Alkyne bridge engineering of donor-π-acceptor polymers for efficient CO2 reduction to CH4 and C2H4 under visible light illumination

Abstract

Developing a conjugated polymer (CPs) for the formation of multi electron products or even C2 products from CO2 while simultaneously suppressing the 2-electron product (CO) is crucial for the efficient utilization of solar power. Herein, we investigated the donor-π-acceptor (D-π-A) CPs using cyclotriphosphonitrile, benzene and alkyne groups as the donor part, acceptor section and π-bridge structure, respectively. The photoinduced carrier separation and reduction capability of CPs can be well regulated by changing the number of π-bridges between the D and A units. Among them, three π-bridges (TTB-PCT) exhibit excellent CO2 reduction to CH4 (17.20 mmol g−1) or C2H4 (0.72 mmol g−1) activity under visible light illumination, which was obviously higher than two π-bridges (DTB-PCT) and four π-bridges (TTTB-PCT). TTB-PCT also exhibits excellent cycling stability (50 h). This research exhibits an innovative approach to exploit efficient metal-free CPs for photo-conversion CO2 into multi-electron products driven by visible light.