Graphene-mediated band gap engineering of WO3 nanoparticle and a relook at Tauc equation for band gap evaluation

Engineering the band gap of semiconductors is often crucial in the quest for developing new and advanced technologies. In this report, the implication of graphene on the band gap optimization of tungsten trioxide (WO3) is discussed. Simple one-step sol-gel process was followed to anchor WO3 nanoparticles in graphene. Graphene induces a redshift in the band gap of WO3. Band gap narrowing of 6.60% is observed for 7wt% graphene-tethered WO3. Interestingly, a profound difference is observed in estimating the band gap energy values followingthe usual Tauc equation. Our observation suggests that the differential form of Tauc equation is better suited to determine the band gap energy of inorganic semiconductors than the typical extrapolationmethod.