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.