Decorating Thermodynamically Stable (101) Facets of TiO 2 with MoO 3 for Multifunctional Sustainable Hydrogen Energy and Ammonia Gas Sensing Applications.

The simultaneous realization of sustainable energy and gas sensors dealing with the emission of pollutants is indispensable as the former thrives on the minimization of the latter. However, there is a dearth of multifunctional nanocatalysts in the literature. This ascertains the importance of multifunctional semiconductors which can be utilized in H 2 generation via overall water splitting and in the gas sensing of global pollutants such as NH 3 . MoO 3 -decorated TiO 2 Z-scheme heterostructures exceptionally escalate the photochemical and photo/electrochemical H 2 evolution performance and gas sensing response of TiO 2 owing to the synergistic relationship between TiO 2 and MoO 3 . Extensive structural, morphological, and optical characterizations, theoretical studies, and XPS results were exploited to develop a mechanistic framework of photochemical H 2 evolution. The photochemical response of the optimum TiO 2 -MoO 3 composition (20 wt % MoO 3 -TiO 2 ) was found to be nearly 12- and 20-fold superior to the pristine TiO 2 and MoO 3 photocatalysts, respectively, with the remarkable H 2 evolution rate of 9.18 mmol/g/h and AQY of 36.02%. In addition, 20 wt % MoO 3 -TiO 2 also showed advanced photo/electrochemical efficiency with 0.61/0.7 V overpotential values toward HER due to the higher electrochemically active surface area and Tafel slope as low as 65 mV/dec. The gas sensing response of 20 wt % MoO 3 -TiO 2 toward NH 3 gas turned out to be 2.5-fold higher than that of the pristine TiO 2 gas sensor.