Enhancing photothermal conversion of spinel zinc cobalt oxide through lattice distortion regulation

Abstract

Spinel oxides, renowned for their structural versatility, are used in various solar photothermal-related applications. However, the relationship between the crystal microstructure and the photothermal conversion is unknown. ZnCo₂O₄, a normal spinel with Co at octahedral sites, provides a model to study the link between octahedral distortion and photothermal conversion. We found that greater Jahn–Teller distortion enhances photothermal conversion efficiency (63.4% → 80.2%). Magnetic and DFT analyses attribute this improvement to a distortion-driven transition of ZnCo₂O₄ from a low-spin semiconductor to a high-spin metallic-like state, which promotes light-to-heat conversion. Tuning electronic behavior via microstructural distortion offers valuable insights for developing efficient photothermal conversion materials.