Unveiling the Trade-Off between H2O2 Photosynthetic Efficiency and Stability for Sustained H2O2 Accumulation

Sustained hydrogen peroxide (H2O2) accumulation remains a critical bottleneck for conjugated organic polymers (COPs). Spirobifluorene-based COPs, namely NBT, BT, and 2FBT, were synthesized using benzothiadiazole derivatives as the crosslinkers to determine H2O2 adsorption and desorption properties. NBT exhibited a superior H2O2 production rate of 6.40 mmol g–1 h–1, an apparent quantum yield of 11.1%, and a solar-to-chemical conversion efficiency of 1.19%. However, its long-term H2O2 accumulation declined relative to both BT and 2FBT, owing to excessively strong H2O2 adsorption arising from hydrogen bonding. Whereas BT exhibited enhanced H2O2 accumulation owing to its favorable production rate, rapid desorption, and minimal decomposition, thereby achieving H2O2 concentrations of 4.0 mmol L–1 in a stirred biphasic system and 19.2 mmol L–1 in a continuous-flow system employing a benzyl alcohol/water biphasic medium. This work proposes a fundamental trade-off between H2O2 photosynthetic efficiency and stability: an efficient H2O2 production rate should be synergistically coupled with weak adsorption and rapid desorption, even though the production rate is not maximal.