Effect of cobalt doping on photocatalytic water splitting activity of NiTi-layered double hydroxide

Abstract

Metal doping has been used as an effective strategy to tune the energy levels of semiconductors. Herein, we dope NiTi layered double hydroxide (NiTi-LDH) with cobalt to prepare a ternary LDH, CoNiTi-LDH, to enhance its photocatalytic performance towards both water oxidation and hydrogen evolution. A CoNiTi-LDH with smaller plate sizes and a higher degree of order is obtained, which allows the band gap to shrink from 2.7 eV to 2.4 eV. CoNiTi-LDH exhibits a photocatalytic water oxidation activity of 366 μmol g⁻¹ h⁻¹, which is more than two times higher than NiTi-LDH (166 μmol g⁻¹ h⁻¹). We observed that appropriate energy levels of CoNiTi-LDH allow it to be an efficient photocatalyst also for hydrogen evolution. We performed detailed characterization studies to elucidate the effect of Co-doping on photocatalytic activity.