Benzothiadiazole Based Bifunctional Monomers: Design, Electronic and Geometric Effects on Their Tri(4‐Ethynylphenyl)amine Based Conjugated Microporous Polymers for Photocatalytic Hydrogen Evolution

ABSTRACT Guided by density functional theory (DFT), four benzothiadiazole based bifunctional monomers with varying electronic properties and geometric sizes have been designed. Utilizing tri(4‐ethynylphenyl)amine (TEA) as a multifunctional monomer, with temperature control, four TEA‐based conjugated microporous polymers (CMPs) TEA‐BT1‐TEA‐BT4 have been synthesized by Sonogashira Hagihara coupling polymerization. The electronic and geometric effects of the bifunctional monomers on the photocatalytic water splitting hydrogen evolution of TEA based CMPs have been investigated in detail. It shows that as the electron donating ability of the bifunctional monomers increases, the thermal stability enhances and the bandgap increases while the specific surface area and hydrogen evolution performance remain relatively unchanged. As the geometric area increases, the thermal stability decreases, the bandgap increases, the specific surface area and hydrogen evolution performance decreases seriously. All four polymers exhibit excellent thermal stability and stable photocatalytic water splitting hydrogen evolution properties. Without the presence of a cocatalyst, TEA‐BT1 gives the highest hydrogen evolution efficiency(115.74 μmol g −1 h −1 ). This research suggests that TEA is a novel and excellent multifunctional block for CMPs based photocatalysts, above all, it provides a new method to optimize CMPs properties to design high efficiency photocatalysts.