TiO2/WO3/graphene for photocatalytic H2 generation and benzene removal: Widely employed still an ambiguous system.

[Display omitted] • Graphene nanoplatelets were included into the TiO 2 /WO 3 system. • Examined in the removal of gaseous benzene, and generation of H 2. • Position of the conduction bands played indeed a key-role. • Specimen with 15 mol% WO 3 and 1 wt% graphene – a five-fold increase in yield. Clean energy, as well as air and water pollution, have emerged as significant challenges in today's society. Photocatalysis offers a potential solution to address these issues. It is an advanced oxidation process that utilises light to activate a semiconductor. Among photocatalytically active materials, titanium dioxide (TiO 2) semiconductors are widely recognised. However, the performance of TiO 2 is hindered by its wide band gap (∼3.2 eV) and high recombination rate of photo-generated electron-hole (e−−h+) pairs. To overcome these limitations, TiO 2 in heterojunction with tungsten trioxide (WO3) has gained substantial attention for various photocatalytic applications. However, the literature reports contradictory behaviours due to variations in synthesis techniques and photocatalytic applications. In this study, we extensively investigated the photocatalytic properties of the TiO 2 /WO 3 system for the removal of gaseous benzene, and H 2 generation. To enhance the transport and lifetime of photo-generated excitons, graphene nanoplatelets were incorporated into the TiO 2 /WO 3 system. We examined several parameters that influenced the photocatalytic activity of the synthesised materials, including the WO 3 to TiO 2 ratio, the presence of graphene, and the specific photocatalytic application. Interestingly, the position of the conduction bands played a crucial role in hydrogen generation. The TiO 2 /WO 3 system exhibited a type-II heterojunction. While the hybridisation of TiO 2 with WO 3 was found to be detrimental to light-induced benzene removal and H 2 generation, the modification of TiO 2 /WO 3 with graphene nanoplatelets significantly improved the photocatalytic hydrogen generation. Notably, the specimen with 15 mol% WO 3 and 1 wt% graphene demonstrated a five-fold increase in yield compared to its counterpart without graphene. These findings provide valuable insights for data-driven catalysis research. [ABSTRACT FROM AUTHOR]