Regulating N-atom Number in Donor-Acceptor Units Covalent Organic Framework (COF) for Photocatalytic H2O2 production from Sunlight and Seawater

The development of photocatalyst by tunning the Donor-Acceptor (D-A) properties into the covalent organic frameworks that regulate the photocatalytic production of highly valued chemical H2O2 by harvesting natural resources such as sunlight and seawater is one of the challenging tasks. In this study, we have demonstrated a systematic strategic-driven analysis to understand the role of D-A properties in an imine-linked covalent organic framework towards photocatalytic H2O2 production. We synthesized three imine-linked COF, among which triazine core containing framework COF-C demonstrated high selectivity for H2O2 generation, with a yield of 3674 μM.h-1 under an O2 saturated aqueous system in the absence of any sacrificial agents. Also, it showed a solar to chemical conversion efficiency (SCC) of 1.3% in pure water with an AQY of 36.2% in blue led (λ∼ 450 nm) in pure water. The COFs demonstrated stepwise 2e- ORR pathways leading toward photocatalytic production of H2O2, with Steller recyclability, which in the future has the potential to became a highly stable material for photocatalytic application. When benzyl alcohol was introduced to form a two-phase catalytic system, the production of H2O2 was remarkably enhanced in many folds. This work represents a series of study of COFs with significant advancement in the design that have enhanced the solar energy utilization and synthesis of value-added products.