Spaced Double Hydrogen Bonding in an Imidazole Poly Ionic Liquid Composite for Highly Efficient and Selective Photocatalytic Air Reductive H 2 O 2 Synthesis.

Photocatalytic oxygen reductive H 2 O 2 production is a promising approach to alternative industrial anthraquinone processes while suffering from the requirement of pure O 2 feedstock for practical application. Herein, we report a spaced double hydrogen bond (IC-H-bond) through multi-component Radziszewski reaction in an imidazole poly-ionic-liquid composite (SI-PIL-TiO 2 ) and levofloxacin hydrochloride (LEV) electron donor for highly efficient and selective photocatalytic air reductive H 2 O 2 production. It is found that the IC-H-bond formed by spaced imino (-NH-) group of SI-PIL-TiO 2 and carbonyl (-C=O) group of LEV can switch the imidazole active sites characteristic from a covered state to a fully exposed one to shield the strong adsorption of electron donor and N 2 in the air, and propel an intenser positive potential and more efficient orbitals binding patterns of SI-PIL-TiO 2 surface to establish competitive active sites for selectivity O 2 chemisorption. Moreover, the high electron enrichment of imidazole as an active site for the 2e - oxygen reduction ensures the rapid reduction of O 2 . Therefore, the IC-H-bond enables a total O 2 utilization and conversion efficiency of 94.8 % from direct photocatalytic air reduction, achieving a H 2 O 2 production rate of 1518 μmol/g/h that is 16 and 23 times compared to poly-ionic-liquid composite without spaced imino groups (PIL-TiO 2 ) and TiO 2 , respectively.