Lattice expansion boosting photocatalytic degradation performance of CuCo2S4 with an inherent dipole moment

Realizing efficient charge separation and directional transfer is a challenge for single-component semiconductors. The spatial electric field generated by dipole moment could promote charge separation. Here, three-dimensional hierarchical CuCo2S4 microspheres with lattice distortion were prepared, and lattice distortion was modulated by changing feed Co/Cu molar ratios in synthesis. CuCo2S4 showed asymmetric crystal structure, leading to generation of dipole moment. The charge separation efficiency of CuCo2S4 was related to lattice distortion, and lattice expansion was in favor for charge separation. The CuCo2S4 with feed Cu/Co molar ratio of 1:4 (CCS-4) showed the maximum lattice expansion and exhibited the highest photocatalytic activity, which was attributable to the highest charge separation efficiency and the largest specific surface area. CCS-4 can remove 95.4% of tetracycline hydrochloride within 40 min photocatalysis, and effectively improve the biodegradability of pharmaceutical wastewater. Importantly, this study provides a new vision for constructing single-component photocatalysts with high photocatalytic performance.