Transition metal-decorated Zr₁₂O₁₂ nanocages as single-atom catalysts for water splitting: A first-principles study

Catalytic water splitting stands out as a highly promising approach to meet the growing global demand in the area of material sustainability. The challenging dissociation of H₂O including adsorption-desorption of hydrogen remains a significant obstacle to improving the catalyst design and performance. In continuation of the effort to identify more effective and agile photocatalysts, Zr₁₂O₁₂ and M@Zr₁₂O₁₂ (M = Ti, V, Cr, or Mn) nanocages have been investigated using Density functional theory (DFT) calculations for their potential in overall catalytic water splitting applications. It has been observed that the M@Zr₁₂O₁₂ nanocages demonstrate high stability, which is crucial in designing single-atom catalysts (SACs) to prevent possible aggregation of the metal. Electronic structure calculations reveal that metal atom loading reduces the bandgap of the Zr₁₂O₁₂ nanocage, thereby increasing the visible light absorption of the catalysts. Additionally, the computed Gibbs free energies indicate that the Mn@Zr₁₂O₁₂ nanocage exhibits a superior performance in hydrogen evolution and oxygen evolution reactions at room temperature among the M@Zr₁₂O₁₂ catalysts explored. However, the oxygen evolution reaction does not proceed on the single metal atom loaded Ti@Zr₁₂O₁₂, V@Zr₁₂O₁₂ and Cr@Zr₁₂O₁₂ catalysts following the Rossmeisl mechanism, suggesting their use for other catalytic applications.