Alkali Halide Boost of Carbon Nitride for Photocatalytic H<sub>2</sub> Evolution in Seawater
Wen-Ming Xu, Xuedong Zhao, Xianghui An, Sha Wang, Jing Zhang, Zishu Li, Wenting Wu, Mingbo Wu
Abstract
for humanity, but the saline in seawater easily competitively absorbs the active sites and poisons the catalyst. Herein, a series of low-cost alkali halide (NaI, KI, RbI, CsI, CsBr, and CsCl), analogous to the saline in natural seawater, was selected to modify carbon nitride (MX-CN) through one-step facile pyrolysis with the assistance of water. MX-CN possesses a large amount of negative charges, which could inhibit anion absorption, to some extent, preventing chloride corrosion. Importantly, it can greatly boost the electron transfer between MX-CN and triethanolamine (TEOA) (sacrificial agent) because the alkali cation in seawater can coordinate with TEOA, and easily come in contact with MX-CN through alkali-cation exchange and electrostatic attraction. Benefiting from it, the PHE performance in seawater is 200 times better than that of original CN in deionized water above, and the apparent quantum efficiency of MX-CN (CsI-CN) under 420 nm light irradiation comes to 72% in seawater, the highest value reported for seawater thus far. This work provides a new research direction for engineering the electron transfer pathway between the photocatalyst and sacrificial agent (e.g., pollutant) in natural seawater.