A quaternary ammonium cyclodextrin polymer for efficient photocatalytic production of hydrogen peroxide from pure water.

The QCD36A 1-1 350 shows excellent photocatalytic activity for H 2 O 2 production under visible light irradiation. [Display omitted] • A quaternary ammonium cyclodextrin polymeric photocatalyst QCD36A 1-1 350 is successfully synthesized. • The quaternary ammonium group in the QCD36A 1-1 350 structure broadened the absorption of visible light. • The introduction of quaternary ammonium groups can facilitate efficient charge transfer, speed up the 2e- ORR process. • A photocatalytic H 2 O 2 yield of 2.51 mmol g−1h−1 was achieved in purified water without an electron donor or aeration. A photocatalytic system can be used to efficiently produce hydrogen peroxide (H 2 O 2) without introducing a sacrificial agent or oxygen (O 2). This system has practical application potential but remains challenging to implement. To increase the H 2 O 2 yield of this system, a quaternary ammonium cyclodextrin polymeric photocatalyst QCD36A 1-1 350 is successfully synthesized using quaternization modification and low-temperature polycondensation. The photocatalyst is used to produce H 2 O 2 from pure water and air by the one-step two electron oxygen reduction reaction. Under irradiation by visible light, QCD36A 1-1 350 produces a higher H 2 O 2 yield (of up to 2.51 mmol g−1h−1) than unquaternized polymers and reported metal-free catalysts under similar conditions. Experimental and theoretical studies clearly show that the introduction of quaternary ammonium groups can effectively broaden the visible light absorption of polymer catalysts, while increasing the hydrophilicity, charge transfer efficiency and surface stability. The practicability of efficient photocatalytic production of H 2 O 2 is realized by increasing the activity and selectivity of the polymer photocatalyst. [ABSTRACT FROM AUTHOR]