Study of native defects and transition-metal (Mn, Fe, Co, and Ni) doping in a zinc-blende CdS photocatalyst by DFT and hybrid DFT calculations

We use first-principles DFT and hybrid DFT calculations to investigate the formation of native defects and transition-metal (Mn, Fe, Co, and Ni) doping in zinc-blende CdS and their effect on the electronic structures. Our results reveal that Cd vacancies, S vacancies, interstitial Cd, and interstitial S are dominant native defects, in good agreement with experimental results. Except interstitial S, other native defects do not contribute to visible light absorption. Transition-metal dopants tend to substitute a lattice Cd atom under S-rich conditions and occupy a tetrahedral interstitial site under p-type and Cd-rich conditions. The doping becomes difficult with increasing the atomic number of the transition metal. Co doping does not contribute to visible light absorption. Mn, Fe, and Ni doping, especially interstitial Ni doping, is able to narrow the band gap, and thus, these transition metals are good dopant candidates to tailor the visible light absorption property of nanosized CdS photocatalysts.