Enhanced Photocatalysis over SrTiO₃ Nanoparticles Modified with Highly Dispersed Nickel Species

The photocatalytic decomposition of methylene blue (MB) from textile wastewater is promising, though many photocatalysts suffer from a wide band gap, unspecific catalytic active sites and inefficient charge carrier separation. Here, a series of SrTiO₃-based catalysts modified with highly dispersed nickel species were synthesized via a facile annealing process in a NH₃ atmosphere obtained from the decomposition of ammonium bicarbonate. The loading amount of nickel is precisely regulated by controlling the concentration of a nickel nitrate hexahydrate solution. The sample containing 0.5 wt% Ni showed a complete degradation of MB under the irradiation of a xenon lamp for 75 min, exhibiting the best performance with an apparent reaction rate constant (k) 3.2 times higher than that of pure SrTiO₃. The enhancement in photocatalytic performance can probably be attributed to the strong metal-support interaction between the highly dispersed Ni species and SrTiO₃, which can modulate the band structure by adjusting the concentration of oxygen vacancies, suppress charge recombination, and thus promote efficient carrier separation. Furthermore, the highly dispersed Ni species appears to enhance the adsorption and activation of the reactants on the catalytic surface. This work demonstrates the potential of SrTiO₃ as a support for a range of highly dispersed catalysts with active metal species that can provide new insights and a practical foundation for the rational design of high-performance SrTiO₃-based composite photocatalytic materials.