Rational Design and Application of Covalent Organic Frameworks for Solar Fuel Production

Abstract

Harnessing solar energy and converting it into renewable fuels by chemical processes, such as water splitting and carbon dioxide (CO2) reduction, is a highly promising yet challenging strategy to mitigate the effects arising from the global energy crisis and serious environmental concerns. In recent years, covalent organic framework (COF)-based materials have gained substantial research interest because of their diversified architecture, tunable composition, large surface area, and high thermal and chemical stability. Their tunable band structure and significant light absorption with higher charge separation efficiency of photoinduced carriers make them suitable candidates for photocatalytic applications in hydrogen (H2) generation, CO2 conversion, and various organic transformation reactions. In this article, we describe the recent progress in the topology design and synthesis method of COF-based nanomaterials by elucidating the structure-property correlations for photocatalytic hydrogen generation and CO2 reduction applications. The effect of using various kinds of 2D and 3D COFs and strategies to control the morphology and enhance the photocatalytic activity is also summarized. Finally, the key challenges and perspectives in the field are highlighted for the future development of highly efficient COF-based photocatalysts.

From conventional inorganic semiconductors to covalent organic frameworks: advances and opportunities in heterogeneous photocatalytic CO2 reduction

“…This remarkably straightforward "design-follows-function" approach has recently triggered intensive research on COFs as alternative platforms for photocatalysis. 5,83,107 The highly ordered organic polymers feature the following advantages: (a) p-stacking interactions between 2D COF sheets facilitate the charge carrier transport along and between COF planes; (b) chromophore building blocks and p delocalization in an extended conjugated structure promote efficient light harvesting; (c) high crystallinity and a high degree of structural order can prevent the recombination of charge carriers; (d) open porous structures and high surface areas enable rapid mass transport and diffusion of molecules as well as access to a high density of catalytically active sites; (e) the aforementioned exibility in designing COF structures allows for the incorporation of building blocks, comprising heteroatoms (N,S, O etc. ), dened binding sites for Lewis acids (typically metal ions) or specic side groups; and (f) the molecular nature of COFs allows one to conduct fundamental studies on charge carrier kinetics and catalysis, guiding the development of clear atomistic structure-property relationships.…”

“…Both electro-and photo-catalysts have been proposed based on metallic particles, inorganic semiconductors, 2D-materials, and metal complexes. [1][2][3][4][5] Among the investigated electro-and photocatalysts for CO 2 reduction, heterogeneous materials typically exhibit long-term stability but low selectivity, while homogeneous molecular catalysts such as metalloporphyrins and metal complexes exhibit high selectivity but relatively low turnover numbers (TON). Immobilization of a molecular or metallic catalyst on solid supports has been found to hinder the detrimental side reactions of homogeneous catalysts such as dimerization and other radical reactions.…”

Novel Microwave-Assisted Synthesis of COFs: 2020–2022

“…Several applications for COFs have been explored, including molecular separations [ 2 ], removal of toxic compounds [ 3 ], gas capture [ 4 ], enzyme immobilization [ 5 ], optoelectronic applications [ 6 ], analytical chemistry [ 7 ], photocatalysis [ 8 , 9 ], electrocatalysis [ 10 ], electrochemical sensors [ 11 ], batteries [ 12 ], and solar fuel production [ 13 ].…”

1,3,5-Triazine and dithienothiophene-based conjugated polymers for highly effective photocatalytic hydrogen evolution

“…1 Unquestionably, the rational design of photocatalysts is the crucial point for high hydrogen evolution reactivity. [2][3][4][5][6][7] Numerous inorganic semiconducting materials including metal oxides [8][9][10] and metal sulfides [11][12][13][14] have been explored as photocatalysts for the hydrogen evolution reaction (HER), but most of the inorganic photocatalysts showed low absorption in the visible light region, which limits their practical application. In recent years, organic semiconductors featuring extended delocalized π-electrons have been started to be used for PHP investigation.…”