Heteroatom-fused tetraphenylethylene-based conjugated microporous polymers for sacrificial photocatalytic H2O2 production

Hydrogen peroxide (H2O2) is an extremely valuable feedstock and environmentally friendly oxidising agent widely used in the modern chemical industry. While current industrial methods for H2O2 synthesis are energy-intensive, photocatalysis presents a sustainable alternative. However, the efficiency of existing photocatalytic systems remains insufficient for practical large-scale application. Herein, a range of tetraphenylethylene-based conjugated microporous polymers (CMPs) have been designed and synthesized through Suzuki-Miyaura polycondensation, incorporating either biphenyl, dibenzo[b,d]thiophene or dibenzo[b,d]thiophene sulfone. We investigate how the presence of dibenzo[b,d]thiophene sulfone units correlates with enhanced photocatalytic activity, which is attributed to increased wettability and improved charge separation. The CMP which contains biphenyl ring functionality shows a H2O2 production rate of 10500 µmol h-1 g-1, which more than doubles to 26650 µmol h-1 g-1 upon incorporation of dibenzo[b,d]thiophene sulfone units, with an apparent quantum yield of 17.1% at 420 nm. This work also explores the stability of CMP photocatalysts for H2O2 production and evaluates a potential superoxide radical-mediated mechanism.