Selective ceramic absorber with vertical pore structure for efficient solar evaporation

Solar-driven interfacial evaporation is a green and potential method to alleviate the water resource crisis. However, high energy utilization efficiency and long-term stability are the two challenges faced by absorbers. Herein, to change the situation, selective ceramic absorbers with continuous vertical pore structure were fabricated by a freeze casting technology for efficient solar evaporation. The perovskite oxide Sm_0.5Sr_0.5CoO_3-δ (selective) and La_0.5Sr_0.5Co_0.5Ni_0.5O_3-δ (nonselective) ceramics were chose to fabricate the absorbers. The comparison of the porous absorbers prepared by Sm_0.5Sr_0.5CoO_3-δ and La_0.5Sr_0.5Co_0.5Ni_0.5O_3-δ indicated that the selective absorber revealed better evaporation performance (1.22 kg m⁻²h⁻¹) than that of the nonselective absorber (1.12 kg m⁻²h⁻¹). The highest evaporation rate (1.27 kg m⁻²h⁻¹) was observed on the Sm_0.5Sr_0.5CoO_3-δ absorber with 60 wt% solid content and −70 ℃ freezing temperature through the optimization of process parameters. Meanwhile, the selective ceramic absorbers showed excellent cycle stability and desalination quality. This work demonstrates the advantage of selective absorption materials and expands the application of ceramic absorbers in solar-driven interfacial evaporation.