Bandgap engineering of KTaO3 for water-splitting by different doping strategies

In this work, different doping strategies are adopted to improve the photocatalytic activity of KTaO3 (KT) by hybrid functional theory. The La and W monodoped KTs are n-type semiconductors and the photocatalytic performance of Ti, Mo, Cr, N, La–Bi, La–Cr, W–N, Cr–N, Cr–Ti doped KTs are limited by either wide bandgaps or the appeared local unoccupied impurity states. The Bi, C monodoped and La–C, Mo–N, Mo–Ti, W–Ti codoped KTs possess suitable bandgaps of 2.12, 2.06, 1.39, 2.66, 2.66, and 2.61 eV for absorbing visible light without the introduction of localized unoccupied states. The band edge alignments suggest that Mo–N and W–Ti codoped KTs possess the ability for spontaneous overall water-splitting, Bi and Mo–Ti doped KTs can only spontaneously produce oxygen, and C doped KTs only spontaneously generate hydrogen. While La–C doped KT is thermodynamically unfeasible to generating both hydrogen and oxygen. Thus, Mo–N and W–Ti codoped KTs are promising photocatalysts for overall water-splitting, and Bi, C, and Mo–Ti doped KTs are considered for Z-scheme photocatalysis.