Introducing Secondary Acceptors into Conjugated Polymers to Improve Photocatalytic Hydrogen Evolution

Abstract

As a class of the efficacious photocatalysts for watersplitting, conjugated polymers (CPs) have drawn considerable attention in recent years. However, the unexpectedly fast charge recombination always constricts their further application, leading to poor photocatalytic behavior. Here, we report a series of dibenzothiophene-S,S-dioxide-based polymers with electron-property-dependent reactivity as well as their photocatalysis in hydrogen evolution. The results reveal that the introduction of a secondary acceptor unit into the repeating units of a CP skeleton is an effective method to enhance the photocatalytic hydrogen production activity, which is conducive to the separation and transport of photogenerated charge carriers. Therefore, the Pt-free B-SO and C 3 N 3 -SO photocatalysts in an A 1 −π−A 2 form exhibit a competitive hydrogen evolution rate (HER) of 778 and 1603 μmol g −1 h −1 under visible light, respectively. Notably, under the same conditions, the 3 wt % Pt-modified B-SO and C 3 N 3 -SO provide a satisfactory HER of 1253 and 2966 μmol g −1 h −1 , respectively. Our study proffered an effective strategy for enhancing the photocatalytic hydrogen evolution of CPs, which could be used for the design and optimization of other photocatalytic systems.

An Efficient Electron Donor for Conjugated Microporous Polymer Photocatalysts with High Photocatalytic Hydrogen Evolution Activity

“…This is also well supported by the photocurrent test, which revealed that DBC-BTDO has a stronger photocurrent response than TPE-BTDO under UV-Vis light irradiation (Figure 3d), implying much more light-induced excitons could be produced during the photocatalytic process and more efficient separation of electrons and holes in the DBC-BTDO photocatalyst. [30][31][32] The photocatalytic performance of the two polymers was estimated by photocatalytic hydrogen production test, in which the dosage for each polymer photocatalyst was 10 mg and ascorbic acid (AA) was used as the sacrificial agent. As shown in Figure 4a,b, the as-synthesized polymer DBC-BTDO shows a HER of 49.34 mmol h -1 g -1 under visible light (λ > 420 nm), and a much higher HER of 104.86 mmol h -1 g -1 under full spectrum irradiation (λ > 300 nm).…”

Sulfide oxidation tuning in 4,8-bis(5-(2-ethylhexyl)thiophen-2-yl)benzo[1,2-b:4,5-b′]dithiophene based dual acceptor copolymers for highly efficient photocatalytic hydrogen evolution

“…Additionally, Zhou et al demonstrated that introducing a secondary acceptor unit into the polymer chain in an A 1 -p-A 2 form enhances the photocatalytic activity for hydrogen evolution. 26 Nevertheless, these series of photocatalysts achieved poor photocatalytic activity because the acceptor units, such as triazine and organoboron, cannot effectively transfer electrons and increase the wettability of polymers, similar to sulfone-based acceptors. Interestingly, it was observed that the all-single acceptor (A-A) homopolymer poly(dibenzothiophene-S,S-dioxide) can also achieve an encouraging photocatalytic hydrogen evolution rate (HER), even without the design of the pull-push effect.…”

Photocatalytic Water‐Splitting by Organic Conjugated Polymers: Opportunities and Challenges

“…Thus, metal-free B-SO and C 3 N 3 -SO are A 1 -π-A 2 photocatalysts for competitive HER with photocatalytic hydrogen generation of 778 and 1603 μmol g À 1 h À 1 , respectively. [96] More recently, Sihui Xiang reported a three donor-acceptor (DÀ A) form of thiophene containing narrow bandgap CPs having pyrene act as a donor and various fused thiophene derivatives as an acceptor through a direct CÀ H arylationcoupling polymerization (Scheme 8). They found that the bandgap of thiophene-based polymer skeleton could be easily engineered by adjusting the variation in fused thiophene rings, such as increasing the number of thiophene rings narrowing (33), pDEN (34), pDTT (35), and pDET (36).…”