Photochemical and Photoelectrochemical Hydrogen Generation by Splitting Seawater

Abstract

Producing hydrogen from water in an efficient manner could significantly reduce consumption of fossil fuels. In this regard the abundant presence of water in oceans offers an important alternative approach for water splitting using seawater. Direct use of seawater for the generation of hydrogen is a difficult and complex process due to the presence of various ions in seawater, which affect the activity of the catalysts and makes the selectivity towards efficient water splitting a challenging task. Herein various ways are reported to efficiently reduce seawater to hydrogen under visible light irradiation by various catalysts already reported by this group. A better performance than pure water was observed in some cases, and in a few cases the opposite was observed, implying that with a proper approach seawater can be efficiently reduced to generate hydrogen.

Thioether-Functionalized 2D Covalent Organic Framework Featuring Specific Affinity to Au for Photocatalytic Hydrogen Production from Seawater

“…6,7 However, various salts in seawater would lead to undesirable decomposition of catalysts and side reactions. 8 Up to now, seawater has been rarely employed in the photocatalytic H 2 production. 9−11 Thus, it is desirable and challenging to develop efficient photocatalysts for H 2 production from seawater.…”

“…A large number of materials that are capable of producing H 2 from water have been developed. − Notably, most of the studies were performed with high pure water. Considering that the majority of liquid water available to mankind at the earth’s surface is seawater, from an economic viewpoint, photocatalytic H 2 production from seawater would be a promising strategy. , However, various salts in seawater would lead to undesirable decomposition of catalysts and side reactions . Up to now, seawater has been rarely employed in the photocatalytic H 2 production. − Thus, it is desirable and challenging to develop efficient photocatalysts for H 2 production from seawater.…”

Alkali Halide Boost of Carbon Nitride for Photocatalytic H2 Evolution in Seawater

“…For example, the amount of hydrogen in the first 4 h of CsI-CN reached 33.62 μmol, which is four times more than that of itself in deionized water (7.89 μmol), 120 times that of CN in simulated seawater (0.27 μmol), and 187 times that of CN in deionized water (0.18 μmol). Considering the existence of various ions (major ions: Na + , Mg 2+ , Ca 2+ , K + , Cl – , and SO 4 2– , making up >90% of the total salt content of seawater) in natural seawater, , the PHE of CsI-CN as a representative sample was studied in saline solution (e.g., NaCl, KCl, KBr, MgCl 2 , CaCl 2 , and Na 2 SO 4 ). In Figure b, it can be seen that both anions and cations have great positive effects on the PHE of CsI-CN, with different enhancing extents.…”

Interfacial engineering of graphitic carbon nitride (g-C3N4)-based metal sulfide heterojunction photocatalysts for energy conversion: A review

“…Photocatalytic H2 production through water splitting is considered to be an ideal pathway for future energy consumption due to its economic and environmental superiority [42,83,137,[296][297][298][299][300][301][302][303][304][305]. Exploration and development of the suitable photocatalysts with excellent performance is essential to transform this technology into industrial application.…”