Donor-acceptor organic polymer with sulfur bridge for superior photocatalytic CO2 reduction to CH4 under visible light illumination

Much progress has been made in the design and preparation of organic polymers for photocatalytic CO2 reduction. However, potocatalytic reduction of CO2 to CH4 using organic polymers is still a great difficulty due to poor CO2 adsorption/activation and eight electron transfer. A donor-acceptor (D-A) organic polymer (TOA-PC) was synthesized by combining cyclotriphosphazene (donor) with s-triazine (acceptor) via sulfur bridge. The photocatalytic activity of as-obtained polymers is remarkably dependent on the electron bridges between the donor and acceptor, effectively changing the photogenerated carrier mobility and CO2 adsorption/activation property of the polymers. When the electron bridge is sulfur atom, the TOA-PC exhibits a high CH4 yield of 2748 μmol g−1 (selectivity: near 100 %) under visible light irradiation without photosensitizers and cocatalysts, which represents the latest CH4-producing yield of photocatalysts. This study demonstrates that implantation of novel electron bridges in polymers is an effective way to enhance CH4 yields.