Microenvironment-regulated peroxymonosulfate activation for selective singlet oxygen generation in a bifunctional Co3O4/PAM hybrid hydrogel evaporator

Singlet oxygen ( 1 O 2 ) is promising for volatile organic compounds (VOC) removal in solar-driven interfacial evaporation (SDIE) systems, owing to its selectivity for electron-rich organic compounds and anti-interference capability. The radical precursor ·SO 5 − from peroxymonosulfate (PMS) is often strongly adsorbed and quenched on catalyst surfaces, impeding efficient 1 O 2 generation. To address this, we developed a bifunctional Co 3 O 4 /polyacrylamide hybrid hydrogel (Co 3 O 4 /PAMHH) evaporator, embedding Co 3 O 4 catalyst in a hydrophilic, hydrogen-bonding PAMHH network. This design precisely lowers the adsorption energy of ·SO 5 − on Co 3 O 4 surface to facilitate its desorption and enrichment within PAMHH pores, thereby establishing an optimal microenvironment for 1 O 2 formation. Scavenging experiments and ESR spectroscopy verified the directional production of 1 O 2 . With this design, Co 3 O 4 –0.2/PAMHH achieves stable phenol (PE) degradation across diverse pH and ionic conditions, achieving 90.4% PE removal in bulk water and 99.3% in condensed water with 2 mM PMS. Leveraging Co 3 O 4 's photothermal properties, an impressive evaporation rate of 3.40 kg m −2  h −1 was achieved under one sun irradiation. This work presents a novel microenvironment-regulated strategy that selectively directs PMS activation toward 1 O 2 , enabling simultaneous high-rate solar interfacial evaporation and efficient VOC removal. It establishes a new paradigm for precise control of reaction pathways in bifunctional solar-driven systems and offers a sustainable solution for integrated water purification and pollutant remediation.