Symbiotic MoO 3 -SrTiO 3 Heterostructured Nanocatalysts for Sustainable Hydrogen Energy: Combined Experimental and Theoretical Simulations.

Highly efficient Z-scheme MoO 3 -SrTiO 3 heterostructured nanocatalytic systems were engineered via a sol-gel chemical route and exploited in green H 2 energy synthesis via overall water splitting. The optical and electronic investigations corroborated the enhancement of the optoelectronic properties of SrTiO 3 after the incorporation of MoO 3 . Emergence of the interfacial charge transfer between SrTiO 3 and MoO 3 is the driving force, which synergistically triggered the catalytic efficiency of MoO 3 -SrTiO 3 heterostructures. The substitution of Ti 4+ by Mo 6+ ions led to the suppression of Ti 3+ mid-gap states, as the potential involved in the Mo 6+ /Mo 5+ reduction is higher than that in Ti 4+ /Ti 3+ . Theoretical studies were employed in order to comprehend the mechanism behind the advancement in the catalytic activity of MoO 3 -SrTiO 3 porous heterostructures, which also possessed a higher surface area. 2% MoO 3 -SrTiO 3 exhibited the optimum catalytic response toward H 2 evolution via photochemical, electrochemical, and photo-electrochemical water splitting. 2% MoO 3 -SrTiO 3 evolved H 2 at the fourfold higher rate than SrTiO 3 with phenomenal 16.06% AQY during photochemical water splitting and photo-degraded MB dye at nearly 88% against the 42% degradation in SrTiO 3 -led photocatalysis. Electrochemical and photo-electrochemical investigations also manifested the superiority of 2% MoO 3 -SrTiO 3 toward HER, as it exhibited accelerated current and photocurrent densities of 25.02 and 27.45 mA/cm 2 , respectively, at the 1 V potential. EIS studies demonstrated the improved charge separation efficiency of MoO 3 -SrTiO 3 heterostructures. This work highlights the multi-dimensional approach of obtaining green H 2 energy as the sustainable energy source using MoO 3 @SrTiO 3 heterostructures.