Aqueous CO<sub>2</sub> Reduction on Si Photocathodes Functionalized by Cobalt Molecular Catalysts/Carbon Nanotubes
Zhibing Wen, Suxian Xu, Yong Zhu, Guoquan Liu, Hua Gao, Licheng Sun, Fei Li
Abstract
Abstract Photoelectrochemical reduction of CO 2 is a promising approach for renewable fuel production. We herein report a novel strategy for preparation of hybrid photocathodes by immobilizing molecular cobalt catalysts on TiO 2 ‐protected n + ‐p Si electrodes (Si | TiO 2 ) coated with multiwalled carbon nanotubes (CNTs) by π–π stacking. Upon loading a composite of Co II (BrqPy) ( BrqPy =4′,4′′‐bis(4‐bromophenyl)‐2,2′ : 6′,2′′ : 6′′,2′′′‐quaterpyridine) catalyst and CNT on Si | TiO 2 , a stable 1‐Sun photocurrent density of −1.5 mA cm −2 was sustained over 2 h in a neutral aqueous solution with unity Faradaic efficiency and selectivity for CO production at a bias of zero overpotential (−0.11 V vs. RHE), associated with a turnover frequency (TOF CO ) of 2.7 s −1 . Extending the photoelectrocatalysis to 10 h, a remarkable turnover number (TON CO ) of 57000 was obtained. The high performance shown here is substantially improved from the previously reported photocathodes relying on covalently anchored catalysts.