base and photocatalytic properties of TiO2-based nanomaterials

In situ fabrication of niobium pentoxide/graphitic carbon nitride type-II heterojunctions for enhanced photocatalytic hydrogen evolution reaction

The effective conversion of sunlight into H₂ by photocatalytic water splitting has emerged as the most promising strategy to alleviate the energy crisis. In this work, niobium pentoxide (Nb₂O₅)/graphitic carbon nitride (g-C₃N₄) type-II heterojunctions with high photocatalytic H₂ evolution rate under both visible and simulated solar light are fabricated via a novel approach involving in situ 'hydrolysis/calcination' loading of Nb₂O₅ nanoparticles on the g-C₃N₄ surface. After the optimisation, the Nb₂O₅/g-C₃N₄ heterojunctions with 5 wt% Nb₂O₅ content delivers high H₂ evolution rates of 2.07 ± 0.03 and 6.77 ± 0.12 mmol g^-1 h^-1 under visible and simulated solar light exposure, respectively, which are 4.1 and 4.2 times superior to those of pure g-C₃N₄. According to the subsequent characterisations, the effective Nb₂O₅/g-C₃N₄ heterojunction offers sufficient contact interface, which is favourable for the efficient separation of photogenerated charges. In addition, the Nb₂O₅/g-C₃N₄ heterojunction possesses a large surface area, which contributes to the interfacial contact between photocatalyst and water. This work provides insights into the synthesis of novel g-C₃N₄-based hetero-photocatalysts with strong solar energy conversion capabilities.