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.