Ultrathin Ti-Deficient TiO<sub>2</sub> Nanosheets with Pt Single Atoms Enable Efficient Photocatalytic Nitrate Reduction to Ammonia
Hayoon Jung, Gihoon Cha, Hyesung Kim, Johannes Will, Xin Zhou, Erdmann Spiecker, Josef Breu, Patrik Schmuki
Abstract
Ti-deficient TiO 2 nanosheets derived from lepidocrocite-type titanate delamination show a p-type conductivity with a band gap widened by the quantum confinement effect to 3.7 eV. This shift in the extended band positions─and thus in the electron transfer level─allows a direct photocatalytic nitrate reduction to ammonia without the use of any hole scavengers; this in contrast to classic TiO 2 . The deposition of Pt single atoms as cocatalysts onto the nanosheets significantly enhances the activity and selectivity toward ammonia, which outperforms classic Pt nanoparticles used as cocatalyst. The present study therefore reports not only on the unique photocatalytic properties of these Ti-deficient TiO 2 nanosheets but also on the beneficial use of the modified electronic properties that enable entirely novel applications, such as the technologically highly important reduction of nitrate to ammonia.